Pre-operative assessment identifies and optimises the patient's comorbidity, informs them, and plans the anaesthetic, and the ASA physical status classification is the shorthand for the first of those: I is a normal healthy patient, II mild systemic disease, III severe systemic disease, IV severe systemic disease that is a constant threat to life, V a moribund patient not expected to survive without the operation, and VI a declared brain-dead patient whose organs are being removed for donation. NICE NG45 then decides which tests are offered by surgery grade and ASA grade, and the Royal College of Anaesthetists' GPAS chapter 2 sets what a pre-assessment service must provide. At the CT1 anaesthetics interview this is the clinic patient you are asked to grade and work up.

Key takeaways

  • ASA I to VI, last amended by the ASA in December 2020, with E added when delay in treatment would significantly increase the threat to life or a body part
  • The ASA says the classification alone does not predict perioperative risk; used with the type of surgery, frailty and deconditioning, it can help
  • Well-controlled diabetes or hypertension, pregnancy, current smoking and a BMI of 30 to 40 are ASA II; poorly controlled diabetes, COPD, BMI of 40 or more, dialysis-dependent renal failure and an MI or stent more than 3 months ago are ASA III
  • An MI, stroke, TIA or stent within 3 months, ongoing ischaemia, shock, sepsis or DIC is ASA IV
  • NICE NG45: full blood count, kidney function and ECG are offered to everyone having major surgery who is ASA II or above; no routine chest X-ray, echo, urine dipstick, sickle test or HbA1c in people without diabetes
  • GPAS chapter 2: every patient is assessed before anaesthesia, and ASA 3 to 5 patients and those having high-risk surgery have their expected morbidity and mortality estimated and documented

What is pre-operative assessment for?

Pre-operative assessment, according to the Royal College of Anaesthetists' GPAS chapter 2, enables patients to be fully informed, reduces stress and anxiety, creates the opportunity to optimise medical conditions before surgery, and minimises cancellations on the day for clinical reasons. It says there must be sufficient time between the decision to operate and the operation for that to happen.

GPAS states that all patients should be assessed before anaesthesia or anaesthesia-led sedation, face to face or virtually, and that most of that assessment is nurse-led under locally agreed protocols. The anaesthetic service should involve consultant and SAS anaesthetists.

Dedicated anaesthetic presence in the clinic is required for shared decision making about the risks and benefits of anaesthesia and surgery in high-risk patients, including arranging and interpreting functional assessments of fitness.

How does ASA grading work?

ASA grading assigns one of six physical status classes on the day of anaesthesia, by the anaesthetist, after evaluating the patient. The American Society of Anesthesiologists' statement, last amended 13 December 2020, gives the definitions.

  • ASA I: a normal healthy patient
  • ASA II: a patient with mild systemic disease
  • ASA III: a patient with severe systemic disease
  • ASA IV: a patient with severe systemic disease that is a constant threat to life
  • ASA V: a moribund patient who is not expected to survive without the operation
  • ASA VI: a declared brain-dead patient whose organs are being removed for donor purposes

NICE NG45 notes that UK anaesthetists often interpret the grades by functional capacity: comorbidity that does not limit activity is ASA 2, comorbidity that does is ASA 3. The ASA itself does not endorse elaborations, so say which convention you are using.

Which examples separate ASA II from III and IV?

The ASA-approved adult examples draw the lines that candidates blur. ASA II is mild disease without substantive functional limitation: a current smoker, a social drinker, pregnancy, obesity with a BMI between 30 and 40, well-controlled diabetes or hypertension, and mild lung disease.

ASA III is substantive functional limitation from one or more moderate to severe diseases: poorly controlled diabetes or hypertension, COPD, a BMI of 40 or more, active hepatitis, alcohol dependence, a pacemaker, a moderate reduction in ejection fraction, end-stage renal disease on regular dialysis, and a myocardial infarction, stroke, TIA or coronary stent more than 3 months ago.

ASA IV is the same events within the last 3 months, ongoing cardiac ischaemia or severe valve dysfunction, a severe reduction in ejection fraction, shock, sepsis, disseminated intravascular coagulation, and renal failure not on scheduled dialysis. ASA V examples are a ruptured aneurysm, massive trauma, an intracranial bleed with mass effect, and ischaemic bowel with major cardiac disease.

The 3-month cut-off for a cardiac event and the BMI of 40 are the two numbers the station tends to probe.

What does the E mean?

The E is added to any ASA class for emergency surgery, which the ASA defines as existing when delay in treatment of the patient would lead to a significant increase in the threat to life or a body part. An ASA II patient with a perforated appendix is ASA II E.

