Clinical Anesthesia Practice and Anesthetic Techniques
Technique selection
Clinical anesthesia questions usually test a decision, not a definition. Preoxygenation replaces alveolar nitrogen with oxygen; three minutes of tidal-volume breathing or four vital-capacity breaths both provide a safe apnea margin in a cooperative patient. Rapid-sequence induction is indicated when aspiration risk is high (full stomach, obstruction, severe reflux), not routinely for every patient. A supraglottic airway is reasonable for spontaneous ventilation with low aspiration risk; a cuffed tracheal tube remains the standard when the airway must be protected.
Confirm tube position with continuous waveform capnography, not auscultation alone. In adults, depth at the incisors is roughly three times the internal diameter in millimeters (7.0 mm → 21 cm), then adjust with auscultation and bronchoscopy if needed. Cuff pressure should be 20–30 cmH₂O to limit mucosal ischemia.
Total intravenous anesthesia requires a reliable infusion and airway plan; propofol has no analgesic effect, so an opioid or regional block is needed. Volatile anesthesia depth is guided by MAC, but 1 MAC does not guarantee unawareness in every patient, and paralysis masks movement.
Traps
Assuming rapid-sequence induction mandates succinylcholine (rocuronium with sugammadex is an alternative); overinflating the cuff; ignoring a rising end-tidal CO₂ or falling saturation after intubation.
Worked example
A 7.5 mm tube is placed in an adult. Expected depth at the lips ≈ 3 × 7.5 = 22.5 cm; confirm with capnography and bilateral breath sounds, then secure.