This is obviously a challenging situation for anyone regardless of experience! You may have all the challenges of keeping the patient safe whilst trying to solve a difficult problem, not knowing whether to call the consultant and manage the surgeon’s expectations as well!

Calling For Assistance

It is vitally important to realise that you should ALWAYS CALL FOR HELP even if you think you know what to do. As you gain more experience you realise that you call for help for 2 reasons – brains or hands or both. In your training years assistance is particularly useful as you may not know what you don’t know and the process of getting help is as much for the patient as for your learning.

In summary, call for help:

• to see how a crisis is managed
• to receive feedback on your own crisis management (while still being supervised)
• to gain insight to things you may not have even considered yet
• to mobilise extra hands to manage a crisis

The difficulty of teaching crisis management in anaesthesia

Teaching crisis management can really be challenging due to multiple factors, each crisis can be substantially different and can also be managed well by different methods. An expert may manage the same issue very differently based on the magnitude of the problem, the number and experience of staff, equipment, environment, patient factors and the type of surgery. With this in mind I have tried to outline a safe and reproducible framework to get you started on your road to effective crisis management as a new trainee.

The 3 phases of crisis management

Phase 1 – Safety

Aim: To mobilise help and perform low risk high yield actions to rapidly stablise the patient and buy some time.

Phase 2 – Diagnosis

Aim: to provide insight into how most experts in anaesthesia rapidly solve diagnostic dilemmas with a probability gambit whilst avoiding fixation errors by systematically ruling out lethal and other diverse causes

Phase 3 – Treatment

Aim: to provide a list of the differentials and essential treatment strategies for each. This resource can be referred to at any time like a checklist.

Phase 1 – safety

1. Check the pulse
2. Scan patient, surgery, monitors
3. Check reading/transducer/monitors
4. Call for Help
5. Stop Surgery
6. First line treatment
   • Airway and breathing: Increase oxygen, switch to hand ventilation
   • Circulatory issues: fluid, ephedrine or metaraminol
7. Optimise anaesthetic depth
8. FINALLY Assess and Treat

a) Check the pulse

Aim: I want to know immediately if my patient has arrested

I can rapidly check this with a good sats prob trace and ECG rhythm. If these are not available, or there’s interference with the sats trace then a finger on the carotid pulse is a useful indication of output.

Tip: to get skilled at anything, just do it more often. Check the pulse of every patient to increase your proficiency

b) Scan patient, surgery and monitors

Aim: To identify and rule out obvious problems by taking a look at the whole situation.

Just like the ‘general inspection’ you perform before any patient assessment, this step is to take in as much info from the room as possible to get an overall feel.  You can identify an resolve many problems with this one step.

Lets go through some common examples:

• The surgeon may have just performed the first incision and that is the obvious temporal cause of the tachycardia or hypertension.
• The severe bradycardia has occurred just as the surgeon inflates the abdomen for pneumoperitoneum during a lap chole. Deflating the abdomen will often resolve this immediately.
• The high ventilating pressures are due to the paralysis wearing off and inspection of the patient under the drapes shows that they are tense and clenching down on the endotracheal tube (ETT).
• The O₂ sats are falling and you notice a green liquid at the mouth of the patient revealing the patient has potentially is aspirated gastric contents
• The monitor alarms for tachycardia – scanning the rest of the screen give you the likely diagnosis…. A low BP might indicate hypovolaemia whereas a simultaneous high BP indicates pain or light anaesthesia.

c) Check the reading

Aim: Measurement error is a common occurrence; so checking your reading is absolutely vital to ensure you are managing a real problem.

No measurement device is perfect and often prone to error. Common examples include

• The sats probe reads <90%. You change the probe to an ear probe and the sats are 99%. The sats probe depends on good blood flow, and the ability to detect wavelengths of blood in the finger. Errors will occur due to a patient being peripherally shut down, nail polish or movement artifact.
• The blood pressure reads 250 on the intra-arterial BP monitor. You find that the transducer has fallen down to grossly overestimate the reading.
• The monitor alarms ‘asystole’! Due to your patient’s barrel chest, the ECG has trouble detecting the QRS complexes.
• The end tidal CO₂ is alarming. On closer inspection, the patient is taking irregular breaths causing some lower CO₂ readings to alarm.

d) Call for Help

Aim: rapidly mobilise assistance while continuing with your basic management.

The first 3 steps can often solve the problem, confirm the problem or confirm there is no problem quite rapidly. Therefore you call for help appropriately, without a false alarm and without delay.

e) Stop the surgery

Aim: To stop a potential trigger/cause of the problem

There will be a number of problems/crises that are directly the result of what the surgeon is doing. The most common issue that surgery causes is pain causing tachycardia and hypertension. In some patients (patients with coronary artery disease, severe aortic stenosis or intracranial pathology) these deviations of BP and HR could cause serious harm. So while not a true crisis, simply checking the reading and asking the surgeon to stop can give you time to give more analgesia.

Other situations the surgeon may be the true cause of a serious complication like severe bradycardia/asystole. This rarely happens in ophthalmic surgery (oculocardiac reflex) and instituting pneumoperitoeum (vagal/bezold-Jarisch reflex). Cessation of retraction on the globe may be all that’s required to reverse the problem. Likewise deflation of penumoperitoneum may be a vital step prior to giving atropine. Another common situation is a patient may become apnoeic during a gastroscopy. An airway is very difficult to manage when you are sharing it with another specialist , and you may need to ask them to urgently remove the gastroscope.

f) First line treatment

Aim: To stop or slow down a patient’s deterioration while waiting for help to arrive

The primary survey is a systematic way of assessing and treating the patients vital organs prior to establishing a diagnosis. In anaesthesia we have the luxury of a reasonably controlled situation where a patient already has an advanced airway (ETT or LMA), an anaesthesia machine to ventilate, BP and heart rate monitoring and iv access. This means our ability to assess and treat ABCs is potentially very rapid!

 If the issue is airway or breathing, for example desaturation, apnoea, high ventilation pressures you can often temporize or stabilise the situation with just 4 manoeuvres:

• Increase the oxygen to 100%
  • To increase oxygen reserves to keep patient safe.
• Increase gas flows (4-6L/min)
  • To increase delivery of oxygen
• Use the manual ventilation circuit with the APL valve at 30-70
  • To help increase pressure to deliver breaths
  • To gain an appreciation of lung compliance which may help diagnose the issue. High pressures = bronchospasm/sputum plug or kink in ETT. Low pressures = dislodged ETT, disconnection of circuit.
• Auscultate the lungs
  • To diagnose multiple causes euch as bronchospasm, aspiration, pulmonary oedema, endobronchial intubation, pneumothorax, sputum plugging

If the issue is circulatory, for example hypotension is a common intraoperative problem, you can stabilise the situation with just 2 manoeuvres:

• Increase fluid rate.
• Give 0.5mg or metaraminol if BP low and HR above 60bpm
• Give 3-6mg ephedrine if BP low and HR below 60bpm

g) Optimise anaesthetic depth

Aim: To rapidly solve issue by targeting depth of anaesthesia

There is a saying that you have far more issues if the patient is ‘light’ than if they’re deep. This essentially means that the problems that occur with too much anaesthesia are easier to solve that with too little anaesthesia.

For example a patient with too much anaesthesia can be

• Rendered apnoeic (not an issue as advanced airways are able to ventilate and oxygenate patients effectively).
• Hypotensive (this is easily treated with fluid and vasopressor)

NB: this is not a one size fits all rule, and an elderly or very sick patient does need careful titration of anesthesia.

A patient with too little anaesthesia may

• React and move causing difficulty with ventilation
• Suffer laryngospasm

Additionally, a patient may be suffering severe hypotension due to potential blood loss or anaphylaxis. In this case optimal anaesthesia depth means something different. I would substantially decrease my anaesthesia dose to prioritise BP over depth of anaesthesia. Practically this means turn off volatile or propofol infusion while stabilising the situation with fluid and metaraminol (or adrenaline if severe).

f) Assess and treat

Aim: To simultaneously provide supportive care, institute a sequence of diagnostic and treatment steps.

By this time you would have done some very useful things to help stabilise and potentially diagnose the problem already. With the assistance of your supervising anaesthetist you will now be able to observe the strategy for diagnosis and treatment.

Below I will outline what I believe is the most efficient and thorough strategy for diagnosis and how you can combine this with sequential treatments.

Phase 2 – diagnosis 

In the initial phase it is vitally important to provide supportive measures as outlined above. This ‘buys’ time to then diagnose and treat the particular issue.

Human physiology can be so complex, that combining the complex effects of anaesthesia and surgery can make diagnosis extremely difficult. There are numerous causes for each altered sign and symptom and going through a review of systems or an exhaustive checklist could cause delays in diagnosis.

As you develop more expertise in your practice you will use your experience to get an overall impression of the situation. Most experts in the field will be able to make a reasonably accurate probability gambit. This method allows you to get to a solution very quickly, which will resolve the situation most of the time.