The ASA also notes that although pregnancy is not a disease, the physiological change is enough to make an uncomplicated pregnancy ASA II.

Does ASA grade predict risk?

ASA grade does not predict perioperative risk on its own, according to the ASA statement, which says that used with other factors such as the type of surgery, frailty and deconditioning it can be helpful. That sentence is the answer to the follow-up question.

GPAS chapter 2 asks each hospital for a consistent, evidence-based system to identify high-risk surgical patients, and says that as a minimum all ASA 3 to 5 patients and those having high-risk surgery should have their expected morbidity and mortality estimated and documented before the intervention.

Older patients having intermediate or high-risk surgery should be assessed for frailty with an established tool, and anticipated airway difficulty, obesity, and a history of anaesthetic complications should reach the anaesthetist as early as possible.

Which tests does NICE NG45 offer?

NICE NG45, published April 2016, offers tests by three surgery grades and three ASA bands. Minor surgery is an excision of a skin lesion or drainage of a breast abscess; intermediate is a hernia repair, varicose veins, tonsillectomy or knee arthroscopy; major or complex is a hysterectomy, prostate resection, thyroidectomy, joint replacement or lung surgery.

Minor surgery

Nothing is routine for ASA 1 or 2. For ASA 3 or 4, kidney function is considered in people at risk of acute kidney injury and an ECG is considered if none is available from the past 12 months.

Intermediate surgery

Nothing is routine for ASA 1. For ASA 2, kidney function is considered in people at risk of AKI and an ECG is considered with cardiovascular, renal or diabetic comorbidity. For ASA 3 or 4, kidney function and an ECG are offered, a full blood count is considered with cardiovascular or renal disease and uninvestigated symptoms, and haemostasis is considered in chronic liver disease.

Major or complex surgery

A full blood count is offered to everyone. Kidney function is considered in ASA 1 at risk of AKI and offered to ASA 2, 3 and 4. An ECG is considered in ASA 1 over 65 without one in the past 12 months and offered to ASA 2 and above. Haemostasis is considered in chronic liver disease, and for ASA 3 or 4 with respiratory disease, senior anaesthetic advice is sought as soon as possible after assessment.

Which tests are not routine?

NG45 says not to routinely offer a chest X-ray, resting echocardiography, urine dipstick, sickle cell testing, or HbA1c to people without diagnosed diabetes. Each of those has a specific exception.

  • Echocardiography is considered for a murmur with any cardiac symptom, or signs of heart failure, after an ECG has been done and discussed with an anaesthetist
  • Urine microscopy and culture are considered if a urinary infection would change the decision to operate
  • Sickle cell disease is asked about, and the specialist team is contacted if the patient is known to have it
  • People with diabetes are offered HbA1c if not tested in the last 3 months, and their most recent result comes with the referral
  • All women of childbearing potential are asked about pregnancy on the day, with a test done with consent if there is any doubt, and the discussion documented

Which traps catch candidates?

The pre-assessment traps at interview are treating ASA as a risk score, grading a well-controlled condition as ASA III, and ordering a routine chest X-ray. Each contradicts the ASA statement or NG45.

  • Saying 'ASA III so high risk' without the surgery, frailty or functional capacity
  • Putting well-controlled diabetes in ASA III, or a stent from 5 years ago in ASA IV
  • A chest X-ray, echo or urine dipstick 'as routine'
  • HbA1c for everyone: it is for people with diabetes not tested in 3 months
  • Forgetting that the final ASA grade is assigned on the day of anaesthesia, by the anaesthetist

What is the interviewer listening for?

In a pre-assessment scenario the assessors are listening for the ASA definition with an approved example, the correct limitation of the grade, the NG45 tests chosen by surgery grade, and the GPAS reason for doing any of it.

  • The six ASA definitions and the E modifier
  • A 3-month cardiac event and a BMI of 40 as the II, III and IV boundaries
  • ASA alone does not predict risk; surgery, frailty and function do
  • Tests by NG45 table, and the five that are not routine
  • Optimisation, information and fewer day-of-surgery cancellations as the purpose

How this comes up at the CT1 anaesthetics interview

Pre-operative assessment comes up in the clinical judgement station as a clinic patient: a 72-year-old with COPD, a stent 18 months ago and a BMI of 41 listed for a hip replacement, and you are asked to grade them and plan the work-up. The station is one of two 15-minute stations, each marked out of 50, and 60 out of 100 is appointable.

The follow-up tests judgement: the surgeon wants to proceed without the ECG, or the patient is found on the morning of surgery to be 8 weeks pregnant. anaestheticinterview's 340-question bank includes pre-assessment scenarios with AI-marked spoken practice, which is where the ASA examples and the NG45 tables get said aloud.