Preoperative Assessment

Question 1

Approach in Assessing People:

Answer 1

1. Identify known health problems and their severity
2. Screen for common conditions ie diabetes, hypertension
3. Identify other risk factors ie smoking, alcohol, obesity
4. Document medication, allergies and any modifications which maybe required.
5. Document problems with previous anaesthetics

Question 2

Systematic Preoperative Assessment:

1. Cardiovascular
2. Respiratory
3. Alcohol
4. Nutritional Status
5. Medication
6. Allergies
7. Pregnancy
8. Previous operations and anaesthetics
9. Dentition

Answer 2

1. Cardiovascular:
   - Drug history ie anticoagulants and antiplatelets
   - Symptoms of left ventricular failure: Exertional dyspnoea, orthopnoea, paroxysmal nocturnal dyspnoea
   - Signs of right-sided heart failure: dependent oedema
   - Blackouts and dizzy spells: Arrhythmias, valvular heart disease, carotid artery disease
   - Clinical examination: arrhythmias, carotid artery and heart murmurs, hypertension, signs of cardiac failure
2. Respiratory:
   - New onset/increased cough, sputum production, wheeze and SOB
   - Pre-existing pulmonary disease ie asthma, COPD, fibrotic lung disease
   - For asthma: previous ITU and hospital admissions, steroid dependency
   - Exercise tolerance to assess functional respiratory reserve
   - Pulmonary function tests for significant dyspnoea
   - Postpone surgery if acute viral illness due to increased risk of bronchospasm and postoperative bacterial pneumonia
3. Alcohol:
   - in acute intoxication, reduced anaesthetic dose requirements, risk of aspiration pneumonia
   - In chronic alcohol abuse, liver enzymes induced hence increased anaesthetic dose requirements.
   - Alcohol-related liver and cardiac disease, coagulopathy
   - Risk of alcohol withdrawal hence appropriate detox protocols
4. Nutritional Status:
   - BMI
   - History of weight loss
   - Signs of malnutrition: low BMI, bodyweight <90% predicted, >20% weight loss, hypoproteinaemia, hypoalbuminaemia. Linked with increased rate of postoperative complications and delayed healing, oedema.
5. Medication:
   a) Long-term steroid therapy
   - Hypoadrenalism hence require continuation or increased steroid dose during perioperative period
   - Signs of hypoadrenalism: hypotension/shock, hyponatraemia, hyperkalaemia. Tx with urgent steroid treatment to prevent Addisonian crisis.
   b) Antiplatelet and anticoagulation therapy:
   - Balance risk of thromboembolic event vs risk of haemorrhage
   - Aspirin usually continued
   - If after stenting and on clopidogrel, postpone surgery/continue clopidogrel if within 6 months of stenting(to allow for stent endothelialization), consult cardiologist/vascular surgeon.
   c) Oral contraceptives and HRT:
   - Risk of venous thromboembolism vs risk of unwanted pregnancy
   - Usually discontinue oestrogen-containing drugs 4-6w before.
   d) Psychiatric drugs
   - Lithium: Mimics sodium in potentiating neuromuscular blocking agents, stop 24h prior to surgery
   - Phenothiazines: Causes hypotension, risk of cessation usually outweighs benefits
   - TCA: Risk of arrhythmias and hypotension
   - Monoamine oxidase inhibitors: Interacts with opiates and vasopressor agents, stop 2-3w before surgery.
6. Allergies:
   - Eg; Antibiotics, iodine, adhesive dressings, latex
7. Pregnancy
   - Avoid surgery in first trimester: increased risk of miscarriage and teratoenicity
   - Avoid surgery in 3rd trimester: Maternal risks and risk of premature labour.
   - A lot of excess risk related to general anaesthesia
   - Other perioperative risks: pre-eclampsia/eclampsia; hypotension on supine position(2nd and 3rd trimesters); hypoxia(due to increased metabolic rate and reduced functional residual capacity); amniotic fluid embolism; Gastro-oesophageal reflux increasing risk of aspiration
8. Previous operations and anaesthetics:
   - Eg; Difficult endotracheal intubation, postoperative nausea and vomiting(minimised using short-acting anaesthetic agents antiemetic ie ondansetron and opiate avoidance)
   - Suspicious family history: Pseudocholinesterase deficiency/scoline apnoea; Malignant hyperpyrexia
9. Dentition: damaged/loose teeth, crowns, poor dentition

Question 3

Benefits of preoperative smoking cessation:

Answer 3

1. Reduced bronchospasm and airway hyper-reactivity
2. Reduced sputum production hence reduced atelectasis
3. Improved ciliary function hence better sputum clearence
4. Reduced carboxyhaemoglobin hence better oxygen-carrying capacity
5. Reduced nicotine-associated systemic and coronary vasoconstriction

Question 4

Significance of obesity in perioperative period:

1. Cardiovascular system
2. Respiratory system
3. Surgical
4. Other

Answer 4

1. Cardiovascular system:
   - Ischaemic heart disease and hypertension more common
   - BP management difficult
   - Increased risk of right-sided heart failure
2. Respiratory system:
   - Airway management difficult
   - Reduced lung volumes
   - Increased incidence of obstructive sleep apnoea
   - Increased risk of perioperative hypoxia
   - Increased risk of atelectasis, pneumonia and PE
3. Surgical:
   - Surgical access difficult
   - Increased wound infection and dehiscence
4. Other:
   - Venous access difficult
   - Increased incidence of diabetes mellitus
   - Increased risk of hiatus hernia and aspiration pneumonia