However, it is very important that we do not miss potentially lethal diagnoses. So I believe that considering the unique lethal diagnoses for a particular patient, surgery and set of signs and symptoms and systematically ruling out these will keep your patient safe from pathology that could cause harm in the immediate future.

If you are unable to satisfactorily diagnose the patient in these first 2 steps it is important to have a systematic method of ruling out the long list of other differentials.

Below I have provided a list of tables with common issues and lists of common differentials.

The phrasing I use in my mind is as follows.

I think it is most likely _____

The serious differentials I must rule out are____

My systematic differentials include _____

For example

24yo male is having an appendicectomy. The BP is 60mmHg post induction.

I think it is most likely that this may be hypotension post anaesthesia in a volume deplete patient.

The serious differentials I must exclude are anaphylaxis, sepsis and lap port injury

*Practically I check for a rash, auscultate and manually ventilate the lungs to check for wheeze and decreased compliance, check the temperature and likelihood of sepsis, and check the port camera screen for untoward signs of blood loss*

My systematic differentials include (see the hypotension table below).

During the ABCs of Anaesthesia Boot Camp we will go through many more examples. At this stage consider the situations that may arise perioperatively and structure diagnostic steps using the framework above.

Phase 3 – treatment

I have outlined suggested treatments for the numerous problems you might face in the theatre environment. As you gain more experience and seniority you will gain more comfort in managing these cases by yourself.

At a junior level I would use this as a guide and always defer to your supervisor for definitive management steps. Ideally you could store these tables on your smartphone and refer to them as needed to help checklist a solution, refresh your memory and eventually tailor specific management.

Hypoxaemia

High ventilating pressures

Tachycardia

Bradycardia

Failure to Breathe

Hypertension

Hypotension

Hypercapnoea

Stridor

Hypercapnoea

Stridor

Delayed Emergence/ Decreased conscious state

The Complexity of Anaesthesia

Due to the nature of our profession, a number of normal occurrences in an anaesthetised patient are also the signs of severe reactions. So it is vital to understand

1. What criteria are needed to diagnose a problem
2. When to start treating for a lethal problem

For example, the common presentation of anaphylaxis is hypotension to 70mmHg, bronchospasm and a rash. However the induction of anaesthesia can cause these very signs due to the nature of the medications.

• Propofol causes hypotension routinely through veno and vasodilation.
• Introducing a endotracheal tube into the trachea often causes bronchospasm as does some of our histamine releasing drugs (see ABCS guide to medications)
• Rashes are also a very common and relatively benign side effect of anaesthesia medications and antibiotics.

So the challenge is to know when to ‘label’ this as an anaphylaxis emergency. One rule I use is that if I have to give 5 doses of metaraminol with limited effect, this triggers a decision to ask myself is this anaphylaxis? I then ask myself what is the harm of treating this as anaphylaxis?

If this was the 24yo male who is otherwise well, there is very little harm of giving 1000ml of fluid and carefully titrating 20-50micrograms of adrenaline iv whilst ventilating with 100% oxygen.

My suspicion is always raised and my threshold lowered if the patient exhibits multiple signs in the context of giving an anaphylactogenic medication like a muscle relaxant or an antibiotic. This means that I may start treating this as anaphylaxis quicker and with less of a BP drop.

Think of all the other common situations caused by anaesthesia and surgery that might mask potentially serious disease.

During your rotation you will commonly see desaturations, high ventilating pressures, tachycardia, bradycardia, hypertension to name a few.

What are these potentially signs of?

There is probably less known about anaesthesia than most other medical specialties. There are many reasons for this. Anaesthesia is quite a new medical specialty. Australia had its first full time anaesthetist in 1909, in 1952 the royal Australasian college of surgeons founded the faculty of anaesthetists and our college of anesthetists only formed in 1992. Not only that there’s very limited exposure to anaesthesia during your training outside of choosing to do an elective in the specialty. As we are generally ‘contracted’ to assist a surgeon with their operation, the patient has far less contact with us, often being only a 5-10min consult prior to the operation. So it’s no surprise that neither medical professionals nor the general public have a good idea of what we do.

What do we do?

I think the running joke, is that after administering some medications to render you unconscious, we then leave and work on our many other pursuits… crosswords, Sudoku, share trading…

The goal of anaesthesia is to facilitate the surgery with minimal physiological and psychological impact to the patient.

People often mention the Triad of Anaesthesia – Analgesia, Hypnosis/sedation and muscle paralysis. I think of this as a combination of the patient’s needs and the surgeons needs. If you were a patient, you would want to be pain free (analgesia) and unaware of the surgery (hypnosis). The surgeon however really just needs the patient to be relatively still (paralysis) to enable them to do an effective operation.

Our job is to enable this to occur. We have great medications that render a patient deeply unconscious, pain free and still. But these medications have very serious and potentially lethal consequences. For example propofol is a very effective hypnotic, but it also decreases heart function and causes vasodilation leading to hypotension. So our job is to fix that. Opioids are powerful analgesics, but also suppress respiratory function to the point of apnoea, so we must assist ventilation and oxygenation. Muscle paralysis agents are great for keeping muscles still and relaxed for the surgeon, but this also paralyses the diaphragm ceasing respiration and very rarely can cause anaphylaxis.

The very medications we use to achieve the triad of anaesthesia, also cause severe consequences to human physiology. Our job is to manage these consequences.

But drugs aren’t the only issue! Surgery is a vast spectrum of procedures as minor as a small mole excision to heart and lung transplant. There is a vast range of surgical actions and complications that we have to constantly be ready for. A procedure may have blood loss as an expected consequence (Liver resection, emergency aortic aneurysm repair) or an unexpected complication (laceration of subclavian vein in a clavicle repair). Or occasionally surgical actions may cause a profound vagal response (squint repair, pneumoperitoneum), operations near the lung may lead to a tension pneumothorax or electrolyte imbalance in a patient with cardiac dysfunction may lead to ventricular tachycardia or other arrhythmias.

Our role is to plan, predict, monitor and ultimately manage and solve these complications often while the surgery is progressing.

Patients

Our patients can have a vast range of medical disorders and varying degrees of functional capacity. If you can imagine the many potential problems that can occur due to the complex combinations of medications and the complexity of each operation – this is made immensely more complex depending on the health of the patient.

The comparison between a young healthy patient who may have expected blood loss from a caesarean section can be far more challenging if they simultaneously have a congenital bleeding disorder or refuse blood products.

Our Scope of Practice

It is logical to expect that the skills you practice every day are the skills you will be proficient at. So these daily ‘rituals’ become the base for our expertise and interests in the health care system

• We lead resuscitation teams
• We specialize in acute and chronic pain management
• We are involved in research
• We are active in hospital committees
• We are very useful specialists in all manner of foreign aid
• We teach and pass on these skills in many different settings to many different levels of students and doctors

Why is this the best specialty for me?

When I was a junior surgical doctor, I was on the ward taking care of some very unwell patients. On this particular day, every few hours I would have to make an emergency call when one of my patients would deteriorate. This was an incredibly stressful experience for me. I did not have the knowledge or skills to help my patients and this was terrifying. Fortunately the anaesthetist who arrived to help seemed incredibly calm. It really seemed that nothing about this situation was stressful, and they steadily assigned tasks to stabilise my patient. This was a pivotal moment. I wanted to be that person. I wanted to feel in control of a situation that seemed so dire. I wanted to learn and experience whatever this anaesthetist had learned and experienced to enable me to be able to help those sick patients.

Anaesthesia is one of the few occupations that the time from action to disaster is quite short. For most other careers and medical specialties, by the time you do an action, prescribe a medication and perform a procedure…. If a mistake is made, there is substantial time to correct this. But anaesthesia is different. After giving a paralytic agent you only have a few minutes to oxygenate the patient before they could die of hypoxaemia. If a patient suffers anaphylaxis, you only have a few minutes to correctly diagnosis and treat before the patient suffers cardiovascular collapse.

This all sounds like anaesthesia must be a very stressful profession, and I confess it is at times. But fortunately our system of rigorous training, the hospitals’ safety policies, the incredible medications and equipment at our disposal means that anaesthesia is incredibly safe. It is about 10x safer to have an anaesthetic than to drive a car for a year.

So if you don’t mind the sometimes stressful situations and trust in your training, you will learn how to manage those crises effectively.

Every specialty has certain repetitive elements. For anesthetists this would be iv cannulas and long stable cases where there isn’t much activity. If you enjoy the challenge of cannulas – difficult or easy – and are able to occupy yourself during those longer cases with other important roles in theatre such as teaching or supervising your trainee, anaesthesia could be a great specialty for you.

Often we don’t have form long-term professional relationships with our patients. Instead we have to try and gain rapport and comfort patients in the 5 minutes before the operation – during the most stressful part of their surgical journey. If you are able to talk easily with people, and gain their confidence with a natural ease, this is a tremendous advantage in a profession with less (awake) patient contact that most others. I don’t mind the lack of patient contact, as it allows me to keep my work and home life separate. I admire those professionals that do form enduring professional connections but it wouldn’t suit my personality.

