Synopsis
Plan and supervise adult general anaesthesia as a continuous process from preparation and induction through maintenance, emergence, transfer and recovery, with monitoring matched to technique and risk.
- General anaesthesia is a titrated state combining unconsciousness, amnesia, analgesia and immobility while preserving oxygen delivery, ventilation and organ perfusion; the required balance changes throughout the operation.
- Before induction, confirm identity, consent and procedure, fasting and aspiration risk, allergies, medicines, airway plan, equipment checks, monitoring, IV access, positioning, blood-loss plan and postoperative destination.
- Core monitoring in all cases includes ECG, non-invasive blood pressure, pulse oximetry and temperature, measured before anaesthesia and every 30 minutes until surgery ends. General anaesthesia adds inspired and expired oxygen and waveform capnography; add agent concentration if inhalational anaesthesia is used, pressure-volume-rate monitoring during mechanical ventilation, quantitative monitoring whenever neuromuscular block is used, and processed EEG for TIVA with neuromuscular block.
Key red flags
A flat capnogram after attempted tracheal intubation indicates oesophageal intubation until excluded, including during cardiac arrest; apparent chest movement or tube misting does not establish tracheal placement.
Sudden loss of the capnogram during maintenance or transfer can indicate circuit disconnection, airway displacement, complete obstruction or cardiac arrest and requires immediate patient-and-equipment assessment.
Unexplained hypotension, inappropriate tachycardia or bradycardia, bronchospasm (with wheeze potentially absent when severe), or unexpected cardiorespiratory arrest may represent perioperative anaphylaxis; skin signs are often absent in severe reactions.
Inappropriately raised end-tidal carbon dioxide, increased oxygen consumption, mixed acidosis, sweating or mottling, unexplained tachycardia or arrhythmia, unstable arterial pressure, masseter spasm after succinylcholine or generalised rigidity form the early malignant-hyperthermia pattern; hyperkalaemia and a rapid core-temperature rise are later signs.
Persistent weakness, shallow breathing, upper-airway obstruction or inability to sustain ventilation at emergence suggests residual neuromuscular block until objectively assessed.
An unresponsive or deteriorating patient in recovery needs an ABCDE assessment for airway obstruction, hypoventilation, drug effect, residual blockade, bleeding, cardiovascular instability, metabolic disturbance and neurological events.
Changed capnogram, airway pressure, expired volume, chest movement, reservoir-bag behaviour or oxygen saturation may reveal disconnection, obstruction, leak, displacement or bronchospasm.
Obstruction, laryngospasm, hypoventilation, bleeding, hypotension, arrhythmia, severe pain, agitation or reduced consciousness requires immediate ABCDE review and anaesthetic help.
Reasoning priorities
Confirm airway ventilation and follow patency and alveolar ventilation continuously.
A sustained waveform after intubation supports tracheal ventilation. A flat capnogram indicates oesophageal intubation until excluded; abrupt later loss prompts immediate assessment for disconnection, displacement, obstruction or absent circulation.
Worked reasoning
A stable adult has completed preoperative assessment and is scheduled for an elective operation requiring general anaesthesia and tracheal intubation.
- Confirm patient, procedure, consent, allergies, fasting, aspiration and airway plan, comorbidity and medicine instructions; brief the trained assistant, check machine, circuit, suction, airway rescue equipment, infusions and postoperative destination.
- Attach ECG, pulse oximetry and NIBP, measure temperature, establish IV access, start inspired and expired oxygen monitoring and waveform capnography, preoxygenate and optimise position and haemodynamics before induction.
- Induce with a technique selected for physiology and aspiration risk, ensure adequate anaesthetic depth and neuromuscular blockade where used, perform the planned airway manoeuvre and confirm tracheal ventilation visually and with a sustained capnogram.
- Maintain hypnosis, analgesia, oxygenation, ventilation, perfusion and temperature; monitor agent delivery, airway pressure, tidal volume, respiratory rate and quantitative neuromuscular function as applicable, and reassess after positioning or surgical changes.
- Plan emergence before closure, establish analgesia and antiemesis, confirm train-of-four ratio above 0.9 after any neuromuscular blocker, and extubate only when ventilation, oxygenation, airway protection and the rescue plan are satisfactory.
- Continue appropriate monitoring during transfer, provide a structured recovery handover, and retain responsibility until stable discharge from recovery or explicit transfer to another named clinician.