description
Clinical Response
"framework as applied to error prevention in anaesthesia [4]. Explain the WHO Surgical Safety Checklist and the role of
critical incident reporting in improving patient safety [3].
⚙
Core Concept
Anaesthesia is intrinsically a high-risk, high-reliability industry — the anaesthetist administers potent drugs with narrow therapeutic indices to unconscious
patients who cannot report symptoms. Drug errors are the most common preventable cause of anaesthetic harm — estimated to occur in 1 in 133
anaesthetics (Webster 2001). The human factors approach (from aviation safety science) and structured systems interventions (WHO Checklist, AIMS)
have transformed patient safety.
(Webster CS — drug error incidence; Reason J — Swiss Cheese Model; WHO Surgical Safety Checklist 2009;
NPSA/NRLS; NAP reports; Flin R — human factors in anaesthesia)
A. Types and Causes of Drug Errors in Anaesthesia
3 marks
Incidence:
Webster et al. (2001): drug administration errors in 1 in 133 anaesthetics (0.75%); Orser et al. (2001): 1 in 10 hospital drug orders contain an error;
Merry et al.: systematic review suggests drug errors may be even more frequent — many go undetected; approximately 1 in 300 anaesthetic drug errors
results in serious patient harm
Error Type
Definition
Anaesthetic Examples
Frequency
Wrong drug
(substitution
error)
A drug different from
the one intended is
administered
Suxamethonium given instead of vecuronium (both clear solutions, adjacent on the trolley);
adrenaline 1:1,000 instead of 1:10,000 (10× overdose); morphine instead of midazolam (similar
syringe labelling)
Most common drug error
class — ~40% of all
anaesthetic drug errors
Wrong dose
Correct drug but
incorrect amount
Paediatric weight-based dosing errors (e.g., propofol 200 mg instead of 20 mg due to decimal
error); neostigmine 5 mg instead of 2.5 mg; 10-fold concentration errors with infusions (e.g.,
noradrenaline concentration mix-up)
~25% of errors; most
dangerous in paediatrics and
high-alert drugs
Wrong route
Drug given by an
unintended route
Epidural drug given IV (e.g., concentrated KCl intended for epidural, given IV); IV drug given
epidurally; oral drug given IV; IV potassium chloride bolus (classic fatal error)
Rare but frequently fatal —
wrong-route errors have
disproportionate harm
Wrong
patient
Drug intended for
one patient given to
another
Allergy-listed drug administered after a handover; blood transfusion ABO mismatch (wrong
patient — see SHOT)
Rare in anaesthesia; more
common in ward drug
administration
Omission
errors
Failure to give a
required drug
Failure to give antibiotic prophylaxis; failure to give thromboprophylaxis; failure to give reversal
agent
Common and often
undetected — particularly
antibiotic timing errors
Timing
errors
Drug given at the
wrong time
Antibiotic given 2h after incision (prophylaxis window missed); anticoagulant given too early
after neuraxial block
Significant — timing of
antibiotics critically affects SSI
rates
Root Causes of Drug Errors (Reason's Error Taxonomy)
Slips and lapses (skill-based errors):
errors of execution in a well-known task — attention failure; e.g., picking up the wrong ampoule during induction under
cognitive pressure; most drug substitution errors are slips
Mistakes (rule/knowledge-based errors):
wrong intention even if execution is correct; e.g., choosing an incorrect dose of a drug (knowledge error), or
applying a rule incorrectly (rule-based error)
Violations:
deliberate deviation from rules or protocols; e.g., bypassing the drug check because of time pressure
Contributory system factors:
look-alike/sound-alike (LASA) drugs on the same shelf; similar ampoule appearance; illegible handwriting; unlabelled syringes;
workload and fatigue; interruptions during drug preparation; inadequate monitoring
B. Human Factors Framework in Anaesthesia
4 marks
⚙
Core Concept
Human factors (also: ergonomics) is the scientific discipline that studies the interaction between humans and the systems they work within — with the goal
of optimising human performance and reducing errors. In anaesthesia, human factors analysis recognises that the vast majority of ""human errors"" are
precipitated or enabled by system failures, not personal failings.
