Circulatory Changes During Anesthetic Induction

Circulatory changes after IV d-tubocurarine (3 mg), thiamylal (4 mg/kg) plus succinylcholine (2 mg/kg) and followed by direct laryngoscopy with or without intratracheal lidocaine spray (2 mg/kg) just before endotracheal intubation (EI), were measured in 40 adult patients. Pretreatment with d-tubocurarine did not alter mean arterial pressure (MAP), heart rate (HR), or central venous pressure (CVP). One minute after thiamylal-succinylcholine and just before laryngoscopy, MAP was 15 torr less than the awake value (p less than 0.05) and HR was 13 beats/min greater than the awake value (p less than 0.05). Laryngoscopy and EI elevated MAP above awake levels and further increased HR in all patients. The magnitude of these responses immediately following EI was not altered by tracheal lidocaine. However, the pressor and HR changes following EI were more transient when tracheal lidocaine was used (20 patients) and these patients were more likely to tolerate the tracheal tube without immediate additional anesthesia. The incidence of ventricular dysrhythmias was not altered by tracheal lidocaine. Compared with awake values, the cardiac index did not change significantly following intubation but stroke volume was decreased (p less than 0.05), with or without tracheal lidocaine.