Summary

This is just a small part of a much larger topic about what anaesthesia, but I hope if gives the reader a small insight into this specialty.

If you have any thoughts or good or bad experiences, near misses and solid wins please contact us and share your thoughts.

When I first began anaesthesia training, I found it very daunting and often stressful to have any kind of conversation the surgeon. This was made even more difficult the more senior they were.

Why is it difficult?

There are many reasons for this.

• Talking to any stranger can be challenging let alone one with so much perceived power and authority.
• Medicine is still a very hierarchical field where the risks of upsetting someone ‘above’ you has a certain ‘risk’ to it especially if you are having a discussion to address conflict.
• You might think your questions are silly or not worth asking

Obvious and not so obvious advantages of having a chat with the surgeon

• Information!
• Rapport and communicative state
• Sound knowledgeable
• Specific critical cases

Information

This will be obvious for many cases but I never assume. I simply ask the question or make statements if what I expect. Remember the answer may be different for the same case depending on the pathology and the surgeon.

For a routine lap cholecystectomy I might ask:

1. Duration
2. Position/ are the arms tucked by the side or out
3. Expected blood loss
4. Antibiotics
5. DVT prophylaxis (TEDS/Calf compressors/enoxaparin)
6. Specific cases
7. Is this patient appropriate?

Rapport and communicative state

In most public hospitals it is rare that you would have already met and worked with most surgeons. It is vitally important that you introduce yourself so they have an idea of who you are and your level of experience.

It is also important to realise that the first time you talk to the surgeon should NOT be if you are concerned about a potential crisis. When you are asking the surgeon about something potentially catastrophic you may have considerable difficulty addressing them if you aren’t a naturally assertive person, and there’s a large hierarchical gradient. By having light and general informative conversations at the beginning of the case it makes communication at critical moments far easier!

Sound knowledgeable

During my early training years these questions weren’t necessarily intuitive for me to ask. I find that my registrars that know which questions to ask appear more engaged with the nuances of the case and do seem more competent. Over time you will gather a range of subtleties because you have actively sort out answers instead of passively reacting (note memory article).

Specific Cases

There are a few cases that have special surgical requirements that will not be apparent unless you have prior experience.

• Avoidance of muscle relaxation

Any case that involves monitoring or repairing a nerve, the surgeon may want to stimulate a nerve and elicit a muscle response. If the patient is paralysed this will not be possible. These cases include thyroidectomies where the recurrently laryngeal nerve needs to be identified and spared and certain plastics and reconstructive cases that involve neural reattachment.

How do you avoid giving muscle paralysis medications when you need a patient to be still?

For many cases that aren’t inside a cavity (laparotomy/laparoscopy, thoracotomy/thoracoscopy), a still patient can be achieved with enough analgesia and hypnotic agent. Note that most LMA spontaneous ventilation anaesthesia has a still patient without giving muscle paralysis.

Cases that need more definitive paralysis

• Many use a remifentanil infusion at approx. 0.1-0.2mcg/kg/min, remifentanil TCI 2-6ng/ml or more frequent repeated doses of fentanyl.
• I choose volatile instead of propofol for maintenance of anaesthesia as it provides a small degree of muscle stillness with calcium mediated inhibition.
• You may have no problem using muscle paralysis as long as it is reversed when the surgeon is stimulating the nerve. This means using a neuromuscular monitor and potentially using a muscle relaxant that has a direct reversal agent like rocuronium or vecuronium.
• Local or regional anaesthesia is another option is some cases to avoid muscle paralysis (though this might be contraindicated by the surgeon so always check).

• Potential blood loss

I recently had a case involving the radiologist operating on an arterial malformation. It was to be performed in an interventional radiology suite remote from the operating theatre complex. There were many variables that I would need to take into account if the patient were to have bleeding complication and these really can only be planned for with a very detailed conversation.

I wanted to know

• The likelihood that a significant bleed could occur (should I pause one of the operating theatres in case we need staff and theatre space)
• The rate of bleeding (can I manage this in the radiology suite or would I have to get theatre space ready)
• How difficult is the bleeding to correct and how long it will take (how much blood and fluid I need to arrange)
• I also had to consider what else is happening in the theatre complex and whether a vascular surgeon was available if the radiologist needed assistance.

• Airway surgery

Surgeons generally need good exposure and access to their operative field. Anaesthetists generally need safe and effective control of the airway and breathing (and circulation).

The dilemma with airway surgery (eg vocal cord operations) is that the more control of the airway the anaesthetist has (with a standard endotracheal tube), the less access the surgeon has.

Fortunately there are a number of solutions to this problem.

Closed circuits include smaller ETTs (microlaryngeal tubes – MLT), laser safe tubes (laserflex) and standard tubes. These are more familiar to anaesthetists, and provide more precise control of ventilation and delivery of gases but do compromise surgical access sometimes.

Open circuits include intermitted apnoeic methods and jet ventilation that can be supraglottic (suspension laryngoscope), transtracheal (Hunsaker, Benjet and rigid bronchoscopy) and subglottic (cricothyroid puncture). These are less familiar, would need intravenous anaesthesia but provide great access for the surgery.

Intermittent apnoeic methods involve oxygenating the patient with a mask and then intermittently allowing the surgeon to access the airway. This is generally only appropriate for shorter cases.

• Specific risks

Certain vascular operations also may have a risk of venous air embolism (eg subarachnoid haemorrhage and clavicles fixations as the veins may be stented open by their adherence to bone).

Certain malignancies may have physiologically active substances that pose a threat to the patient. These include phaeochromocytomas and carcinoid tumours.

In general I consider the pathology and try to ask questions that are relevant to its potential impact of the patients physiology.

Is this patient appropriate for surgery?

Very occasionally you will encounter a patient who is very very high risk who may have limited benefit from the surgery. I have gotten into the habit of saying to the surgeon….

‘This is very very high risk for the patient, what is the likely benefit of this operation’

Often the surgery is entirely appropriate but infrequently a patient will arrive without full understanding of the risks and the anaesthetist is often well placed to communicate this and present the risk/benefit situation in a holistic sense.

Summary

Having a detailed conversation with the surgeon is a vital part of the WHO surgical safety checklist and it’s important to go even further to gain specific information as it relates to your particular case.

If you have any thoughts or good or bad experiences, near misses and solid wins please contact us and share your thoughts.

But every now and again the game changes and safety is not guaranteed. There may be a relatively new assistant who doesn’t know all the checks, you may be in a new hospital without rigorous standards, you may need to induce a patient urgently on the ward and the staff there may not know exactly what you require.

I think it is vitally important that you check all the essential equipment and medications yourself at the start of every list. Daily rehearsal of this checklist will almost guarantee that

1. You will never proceed with an induction without vital equipment
2. You will never stall an urgent induction uncertain if you have everything or not

I have seen both errors occur on a number of occasions and that is what prompted me to put together what I call the 4Ms checklist. It’s just a simple mnemonic to allow you to quickly and safely check that you have all the crucial equipment and meds before inducing anaesthesia.

Disclaimer: Now its important to note that this checklist is not exhaustive and changes depending on the individual situation, the hospital, the patient, support staff and your experience level.

For example if you are a junior anaesthesia trainee, you may include a video laryngoscope in your checklist for any solo inductions. BUT as you gain experience this may not be necessary except for perceived difficult airways.

Anaesthesia checks

The checks are divided into 3 levels. Level 2 and 3 are relevant for us.

• Level 1
  • Done by engineering. Not for anaesthetists, we just check the service label.

• Level 2 (at the beginning of any list)
  • Service label
  • High pressure system
  • Low pressure system
  • Suction
  • Auxillary

• Level 3 (before each new case)
  • Check a changed circuit, vaporizer and all auxillary equipement

The 4Ms Checklist

Machine or BMV

Most machines have an automated checking process now. I simply check that the ‘log’ that shows me the machine and circuit have been checked and there isn’t a large leak. Generally a leak <250ml is safe.

I check that there is a spare self-inflating bag and mask (BMV). If the machine has any issues (or you don’t have a machine) the BMV is your best friend. It enables you to deliver positive pressure ventilations with or without oxygen connected. This is all you may have to ventilate an apnoeic patient on the ward.

Open the spare oxygen cylinder. If the gas pressure is <5000kPa it needs to be changed. Do not forget to close the cylinder. If you were to leave it open, it would slowly leak. Also if there was an failure of piped oxygen, the cylinder would then empty and only then would you realise you had no further oxygen.
In the event of failure of pipeline oxygen, you can open the cylinder to give you back up oxygen while you solve the problem.

Finally check your scavenging is adequate.

