Clinical Anesthesia Management: Planning, Crises, and Perioperative Care
Preoperative and intraoperative planning
Clinical management questions test systematic preparation more than isolated facts. Preoperative assessment identifies airway risk, aspiration risk, cardiopulmonary reserve, allergies, and medication interactions. Fasting guidelines reduce aspiration risk; clear liquids are generally permitted up to two hours before induction, while light meals require longer. A difficult-airway plan includes preoxygenation, awake fiberoptic intubation when indicated, video laryngoscopy, supraglottic rescue, and front-of-neck access. Positioning affects ventilation, perfusion, and nerve injury; prone positioning requires careful eye, pressure-point, and abdominal protection.
Crises
Malignant hyperthermia presents with unexplained hypercapnia, tachycardia, rigidity, and hyperthermia; stop triggering agents, call for help, give dantrolene, and cool the patient. Local anesthetic systemic toxicity requires airway support and lipid emulsion for cardiovascular instability. Anaphylaxis presents with hypotension, bronchospasm, and rash; epinephrine is first-line. In the operating room, follow ACLS principles while addressing reversible causes such as hemorrhage, hypoxia, tension pneumothorax, and drug error.
Fluids and blood loss
Estimate blood volume by weight; an adult approximation is 70 mL/kg. Allowable blood loss uses the initial hematocrit, target hematocrit, and estimated blood volume. Replace losses with crystalloid, colloid, or blood products according to ongoing bleeding, hemodynamic status, and laboratory values. Avoid reflexive large-volume crystalloid in patients at risk for pulmonary edema.
Worked example: A 70-kg patient has an estimated blood volume of about 4,900 mL. If the initial hematocrit is 40% and the target is 30%, allowable blood loss = 4,900 × (40 − 30)/40 = 1,225 mL. Rule of thumb: plan transfusion before the patient reaches the target, and reassess with vital signs, urine output, and serial hematocrit.
Trap: do not treat malignant hyperthermia with antipyretics alone, and do not delay dantrolene while waiting for confirmatory testing.