Effects of L-NAME, Aminoguanidine and Hydroxocobalamin on Aortic Contractile Responses in Endotoxemic Rats during Halothane Administration / 대한마취과학회지

BACKGROUND: Recent studies demonstrated that volatile anesthetics suppress the NO-cGMP system in the vascular system. It has been known that the hemodynamic changes produced by volatile anesthetics in septic patients are mediated by upregulation of iNOS leading to excessive release of NO. The mechanisms underlying suppression of the NO-cGMP system by anesthetics are still controversial. It has been elucidated that nitric oxide synthase (NOS) plays a major role in the regulatory function in the L-arginine-NO system. So we examined the effects of NOS inhibitor (L-NAME, aminoguanidine) and NO scavenger (hydroxocobalamin) on vascular smooth muscle contractile function in lipopolysaccharide (LPS)-treated rat aorta during halothane administration. METHODS: Aortic ring preparations were obtained from LPS-treated (1.5 mg/kg, ip, for 18 h) rats. We evaluated the effects of hydroxocobalamin, L-NAME and aminoguanidine on contractile responses to phenylephrine during halothane (1 & 2 MAC) administration respectively. Statistical significances (P<0.05) were analyzed according to data characterictics by repeated measures ANOVA test and student's t-test. RESULTS: The contractile responses to phenylephrine in LPS-treated rats aorta were significantly (P<0.05) increased in the presence of hydroxocobalamin and L-NAME. During the halothane (1 and 2 MAC) administration, the contractile responses to phenylephrine in LPS-treated rats aorta were increased significantly (P<0.05) in the presence of hydroxocobalamin and L-NAME. CONCLUSIONS: From these results, it is suggested that hydroxocobalamin and L-NAME may be useful in the therapy of septic shock.

A Case of Cardiac Arrest due to Drug Interaction between Halothane and Aminophylline: A case report / 대한마취과학회지

Although halothane is generally anesthetic of choice for asthmatics due to its bronchodilatory action, its combined use with aminophylline should be discouraged. This report is a 43-year-old male who had primary closure and open reduction internal fixation (ORIF) for facial avulsion injury and zygomatic tripod fracture under N2O-O2-halothane anesthesia. About 90 minutes after the procedure, the patient who had aminophylline infusion for an acute bronchospasm developed a sudden cardiac arrest. The immediate cardiopulmonary resuscitation was applied and the patient was recovered without any neurological deficit. At the time, the serum theophylline concentration of the patient was 16 microgram/ml which was in the range of normal therapeutic dose. The cause for this cardiac arrest by halothane is unknown, but possibly a drug interaction between halothane and aminophylline might have contributed, since halothane sensitizes the heart to exogenous catecholamines.

Effects of Inhalational Anesthetics on Contractile Responses and Nitric Oxide Synthase Activity in Endotoxemic Rats / 대한마취과학회지

BACKGROUND: Recent studies revealed that inhalational anesthetics (IA) attenuate NO production. But the hemodynamic changes produced by IA in septic syndrome patient are still sufficient to threaten patient, surgeon and anesthesiologist. So we examined which IA is proper to maintain vascular contractile force and evaluated the effects of NOS inhibitors on contractile force of septic rat aorta under IA. METHODS: Aortic ring preparation was obtained from LPS-treated (1.5 mg/kg, i.p. for 18h) rats. The development of sepsis was confirmed by iNOS activity and iNOS expression using RT-PCR. Contractile responses of aorta to phenylephrine admministation in the presence or absence of halothane, enflurane and isoflurane were evaluated. We also evaluated the effects of NOS inhibitors, one is NG-nitro-L-arginine methyl ester (L-NAME) and the other is aminoguanidine. Statistical significances (p<0.05) were analyzed according to data characteristics by unpaired t-test and paired t-test. RESULTS: The contractile responses to phenylephrine admministration were attenuated in LPS-treated rings. Isoflurane, even at the dose of 2 MAC, didn't affect the contractile response while both halothane and enflurane decreased the contractile response even at the dose of 1 MAC. The potentiation of contractile responses by NOS inhibitors were not affected during administeration of IA. CONCLUSIONS: From these results, it is suggested that isoflurane is the safest inhalational anesthetic and NOS inhibitors, especially L-NAME, may be very useful in the therapy of septic shock patients during general anesthesia.

The Potency of Mivacurium during Halothane or Enflurane Anesthesia in Infants and Preschool Children / 대한마취과학회지

BACKGROUND: The dose-responses of neuromuscular blocking agents may be influenced by many factors including age and inhalation anesthetics. This study was designed to determine the dose-response relationships of a new, short-acting muscle relaxant, mivacurium during nitrous oxide-halothane or nitrous oxide-enflurane anesthesia in two age groups, infants and 1 to 6 years old preschool children. METHODS: Neuromuscular blockade was monitored by recording the accelerographic activity of the adductor pollicis muscle resulting from supramaximal stimulation at the ulnar nerve at 2 Hz for 2 seconds at 10-second intervals. To estimate dose-response relationships, 24 infants or children of two anesthetic subgroups for each age group received single bolus doses of 45~100 g/kg of mivacurium. The ED50 and ED95 were estimated from linear regression plots of log-dose vs probit of twitch depression. The lag time, onset time and maximal depression of twitch height for the selective medium dose were mesured. RESULTS: The ED50 and ED95 for the infants group were 38.2 and 53.3 g/kg during halothane anesthesia, and 29.8 and 48.6 g/kg during enflurane anesthesia, respectively. And, those for preschool children group were 49.4 and 90.7 g/kg during halothane anesthesia, and 32.3 and 81.4 g/kg during enflurane anesthesia, respectively. There was a parallelism of the dose-response curve between halothane and enflurane anesthesia in either age group. Also, there was statistically significant difference in the maximal twitch depression for the selective medium dose of mivacurium between halothane and enflurane anesthesia in either group. CONCLUSIONS: The potency of mivacurium during enflurane anesthesia is higher than that during halothane anesthesia in infants and preschool children, and during either inhalation anesthesia the dose of mivacurium is less required in infants than preschool children.