Medications (SPA drugs)

• Muscle relaxant (esp Suxamethonium)
• Propofol
• Metaraminol (Aramine)
• Adrenaline
• Atropine
• (Fluid)
• (opioids)

Most problems during induction and anaesthesia can solved with the medications above. Firstly, for satisfactory anaesthesia you need a rapid acting hypnotic (propofol) and muscle relaxant (suxamethonium) and depending on the case an opioid as well (fentanyl).

The common problems that occur will be due to propofol causing hypotension in an already sick patient; therefore you will commonly use metaraminol (an easily titrate-able alpha agonist to increase peripheral vascular resistance and BP). In a very unwell peri-arrest patients they may arrest during or after induction so having access to adrenaline seems a reasonable option.

With a slow circulation the medications will have a very long circulation time so to avoid needing repeated flushes having a fluid line is incredibly useful.

Monitoring

• E_TCO₂
• Sats
• BP
• ECG

There are a large number of monitors that you could use for anaesthesia. But there’s only a few crucial monitors that will make a tangible difference during an urgent induction.

It is absolutely vital to have oxygen saturations. It will be the first sign that oxygenation is failing and allow you to rapidly diagnose and treat the problem.

It will also give you an indication of heart rate if you do not have ECG available.

E_TCO₂ is the gold standard for confirming tracheal intubation and is again mandatory in most hospitals for intubation. It is also a good indicator of cardiac output. With a steady respiratory rate and tidal volume, the E_TCO₂ should be steady. A dramatic fall could indicate loss of cardiac output. It also enables you to titrate your ventilation to appropriate PaCO₂ levels when correlated with an arterial blood gas.

Non-invasive or invasive arterial blood pressure monitoring is almost vital in difficult inductions. Hypotension will be one of the most common complications of anaesthesia and rapidly treating severe hypotension is only possible with accurate monitoring.

ECG

Electrocardiographic monitoring displays an accurate heart rate and identifies lethal rhythms, which may be more common in the sick patient.

MABELS

• Masks
• Airway
  • Oropharyngeal airway (Guedels, OPA),
  • nasopharyngeal airway (NPA),
  • laryngeal mask airway (LMA)
• Bougie, Stylet
• ETT (range of sizes)
• Laryngoscope (MAC 3 and 4 blade, check the lights)
  • Video laryngoscope
• Suction

I have used a well-known mnemonic ‘MABELS’ for my airway equipment check.

You need to have all the relevant adjuncts so you have the best chance of oxygenating the patient with at least 1 of the 3 main techniques – BMV, LMA, ETT.

Specific things to mention:

• a range of ETT sizes is required. For the most difficult airways, you may only be able to pass a size 6 ETT.
• Laryngoscope lights often fail so having a spare is wise
• I have never needed to change a size 4 MAC blade to a size 3 so that is always my first option. The size 3 blade often isn’t long enough to insert into the vallecula and dimishes your laryngeal view.
• Suction is the most difficult thing to replace if it is not working. The pharynx will often be soiled with sputum, blood, stomach contents or saliva making intubation near impossible when you can’t visualize the vocal cords. If suction is not working, it is very difficult and slow to problem solve.

SUMMARY

Checklists are a simple and high yield method of enhancing safety. It allows us to offload the straightforward tasks so that we can then focus our cognitive reserves on more complex issues.

Having this checklist and ensuring my trainees are familiar with it has helped me on numerous occasions to rapidly and safely anaesthetise sick patients.

If there’s anything you have found really useful in your anaesthesia equipment preparation or would like to contribute please contact us.

Anaesthesia medications are some of the most effective and deadly medications available for human consumption. Fortunately when used by an anaesthetist, they are remarkable safe and effective. Through the 5 years of formal anaesthesia training you end up using a unique group of medications on a daily basis and develop immense familiarity with their use and how to manage the common side effects and rare deadly complications. For these reasons, very few doctors use these medications.

We also have to pass 2 very difficult exams that test us on incredibly detailed aspects of these meds like these:

Scary right? But don’t worry, now I realise that to use these medications safely you don’t need to know the hundreds of little details like pKa, protein binding or clearance rate. You just need to know a few points of different, a few hacks that anaesthetists use when making decisions.

In this article I want to give anaesthesia trainees a hack/focused guide to using these incredible medications. Essentially this means covering all the things that actually matter for the day-to-day use without all the minutiae!

• When to use them
• Doses
• Favorable characteristics
• Reasons to be cautious
• And the really serious complications
• Useful tips

So what are these classes of medications?

• Intravenous induction agents
• Volatile hypnotics agents
• Muscle relaxants
• Opioids
• Local anaesthetics

IV induction agents

What iv induction agent would you use?

1. 50yo 70kg male with no medical issues need a laparoscopic cholecystectomy
2. 40yo 80kg female patient presents for laparoscopic ovarian cystectomy. She has previously had severe PONV lasting for 2 days.
3. 60yo 80kg patient for cardiac bypass surgery, has had recent major AMI and blocked LAD and Left circumflex arteries now with decreased LV ejection fraction of 30%.
4. 21yo 70kg male for emergency laparotomy after motor vehicle accident. Bp 70/60, HR 130 and GCS 10 with suspected 3L blood loss.

Volatile agents

What inhalational agent would you use?

1. 50yo male with no medical issues presents for a laparoscopic cholecystectomy
2. 30yo female patient requests analgesia for labour
3. The previous patient needs an emergency GA Caesar.
4. A patient needs a long craniotomy for brain tumour
5. 70yo patient with severe cardiac disease and end stage renal failure has an axillary nerve block for radiocephalic AV fistula. The patient starts to feel some pain in the middle of the case but you have used the maximum amount of local anaesthetic allowed. You don’t want to give a full GA because of the patients comorbidities
6. 20yo patient for an emergency appendicectomy tells you he has a family history of malignant hyperthermia.

Muscle relaxants

What muscle relaxant would you use?

1. 50yo male with no medical issues presents for a laparoscopic cholecystectomy
2. 60yo female with small bowel obstruction for emergency laparotomy
3. 30yo female for long craniotomy. Surgeons require a very still operative field
4. 50yo male needs GA for bowel resection for cancer. Had anaphylaxis during a previous anaesthetic 20 years ago. Never tested.
5. 40yo male with large beard and obstructive sleep apnoea (OSA) for a tonsillectomy.
6. 20yo female asthmatic for diagnostic laparoscopy.
7. 1yo child is undergoing inhalational induction for lip laceration repair. She has laryngospasm and her sats decrease to 50% as you are unable to oxygenate, ventilate or obtain iv access.
8. 60yo female with small bowel obstruction for emergency laparotomy. Just arrived on ward after being in ICU bedridden for 3 months with pneumonia and respiratory failure.
9. 60yo female for a laparoscopic hysterectomy. Has chronic renal impairment eGFR 20.

Useful tips

When to reverse?
Usually a patient is ready to reverse paralysis with neostigmine 0.05mg/kg (2.5mg) and glycopyrrolate 5mcg/kg (400mcg) when they have 2-3 twitches present on train of four monitoring. This causes and increase in ACh at the neuromuscular junction displacing the muscle relaxant and allowing recovery of muscle function. Sugammadex directly bind to the rocuronium or vecuronium so doesn’t need recovery of twitches before administration. However deeper levels of muscle paralysis will need larger doses of sugammadex.

Opioids

What opioid would you use?

1. 50yo male with no medical issues presents for a laparoscopic cholecystectomy
2. 60yo female with small bowel obstruction for emergency laparotomy
3. 50yo female for thyroidectomy
4. 30yo female for long craniotomy. Surgeons require a very still operative field
5. 50yo male with known difficult airway, impossible bag mask ventilation and grade 4
   intubation previously. LMA ventilation no known. What would you do for the awake fibreoptic intubation?
6. 80yo for cataract operation. Wants sedation for the case.
7. 90yo patient for BCC excision from lip. Multiple comorbidities so want to avoid GA.
8. 50yo male for cardiac bypass surgery

Useful tips

Reversal agent
Opioid use creates a high risk of sedation and respiratory depression with apnoea as a potential consequence. The availability of naloxone dramatically enhances safety. Doses of 0.5-1mcg/kg can be given for unwanted respiratory depression and deep sedation. For respiratory arrest given a full 400mcg may be needed and can be given iv/sc/im.
NB that it has a short duration of action, longer than many opioids and it may have to be re-administered.

Local Anaesthetics

What local anaesthetic would you use?

1. 20yo female for finger laceration
2. 50yo male for supraclavicular brachial plexus nerve block for shoulder reconstruction
3. 60yo female for femoral nerve block for total knee replacement
4. 80yo male with rib fractures for paravertebral catheter
5. 30yo female for labour epidural
6. 70yo female with end stage renal failure for radiocephalic AV fistula formation.
7. 60yo post laparotomy for TAP blocks
8. The surgeons asks for 1% lignocaine with adrenaline but the hospital only stocks 1% lignocaine plain.

