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AS10.1-4 | Patient Safety in Anaesthesiology — Practice Quiz
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A 58-year-old patient is placed in the lateral decubitus position for a right thoracotomy. At the end of the 4-hour procedure, the anaesthetist notices that the patient's left arm was abducted beyond 90 degrees and the head was not adequately supported with a pillow. Which nerve is MOST likely to have been injured?
Arm abduction beyond 90 degrees in the lateral position stretches the upper trunk of the brachial plexus (C5-C6 roots). The brachial plexus crosses the first rib and runs under the clavicle, making it vulnerable to stretch injury when the arm is over-abducted or the head is not supported to maintain neutral alignment.
Brachial plexus upper trunk (C5-C6) is the most common position-related nerve injury; prevention requires arm abduction ≤90°, neutral head position, and padded axillary roll in the lateral decubitus position.
The key mechanism here is stretch from arm over-abduction in the lateral position. The radial nerve is injured at the spiral groove by direct compression (e.g., arm hanging off the table). The ulnar nerve is compressed at the medial epicondyle. The common peroneal nerve is at risk at the fibular head in lithotomy — not relevant here. Brachial plexus upper trunk injury from stretch is the answer.
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During a prolonged lithotomy procedure, a patient develops compartment syndrome of the lower leg postoperatively. Which haemodynamic mechanism most directly contributed to this complication?
In the lithotomy position, venous pooling occurs in the raised legs during prolonged procedures, and reperfusion oedema occurs when the legs are lowered at the end of surgery. This raises intracompartmental pressure above the perfusion threshold, causing compartment syndrome. The mechanism is ischaemia-reperfusion, not simple arterial hypotension.
Lithotomy-related compartment syndrome is a two-hit injury: venous stasis during prolonged elevation + reperfusion oedema on lowering. Risk increases with procedures exceeding 4 hours; preventive measures include limiting elevation time and gradual leg lowering.
Compartment syndrome in lithotomy results from venous stasis during the elevated-limb phase followed by reperfusion oedema when legs are lowered — a two-hit mechanism. Hypotension is a contributing factor but not the primary driver. Stirrups cause nerve compression injuries, not compartment syndrome. Elevated position actually impairs venous return (not increases it).
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A 70-year-old patient with a BMI of 39 kg/m² is anaesthetised in the supine position for an elective inguinal hernia repair. During the procedure, the pulse oximetry drops to 88% and airway pressures rise. Which perioperative hazard is MOST likely responsible?
Obesity causes cephalad diaphragm displacement and reduced functional residual capacity (FRC). Under general anaesthesia in the supine position, this effect is amplified, rapidly leading to basal atelectasis, hypoxaemia, and increased airway resistance. This is one of the most predictable perioperative hazards in obese patients.
Obese patients under GA in the supine position rapidly develop atelectasis due to reduced FRC and cephalad diaphragm shift; perioperative hazard prevention includes recruitment manoeuvres, PEEP, head-up tilt, and minimising GA duration.
The combination of obesity, supine position, and general anaesthesia points strongly to atelectasis. Endobronchial intubation would be unilateral and detected at intubation. Venous air embolism causes cardiovascular collapse with a mill-wheel murmur. Tension pneumothorax produces tracheal deviation and hemodynamic instability. Atelectasis from diaphragm displacement is the most likely mechanism here.
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As part of the WHO Surgical Safety Checklist, which action is performed during the 'Sign Out' phase at the end of a procedure?
The Sign Out phase (performed before the patient leaves the operating room) includes: confirmation of the procedure performed, instrument/swab/needle count, specimen labelling, and any equipment concerns. This is distinct from the Sign In (patient identity, site, consent, allergies) and Time Out (team introductions, critical concerns) phases.
WHO Surgical Safety Checklist has three phases: Sign In (before induction), Time Out (before incision), and Sign Out (before patient leaves). The Sign Out specifically verifies procedure name, counts, specimens, and any equipment concerns — reducing retained surgical items and handover errors.
Each phase of the WHO checklist has distinct responsibilities. Sign In = patient identity and consent confirmation (before induction). Time Out = team introductions, procedure/site confirmation, antibiotic check (before incision). Sign Out = procedure name, counts, specimens (before patient leaves OR). The answer describes Sign Out functions.
