Anaesthetics Fundamentals Vocabulary

Vocabulary and key clinical concepts for novice anaesthetic trainees covering induction, monitoring, ventilation, and emergencies.

Anaesthetic

A term derived from the Greek word for ‘loss of sensation’, referring to any of the five ways to bring about the loss of sensation.

Local Anaesthesia

A type of anaesthesia used to numb the procedural site, which can be performed by a surgeon without an anaesthetist.

Regional Anaesthesia

Also referred to as ‘nerve blocks’, involving the injection of local anaesthetic close to a specific nerve or plexus.

Spinal Anaesthesia

A procedure where a needle is passed between lumbar vertebrae into the subarachnoid space to inject drugs before being removed.

Epidural Anaesthesia

The placement of a small catheter into the epidural space, allowing drug boluses or infusions over a long timeframe.

General Anaesthesia (GA)

A technique where the patient is made unconscious, varying by the type of airway used and the induction sequence.

Definitive Airway

An airway provided by an endotracheal tube (ETT) that features an inflatable balloon sitting below the vocal cords to protect against aspiration.

Regurgitation

The passive movement of gastric contents into the pharynx.

Aspiration

The entry of liquid or solid material (such as gastric contents) into the trachea and lungs.

Delayed Sequence Induction (DSI)

A slower induction sequence used in elective procedures for patients at low risk of regurgitation or aspiration.

Rapid Sequence Induction (RSI)

An induction common in emergency cases, designed to minimize the time between loss of consciousness and ETT placement to prevent aspiration.

ASA Score

The American Society of Anesthesiologists score used to assess a patient’s physical status and risk; the scale ranges from $1$ (fit and well) to $6$ (brain-dead donor).

Spontaneous Ventilation (SV)

A mode of anaesthesia where the patient maintains their own respiratory effort during the procedure.

Invasive Positive Pressure Ventilation (IPPV)

Also known as ‘controlled ventilation’, where the ventilator performs the breathing because the patient does not maintain their own effort.

Initial Assessment of Competence (IAC)

The assessment suggesting a trainee has covered required skills during the novice period and is ready for work on-call.

Entrustable Professional Activity (EPA)

Descriptors of clinical work used to record progress, such as EPA 1 (pre-operative assessment) and EPA 2 (general anaesthesia for ASA 1/2 patients).

BONES Mnemonic

A tool used to predict difficult facemask ventilation: Beard, Obesity, No teeth, Elderly ($>55$), and Snoring.

LEMON Mnemonic

A tool used to predict difficult intubation: Look externally, Evaluate 3-3-2, Mallampati, Obstruction, and Neck mobility.

3-3-2 Rule

Airway measurement criteria: Mouth opening (at least $3$ fingers), hyomental distance (at least $3$ fingers), and thyroid notch to mandible (at least $2$ fingers).

Mallampati Score

A grading based on how much of the soft palate is visible with the patient sitting, maximal mouth opening, and tongue protrusion.

Apfel Score

An assessment of four factors (female, non-smoker, history of motion sickness/PONV, and post-op opioids) to estimate the risk of post-operative nausea and vomiting.

NELA Score

A risk score estimating the 30-day risk of morbidity and mortality for patients undergoing emergency laparotomy.

Circle System

A common breathing circuit where gas flows in a closed loop, recirculating gases and requiring the removal of CO2.

Adjustable Pressure Limiting (APL) Valve

A one-way valve that allows gas to leave the circle system, used to generate positive inspiratory pressure when ventilating by hand.

Auxiliary Common Gas Outlet (ACGO)

A port and switch (the 'switch of death') used to deliver gases to a non-circle breathing system.

Oxygen Flush

A button providing $100\%$ oxygen at $400\,kPa$ and $35–75\,L/min$ directly into the circuit, bypassing vaporisers.

Metaraminol

A predominant $\alpha_1$-agonist used to treat hypotension by increasing Systemic Vascular Resistance (SVR).

Ephedrine

A drug with direct and indirect $\alpha_1$ and $\beta$-agonist effects that increases both SVR and Heart Rate (HR).