(Reason J — Human Error 1990; Helmreich RL — aviation safety to medicine; Flin R;
RCOA human factors in anaesthesia)
James Reason's Swiss Cheese Model
Every defensive barrier in a system (training, protocols, checklists, monitoring, double-checks) has ""holes"" (weaknesses, failures); normally multiple barriers
overlap and holes do not align; an adverse event occurs when all barriers fail simultaneously — holes align to create an uninterrupted pathway from hazard to
harm; the key implication: errors are rarely the result of a single person failing — they result from system-wide weaknesses aligning; blame of the ""sharp-end""
individual is counterproductive — the ""blunt-end"" (organisational, management, design) failures must be addressed
Human Factors
Domain
Application to Anaesthetic Drug Error Prevention
Situational
awareness (SA)
The ability to perceive what is happening (Level 1), understand its meaning (Level 2), and project future states (Level 3); maintaining SA requires
active scanning — checking monitors, reassessing drug labels, anticipating the next step; SA loss (""fixation error"") is a common precursor to drug
errors in crisis situations (e.g., cardiac arrest → fixating on defibrillation → missing a drug dose error)
Cognitive aids
(checklists,
protocols)
Working memory is limited — under stress, normal cognitive capacity reduces dramatically; checklists offload memory to the system; WHO Surgical
Safety Checklist; Stanford Emergency Manuals (Delphi-developed crisis checklists for MH, AFE, anaphylaxis, LAST); ISBAR handover structure;
colour-coded syringe labels (AAGBI/ISO standard: opioids = blue, muscle relaxants = orange/red, hypnotics = yellow)
Communication
and teamwork
Closed-loop communication — the receiver confirms receipt and reads back what was heard; avoids ""errors of commission"" where a drug is given
because of a miscommunication; crew resource management (CRM) — aviation-derived: speak up culture, assertive follower (anyone in the team can
challenge a decision), formal challenge-and-response for drug preparation; pre-operative briefing + debriefing (part of WHO checklist)
Drug labelling
and workspace
design
AAGBI recommendation: ALL syringes labelled before use with drug name, concentration, date/time, preparer; pre-filled labelled syringes reduce
preparation errors; separate storage locations for LASA drugs (different shelf, staggered, coloured alerts); use of 10 mL syringes for IV and 20 mL
syringes for epidural — prevents wrong-route errors (Luer-lock vs non-Luer connectors for epidural/enteral lines — NPSA guidance: use NRFit
connector for neuraxial routes since 2020 — physically impossible to connect to an IV line)
Fatigue and
workload
management
Sleep deprivation → ↓ cognitive performance equivalent to alcohol intoxication at 24h awake; European Working Time Directive (max 48h/week)
partially addresses this; handover standardisation (ISBAR) critical during fatigue-associated periods (night shifts, long cases)
Simulation
training
Deliberate practice of rare, high-stakes events in a safe environment → builds pattern recognition and practised responses; simulation for malignant
hyperthermia, anaphylaxis, LAST, laryngospasm, cannot intubate/cannot oxygenate — converts a novel scenario to a familiar one; reduces errors from
""first time in real life"" unpreparedness
C. WHO Surgical Safety Checklist & Critical Incident Reporting
3 marks
WHO Surgical Safety Checklist (2009)
Background:
developed by WHO as part of the Safe Surgery Saves Lives initiative (2008); Haynes et al. (NEJM 2009): implementation of the checklist in 8
hospitals globally → ↓ in-hospital mortality from 1.5% to 0.8% (47% reduction); ↓ complication rate from 11% to 7%; became mandatory in NHS England from
February 2010
Three phases of the checklist:
Sign In (before induction):
patient confirmed identity, site, procedure, consent; site marked if applicable; anaesthesia machine and drugs checked;
pulse oximeter applied and working; patient allergy check; difficult airway/aspiration risk assessment; blood loss >500 mL anticipated (≥7 mL/kg in
children) — blood/fluids/warming equipment available?
