AS10.1-4 | Patient Safety in Anaesthesiology — Glossary

An error committed by the healthcare worker directly in contact with the patient at the moment of the incident — the anaesthesiologist who injects the wrong drug; produces immediate, visible harm but is typically the final, unguarded step in a chain of latent failures.

A six-category (I–VI, with 'E' suffix for emergency) scale grading a patient's severity of pre-existing systemic disease as one input into perioperative risk estimation; it does NOT grade operative complexity or predicted anaesthetic difficulty.

A cylindrical pad placed under the chest wall just caudal to the axilla (not under the axilla itself) when a patient is positioned in the lateral decubitus position, designed to protect the brachial neurovascular bundle of the dependent arm from compression by the thorax.

A positioning-related peripheral neuropathy arising from longitudinal or lateral tension on the C5-T1 nerve roots or trunk, most commonly from arm abduction >90°, lateral neck deviation, or downward shoulder stretch in the lateral decubitus position.

A validated six-domain tool (sensory perception, moisture, activity, mobility, nutrition, friction/shear; scored 6–23) used to stratify pressure-injury risk; scores ≤18 indicate need for additional preventive measures.

A validated clinical scoring system that assigns point values to approximately 40 venous thromboembolism risk factors, categorising surgical patients into low, moderate, and high risk to guide thromboprophylaxis intensity and timing.

Acute obstruction of the central retinal artery, most commonly caused by direct external pressure on the globe compressing the intraocular vessels — a positional emergency requiring immediate correction of the pressure source and ophthalmological assessment.

A three-step communication cycle in which the sender states a request explicitly (drug, dose, route), the receiver repeats it back verbatim for confirmation, and the sender explicitly confirms; any break in the loop constitutes a communication failure.

A surgical emergency in which raised pressure within an osteofascial compartment (>30 mmHg, or ΔP <30 mmHg) causes ischaemia of the enclosed muscle and nerves; in the operative setting it most commonly affects the calves in prolonged lithotomy and requires fasciotomy.

A training framework adapted from aviation that teaches healthcare teams to use all available resources, communicate assertively across hierarchy gradients, share situational awareness, and debrief after adverse events; shown to reduce communication-related errors in operating theatres.

Programmable algorithms embedded in smart infusion pumps that cross-reference the entered drug, concentration, weight, and dose against a validated drug library and alert the user when a programmed infusion rate is outside the acceptable range for that drug-weight combination.

An error of omission is the failure to take a required action (not administering prophylactic antibiotics before incision); an error of commission is the performance of an incorrect action (administering a drug to the wrong patient); both categories cause preventable harm.

A human-factors design strategy that makes it physically impossible or extremely difficult to perform an unsafe action — e.g., using non-interchangeable connectors on nitrous oxide and oxygen pipelines so that the gases cannot be accidentally transposed; the highest-reliability level of error prevention.

The volume of gas remaining in the lungs at the end of a normal passive expiration; reduced by the supine position, general anaesthesia, obesity, and pregnancy, predisposing to atelectasis and hypoxaemia.

An organisational philosophy that distinguishes between honest errors (to be learned from without punishment) and reckless or negligent behaviour (subject to accountability), creating the psychological safety required for healthcare workers to report near misses and adverse events without fear.

A systemic deficiency in design, organisation, staffing, training, or maintenance that creates the conditions in which active errors occur — e.g., storing LASA drug ampoules in the same drawer; the true root cause of most adverse events, addressable only by system redesign.

Drug pairs whose ampoule appearance, labelling, or names are visually or phonetically similar, making confusion in preparation or administration probable without specific precautions; examples in anaesthesia include adrenaline/oxytocin, vecuronium/vasopressin, neostigmine/suxamethonium.

A four-class (I–IV) scale that grades the oropharyngeal view during mouth opening with tongue protrusion, used to predict difficult direct laryngoscopy; distinct from the ASA physical-status scale, which grades systemic disease.

The failure of a planned action to be completed as intended (error of execution) or the use of a wrong plan to achieve an aim (error of planning); defined by the Institute of Medicine report 'To Err is Human' (1999) and framed as a predictable product of defective systems rather than solely of individual negligence.

Any preventable event that may cause or lead to inappropriate medication use or patient harm while the medication is in the control of the healthcare professional or patient; classified in anaesthesia as wrong drug, dose, route, patient, time, or concentration.

An error or unsafe condition that was detected and corrected before reaching the patient, or that reached the patient without causing measurable harm; the most important learning resource in patient safety because near misses reveal system vulnerabilities at a stage when correction is still possible.

A patient-centred, evidence-based bundle of strategies to reduce unnecessary transfusion, including pre-operative anaemia optimisation, surgical haemostasis techniques, autologous salvage, and restrictive transfusion triggers (Hb ~7–8 g/dL in most elective surgical patients).

The time span encompassing preoperative preparation (from decision to operate), intraoperative management, and postoperative recovery through the point of hospital discharge or 30 days post-procedure, during which the anaesthesiologist has a continuous patient-safety responsibility.

Ischaemic infarction of the retrobulbar (posterior) optic nerve, occurring without direct orbital pressure, caused by reduced optic nerve perfusion in settings of hypotension, anaemia, and prone positioning — a rare but potentially permanent cause of postoperative blindness.

The core temperature drop of 1–1.5°C occurring in the first 30–60 minutes after induction of general or neuraxial anaesthesia, caused by anaesthetic-induced vasodilation shunting warm core blood to the cooler periphery, not by heat loss to the environment.

A structured clinical communication tool: Situation (what is happening now), Background (relevant clinical context), Assessment (the communicator's clinical interpretation), Recommendation (what action is requested); used at handovers, escalation calls, and critical communications.

An accurate, shared mental model of the current state of the patient and environment, including what has happened, what is happening now, and what is likely to happen next; degraded situational awareness (from poor briefing, distraction, or information siloing) is a precursor to most clinical crises.

A conceptual model of accident causation (James Reason, 1990) in which multiple defensive barriers each have weaknesses (holes); harm results when holes in multiple layers align simultaneously, allowing an error trajectory to pass through all defences to the patient.

A drug-labelling strategy that capitalises the distinguishing letters of look-alike/sound-alike drug name pairs (e.g., vecuRONIUM vs vasoprESSIN) to make visual differentiation easier; recommended by the ISMP and WHO as a low-cost, evidence-supported intervention.

An antifibrinolytic agent (lysine analogue) that competitively inhibits plasminogen binding to fibrin; shown in the CRASH-2 trial to reduce all-cause mortality and haemorrhagic mortality in trauma when given within 3 hours of injury.

A crew-resource-management principle requiring any team member who identifies a safety concern to raise it assertively at least twice; if not acknowledged, the team member is empowered to escalate or stop the unsafe action, regardless of seniority.

Entry of air into an open venous sinus or large vein, most hazardous in the sitting (beach-chair) position during posterior cranial fossa surgery where open dural venous sinuses are above the level of the heart; produces a 'mill-wheel' murmur and cardiovascular collapse.

The three predisposing factors for venous thrombosis: venous stasis (reduced flow), endothelial injury, and hypercoagulability; all three are amplified in the perioperative period by immobility, surgical trauma, and the stress-response coagulation cascade.

A structured three-pause patient-safety tool (Sign-In before induction, Time-Out before incision, Sign-Out before leaving theatre) introduced globally in 2009, shown in an eight-site RCT to reduce major complications by 36% and in-hospital mortality by 47%.