Useful tips

Adding adrenaline
1:200 000 adrenaline is 5mcg/ml. This is a common amount in many lignocaine and bupivacaine solutions.
If you want to make a 1:200 000 solution of something you just need to add adrenaline so the final concentration is 5mcg/ml

In the example above, the surgeon asks for 1% lignocaine with adrenaline but the hospital only stocks lignocaine. You can take 20ml of 1% lignocaine, and add 100mcg of adrenaline to make 5mcg/ml adrenaline.

100mcg is either 1 ml of 1:10 000 adrenaline (the big 10ml vial)
OR
0.1ml of the 1:1000 adrenaline (the small 1ml vial)

Always check with someone else when you do unfamiliar or complex dilutions with dangerous substances.

How to calculate max dose by volume

The max dose in ml for 0.75% ropivacaine or 0.5% bupivacaine is 0.4ml/kg.

What does % actually mean?

x% of a solution = 10x mg/ml
so 1% lignocaine = 10mg/ml
0.75% ropivacaine = 7.5mg/ml

If you are in doubt, check the vial and it will give you the percent of solution AND the total mg in the vial.

ANSWERS

What iv induction agent would you use?

1. 50yo 70kg male with no medical issues need a laparoscopic cholecystectomy

I would choose propofol at 150mg and titrated to effect for induction.

2.40yo 80kg female patient presents for laparoscopic ovarian cystectomy. She has previously have severe PONV lasting for 2 days.

I would run propofol TCI at 4-6mcg/ml plasma concentration. I would additionally give 4mg dexamethasone after induction and have ondansetron and droperidol available PRN post op.

3. 60yo 80kg patient for cardiac bypass surgery, has had recent major AMI and blocked LAD and Left circumflex arteries with now decreased LV ejection fraction of 30%.

I would give 3-5mg of midazolam and 300-400mcg of fentanyl titrated slowly during the induction phase. Once the patient was unresponsive I would commence gentle ventilation with Sevoflurane and paralyse the patient.

4. 21yo 70kg male for emergency laparotomy after motor vehicle accident. Bp 70/60, HR 130 and GCS 10 with suspected 3L blood loss

With fluids/blood running through a large IV, I would give 40mg ketamine, 2mg midazolam and 100mg of suxamethonium with metaraminol running and adrenaline ready.

What inhalational agent would you use?

1. 50yo male with no medical issues presents for a laparoscopic cholecystectomy

I would use Sevoflurane for maintenance with an adequate MAC.

2. 30yo female patient requests analgesia for labour

I would offer a number of approaches. Nitrous would be a fast safe primary measure.

3. The previous patient needs an emergency GA Caesar.

I would use Sevoflurane maintenance at a lower concentration supplemented with approx 50% nitrous/oxygen mix to maintain uterine tone. If there is an issue with bleeding due to uterine atony I would switch to propofol TIVA for maintenance of anaethesia

4. A patient needs a long craniotomy for brain tumour

I may use Desflurane at low flows to facilitate rapid awakening.
(That being said I rarely use Desflurane due to it’s severe impact on as an ozone depleting gas and would often prefer Sevoflurane or propofol TIVA).

5. 70yo patient with severe cardiac disease and end stage renal failure has a axillary nerve block for radiocephalic AV fistula. The patient starts to feel some pain in the middle of the case but you have used the maximum amount of local anaesthetic allowed. You don’t want to give a full GA because of the patients comorbidities

After asking the patient to cease operating, I would titrate small doses of an opioid (alfentanil/fentanyl), give 50-70% nitrous, and potentially small doses of midazolam and ketamine depending on how satisfactory my first measures were.

(In reality you may need to proceed to a cautious GA depending on the situation and you may request the surgeon to give further small doses of lignocaine with adrenaline appreciated the risk benefit of doing so)

6. 20yo patient for an emergency appendicectomy tells you he has a family history of malignant hyperthermia.

I would use a ‘non triggering anaesthetic’ following MHANZ http://malignanthyperthermia.org.au guidelines, using propofol TIVA for induction and maintenance of anaesthesia

What muscle relaxant would you use?

1. 50yo male with no medical issues presents for a laparoscopic cholecystectomy

I would use vecuronium (a range of anaesthetists would use any of the non depolarizing muscle relaxants, ie not sux)

2. 60yo female with small bowel obstruction for emergency laparotomy

After ensuring the potassium is normal, I would choose suxamethonium.
(many would use 1.2mg/kg of rocuronium)

3. 30yo female for long craniotomy. Surgeons require a very still operative field

I would induce with atracurium and run an infusion of cisatracurium at 0.5mg/kg/hr and use the neuromuscular monitor.
OR I would induce with rocuronium/vecuronium and run and infusion or use intermittent bolus doses guided by a neuromuscular monitor
OR I would induce with rocuronium/vecuronium/atracurium and use remifentanil to maintain a still patient.

4. 50yo male needs GA for bowel resection for cancer. Had anaphylaxis during a previous anaesthetic 20 years ago. Never tested.

Assuming I cannot delay the surgery for anaphylaxis testing, I would use cisatracurium for its very low anaphylaxs rate.
Other may argue vecuronium also has a low rate of anaphylaxis (but this could be due to its less prevalent use)

5. 40yo male with large beard and obstructive sleep apnoea (OSA) for a tonsillectomy.

I would use rocuronium for its fast onset (so I decrease/eliminate the need to bag mask ventilate- this can be difficult/impossible to do if someone has a beard) and additionally I can directly reverse the patient to ensure his has optimal respiratory function (in light of his OSA)

6. 20yo female asthmatic for diagnostic laparoscopy.

I would use rocuronium or vecuronium. These procedures can be very quick and you may need to reverse with a direct reversal agent (sugammadex).

Prior to having a direct reversal available, intubating conditions were made satisfactory by using a smaller dose of rocuronium and waiting longer for it to work + larger dose of opioid + larger dose of propofol. Using a smaller dose of rocuronium (ED95 of 0.3mg/kg) allowed reversal to be possible sooner in such a fast case.

I would avoid atracurium due to histamine release increasing bronchospasm risk.

7. 1yo child is undergoing inhalational induction for lip laceration repair. She has laryngospasm and her sats decrease to 50% as you are unable to oxygenate, ventilate or obtain iv access.

After sending for immediate help I would give im suxamethonium at 4mg/kg to gain control of the airway.

8. 60yo female with small bowel obstruction for emergency laparotomy. Just arrived on ward after being in ICU bedridden for 3 months with pneumonia and respiratory failure.

I would avoid suxamethonium due to the increase risk of hyperkalemia. I would induce with 1.2mg/kg of rocuronium.

9. 60yo female for a laparoscopic hysterectomy. Has chronic renal impairment eGFR 20.

I would use atracurium as it has non organ dependent metabolism.

What opioid would you use?

1. 50yo male with no medical issues presents for a laparoscopic cholecystectomy

There are many correct options for this case with a large variety in what anaesthetists do. Some would induce with alfentanil and give longer lasting analgesia with morphine or fentanyl. Others would induce and give further analgesia with only fentanyl.

2. 60yo female with small bowel obstruction for emergency laparotomy

I would induce with fentanyl and use fentanyl for further analgesia. She will need multimodal analgesia post op including a fentanyl PCA. (others may induce with alfentanil/fentanyl and continue with morphine and morphine PCA).

3. 50yo female for thyroidectomy

I would use remifentanil throughout the case to avoid the need for muscle paralysis to facilitate recurrent laryngeal nerve monitoring. (this can also be done by using muscle paralysis and ensuring it has been cleared prior to surgeons nerve monitoring)

4. 30yo female for long craniotomy. Surgeons require a very still operative field

I would run remifentanil for the case to facilitate a very still patient throughout the case. (again many ways to do this, including running a muscle relaxant infusion with nerve monitoring or deep anaesthesia – but this might increase ICP)

5. 50yo male with known difficult airway, impossible bag mask ventilation and grade 4
intubation previously. LMA ventilation no known. What would you do for the awake fibreoptic intubation?

I would use a combination of topicalisation with local anaesthetic and opioid to decrease cough reflex and increase tolerance of the procedure. I run remifentanil at 0.05-0.1 mcg/kg/min. (others use alfentanil or fentanyl in bolus doses)

6. 80yo for cataract operation. Wants sedation for the case.

Would use small doses of fentanyl (25-50mcg). You could use small doses of alfentanil but this might increase the risk of apnoea due to its faster onset.

7. 90yo patient for BCC excision from lip. Multiple comorbidities so want to avoid GA.

I would use carefully titrated doses of alfentanil for its fast onset and fast offset. (250mcg)

8. 50yo male for cardiac bypass surgery

I would use up to 5mcg/kg of fentanyl for induction followed by further doses of fentanyl.

What local anaesthetic would you use?

1. 20yo female for finger laceration

I would use lignocaine without adrenaline.

2. 50yo male for supraclavicular brachial plexus nerve block for shoulder reconstruction

I would use 20ml of 0.375% ropivacaine for long lasting sensory block with minimal motor block. Some would use 20ml of 0.75% ropivacaine.

