AS4.1-7 | General Anaesthesia — Glossary

A scoring system (0–10) used in PACU to assess readiness for discharge based on activity, respiration, circulation, consciousness, and SpO₂; discharge typically when score ≥9.

Drug (e.g., neostigmine) that inhibits acetylcholinesterase, increasing acetylcholine at the NMJ to displace non-depolarising NMBAs and restore neuromuscular function.

A 4-point score (1 point each: female, non-smoker, PONV/motion sickness history, postoperative opioids); score 3–4 warrants triple PONV prophylaxis.

Paired pyramid-shaped cartilages sitting on the posterosuperior surface of the cricoid lamina; their vocal processes anchor the posterior ends of the true vocal folds; seen as posterior 'knobs' during laryngoscopy.

A classification of systemic disease severity assigned preoperatively; grades I (healthy) to VI (brain-dead). The 'E' suffix denotes emergency. It grades disease, not operative risk or airway difficulty.

ASA I–III stable are generally suitable for day surgery; ASA IV and unstable ASA III require inpatient setting; the 'E' emergency suffix makes any case inpatient by definition.

Accidental intraoperative consciousness with or without recall; incidence ~0.1–0.2%; risk factors: RSI, light anaesthesia, inadequate NMBA reversal.

The use of multiple agents at lower individual doses to achieve all four components of anaesthesia (unconsciousness, analgesia, amnesia, muscle relaxation), thereby reducing dose-dependent adverse effects.

A processed EEG-derived numerical index (0–100) of anaesthetic depth; target range 40–60 for adequate unconsciousness; >60 risks awareness; <40 risks excessive depth.

A measure of an inhalational agent's solubility in blood; low coefficient means rapid equilibration between alveoli and blood, producing faster induction and emergence.

Continuous measurement of exhaled CO₂ concentration; normal ETCO₂ 35–45 mmHg; gold standard for tracheal tube confirmation; detects apnoea, oesophageal intubation, cardiac arrest, and bronchospasm.

The time for plasma drug concentration to fall 50% after terminating an infusion of a given duration; for remifentanil this is consistently 3–5 minutes regardless of infusion length.

The classification of the laryngoscopic view during direct laryngoscopy: Grade I = full glottis visible; Grade IV = neither epiglottis nor glottis visible.

The only complete cartilaginous ring of the respiratory tract, forming the inferior skeleton of the larynx; its completeness allows Sellick's manoeuvre (cricoid pressure) to occlude the oesophagus.

The fibrous membrane spanning the gap between the inferior border of the thyroid cartilage and the superior border of the cricoid arch, located in the anterior midline of the neck; the access site for emergency surgical airway.

A specific antidote for malignant hyperthermia; inhibits ryanodine receptor calcium release from the sarcoplasmic reticulum; dose 2.5 mg/kg IV repeated as needed.

Planned anaesthesia for surgery or procedures in which the patient is admitted, treated, and discharged home on the same calendar day without an overnight hospital stay.

Neuromuscular blockade produced by suxamethonium via sustained depolarisation of the motor end-plate, characterised by initial fasciculations followed by flaccid paralysis.

A clinical situation in which a trained anaesthesiologist encounters difficulty with mask ventilation, supraglottic device placement, laryngoscopy, intubation, or tracheostomy — requiring a pre-planned staged strategy.

All of: fully awake and oriented; pain score ≤3/10; no active PONV; SpO₂ ≥95% on room air; able to mobilise safely; confirmed adult escort home; written discharge instructions provided.

A cataleptic trancelike state produced by ketamine, characterised by amnesia, analgesia, and immobility with partial preservation of pharyngeal reflexes and heightened sympathetic tone.

The transition from the anaesthetic state back to full consciousness; the second period of maximum physiological vulnerability, requiring systematic management of reversal, extubation criteria, and PACU monitoring.

Specific NORA risks in the endoscopy suite: absence of full anaesthetic machine, shared airspace with operator, carbon dioxide insufflation distension, aspiration risk in GORD/obese patients, limited suction and resuscitation resources.

A cuffed tube placed through the larynx into the trachea under direct or video laryngoscopy to secure and protect the airway during general anaesthesia; position confirmed by capnography.

A mixed alpha- and beta-adrenergic agonist used as a vasopressor during anaesthesia; dose 3–6 mg IV bolus; increases heart rate and blood pressure; preferred when hypotension is associated with bradycardia.

An anaesthetic technique optimised to minimise residual drug effects, enabling patients to meet all discharge criteria within 2–4 hours of procedure completion.

The vocal apparatus of the larynx, comprising the two true vocal folds and the inter-fold space (rima glottidis); the narrowest point of the adult airway.

Spontaneous degradation of atracurium at physiological temperature and pH, independent of organ function; ensures predictable offset in hepatic and renal failure.

Mechanical ventilation delivered by the anaesthetic machine, pushing gas into the lungs at set tidal volumes; standard during general anaesthesia with ETT.

A supraglottic airway device inserted into the laryngopharynx without laryngoscopy; avoids the need for NMBAs and ETT; preferred for suitable day surgery cases (non-aspiration risk, no muscle relaxation required).

Ventilatory strategy using low tidal volumes (6–8 mL/kg ideal body weight) and PEEP to reduce ventilator-induced lung injury; standard practice during general anaesthesia.

The curved laryngoscope blade whose tip is placed in the vallecula; indirect epiglottis elevation by anterior lifting force on the glossoepiglottic fold; most widely used in adults.

