Anesthesiology
-
The effect of three different depths of enflurane anesthesia (1.0, 1.4, and 1.8 MAC) upon laryngeal and respiratory responses to tracheal instillation of distilled water in nine female patients in whom a double-cuffed endotracheal tube had been inserted was investigated. The laryngeal responses were monitored by measuring the pressure in the saline-filled cuff positioned within the larynx, and the respiratory responses were monitored by measuring ventilatory flow and tracheal airway pressure. Increases in laryngeal cuff pressure in response to tracheal irritation were 19.7 +/- 4.5 cmH2O (mean +/- SD) at 1.0 MAC, 13.9 +/- 3.6 cmH2O at 1.4 MAC, and 7.6 +/- 1.8 cmH2O at 1.8 MAC, respectively (P less than 0.01 for anesthetic dose). ⋯ At 1.4 and 1.8 MAC, the same stimulation caused only apnea and constriction of the larynx in the majority of patients. These results indicate that changes in depth of anesthesia can modify the laryngeal and respiratory responses to tracheal irritation. The close association of laryngeal and respiratory responses may be an integral part of the defensive reflex synergism.
-
Comparative Study
Effects of ketamine, halothane, enflurane, and isoflurane on systemic and splanchnic hemodynamics in normovolemic and hypovolemic cirrhotic rats.
The effects of ketamine, halothane, enflurane, and isoflurane on systemic and splanchnic hemodynamics in cirrhotic rats that were either normovolemic or hypovolemic following hemorrhage were characterized. Rats received at random either ketamine (30 mg/kg iv, 1.5 mg.kg-1.min-1 iv), halothane, enflurane, or isoflurane (1 MAC). Conscious rats were considered the control group. ⋯ After hemorrhage portal venous tributary blood flow decreased significantly in all groups except in enflurane group. During halothane and enflurane anesthesia hepatic arterial blood flow and hepatic arterial fraction of cardiac output decreased (P less than 0.01) and they were maintained in the other groups. After hemorrhage hepatic arterial fraction of cardiac output in conscious rats was higher than in those receiving ketamine, halothane, or enflurane (P less than 0.05) and was similar to those receiving isoflurane.(ABSTRACT TRUNCATED AT 250 WORDS)