Glycopyrronium

An antimuscarinic (mAChR antagonist) commonly used to treat bradycardia by increasing heart rate.

Waveform Capnography

The gold standard for confirming tracheal intubation, detecting CO2 concentration over the patient's respiratory cycle.

End-tidal CO2 (EtCO2)

The concentration of carbon dioxide at the end of expiration; normal levels are $4.5–5.5\,kPa$.

Dead Space

Portions of the lung that are ventilated but where gas exchange does not take place, causing arterial CO2 to be higher than EtCO2.

PEEP

Positive End-Expiratory Pressure; alveolar pressure above atmospheric pressure that holds alveoli open at the end of expiration.

Lung Compliance

The ease with which the lungs can be inflated, calculated as the change in volume for a given change in pressure.

Lung-Protective Ventilation

A strategy using small tidal volumes ($6\,ml/kg$) and PEEP to prevent ventilator-induced lung injury.

The Triad of Anaesthesia

The three goals of balanced anaesthesia: Hypnosis (unconsciousness), Analgesia, and Immobility in response to noxious stimuli.

Co-induction

The process of using a combination of drugs (e.g., fentanyl and propofol) to exploit synergy and reduce the dose of the induction agent.

Functional Residual Capacity (FRC)

The volume of gas left in the lungs at the end of a normal, passive expiration; it acts as an oxygen reservoir during apnoea.

Nitrogen Washout

The process of replacing nitrogen in the FRC with oxygen during pre-oxygenation to increase safe apnoea time.

Sterile Flightdeck

A concept adapted from aviation prohibiting non-essential activity/conversations during critical stages like induction and emergence.

MAC

Minimum Alveolar Concentration; the concentration of volatile agent in the alveoli required to prevent movement to standard stimulus in $50\%$ of patients.

The Second Gas Effect

The acceleration of volatile onset when nitrous oxide is used as a carrier gas due to its relative solubility in blood.

Accidental Awareness during General Anaesthesia (AAGA)

Unintended patient perception during general anaesthesia, divided into explicit (conscious recollection) and implicit (subconscious) memory.

Atracurium

A non-depolarising muscle relaxant that is a competitive antagonist at nACh receptors and undergoes organ-independent Hoffman elimination.

Lithotomy Position

A patient position (supine with legs flexed in supports) that carries risks for lower limb nerve injury and compartment syndrome.

Tourniquet Pain

A syndrome characterized by increasing heart rate and blood pressure resulting from sympathetic stimulation during prolonged tourniquet inflation.

Ondansetron

A Serotonin ($5-HT_3$) antagonist used to prevent and treat post-operative nausea and vomiting; side effects include QT prolongation.

Pulse Pressure Variation (PPV)

A dynamic metric measured via an arterial line used to determine if a patient is fluid responsive ($PPV > 10\%$ suggesting hypovolaemia).

Nociception

The neural processes involved in producing the sensation of pain, involving primary, secondary, and tertiary afferent neurons.

LAST

Local Anaesthetic Systemic Toxicity; a dangerous state presenting with slurred speech, slurring, seizures, or cardiovascular collapse.

Laryngospasm

A protective reflex causing partial or full closure of the vocal cords, managed by breaking the spasm with High CPAP, propofol, or suxamethonium.

Train of Four (TOF)

A peripheral nerve stimulator mode delivering four electrical currents to monitor depth of neuromuscular blockade.

Post-Tetanic Count (PTC)

A stimulation mode used when zero twitches are present on TOF to differentiate between deep and profound neuromuscular blockade.

Sugammadex

A reversal agent that encapsulates rocuronium molecules to permanently terminate their effect at the NMJ.

Negative Pressure Pulmonary Oedema (NPPE)

A condition occurring when a patient attempts to inspire against an occlusion (like biting a tube), causing rapid fluid shifts in the lungs.

Malignant Hyperthermia (MH)

A life-threatening hypermetabolic reaction to volatile agents or suxamethonium, treated with dantrolene at a dose of $2.5\,mg/kg$.