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AS10.1-4 | Patient Safety in Anaesthesiology — PBL Case

CLINICAL SETTING

Mrs Kavitha Menon, a 61-year-old woman weighing 105 kg (BMI 38 kg/m²), was admitted for elective total abdominal hysterectomy under general anaesthesia. She had well-controlled type 2 diabetes mellitus and hypertension. Preoperative assessment noted a Mallampati Class II airway and ASA Physical Status III. She fasted from midnight the previous evening (approximately 12 hours for solids and 8 hours for clear fluids, per ward instruction). She was placed in the supine position with both arms extended on arm boards at approximately 80° abduction. The procedure lasted 3 hours 20 minutes. At the conclusion of the case, the anaesthetic registrar handed over to the recovery nurse with a brief verbal statement: 'She's had GA for TAH — vital signs stable, she had a small blood pressure drop intraoperatively which we managed, she's all yours.' The registrar then left the recovery area. The following morning on ward review, Mrs Menon reported tingling and weakness of the right hand affecting the thumb, index, and middle fingers. She could not extend her right thumb. The attending surgeon referred her for neurological review. Separately, during the departmental M&M meeting the following week, a review of the anaesthetic chart revealed that a 10-mL syringe and a 5-mL syringe — both unlabelled and containing clear solutions — were documented as present on the drug tray during the period when the vasopressor was given. The anaesthetic registrar acknowledged that the metaraminol syringe had not been labelled as she prepared it 'because the surgeon was asking for retraction immediately and I was distracted.'

Trigger 1: The nerve injury — what happened and why?

On neurological examination, Mrs Menon has weakness of thumb abduction, thumb opposition, and index finger extension on the right side, with reduced sensation over the lateral two-thirds of the palm and the palmar surface of the thumb, index, and middle fingers. There is no wrist drop. Nerve conduction studies confirm median nerve injury at the level of the wrist and proximal forearm.

DISCUSSION POINTS

  • What positioning factors during this case most likely caused Mrs Menon's median nerve injury? Describe the anatomical pathway of the median nerve and the specific mechanism by which supine arm board positioning can injure it.
  • What additional nerve injuries should be specifically screened for in any patient who has spent more than 3 hours with arms on arm boards? For each nerve, name the specific vulnerable anatomical site and the prevention measure.
Click to reveal Trigger 2: The perioperative hazards — what else was at risk? (discuss previous trigger first!)

Trigger 2: The perioperative hazards — what else was at risk?

Reviewing the intraoperative monitoring data: Mrs Menon's SpO₂ fell to 91% at 90 minutes into the procedure. The anaesthetist increased FiO₂ from 0.5 to 0.8 and the SpO₂ recovered to 96% within 5 minutes. Airway pressures had been gradually rising from a peak of 18 cmH₂O at intubation to 28 cmH₂O at the time of desaturation. The blood pressure drop noted at handover was: MAP fell from 88 mmHg to 57 mmHg at 45 minutes post-induction, treated with two boluses of metaraminol (total dose 2 mg) and 500 mL of Hartmann's solution.

DISCUSSION POINTS

  • The anaesthetist responded to the desaturation by increasing FiO₂. Was this the optimal first response? Apply your understanding of the physiological mechanism of anaesthesia-induced atelectasis in an obese patient to explain what additional intervention should have been performed, and why simply increasing FiO₂ may be insufficient for a shunt physiology.
  • The preoperative fasting instruction was 'nil by mouth from midnight.' Using the ASA 2-4-6-8 fasting guidelines, was this instruction correct? What are the evidence-based fasting times for clear fluids and for solids, and what is the clinical rationale for differentiating them?
Click to reveal Trigger 3: The communication failures and the medication near-miss (discuss previous trigger first!)

Trigger 3: The communication failures and the medication near-miss

At the M&M meeting, the registrar's handover statement is reviewed: 'She's had GA for TAH — vital signs stable, she had a small blood pressure drop intraoperatively which we managed, she's all yours.' The recovery nurse testifies that she was not told the magnitude of the blood pressure drop, what drug was used, the total dose given, or what to monitor for. The nurse had noted that the patient looked pale on arrival but did not ask for more information because 'the registrar seemed in a hurry.' Separately, when asked about the unlabelled syringe at M&M, the registrar states: 'I knew which syringe was which — they looked different sizes.' The department chair asks: 'What if you had been called out of the room for 10 minutes?'

DISCUSSION POINTS

  • Classify the handover communication failure using the SBAR framework. List the specific SBAR components that were absent from the registrar's statement, and write a model SBAR handover for this case that would have been complete.
  • Apply James Reason's Swiss Cheese Model to the unlabelled syringe event: identify the active failure layer and at least two latent failure layers. Explain why the registrar's defence ('I knew which was which') does not constitute an adequate safety argument, and propose one system-level intervention that would make the safe action the default for every case.

Group Task Assignments

Group 1: Collaborative Task

  • As a group, construct a one-page 'Position Safety Checklist' for a 3-hour elective abdominal procedure in the supine position. The checklist should cover: pre-positioning (patient factors to assess), positioning setup (specific steps for arm boards, padding, neutral positions), intraoperative monitoring intervals (what to check and how often), and post-procedure assessment (which nerves and pressure points to examine before extubation). Format it so it could be laminated and used in a real operating theatre.

Group 2: Collaborative Task

  • Design a structured 'OR-to-Recovery Handover Card' for your department, covering the minimum information elements that must be verbally communicated for every general anaesthetic case. Base it on the SBAR framework but adapt it to the anaesthetic recovery context. Include: what drug was used for haemodynamic instability and at what total dose, airway events, ongoing monitoring requirements, and specific thresholds for calling the anaesthetist back.

Learning Issues

Research these questions and bring your findings to the discussion.

  1. [AS10.1] What are the anatomical sites of vulnerability for the median, ulnar, radial, and common peroneal nerves during standard surgical positions (supine, lithotomy, lateral decubitus, prone)? For each nerve, what is the specific positioning step that prevents injury?
  2. [AS10.2] What is the mechanism by which general anaesthesia causes a reduction in FRC, and why does this effect disproportionately affect obese patients? What are the specific interventions (PEEP, recruitment manoeuvres, positioning) that prevent or reverse anaesthesia-induced atelectasis, and at what point intraoperatively should each be applied?
  3. [AS10.3] What are the key components of the SBAR framework as applied to anaesthetic recovery handover? What evidence exists that structured handover tools reduce adverse events in the postoperative period, and what are the barriers to their consistent use in operating theatres?
  4. [AS10.4] According to James Reason's Swiss Cheese Model, how do active failures and latent failures combine to cause adverse events? Apply this model to the unlabelled syringe scenario: identify each failure layer, and for each layer propose a specific intervention that reduces the probability of harm reaching the patient.