Anaesthetic pre-assessment

Notes

Introduction

All patients will be reviewed by an anaesthetist prior to their surgery.

This generally occurs on the morning of the operation by the anaesthetist who will be looking after the patient. It is a time for the anaesthetist to undertake a systematic review of the patient, review any investigations and arrange urgent ones if essential to proceeding with surgery safely.

It is also an essential time to explain the anaesthetic approaches available and explain the relevant benefits and risks of each to allow a shared decision to be reached with informed consent.

Elective vs emergency

Pre-op assessment is similar in the elective and the emergency setting however there are some key differences.

Patients booked for emergency procedures will usually not have the benefit of being reviewed in a pre-assessment clinic. They may have undiagnosed and poorly controlled conditions that increase peri-operative risk.

There is also limited time for optimisation in the emergency setting and it can sometimes be challenging to balance optimisation of a clinical condition versus urgency of surgery. It is important to keep the patient, and if this is not possible their next of kin, involved in these often difficult decisions. 

Structured approach

Anaesthetic pre-op assessment requires a clear and structured approach.

A structured approach ensures key details are not missed. As with any patient interaction begin with an introduction. Confirm the patient’s identity, the planned procedure and why it is required. Briefly explain the purpose of the pre-operative assessment.

Below we will discuss aspects of a routine pre-op assessment, highlighting certain points of particular importance.

Previous anaesthetic history

Take a full history of patients’ previous anaesthetics, whether they were general or regional and how they found the experience.

This is an important part of the assessment - key to the safe administration of anaesthetics. It is important to ask specifically about common and serious problems as outlined below.

Post operative nausea & vomiting

This is a relatively common side effect of general anaesthesia. It is important to ask about this and if the patient is concerned, to reassure them that there are specific steps that can be taken to reduce the chance of it happening. These steps include using regional anaesthesia where possible, use of more than one antiemetic and use of TIVA (total intravenous anaesthesia).  

Difficult airway

It is important to ask patients about this and also review old anaesthetic charts to see if airway management has been an issue and if so what approach worked and what didn’t. Patients who have difficult airways may have an alert in the notes and also carry around a card to give to healthcare professionals. 

Malignant hyperthermia

Patients may not know the terminology 'malignant hyperthermia' and be vague in their description. Often they have other family members affected and have undergone specific testing.

Suxamethomium apnoea

Patients may be vague about this explaining “it took a while for me to wake up”. As with malignant hyperthermia they may have other family members affected and undergone specific testing.

Family history of issues with anaesthesia

It is important to ask about family history of any adverse reactions to anaesthesia particularly for patients who have not had anaesthetics in the past. Patients should be asked about a family history of suxamethonium apnoea or malignant hyperthermia.

NOTE: Patients who have had a serious complication associated with anaesthesia should have a letter given to them and a copy kept in the notes with details on what occurred and advice for future anaesthetics. 

Past medical history

A detailed past medical history is required to identify risk factors for poor outcomes and adjust the anaesthetic plan.

A detailed systematic organ review should be conducted with a focus on how affected the patient is by each of these in order to assess severity of disease. It is useful to ask about any recent illnesses or admissions to hospital. Below we will outline a framework and highlight common and important co-morbidities to discuss.

Cardiovascular disease 

  • Hypertension: Is it well controlled, what anti-hypertensives do they take, is there end organ dysfunction?
  • Atrial fibrillation: Are they on anticoagulants, have they had a stroke or other thrombotic complications?
  • Cardiovascular disease: Have they had and MI? When and how it was treated, are they on dual antiplatelets for a drug eluting stent, have they had a recent angiogram &/or ECHO? Also establish if there is a history of angina, syncope, orthopnoea, paroxysmal nocturnal dyspnoea. 

Respiratory disease 

  • Asthma/COPD: Frequency of exacerbations, time of last chest infection/exacerbation, admissions to hospital &/or ICU, frequency of symptoms and inhaler use?
  • Obstructive sleep apnoea: Do they use overnight CPAP and if so have they brought their CPAP machine to hospital?

Diabetes

Identify whether the patient has insulin dependant diabetes or not and their level of control. Review blood sugars, HbA1c and medications. It is important to make a brief assessment of end organ damage (cardiovascular disease, nephropathy, neuropathy, retinopathy).

Gastrointestinal system

  • Gastro-oesophageal reflux disease: This is important in regards to airway management. It is important to find out if it is well controlled or not by asking how often this affects the patient, what triggers it (e.g. certain foods or lying flat), whether does acidic fluid or food actually come up into the mouth and how bad has it been recently. Patients may be on a proton pump inhibitor or H2 receptor antagonists, if they are, make sure they have had their regular dose.  
  • Bowel obstruction: Patients with bowel obstruction should have an NG tube placed and fully aspirated prior to induction of general anaesthesia.

Renal

Assess the severity of disease. If they have end stage renal disease find out if they are on renal replacement therapy and if so what and how often, if they have a fluid restriction and if they produce urine. 

Neurological

  • Stroke/TIA: Ask whether a functional deficit remains and if they are on anticoagulation or antiplatelets.
  • Epilepsy: Ask about the type of epilepsy, how well controlled it is and what medications they take.
  • Dementia & delirium: There may be issues around capacity and consent, operations often precipitate or worsen delirium.

Musculoskeletal

If musculoskeletal disease affects the cervical spine mobility or stability and mouth opening it has potentially serious implications on airway management e.g. rheumatoid arthritis, ankylosing spondylitis.

