What is the step‑by‑step procedure for administering general anesthesia to an adult patient?

How to Administer General Anesthesia to an Adult Patient

General anesthesia requires a systematic approach beginning with pre-oxygenation in the head-up position using positive pressure techniques, followed by induction with appropriate agents, maintenance with continuous monitoring of vital signs and capnography, and vigilant management throughout until full recovery.

Pre-Oxygenation and Patient Positioning

• Position the patient head-up (reverse Trendelenburg) and apply positive pressure pre-oxygenation using either high-flow nasal oxygen (HFNO >30 L/min), non-invasive ventilation, or facemask with continuous positive airway pressure before inducing anesthesia 1.
• This positioning increases functional residual capacity and extends safe apnoea time during laryngoscopy 1.
• For patients at risk of difficult airway management (obesity, limited mouth opening, restricted neck mobility), HFNO is particularly important as it can delay desaturation during prolonged intubation attempts 1.

Monitoring Setup Before Induction

Establish all monitoring before administering any anesthetic agents 2:

• ECG (electrocardiogram) 2
• SpO2 (pulse oximetry) 2
• NIBP (non-invasive blood pressure) 2
• Capnography (end-tidal CO2 monitoring) 2
• Set patient-specific alarm limits and enable audible alarms 2

Induction of Anesthesia

• Administer neuromuscular blocking agents routinely to facilitate tracheal intubation 1.
• Common induction approach includes intravenous propofol (typically 1-2 mg/kg) combined with an opioid such as fentanyl or alfentanil for balanced anesthesia 3, 4.
• Continue oxygen delivery through facemask ventilation after induction 1.
• During laryngoscopy attempts when facemask ventilation is not possible, maintain apnoeic oxygenation with nasal cannulae (preferably high-flow) to prolong safe apnoea time, ensuring airway patency 1.

Critical pitfall: HFNO has limitations and should not be started as a rescue technique when facemask ventilation has already failed 1.

Airway Management

• Use videolaryngoscopy as first-line for tracheal intubation rather than direct laryngoscopy, as it improves first-attempt success rates, reduces hypoxaemia, and decreases risk of oesophageal intubation 1.
• Limit the number and duration of intubation attempts while maintaining oxygenation 1.
• Confirm successful tracheal intubation with waveform capnography before proceeding 1.
• Continue capnography monitoring throughout the entire anesthetic period, during transfer to recovery, and until the artificial airway is removed and the patient responds to verbal contact 2.

Maintenance of Anesthesia

Monitor continuously throughout the procedure 2:

• Age-adjusted minimum alveolar concentration (MAC) when using inhaled anesthetic agents 2
• Capnography waveform 2
• ECG, SpO2, and NIBP 2

For total intravenous anesthesia (TIVA) with neuromuscular blocking drugs:

• Use processed electroencephalogram (pEEG) monitoring starting before induction and continuing until full recovery from neuromuscular blockade is confirmed 2.
• Consider pEEG monitoring for high-risk patients even with inhalational techniques 2.

Neuromuscular blockade management:

• Use quantitative neuromuscular monitoring whenever neuromuscular blocking drugs are administered 2.
• Continue monitoring from before initiation of blockade until train-of-four ratio >0.9 is confirmed 2.

Additional monitoring considerations:

• Measure capillary blood glucose at least hourly in patients with treated diabetes 2.

Optimal Balanced Technique Principles

Use an opioid-sparing approach and minimize neuromuscular blocking agents 4:

• Avoid routine preoperative midazolam 4
• Avoid deep anesthesia (maintain appropriate depth using pEEG when indicated) 4
• Use the minimal number of drug combinations necessary 4
• Select shorter-acting agents administered at the lowest effective doses 4

Recovery and Transfer

• Continue all monitoring (ECG, SpO2, NIBP, capnography) during transfer to the post-anesthesia care unit 2.
• If an airway device remains in place, capnography must be used during transfer 2.
• Appropriately reverse residual neuromuscular paralysis and confirm train-of-four ratio >0.9 before extubation 2, 4.
• Maintain capnography until the artificial airway is removed and verbal contact is re-established 2.

Documentation

• Create an accurate anesthetic record summarizing information from all monitoring devices 2.
• Automated electronic anesthetic record systems integrated into the hospital's electronic health record are recommended 2.

Key Safety Principles

An anesthetist must be present throughout the entire conduct of anesthesia 2. The essence of safe general anesthesia is maintaining oxygenation while achieving the necessary depth of anesthesia for the surgical procedure, with continuous vigilance and appropriate monitoring to detect and respond to physiological changes immediately.