Effects of Clonidine on Postanesthetic Shivering When Administered Late Intraoperatively / 대한마취과학회지

BACKGROUND: Postoperative administration of clonidine is an effective treatment for shivering. However, the ability of this drug to stop postanesthetic shivering when administered intraoperatively remains controversial. Furthermore, the efficacy of clonidine during isoflurane and propofol/fentanyl anesthesia remains unknown. We therefore evaluated the incidence of postanesthetic shivering in patients given clonidine during isoflurane/N2O or propofol/fentanyl/N2O anesthesia. METHODS: Sixty patients scheduled for hysterectomy were divided into 4 groups (each group n = 15):(Group 1:isoflurane/clonidine; group 2:isoflurane/saline; group 3:propofol,fentanyl/clonidine; group 4:propofol,fentanyl/saline). The patients of groups 1 and 2 were anesthetized with N2O/O2/isoflurane and in group 3 and 4 with a continuous infusion of propofol (5 10 mg/kg), fentanyl (0.5 microgram/kg) and N2O. Five minutes before tracheal extubation, patients in each group were randomly assigned to receive saline or 2.5 microgram/kg clonidine intravenously. Postanesthetic shivering was evaluated by a blind investigator. We checked mean arterial pressure, pulse, rectal temperature at baseline, immediately after extubation, and subsequently at 5 min intervals for 60 min. RESULTS: Postoperative shivering was observed in 33% of the patients given isoflurane without clonidine and in 13% of the patients given propofol without clonidine (p < 0.05). No patient given clonidine shivered. The incidence of postanesthetic shivering was less after propofol anesthesia than after isofurane/ N2O anesthesia. Clonidine administration 5 minutes before tracheal extubation improved hemodynamic changes without respiratory depression. CONCLUSIONS: A late intraoperative bolus adminstration of 2.5 microgram/kg clonidine prevents postoperative shivering in patients given either type of anesthesia.

The Effects of Acute Cystitis on the Sensory Receptors in the Feline Urinary Bladder / 대한마취과학회지

BACKGROUND: Using the urinary bladder as a model, neurophysiological studies of visceral primary afferents supplying inflamed tissue have been studied. In this study we have examined the response of the hypogastric afferents supplying the urinary bladder of the cat to intra-arterially injected algesic chemicals after experimental inflammation. METHODS: Twenty units were recorded from the strands of hypogastric nerve. Once a unit was found, the conduction velocity was determined by extracellular recording of single fiber. When the response of the unit excited by mechanical stimuli was found, chemical stimuli were applied by intra-arterial injection of algesic chemicals (bradykinin, KCl). And then, irritant chemical, 3% mustard oil injected into the urinary bladder for the induction of an experimental inflammation. After removal of the irritant and with the empty bladder, the response of the afferent unit to chemical stimuli by intra-arterially injected bradykinin and KCl were studied again. RESULTS: All units were found to be A delta fibers and responded to both mechanical and chemical stimuli. After experimental inflammation, the basal tone and spontaneous contraction of the urinary bladder were increased and spontaneous nerve activity of the hypogastric afferents appeared. Bladder contraction and nerve activity to intra-arterially injected bradykinin decreased more than those of controls before inflammation. The ratio of nerve activity to the bladder contraction after experimental inflammation was increased. CONCLUSIONS: The hypogastric afferents were sensitized after inflammation, which showed increased nerve response to intra-arterially injected bradykinin comparing to the contraction response of the urinary bladder.