Clinical Anesthesia: Preoperative Care, Anesthetic Management, and Crises
Preoperative assessment
Focused history with functional capacity (4 METs or better predicts tolerance), airway examination (mouth opening, thyromental distance, Mallampati, cervical mobility, dentition), aspiration risk, and NPO intervals (clear fluids 2 h, breast milk 4 h, light meal 6 h, fatty meal 8 h). Test only when the result changes management. Document ASA physical status and a primary and backup airway plan.
Induction and maintenance
Titrate induction agents to lean body weight and hemodynamics: propofol causes vasodilation and apnea; etomidate stabilizes hemodynamics but suppresses the adrenal axis; ketamine preserves sympathetic tone. Succinylcholine 1-1.5 mg/kg is contraindicated in hyperkalemia, burns beyond 24-48 h, denervation, crush injury, and known pseudocholinesterase deficiency, where the prolonged block is managed with continued sedation and ventilation (sugammadex does not reverse it). Rocuronium 1.2 mg/kg achieves intubating conditions in about 60 s and is reversible with high-dose sugammadex.
Intraoperative crises
Bronchospasm: deepen the volatile, give beta-agonists, consider epinephrine. Anaphylaxis: stop the trigger, fluids, titrated epinephrine 10-100 mcg IV. Local anesthetic systemic toxicity: stop injection, secure the airway, give 20% lipid emulsion 1.5 mL/kg bolus then 0.25 mL/kg/min. Malignant hyperthermia: dantrolene 2.5 mg/kg, remove triggers, hyperventilate, cool. Laryngospasm: 100% oxygen with CPAP, deepen anesthesia, small propofol dose; succinylcholine only if hypoxemia progresses.
Traps
Giving lipid before airway support in LAST; succinylcholine weeks after spinal cord injury; dosing propofol by actual body weight in obesity; ordering tests reflexively.
Rule of thumb
1% solution = 10 mg/mL. Lidocaine plain ceiling about 4.5 mg/kg = 300 mg in a 70-kg adult = 30 mL of 1%; with epinephrine about 7 mg/kg.