Women

If of childbearing age ask if they could be pregnant (informed consent is required for pregnancy tests). Ask if they are on any hormonal therapies which has increased associated DVT/PE risk (e.g. combined oral contraceptive pill, HRT).

Functional assessment

This assessment aims to give you an impression of an individuals fitness and functional level.

It is important to try and get an idea where possible on the level of fitness of your patients as this correlates with the ability to cope with the stress of surgery. Asking questions such as how far they can walk on the flat and how many flights of stairs they can climb until they need to stop and what stops them going further is important.

Not all patients are fully mobile or have stairs at home so it can be difficult assess their level of function. Some patients will have had formal exercise tests to get an accurate measure of their cardiovascular capacity.    

Medication history

Medication history includes a review of regular medications and any peri-operative adjustments.

It is important to find out all the medications they take including over the counter and herbal remedies. It is also important to ask when they last took them and make sure they have kept up to date with appropriate medications e.g. analgesia.

Patients on long-term steroids must have these continued and may require higher doses during the peri-operative period (depending on surgery severity). Drugs may be omitted or have their dosage adjusted pre-operatively:

  • Day of surgery:
    • ACE-inhibitors

    • Certain insulin types & oral hypoglycaemics (dose day before surgery may be adjusted)

  • Held for variable length of time pre-operatively (when indicated):
    • Clopidogrel (5 days) 

    • Ticagrelor (5 days)

    • Aspirin (7 days)

    • DOACs (depends on agent, surgical bleeding risk and renal function, may be on LMWH bridging therapy)

    • Warfarin (5-7 days, may be on LMWH bridging therapy)

    • LMWH (depends on the dose, renal function and indication)

    • Combined oral hormonal contraceptive & hormonal replacement therapy (4 weeks if indicated to reduce VTE risk)

It is important to note each individual patient will have a peri-operative plan designed for them. Not all the medications above will be held for all surgeries and for all patients. For more on the pre-operative management of anticoagulants, antiplatelets and oestrogen containing medications see our note on the pre-assessment clinic.  

Allergies

Allergies to medications, latex, food and all other substances should be checked pre-operatively.

Try to establish the presence of a true allergy (rash, respiratory & cardiovascular compromise, anaphylaxis) as opposed to an intolerance (nausea, vomiting, diarrhoea) - this can be difficult.

Further assessment

There are a number of additional essential components to the anaesthetic assessment.

Smoking, illicit drugs & alcohol

Review in all patients and where applicable have a plan on post-operative management. This may include prescribing nicotine replacement or medications to help with alcohol and drug withdrawal. 

Fasting status

Ideally patients are adequately fasted pre-op however particularly in the emergency setting this is not always achievable. Patients with serious illness, trauma, pain and opiate analgesic requirements have delayed gastric emptying meaning that they may not be effectively starved pre-operatively. This has implications for airway management with general anaesthesia and a rapid sequence induction is usually carried out to minimise the risk of regurgitation and aspiration of gastric contents. 

Airway assessment

A full and comprehensive airway assessment is vital. This will be covered in its own upcoming note! 

Examination of other systems

Time is taken to conduct a brief examination, listening to the lungs and checking for murmurs. A more detailed examination is undertaken if there are particular concerns.  

Review observations and investigations

A set of pre-operative observations should be available and for elective procedures, relevant investigations should have already been carried out with the results available. Patients having emergency surgery may not have all the investigations that are needed and this should be identified and when possible addressed.  

Risk assessment

All patients should have either qualitative or quantitative risk or both discussed and documented in the notes prior to surgery

Consent

In addition to the surgical consent, the anaesthetists will consent the patient for the planned anaesthetic.

Information and risk discussed should be specific to each patient and given in way that they can understand. They should have time to consider all the options available to them including the option of not proceeding with the operation. 

Where patients are unable to give consent they should still be involved in the process as much as possible and decisions made with their next of kin or advocates. If this is not possible an IMCA (independent mental capacity advocate) or principles of best interests are used. Details of conversations around consent should be fully documented in the notes. 

Before, after and during the consent process address any questions and concerns the patient may have.

Pre-medications

Pre-medications are commonly used to aid with pain-control or reduce the risk of aspiration.

  • Analgesia: Most patients will be given at least paracetamol pre-operatively. If there are no contra-indications and low risk of bleeding or acute kidney injury, NSAIDs are also given. Opioids and neuroleptics are sometimes also used in specific clinical scenarios (e.g. chronic pain, neuropathic pain, specific operations).
  • Managing regurgitation and aspiration risk: Proton pump inhibitor (e.g. omeprazole) or H2 receptor antagonists (e.g. ranitidine) are commonly used for high risk patients. Acid neutralisers such sodium citrate and prokinetics such as metoclopramide may also be used in some scenarios. 
  • Anxiolytics: These are not routinely used peri-operatively. For very anxious patients midazolam is the most common drug used. It is usually given in oral or buccal forms around 30 minutes prior to anaesthesia. Patients need to be in a safe monitored environment especially if buccal preparations are used. 
  • Antimuscarinics: These are infrequently used but may be considered either to reduce airway secretions in certain patient groups or prevent bradycardia in paediatric patients undergoing general anaesthesia. 
Author Dr. Martha Belete Martha is an anaesthetic registrar in the South-West of England.
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