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During handover of a post-operative patient to the recovery room nurse, the anaesthetist uses the SBAR format. What does the 'R' in SBAR stand for, and what information should it include?
SBAR stands for Situation, Background, Assessment, Recommendation. The 'R' (Recommendation) specifies the concrete actions the sender wants the receiver to take — e.g., 'please monitor oxygen saturation closely, administer ondansetron 4 mg IV if nausea occurs, and call me if urine output falls below 30 mL/hour.' This closes the communication loop with actionable instructions.
SBAR (Situation-Background-Assessment-Recommendation) is a validated structured handover tool. The Recommendation component is critical — it converts clinical information into explicit requested actions, reducing errors of omission during high-risk handovers such as anaesthetic recovery room transfer.
SBAR is a structured communication tool: Situation (what is happening now), Background (relevant context), Assessment (the sender's clinical interpretation), Recommendation (specific requested actions). The 'R' is Recommendation — actionable requests to the receiving team, not a risk list or drug record.
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An anaesthetic nurse who observes the surgeon about to make an incision at the wrong site hesitates to speak up because the surgeon is a senior professor known for not tolerating interruptions. This scenario BEST illustrates which communication failure in the perioperative setting?
Hierarchy-induced silence occurs when junior or non-physician team members fail to voice safety concerns because of perceived authority or fear of negative consequences from senior colleagues. It is the single most common reason why correct information fails to prevent an adverse event in the operating theatre — the information existed but was suppressed by the social hierarchy.
Hierarchy-induced silence contributes to over 70% of sentinel events in operating theatres. Mitigation includes an explicit culture of 'every team member is expected to speak up for safety,' structured assertive communication scripts (e.g., 'I need you to stop and verify the site'), and anonymous reporting systems.
Broken closed-loop communication is when a message is sent but not acknowledged or actioned. Fixation error is when a clinician locks onto one diagnosis and ignores contradicting data. Cognitive overload occurs when an individual receives more information than they can process. This scenario specifically depicts a competent team member self-silencing due to perceived authority — the classic hierarchy-induced silence pattern.
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A patient receives vecuronium 10 mg IV instead of the intended vecuronium 1 mg. On investigation, it was found that the 10-mg vial was stored adjacent to a 1-mg syringe of the same drug in an unlabelled tray. This error is BEST classified as which type of medication error?
This is a dose administration error, specifically a look-alike/sound-alike (LASA) medication error facilitated by similar packaging and proximity storage. The correct dose was known (1 mg), but the wrong vial (10 mg) was drawn and given because it was stored adjacently without clear visual differentiation. This is a systems-level vulnerability — unlabelled trays and LASA storage are the latent conditions.
Look-alike/sound-alike (LASA) drug proximity errors are a leading cause of anaesthetic medication errors; prevention includes colour-coded labels, standardised drug tray layouts, separate storage of LASA agents, and individual syringe labelling immediately upon preparation.
The error occurred at the administration step, not prescribing (the intended dose was correct) or transcription. The LASA + proximity storage created the conditions for this dose error. Monitoring error would describe a failure to detect the wrong dose after it was given — a separate issue. The primary error here is at the administration stage.
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An anaesthetist intends to give metoprolol 5 mg IV for intraoperative tachycardia but inadvertently draws up metaraminol 5 mg (both ampoules are clear, colourless, and appear similar). The anaesthetist administers the full syringe before checking the label. This event MOST closely represents which type of error according to James Reason's classification?
A slip is an error of execution in which the plan was correct but the action was performed incorrectly — the anaesthetist intended the right drug (metoprolol) but picked the wrong vial. Slips are often facilitated by look-alike appearance, distraction, or automaticity in familiar tasks. Reason's taxonomy: mistakes = wrong plan; lapses = omissions; slips = wrong execution; violations = deliberate rule-breaking.
Slips (errors of execution) are the most common type of medication error in anaesthesia and are amenable to system-level fixes: standardised labelling, separation of LASA agents, and mandatory read-back before administration. Individual vigilance alone is insufficient to prevent slips.
The anaesthetist had the correct therapeutic intention (treat tachycardia with metoprolol) — so this is not a mistake (wrong plan). Nothing was forgotten (not a lapse). No rule was deliberately broken (not a violation). The error occurred at execution — the wrong vial was picked because of look-alike appearance. This is the textbook definition of a slip in Reason's human error taxonomy.
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