Anesthetic Techniques and Intraoperative Management
Anesthesia is a controlled physiologic state
General anesthesia combines hypnosis, amnesia, analgesia, immobility, and autonomic stability. Understand inhaled agents (MAC, blood-gas solubility, effects on blood pressure and bronchi), propofol TIVA (context-sensitive recovery, infusion syndrome), opioids, muscle relaxants, reversal, and multimodal analgesia. Intraoperative management includes ventilation strategy, fluid balance, temperature, positioning, glucose, blood loss, and PONV prophylaxis. Depth monitoring is useful when paralysis masks movement, especially with TIVA.
Traps: MAC 1.0 does not guarantee amnesia in every patient; age and adjuvants shift requirements. Nitrous oxide expands closed spaces and is avoided in some bowel or middle-ear surgery. Propofol infusion syndrome is suggested by acidosis, rhabdomyolysis, hyperkalemia, and renal failure. Do not treat hypotension with fluid alone without assessing cause. Awareness risk rises with paralysis, emergency surgery, and light anesthesia.
Worked example: a 70-kg patient induced with propofol 2 mg/kg = 140 mg. If the patient is frail and elderly, reduce to 1–1.5 mg/kg and titrate. For maintenance, 1 MAC sevoflurane is approximately 2% in an adult; adjust for age and hemodynamics.
Rule of thumb: titrate to clinical effect and monitor ventilation, perfusion, temperature, and depth-not just the vaporizer dial.