A life-threatening pharmacogenetic hypermetabolic crisis of skeletal muscle triggered by volatile anaesthetics and suxamethonium in susceptible individuals (RYR1 mutation); treated with dantrolene.

A bedside assessment of the oropharyngeal view with the patient awake, mouth fully open, and tongue protruded, used to predict difficulty with laryngoscopy. Entirely distinct from ASA physical status.

The straight laryngoscope blade that passes posterior to the epiglottis and directly lifts it to expose the glottis; preferred in neonates and young infants where the epiglottis is large, floppy, and omega-shaped.

The alveolar concentration of an inhalational anaesthetic at 1 atm at which 50% of patients do not move in response to a standard surgical (skin incision) stimulus; a measure of potency.

Equipment verified to be non-ferromagnetic and free of electromagnetic interference risks within the MRI magnetic field; required for all items brought into Zone III/IV of an MRI suite.

Combining analgesics with different mechanisms (paracetamol, NSAIDs, local anaesthetics, opioids as rescue) to achieve effective pain control while minimising opioid-related side effects including PONV and sedation.

Mechanism by which ketamine and nitrous oxide reduce central sensitisation; ketamine at sub-anaesthetic doses provides analgesia via this mechanism as part of multimodal analgesia.

Competitive antagonism of nicotinic acetylcholine receptors at the NMJ by agents such as vecuronium or rocuronium, producing flaccid paralysis without fasciculations.

Anaesthesia administered outside the traditional operating suite — in radiology, endoscopy, cath lab, radiotherapy, or emergency departments; associated with higher complication rates due to resource constraints.

A relative contraindication to day surgery due to increased sensitivity to opioids and sedatives and postoperative apnoea risk; STOP-Bang score ≥5 warrants extended PACU observation or inpatient admission.

Paradoxical increase in pain sensitivity following prolonged high-dose opioid use, particularly remifentanil; may require multimodal strategies and opioid rotation.

Phase 1 = immediate PACU monitoring until return of consciousness and stability; Phase 2 = step-down lounge until discharge criteria are met for home discharge.

A selective alpha-1 adrenergic agonist; dose 50–100 mcg IV; increases SVR and blood pressure without increasing heart rate; preferred when hypotension occurs with tachycardia.

A recess on each side of the larynx between the thyroid cartilage and the lateral hypopharyngeal wall; contains the internal laryngeal nerve; a misdirected laryngoscope blade may enter the piriform fossa.

An enzyme present in plasma (not the NMJ) that metabolises suxamethonium and mivacurium; deficiency leads to prolonged neuromuscular block.

The most common postoperative complication (~30%); risk factors: female sex, non-smoker, PONV/motion sickness history, opioids, volatile anaesthetics; prophylaxis: ondansetron, dexamethasone.

Standard pharmacological prevention of PONV using ondansetron 4–8 mg IV ± dexamethasone 4–8 mg IV; TIVA with propofol is itself antiemetic.

Analgesic medication given before surgical incision (e.g., paracetamol + NSAID 1 hour before) to reduce central sensitisation and postoperative pain — reduces intraoperative and postoperative opioid requirements.

Administration of 100% O₂ by tight-fitting mask for 3–5 minutes before induction; denitrogenates the functional residual capacity, extending the safe apnoea window to 3–5 minutes.

An induction technique designed to minimise aspiration risk; involves preoxygenation, fentanyl, induction agent, and rapid-onset NMBA (suxamethonium or high-dose rocuronium) with cricoid pressure.

An ultra-short-acting opioid (context-sensitive half-time 3–5 min regardless of infusion duration) used intraoperatively in TIVA; its rapid offset necessitates pre-emptive post-procedure analgesia before infusion discontinuation.

Application of backward pressure on the cricoid cartilage to occlude the oesophagus and reduce aspiration risk during rapid-sequence induction; remains controversial but widely used.

The combination of neck flexion on the thorax and head extension at the atlanto-occipital joint that aligns the three airway axes to optimise the direct laryngoscopic view.

The space immediately below the true vocal cords, extending to the lower border of the cricoid cartilage; the narrowest fixed point of the paediatric airway (age <8–10 years).

A modified gamma-cyclodextrin that reverses steroidal non-depolarising NMBAs (rocuronium > vecuronium) by encapsulation, without muscarinic side effects.

The alignment of the oral, pharyngeal, and laryngeal axes into a single straight line achieved by the sniffing position, enabling direct laryngoscopic visualisation of the glottis.

The distance from the chin (mentum) to the thyroid notch with the head fully extended; <6 cm indicates an anteriorly placed larynx and predicts potential difficulty with direct laryngoscopy.

Anaesthetic maintenance using entirely intravenous agents (typically propofol + remifentanil infusion) without volatile agents; preferred in day surgery for reduced PONV and rapid, clean emergence.

A neuromuscular monitoring technique using four supramaximal stimuli at 2 Hz; a TOF ratio ≥0.9 indicates adequate recovery of neuromuscular function and safe extubation.

Three scroll-shaped bony projections (superior, middle, inferior) on the lateral wall of the nasal cavity; the inferior turbinate is most relevant to nasal airway instrumentation — tubes must pass below it along the floor of the nose.

The portion of the airway from the nasal and oral openings to and including the larynx; the segment managed by mask ventilation and laryngoscopy.

The recess between the base of the tongue and the anterior surface of the epiglottis; the target for the tip of the curved (Macintosh) laryngoscope blade in direct laryngoscopy.