A3. The operative risk

In all of medicine, a procedure is generally only undertaken if the potential benefits outweigh the risks. Operative risk is the risk of death or complication during or after a surgery. If the operative risk is unacceptably high, the patient is considered inoperable. Shared decision-making with the patient is important, as it’s up to the patient whether they want to take the risk or not.

A high operative risk may be acceptable in cases where the surgery could be lifesaving. A good example of this is surgery for ruptured AAA, which carries a high risk but not going through with surgery carries an even higher risk.

The operative risk of a specific patient depends on:

• Disease-related factors (e.g., the nature and the severity of the surgical condition)
• Patient-related factors (e.g., anatomical features, compliance, past surgical history, comorbidities, functional reserve, social status, lifestyle)
• Surgery-related factors (e.g., surgeon’s knowledge and experience, technical and decision-making skills; anaesthesia; operative access and exposure; type of the procedure and its complexity and duration; overall surgical trauma; the level of contamination; whether the surgery is acute or not)

Risk factors

Some of the risk factors which contribute to operative risk include:

• Modifiable risk factors
  • Smoking
  • Alcohol intake
  • Obesity
  • Diabetes mellitus
  • Hypertension
  • Cardiovascular disease
  • Mental disorders
  • Malnutrition
• Non-modifiable risk factors
  • Old age
  • Gender
  • Genetics
  • Family history
  • COPD
  • Previous stroke or AMI
  • Heart failure
  • CKD

Modifiable risk factors can be reduced to the point where the operative risk goes from unacceptably high to “acceptably” high.

Risk stratification

To obtain a better understanding of operative risk, sometimes extra examinations and/or tests are needed. For example, pulmonary function test and/or chest x-ray­ in case of severe respiratory disease (COPD, untreated asthma) or chest surgery. As another example, echocardiography in case of cardiac disease.

The ASA (American Society of Anaesthesiology) functional classification gives some insight into the operative risk of the patient:

• ASA 1 – healthy, non-smoking patient
• ASA 2 – patient with well-controlled disease with normal quality of life
  • Overweight, well-treated hypertension
• ASA 3 – patient with disease which impacts normal functioning of patient
  • Poorly treated DM, stable angina
• ASA 4 – unstable patient with disease is a constant threat to life
  • AMI, stroke, etc.
• ASA 5 – patient unlikely to survive for > 24 hours without surgery
  • Ruptured AAA, polytrauma
• ASA 6 – brain dead patient

The revised cardiac risk index (RCRI) can be used to estimate the risk of major cardiac complications after noncardiac surgery.

Quantifying the patient’s functional status is important in operative risk stratification. The ECOG or Karnofsky Performance Status Scale are used for this.

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