3. 60yo female for femoral nerve block for total knee replacement

I would use 20ml of 0.375% ropivacaine for long lasting sensory block with minimal motor block. Some would use 20ml of 0.75% ropivacaine.

4. 80yo male with rib fractures for paravertebral catheter

I would start with 40ml of 0.375% ropivacaine. And run an infusion of 0.125-0.25% bupivacaine with boluses as per local hospital guidelines.

5. 30yo female for labour epidural

I would commence analgesia with up to 20ml of 0.2% ropivacaine followed by patient controlled epidural analgesia (PCEA) boluses with 0.2% ropivacaine and 2mcg/ml fentanyl as per local hospital guidelines. (usually 5ml bolus q15mins max 60ml in 4 hrs).

6. 70yo female with end stage renal failure for radiocephalic AV fistula formation.

I would use a mixture of 2% lignocaine and 0.75% ropivacaine for a fast onset longer lasting block. (many ways of doing this depending on hospital and surgeon speed).

7. 60yo post laparotomy for TAP blocks

I would use approx. 40ml of 0.375% ropivacaine for a large volume block to spread across the fascial plane. Nerve blocks need less volume as the effect site ie nerve bundle is a more localized area.

8. The surgeons asks for 1% lignocaine with adrenaline but the hospital only stocks 1% lignocaine plain.

I would take 20ml of 1% lignocaine and add 100mcg of adrenaline to make 1% lignocaine with 1:200000 adrenaline. See tips below.

Summary

There is a wide range of options for many of the examples outlined. Consultants choose one medication over another not necessarily because the evidence for its use is better. It may be familiarity, expense, environmental concerns or the pattern of use with consideration of the other agents selected for a case.

There’s often only a few points of difference for each medication that determines its benefit or another so try to use the tables above in your selections.

Every time you select a medication give reason for its use to gain familiarity with the pros and cons of each medication.

Glossary

PONV postoperative nausea and vomiting
TCI target controlled infusion. Enter age and weight, syringe driver then allows you to target and plasma or effect site concentration using pharmacokinetic modeling.
ICP intracranial pressure
TIVA total intravenous anaesthesia
GA general anaesthesia

• A consultation performed by an anaesthetist prior to administration of anaesthesia.
• The aim of the pre-operative consult is to minimize perioperative mortality & morbidity and prevent last minute unplanned cancellation through proper assessment and decision-making.

To do this we assess with a history, examination and investigations (Hx/Ex/Ix)

The Anaesthetic History

Issues with previous anaesthetics

• Outcomes and any complications (cardiac, respiratory, anaphylaxis)
• Any rare disease that may run in families (Malignant hyperthermia, Pseudocholinesterase deficiency)
• Postoperative nausea and vomiting

Medical History

Specifically we want to identify whether the global function of the patient is satisfactory and then systematically review individual organ systems for disease severity and stability.

Global function

Exercise tolerance or ability to achieve a certain number of metabolic equivalents

METS and Functional Capacity

• Ratio of work metabolic rate to resting metabolic rate
• Scale defined by the Duke Activity Status index.
• 1kcal/kg/hr (the energy cost of a sitting quietly)
• 5mlO₂/kg/hr or 250ml/min in 70kg 40 yr old male
• https://sites.google.com/site/compendiumofphysicalactivities/home

Examples

1-4 mets: eating, dressing, dishwashing and walking around the house

4 mets: laundry, hanging wash, washing clothes by hand, moderate effort. Stair climbing slow pace

4.3 mets: walking, 5.6kmh, level, brisk, firm surface, walking for exercise

4-10 mets: climbing flight of stairs, walking on level ground at >6km/h, running briefly, playing golf

>10 mets: strenuous sports, swimming, singles tennis, football

How does Functional capacity/METS/exercise tolerance relate to perioperative risk?

• Exercise tolerance is a major predictor of perioperative risk
• Perioperative cardiac and long-term risks are increased in patients unable to meet a 4-MET demand during most normal daily activities
• Physiological response to surgery increases O₂ demand, requiring a subsequent increase in cardiac output.
• In 1 series of 600 consecutive patients undergoing major non-cardiac procedures, perioperative myocardial ischemia and cardiovascular events were more common in patients who reported poor exercise tolerance (inability to walk 4 blocks or climb 2 flights of stairs),
• Even after adjustment for baseline characteristics known to be associated with increased risk

The likelihood of a serious complication occurring was inversely related to the number of blocks that could be walked (p<0.006) or flights of stairs that could be climbed (p<0.01).

Systematic review of systems

For each medical condition we use a Hx/Ex/Ix to assess Stability and Severity of each disease.

Further assessment should also reveal to us the Cause and complications of each disease

And any specialist management/medications and relevant complications of these to gain a detailed picture of the disease

Examples

Ischaemic heart disease

Review hx/ex/ix of angina and MI.

Severity:

• Timing, freq, details of MI and angina episodes including angina grading (Canadian Cardiovascular Society Grading), ECG changes, Echo/stress test findings esp ejection fraction and grade or systolic/diastolic/LV/RV function, Angiography demonstrates which vessels and myocardial region is at risk.
• It is not enough just to state that a patient has a medical condition ie “IHD”. There is a huge difference between a patient who has been suffering from angina for 5 years, is stable and only occurs once a week after walking up 3 flights of stairs to one that has new onset angina occurring with minimal exertion.

Stability:

• How often patient has episode

Cause:

• Cardiac risk factors (male, smoker, diabetes, chol, htn), or other pathology – aortic stenosis, periop MI,

Complications:

• Ischaemic cardiomyopathy, incompetent valve, heart block, heart failure

Specialist management:

• Cardiac bypass surgery, stents (drug eluting or bare metal stent), medications (aspirin/clopidogrel, statin, betablocker,)

This format can be completed for any medical condition to gain a thorough picture of that particular disease. EASY!

Medications

Most of a patient’s medications are continued in the perioperative period. It is important that we reassure them that even if they are fasting, they can take the meds with a ¼ cup of water. Other health practitioners may inform them to cease all of their meds on the day of surgery but this not the current recommendation.

Meds that may need cessation

Anticoagulants

The need to cease medications will depend on the risk of significant bleeding from surgery (or anaesthesia technique if neuraxial block is performed) and the risk of complications if they are ceased. Often this requires a discussion with the surgeon and physician (cardiologist, haematologist, general med) to ascertain how best to manage.

The common anticoagulants you will encounter are aspirin, clopidogrel, warfarin, enoxaparin and heparin.

General guide

Aspirin

Does not need cessation except for high bleeding risk surgery (neuro/TURP). If so, cease 7 days prior.

Clopidogrel

Cease 5-10 days depending on risk.

Warfarin

Cease 5-7 days and ensure INR normal

Enoxaparin

Prophylactic dose: 12 hrs

Therapeutic dose: 24hrs

Heparin

6 hrs

Diabetic medications

There are a number of different guidelines for this. A reasonable rule would be to omit oral hypoglycaemics (OHG) on the day of surgery.

Patients on insulin are a little more complicated. Refer to the perioperative management of diabetic patients guideline on the hospital intranet. As a general rule

• Continue long acting Lantus and Levemir.
• Morning operation – withhold short and intermediate acting
• Afternoon operation – take ½ dose of short and intermediate acting/premix insulin
• Minimise fasting times (patient 1^st on list)
• Monitor BSL 4 hourly pre and post op then QID for 48hrs
• Manage BSL with sliding scale
• Commence dextrose infusion???

Allergies

Document each allergy and specifically what the reaction is. A local rash to penicillin is will have different consequences compared to true anaphylaxis.

Most ‘allergies’ are no more than known side effects to drugs,  for example vomiting or constipation after an opioid (morphine or oxycodone). While it is worth noting, this is not true allergy.

Local rashes may be allergic in nature but not a type 1 hypersensitivity ‘anaphylactic’ reaction.

If the patient is unsure of the reaction, ascertaining the context is helpful – whether they needed to go to hospital or ICU, was it life-threatening, or was it at the GP not requiring any medication?

Fasting

The patient should be fasted to avoid the risk of aspiration of gastric contents into the lungs.

Solids 6 hours

Clear fluids 2 hrs

Breast milk 4 hrs

Investigations

The principle of ordering any test is

• How likely is it to show an abnormality?
• Would that abnormality be significant in the perioperative period?

This decision is made by assessing the patient’s age, general health, medications and particular operation.

So as a general rule

1. Patients <40 years of age may require no routine investigations
2. Healthy patients between 40-60 years of age may require no investigations or may need an ECG, FBE, UEC depending on extent of surgery.
3. Health patients >60yrs of age are more likely to need a ECG, FBE, UEC and with major surgery a CXR.

For patients with medical comorbidities and on medications, they may need investigations again depending on the extent of surgery.