Time Out (before skin incision — ENTIRE TEAM pauses):
confirmation of patient, procedure, site; surgeon, anaesthetist, nurse introduce themselves
by name and role; surgeon states anticipated critical steps, blood loss, specific concerns; anaesthetist states specific patient concerns; nurse confirms
sterility, equipment, other concerns; prophylactic antibiotic confirmation (given within last 60 minutes)
Sign Out (before patient leaves operating room):
nurse verbally confirms: procedure name recorded; instrument/swab/needle counts correct;
specimen labelling; equipment problems to address; surgeon, anaesthetist, nurse review key recovery/post-op concerns
Critical Incident Reporting
Definition (Heinrich, aviation → medicine):
a critical incident is any event or situation which did, or could have, led to unintended harm to a patient; includes
""near misses"" (prevented from causing harm by chance or intervention) — near misses are particularly valuable learning resources because they reveal
system failures before harm occurs
UK reporting systems:
NRLS (National Reporting and Learning System) — national NHS incident reporting; AIMS (Anaesthesia Incident Monitoring Study —
Australian/NZ; now global); SHOT (haemovigilance); NAP reports (National Audit Projects — RCOA/AAGBI — large-scale prospective audits: NAP3 [neuraxial
complications], NAP4 [airway complications], NAP5 [awareness], NAP6 [anaphylaxis], NAP7 [perioperative cardiac arrest])
Principles of effective reporting systems:
anonymous + non-punitive (Reason: ""blame-free culture"" — individuals report without fear of repercussion → ↑
reporting → more learning); standardised (structured report format); confidential; timely feedback to reporters (closes the learning loop); systemic analysis (root
cause analysis — Ishikawa fishbone diagram identifies: people, methods, machines, materials, measurement, environment contributing to an error); shared
learning nationally and internationally
Morbidity and Mortality (M&M) meetings:
departmental case review of adverse events; culture shift from ""name, blame, shame"" to systems analysis and
learning; Safer Anaesthesia From Education (SAFE) — RCOA initiative promoting simulation and human factors training to reduce preventable harm
Viva Corner
Q.
A colleague draws up what they believe is vecuronium but actually draws up suxamethonium — the patient receives it unexpectedly. Analyse this event
using a human factors framework and outline what system changes could prevent recurrence.
This is a classic wrong-drug (substitution) error — a slip-type error at the sharp end of care, but with multiple blunt-end system vulnerabilities. Analysis: (1)
Immediate causation: the two ampoules are likely to be LASA (look-alike, sound-alike) — similar clear solutions, similar vial appearance, stored proximally; under the
cognitive load of induction, pattern recognition shortcuts (""this ampoule is the right shape and is in the right location"") replaced careful label reading — a predictable
consequence of human cognitive architecture, not personal incompetence. (2) Contributing system factors: ampoules stored together or in similar locations; no
double-check protocol for neuromuscular blocking agents (high-alert drugs); no colour-coding or physical differentiation; time pressure at induction; no independent
check by another team member. (3) Swiss Cheese analysis: multiple barriers (labelling system, storage separation, double-check, ampoule colour differentiation) all
had holes that aligned — any one of these intact would have prevented the error. Recommended system changes: (a) Physical separation — suxamethonium stored
in a locked refrigerator separately from other NMBDs; (b) Colour-coded labels — all NMBDs labelled with the AAGBI/ISO standard orange/red neuromuscular
blocking agent sticker — applied during preparation; (c) ""Tall Man"" lettering — sUXAMethonium vs VECURONIUM — emphasises distinguishing letters; (d) Pre-
drawn labelled syringes — using pharmacy-prepared standardised syringes where possible; (e) Double-check protocol for all high-alert drugs (NMBDs, high-
concentration electrolytes, epidural drugs) — a second team member independently confirms drug and dose before administration; (f) Dedicated NMBD labelling —
a bright orange warning sticker on all NMBD syringes reading ""NEUROMUSCULAR BLOCKING AGENT — CAUSES PARALYSIS""; (g) Simulation training for drug
error recognition and management; (h) Incident report submitted to NRLS — data feeds into national learning and may trigger NPSA alert if a pattern is identified.
★
Examiner's Pearl
Drug error incidence: 1 in 133 anaesthetics (Webster 2001); wrong drug = most common (40%). Reason's Swiss Cheese: errors occur when holes in multiple defensive
barriers align; blame the system, not the individual. Human factors interventions: syringe labelling (ALL syringes labelled before use); NRFit connector for neuraxial
(prevents wrong-route); LASA drug separation; closed-loop communication; CRM simulation training. WHO Checklist: Sign In + Time Out + Sign Out; Haynes NEJM
2009 — 47% ↓ mortality. Critical incident reporting: anonymous + non-punitive = ↑ reporting + learning. NAP reports: the gold standard of UK anaesthetic adverse event
surveillance.
References:
Webster CS et al. The frequency and nature of drug administration error during anaesthesia (Anaesth Intensive Care 2001;29:494-500). Reason J. Human Error (Cambridge
University Press 1990). Haynes AB et al. WHO Surgical Safety Checklist (NEJM 2009;360:491-499). Flin R et al. Anaesthesists' attitudes to teamwork and safety (Anaesthesia 2006;61:145-
151). NPSA. NRFit neuraxial connectors guidance 2020. RCOA NAP Reports series."
