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AS3.1-6 | Preoperative Evaluation and Medication — PBL Case

CLINICAL SETTING

Mr. Rajan Varma, a 68-year-old retired schoolteacher, is admitted to the surgical ward at 6 PM for urgent loop colostomy the following morning. He presented with acute large-bowel obstruction secondary to a sigmoid carcinoma. The surgeon approaches you, the on-call anaesthesiologist, to complete the pre-anaesthetic assessment that evening. Mr. Varma appears anxious but cooperative. He tells you he has had 'blood pressure problems for years' and takes 'two tablets in the morning and one at night'. He also mentions he 'gets short of breath going up stairs' and has been using a blue inhaler for about five years. Earlier that afternoon, while being wheeled to his ward bed, he experienced 10 minutes of central chest tightness which resolved spontaneously. He is now pain-free. His nursing observations show BP 168/102 mmHg, HR 92 bpm, SpO2 91% on room air, RR 22, temperature 37.1°C. His weight is documented as 89 kg.

Trigger 1: History, Medications, and the New Chest Pain

You sit down with Mr. Varma and take a structured pre-anaesthetic history. He identifies himself as a former smoker (40 pack-years, quit 2 years ago) who drinks occasionally. He underwent appendicectomy in 1998 under general anaesthesia without documented complications. His daughter, who is present, volunteers that her grandfather (Mr. Varma's father) 'died on the operating table many years ago — they said his temperature shot up and he went rigid'. Mr. Varma's current medications are: amlodipine 5 mg OD, ramipril 10 mg OD, atenolol 50 mg OD, aspirin 75 mg OD, and salbutamol MDI 2 puffs PRN. He has no documented allergies. His ECG taken 1 hour ago shows sinus rhythm with new ST-segment depression of 1.5 mm in leads II, III, and aVF compared to a 2019 ECG in his notes.

DISCUSSION POINTS

  • What are the most critical findings in this history for anaesthetic planning, and what immediate investigations should be requested tonight?
  • How should the family history of intraoperative hyperthermia and rigidity change Mr. Varma's anaesthetic plan, and what specific precautions would you implement?
Click to reveal Trigger 2: Airway Examination and Risk Stratification (discuss previous trigger first!)

Trigger 2: Airway Examination and Risk Stratification

You proceed with the clinical examination. Airway assessment: mouth opens to 3.8 cm inter-incisor gap; Mallampati Class III on examination; thyromental distance 5.8 cm; neck extension is moderately reduced due to cervical spondylosis. He has two loose upper incisor teeth. Cardiovascular exam: JVP not elevated; HS I + II, no murmurs; no peripheral oedema. Respiratory exam: bilateral expiratory wheeze, prolonged expiratory phase; using accessory muscles. Abdomen: distended, tympanic, tender in the left iliac fossa; no signs of peritonism. The on-call cardiologist phones to say the new ECG changes likely represent demand ischaemia (Type 2 MI) secondary to the bowel obstruction and physiological stress, and that urgent surgery is likely the definitive treatment — but wants troponin levels and suggests invasive monitoring intraoperatively.

DISCUSSION POINTS

  • Assign and justify an ASA physical status classification for Mr. Varma. How does the E suffix apply here, and how does this differ from grading his airway difficulty?
  • Given the multiple concurrent difficult airway predictors, what is your airway management plan and what equipment must be immediately available?
Click to reveal Trigger 3: Fitness Determination, Premedication, and Consent (discuss previous trigger first!)

Trigger 3: Fitness Determination, Premedication, and Consent

Investigations return: Hb 10.4 g/dL, WBC 14.2 × 10⁹/L, platelets 228. Na 131 mmol/L, K 3.2 mmol/L, creatinine 128 µmol/L, urea 12.1 mmol/L. Troponin I: 0.42 ng/mL (high sensitivity, ULN 0.034). Chest X-ray shows hyperinflated lung fields consistent with COPD; no consolidation or pneumothorax. The surgical team confirms the procedure cannot be safely delayed beyond morning. You must now complete the preoperative fitness document, prescribe premedication, and obtain informed consent from Mr. Varma, who is worried he 'might not wake up'. The operating list is at 08:00. It is now 21:30.

DISCUSSION POINTS

  • Write a structured fitness determination statement for Mr. Varma. What conditions or caveats would you attach to your 'fit for urgent surgery' declaration?
  • Prescribe appropriate premedication for Mr. Varma tonight and on the morning of surgery. For each agent, state the drug, dose, route, timing, and your specific rationale given his clinical profile — including the MH risk, COPD, and troponin elevation.

Group Task Assignments

Group 1: Collaborative Task

  • Produce a one-page pre-anaesthetic assessment summary for Mr. Varma that covers: structured history (with medication perioperative plan), airway findings (Mallampati + other predictors), ASA classification with justification, investigation interpretation, fitness statement with conditions, anaesthetic plan highlights (including MH precautions), and premedication chart for tonight and morning.

Group 2: Collaborative Task

  • Prepare a 5-minute oral presentation for the group explaining: (1) why ASA physical status and Mallampati classification are different tools measuring different things, and (2) why the family history of intraoperative hyperthermia triggers a specific protocol change — what drugs must be avoided and what must be prepared.

Learning Issues

Research these questions and bring your findings to the discussion.

  1. [AS3.1] What are the three core goals of the preoperative evaluation, and how do risk identification and risk optimisation differ in an urgent versus elective setting?
  2. [AS3.2] How should each of Mr. Varma's current medications be managed perioperatively? Specifically: should ramipril be withheld? What is the perioperative plan for aspirin in a patient with possible Type 2 MI? What does atenolol continuation or withdrawal risk in this context?
  3. [AS3.3] What combination of airway findings constitutes a 'predicted difficult intubation'? How does the LEMON framework apply to Mr. Varma, and what is the difference between a difficult intubation and a difficult mask ventilation?
  4. [AS3.4] How do you interpret a troponin elevation in the context of acute physiological stress (Type 2 MI vs Type 1 MI), and does this change the decision to proceed with urgent surgery?
  5. [AS3.5] What does 'conditionally fit for urgent surgery' mean in documentation terms? What conditions must be explicitly stated, and how does a fitness statement for urgent surgery differ from one for elective surgery?
  6. [AS3.6] What premedication choices are safe and appropriate for a patient with possible demand ischaemia, COPD, malignant hyperthermia risk, and an anxious state the night before urgent surgery? What agents must be avoided?