Full blood examination (Hb, WCC, Platelets)
Hb: Anemia or recent bleeding history or signs, cardiac/renal/hepatic disease, surgery with risk of significant blood loss, cancer, chronic disease (Rheumatoid arthritis).
Meds: bone marrow suppressing meds (prednisolone, methotrexate)
WCC: infection
Platelets: pregnancy, patient with thrombocytopaenic disease (acquired or hereditary), heparin

UEC (sodium, potassium, creatinine, urea, HCO3-)
Cardiac/hepatic/renal disease/intracranial pathology, infection, diabetes, hypertension, dehydration.
Meds: Diuretics, and patient on iv fluids

ECG: Electrocardiogram
Cardiac/resp/renal disease, arrhythmias,

Blood glucose
Diabetes, steroids treatment,

Chest x-ray
Cardiac/resp disease, heavy smoking

COAGs (INR, APTT, fib)
Inherited or acquired coagulopathy, major surgery especially if significant blood loss likely, Liver disease
Meds: on anticoagulants, heparin, warfarin.

Blood group and hold (G&H)
Surgery with possibility of significant blood loss and caesarean sections.
Most blood banks can issue blood very quickly (10mins)
If the blood group detects unusual antibodies are present, then obtaining appropriate blood can take much longer… even days!
Crossmatch blood is needed when there is a high likelihood of transfusion that requires blood immediately
Eg. Ceasarean, liver resections, elective aneurysm operations, cardiothoracic operations, multilevel spinal surgery, extensive burns debridements, long operations, or patients with inherited or acquired coagulopathies.

Liver functions tests
Cardiac/hepatic disease alcoholic, biliary, gastric and large bowel surgery, hepatotoxic drugs, jaundice,

Thyroid function tests
Check prior to thyroid surgery.

Special tests
Cardiac: Echocardiogram, stress test, cardiopulmonary exercise testing, angiogram.
Respiratory: sleep study, respiratory function test.

Be flexible. The basic principles will always apply, but depending on the anaesthetist, the surgeon, the hospital and new evidence, there may be changes to these recommendations

Further reading and references

I have sent these PDF resources to you for reading if you are keen to do so. My document is the bare essentials for you to understand how we approach preoperative assessment but feel free to read in more depth.

• Developing Anaesthesia Textbook Dr David Pescod
• Western Health PAC guidelines – preadmission staff 2013
• Introduction to Anaesthesia, peri-operative Medicine & pain management for medical students by Dr Richard Horton
• Pre-operative assessment of the elderly by Dodds and Murray 2001 CEPD BJA
• ACC AHA 2009 Guidelines on Perioperative Cardiovascular evaluation and Care for Noncardiac surgery

Why?

• You are able to keep track of all your experience
• You are able to keep track of your stats/efficacy
  This will allow you to categorically state how many cases you have done –
  – which is concrete evidence of experience, self audit and improvement whenever you are being assessed, interviewed or reviewed
• Retyping your cases and any learning experiences will have the added advantage of helping you to memorise learning points

I remember how impressed the interview panel was when I applied for my second anaesthesia job. Most cover letters simply stated all the ‘words’ about how great a candidate is. How great they are at team work and communication and hard work and being generally awesome…. But I was able to state matter of fact that I had the participated in 256 anaesthetics, 87 intubations with a success rate of 80% at the end of the 3 month rotation. I could see they were impressed because not many people could present them with these facts. They even suggested on that back of that experience that I should be applying for a more senior role.

How?

There are some great apps (Vaper is one that is commonly talked about) and online systems out there but I’ve found that with extensive experience and heartache the best system is either a de-identified notebook or spreadsheet.

I know a number of people who have lost logbooks because of online systems failing or being deleted.

See the attached excel file for relevant areas to note. You may choose to use some columns and not others and that’s fine – tailor it to what you want to record and measure.

Also you may want to use a system to identify attempts at iv/ett /lma and success…. Eg using a different colour.
And over time you should see a trend of increasing success. If you are not, then this is something you can discuss with your supervisor.

Summary

Most importantly keeping a logbook shows your supervisor that you are interested in self auditing and measuring quality in your own practice.

This is a great process to be involved in for yourself, your career and your patients’ care!

Aim

• To give you a step by step system to choose how to ventilate your patients
• To give you some information about ventilation of the sickest lungs as some principles may apply to healthy lungs as well

Terminology

Tidal volume (Vt) – volume of one breath

Minute ventilation (MV) – total volume of respiration in 1 minute

Respiratory rate (RR) – number of breaths per minute

Positive End Expiratory Pressure (PEEP) – the pressure in the lungs that exists at the end of expiration.

Inspiratory: expiratory Ratio (I:E) – the ratio of time spent in inspiration to expiration. Usually set at 1:2 per 5 second IE cycle. (1.66: 3.33)

Inspiratory pause – interval from the end of inspiratory flow to the start of expiratory flow. Often as a percentage of inspiratory time.

Compliance – a measure of the distensibility of the lung. Shows a sigmoidal curve whereby at low and high lung volumes, the compliance is low. Lung volumes around functional residual capacity (FRC) have high compliance

Pressure volume graph

How does mechanical ventilation damage lungs?

1. Volutrauma
2. Barotrauma
3. Atelectrauma
4. Infection

How do we minimise damage for sickest lungs? (ARDS)

1. Low volume 6ml/kg ventilation (ARDSnet) (↓mortality (31vs40%) and ↑ventilator free days (some evidence in non ARDS lungs)
2. Minimise plateau pressure <30cmH₂O
3. PEEP
   • Adv: ↑FRC. ↓collapse and derecruitment. ↓WOB
   • Disadv: alveolar overdistension. Deadspace ventilation. Hypotension. ↑ICP
   • Ideal PEEP is that which prevents derecruitment and causes minimal overdistension
   • Aim at PEEP that gives highest PaO₂ and minimum FiO₂.
   • Practically I check the spirometry loop by pressing the relevant press button on the monitor – and find the PEEP that gives the best compliance.
4. Recruitment
5. Maintain oxygenation
6. Permissive hypercapnoea in sick lungs (eg asthmatics)
   • Oxygenation keeps the patient safe
   • Most patients will have minimal harm from high CO₂.
   • Over ventilation of sick lungs may cause more harm

Modes of ventilation

(For GE machines though similar modes will be available on other ventilators)

Select

a) Mode – pressure or volume control
b) RR
c) PEEP
d) Choose amount of pressure support for patient triggered breaths
e) Fine details that I use: IE ratio, max pressure, trigger threshold (ask your consultant and test these)

1. Volume control ventilation (VCV)
   • Set the volume and RR
   • Check pressure limit (autoset to 40cmH₂O)
   • Constant flow
2. Pressure control ventilation (PCV)
   • Set pressure and RR
   • Constant pressure
   • Decreasing flow
3. Synchronized intermittent mandatory ventilation (SIMV)
   • Choose volume and RR
   • Choose pressure support for patient initiated breaths.
   • Any patient initiated breaths will either be pressure supported or volume controlled
4. SIMV-PC (pressure control)
   • Like SIMV except set pressure, RR and pressure support for trigged breaths
5. PSVPro (pressure support ventilation Pro)
   • Choose pressure support delivered for any patient initiated breaths.
   • If long period of apnoea – it will fall to back up mode with SIMV-PC mode with preset settings.
6. PCV-VG (pressure control ventilation – volume guaranteed)
   • Set volume and RR and PEEP
   • The machine will use the lowest pressure to achieve the set VT.

Practical Principles

1. Volutrauma seems to be what causes harm in sick lungs so I generally target a maximum volume by using VCV or PCV-VG
2. In any circuit with a potential leak (eg. LMA or uncuffed paediatric tubes) part of the target volume may leak out. Therefore I will use pressure targets (PCV or SIMV-PC). This ensures a stable volume is delivered.
3. If the high pressures are the limiting factor with ventilation (eg severe asthma or restrictive lung disease) a pressure controlled mode may be the best option to maximise tidal volume and therefore oxygenation.
4. At the end of a case when paralysis is not required for anaesthesia or surgery I will change to pressure supported mode eg. SIMV- PSV
   This allows one to deliver a set number of breaths while also supporting any patient triggered breaths.
   Once the patient is triggering frequent breaths I change to a completely pressure supported mode eg PSVPro or switch to the bagging circuit to allow the patient to breath buy themselves.
5. Choosing FiO₂
   • Select <100% oxygen to avoid oxygen toxicity/atelectasis
   • Avoid very low FiO₂ as there will be minimal reserves if patient extubated risking hypoxaemia
   • Most anaesthetists choose somewhere between 40-80% FiO₂.
   • Consider the risk/benefit of oxygen level for each case* (see cases 11 and 12)*Consider the patient who has a greater chance of dislodgement of ETT.These are often cases where there is a shared airway (ENT/ airway surgery) or surgery where you have limited access to the ETT (prone surgery, large head and neck cases).If the ETT is dislodged then:
     If on a lower FiO₂, the time to hypoxaemia is shorter
     If on a higher FiO₂, the patient has greater reserves of oxygen when the ETT is dislodged. Therefore you will have more time to remedy the situation with a decreased risk of hypoxaemia.*Consider a patient whose lungs are prone to worsening hypoxaemia (eg COAD with current infective exacerbation/ asthmatic with an exacerbation/ patient who has aspirated gastric contents on induction)If the patient’s lungs happen to deteriorate then:
   • If on a higher FiO₂, the sats will remain normal in spite of worsening oxygenation.
     You will only realize there is a problem when the lungs are so bad that even a high FiO₂ is not enough to keep the sats normal.
     At this stage you will have no room to increase the FiO₂ to keep the patient safe while you assess and treat the problem.
   • If on a lower FiO₂, the sats will fall as the lung condition worsens.
     You will realize that something is occurring sooner.
     You now have time to keep the patient safe by increasing FiO₂, while you assess and treat the problem.
   • Regular assessments, auscultation and ABGs to calculate Aa gradient will also be valuable during case to assess worsening disease

Step by Step to Ventilator Settings

1. Does patient have airway requiring high pressures to ventilate (asthma, restrictive disease) or is there a leak in the circuit (LMA or uncuffed tube), or are you doing one lung ventilation?

