Steps of General Anesthesia

1. Preoperative Assessment & Preparation

• History: Previous anesthetic responses, current medications (prescription and OTC), allergies, medical/surgical history, family history of anesthetic complications (e.g., malignant hyperthermia)
• Airway assessment: Mallampati score, mouth opening, neck mobility, thyromental distance — to anticipate difficult intubation
• Physical exam & labs: Baseline vitals, relevant lab work, ECG, imaging as indicated
• Fasting (NPO) status: Confirmed to reduce aspiration risk (typically ≥6 h for solids, ≥2 h for clear liquids)
• Informed consent

Morgan and Mikhail's Clinical Anesthesiology, 7e

2. Premedication

Miller's Anesthesia, 10e

3. Monitoring & Intravenous Access

• Standard ASA monitors applied: ECG, pulse oximetry (SpO₂), non-invasive BP, capnography (ETCO₂), temperature
• IV access established (at minimum one large-bore peripheral IV)
• Preoxygenation: 100% O₂ by face mask for 3–5 min (denitrogenates the lungs, extends the apnea window before desaturation during intubation)
• Additional invasive monitoring (arterial line, central line) placed if indicated by patient risk or procedure

4. Induction

Induction Agents

• IV (standard in adults): Propofol (most common — unconsciousness in 30–40 sec), etomidate (preferred in hemodynamic instability / poor cardiac reserve), ketamine (preferred in shock; maintains SVR and cardiac output), thiopental (historical)
• Inhalational (standard in children without IV access): Sevoflurane — nonpungent, well-tolerated, fast onset

Sequence

1. Pre-oxygenation (as above)
2. IV induction agent administered
3. Opioid (e.g., fentanyl 1–3 mcg/kg) to blunt laryngoscopy response
4. Loss of consciousness confirmed
5. Neuromuscular blocking agent (NMBA) administered to facilitate intubation:
   • Succinylcholine (depolarizing) — fastest onset/offset; used for rapid sequence intubation (RSI)
   • Rocuronium, vecuronium (non-depolarizing) — used routinely
6. Mask ventilation during onset of NMBA
7. Laryngoscopy and endotracheal intubation (or supraglottic airway device, e.g., LMA, depending on case)
8. ETT position confirmed (bilateral breath sounds, ETCO₂ waveform, CXR if needed)
9. Hemodynamic control: Esmolol blunts HR/BP surge during laryngoscopy; phenylephrine treats hypotension; sodium nitroprusside/clevidipine treats hypertension

Lippincott Illustrated Reviews: Pharmacology; Miller's Anesthesia, 10e; Morgan and Mikhail, 7e

5. Maintenance

Techniques

Key Principles

• Volatile agents: Alter consciousness but not pain perception → must be combined with opioids for analgesia
• Depth monitored by: Vital signs, end-tidal anesthetic concentration (compared to MAC — Minimum Alveolar Concentration), BIS monitor (bispectral index, 40–60 target for GA)
• Muscle relaxation: Maintained with intermittent NMBA doses or infusion (monitored by train-of-four nerve stimulation)
• Ventilation: Controlled mechanical ventilation; lung-protective strategy (tidal volume 6–8 mL/kg IBW, PEEP) commonly used
• Fluids: Crystalloid/colloid/blood products titrated to hemodynamic goals
• Analgesia: Opioids (fentanyl, remifentanil, morphine), regional blocks, NSAIDs, acetaminophen (multimodal)

Lippincott Illustrated Reviews: Pharmacology; Miller's Anesthesia, 10e

6. Emergence & Extubation

Steps

1. Discontinue maintenance agents as surgical closure begins
2. Reverse neuromuscular blockade: Neostigmine + glycopyrrolate, or sugammadex (for rocuronium/vecuronium) — confirmed by train-of-four monitoring
3. Suction oropharynx gently
4. Increase FiO₂ to 100% (washout of volatile agents)
5. Stimulate patient (verbal and tactile) — look for purposeful movement, eye opening
6. Return of spontaneous ventilation confirmed
7. Extubation criteria met:
   • Patient awake, following commands
   • Sustained head lift ≥5 seconds
   • Adequate tidal volumes and respiratory rate
   • SpO₂ acceptable on spontaneous breathing
   • Protective reflexes (gag, cough) present
8. Extubate — either awake (standard) or deep (to minimize coughing, e.g., asthma, ophthalmic cases)
   • IV lidocaine 1.5 mg/kg given 1–2 min before extubation blunts the cough reflex

Morgan and Mikhail's Clinical Anesthesiology, 7e; Cummings Otolaryngology, 6e

7. Postoperative Recovery (PACU)

• Patient transferred to the Post-Anesthesia Care Unit (PACU)
• Continued monitoring: ECG, SpO₂, BP, RR, temperature, pain score, level of consciousness
• Oxygen supplementation until fully awake
• Management of: pain (analgesics), nausea/vomiting (antiemetics), shivering (meperidine, warming), hypotension, residual sedation
• Discharge criteria (Aldrete score or modified criteria): stable vitals, adequate pain control, ability to ambulate/void, no active N/V

Summary Table