Yes → choose Pressure control mode (PCV)
No → choose volume control mode (VCV)

2. Do you want the patient to eventually breath on their own

Yes → add a pressure support mode eg SIMV if VCV, or SIMV-PC if PCV or PSVPro

3. Tidal volume

• Either dial up 6ml/kg for VCV or choose a pressure that roughly delivers 6ml/kg

4. Respiratory rate

• Generally choose 12 breaths per minute.
• If obstructive lung disease choose lower rate (eg. As low as RR of 4 if severe asthma)
• If restrictive lung disease choose higher rate (eg as high as 20-40 may be required to compensate for very low volumes)
• If you want EtCO₂ to increase to encourage spontaneous ventilations, use a lower RR
• Titrate to EtCO₂ as required.

5. PEEP
• Generally add 0-10cmH₂O of PEEP to maintain lungs at highest compliance
• I use 5cmH₂O for most patients
• Choose 0 peep if high pressures limit your ability to deliver a tidal volume (asthma, severe restrictive)
• 5-10 in obese patients to maintain oxygenation and prevent atelectasis

6. FiO₂

• Maintain Oxygen sats normal for patient or >94%
• FiO₂ 60% for most cases
• Is there difficulty accessing your ETT?
  Yes → choose higher FiO₂ ~ 70-80%
• Is there lung pathology that may worsen?
  Yes → use lowest FiO₂ that safely oxygenates patient (>40% is usually safe)

Examples
What are your ventilator settings for these cases? (Answers on the last page of this PDF document.. don’t look!)

To give you a grasp of the important valve lesions, identify severity and how to manage a safe anaesthetic.

What is common?

Aortic stenosis (AS) and mitral regurgitation (MR)

What is deadly?

AS, mitral stenosis (MS), hypertrophic obstructive cardiomyopathy (HOCM)

What preparation?

The usual setup for anaesthesia and
Arterial monitoring
Metaraminol, ephedrine (and adrenaline)
Echo to assess cardiac output and valve function in real time
Defibrillation pads depending on severity

Severity memory aid (from the ACC AHA guidelines)

But you may have realised that there is the occasional patients who might have a potentially devastating or critical disease. If you were to go about your induction without appreciating the key priorities for each disease, the patient may have a needlessly adverse outcome.

I will outline what I believe are the most important or critical inductions relevant to a patients haemodynamic status.

After exploring this topic I want you to be able to

a) Assess a patient and identify the unique priorities for the patient’s disease
and
b) Create a definitive plan for the induction

These critical patients include:

1. Critical cardiac
2. Hypovolaemic shock
3. Severe pulmonary hypertension
4. Subarachnoid haemorrhage
5. Tamponade
6. Valve lesions – see other post

1. Critical cardiac (60yo male – 70kg, ischaemic cardiomyopathy ejection fraction 15%)

Key priorities

Maintain preload, normal HR, normal rhythm, contractility and normal afterload for coronary perfusion.

Induction meds and doses

Fentanyl 300mcg, Midaz 5mg, rocuronium 100mg. Slowly increase depth of anaesthesia with bag mask ventilation with volatile until ready to intubate maintaining BP with metaraminol and ephedrine.

Reasoning

By using minimal (if any) Propofol, I minimise decrease in contractility and afterload. Fentanyl is typically a very cardiovascularly stable opioid that will decrease propofol requirements and minimize tachycardia on intubation.
The period of bag mask ventilation is to slowly build up the volatile concentration to allow a slow increase in depth of anaesthesia. This has less haemodynamic compromise that may occur with a larger dose of propofol.
Fentanyl has the appropriate balance of onset and efficacy. It does not commonly cause sudden bradycardia or chest wall rigidity that can occur with faster onset opioids like alfentanil or remifentanil .
Any hypotensive episodes could be due to vasodilation or poor contractility so I adjust metaraminol and give ephedrine boluses to maintain BP during this period.

2. Hypovolaemic (21yo male -70kg, motor vehicle accident, abdomen bleed 3L blood loss)

Key priorities

I aim to maintain preload and afterload in a severely hypovolaemic patient

Induction meds and actual doses

Note that in a severely hypotensive patient you may need very little medication to achieve anesthesia. I’ve given ranges of agents that I have given in my experience.

Midazolam 2-5mg, ketamine 20-50mg, 100mg suxamethonium with metaraminol running and ephedrine/adrenaline ready and fluids/blood running.

Reasoning

This induction is less about avoiding tachycardia. The patient is suffering a devastating loss of preload and afterload and will need tachycardia to maintain cardiac output. I care far more about minimizing loss of preload/afterload and using metaraminol to maintain a lower but adequate BP (termed hypotensive resuscitation).
The term hypotensive resuscitation refers to the maintenance of a low but adequate BP to simultaneously maintain vital organ perfusion without having a high BP that increases blood loss and could dislodge a clot that has already formed on an injured vessel. I usually aim for a systolic BP of 70-90mmHg as long as there is no evidence of end organ compromise eg ischaemic ECG changes.

3. Severe Pulmonary Hypertension (50yo female – 50kg with pulmonary fibrosis)

Key priorities

I aim to maintain cardiac function especially right heart function with good preload, contractility and afterload whilst keeping pulmonary vascular resistance low

Induction meds and actual doses

Fentanyl 200-300mcg, Propofol 50mg, rocuronium 100mg, with metaraminol running. I would prioritise achieving good oxygenation and ventilation with minimal ventilating pressures throughout the induction to avoid rises in pulm vascular resistance.

Reasoning

I think of this situation as all about right heart function and maintaining cardiac output against a very high afterload (due to the pulmonary vasculature) to the right heart.

i.e. Make sure the right heart is happy (adequate BP for coronary perfusion with metaraminol, fluid for preload, use lower doses hypnotics to avoid loss of contractility. Avoid tachycardia with cardiostable opioid like fentanyl.

The main factors that increase pulmonary vascular resistance include hypoxaemia, hypercapnoea, acidosis and high ventilating pressures. I pay close attention to airway management and ventilation to minimise the effects of intubation

4. Subarachnoid Haemorrhage (50yo female -80kg with grade 3 SAH, for early clipping)

Key priorities

To avoid an increase in transmural pressure gradient (TMPG), whilst maintaining cerebral oxygen delivery.

Induction meds and actual doses

Alfentanil 1500mcg, Propofol 150-200mg, suxamethonium 100g (or rocuronium 80mg) with esmolol 40mg ready for in case of tachycardia/hypertension

Reasoning

The highest mortality event with SAH, is due to a rebleed (mortality 50-70%). Therefore, I prioritise avoiding a high BP above avoiding transient hypotension. To do this I give reasonable doses of all agents and use suxamethonium so I am confident the patient is well paralysed prior to intubation. AND I have an agent (esmolol or propofol) ready in case the patient does become hypertensive.

5. Tamponade (60yo male, 80kg, with tamponade post CAGS)

Key priorities

Maintain high preload, contractility and high afterload to maintain coronary perfusion pressure

Induction meds and actual doses

Inhalational induction with Sevoflurane and lignocaine to spray the cords prior to passing the ETT.
Metaraminol, ephedrine and adrenaline given as required to maintain key priorities above.

Reasoning

Typically in the highest risk cases this would be done with a cardiac anaesthetist and cardiothoracic surgeon. You would attempt a partial drainage of the pericardial fluid to relieve the tamponade effect. The surgeons and patient would be prepped and draped ready for sternotomy in the event that the patient haemodynamics collapsed.

The induction would often be an inhalational induction to avoid positive pressure ventilation compromising venous return, however this induction has also been done safely as cautious intravenous induction.

Summary

This is obviously a guide but one that I found very useful is thinking about the most important cardiovascular lesions. It becomes even more difficult if a patient has more than 1 critical pathology so I found this is good framework to think about the most complex situation that could arise in your practice.

If you have experience with any other lesions please contact us here and contribute