The effect of priming with rocuronium on onset time and intubation conditions during endotracheal intubation with low-dose rocuronium / 대한마취과학회지

BACKGROUND: A priming dose of rocuronium can shorten the onset time of neuromuscular blockade. The purpose of this study was to evaluate the effect of priming with rocuronium on the onset time and intubation conditions during tracheal intubation with low-dose rocuronium (0.35 mg/kg) and to compare results with those for rocuronium 0.45 mg/kg. METHODS: One hundred twenty four patients were randomly allocated to three groups. Following induction of anesthesia, groups I and III received normal saline while group II received a priming dose of rocuronium (0.05 mg/kg). Three minutes after priming, groups I, II and III received, respectively, 0.45 mg/kg, 0.3 mg/kg and 0.35 mg/kg rocuronium. Intubation was performed 2 minutes after the administration of an intubating dose and intubation conditions were evaluated. Neuromuscular blockade was assessed by accelerography. RESULTS: The proportion of cases having optimal intubation conditions in group I was higher than in groups II and III. There was no significant difference in the onset times among groups. Neuromuscular blockade at 60, 90 and 120 seconds after an intubating dose was similar among all groups except at 60 sec. Maximal blockade for group I was deep compared to groups II and III. CONCLUSIONS: Rocuronium 0.35 mg/kg does not provide satisfactory intubation conditions. There are no effects on onset time and intubation conditions due to priming during tracheal intubation with rocuronium 0.35 mg/kg.

Comparative acute toxicity of quaternary ammonium lidocaine derivative QX-314 to lidocaine in mice

BACKGROUND: The current study examined the acute systemic toxicity of QX-314 that there have been few research results for this so far. In order to be useful as a drug, it must be shown to have minimal toxicities. Hence, we compared the CNS and cardiac toxicities of QX-314 to the conventional local anesthetic lidocaine. METHODS: Acute toxicity was evaluated by determining the individual intravenous CD50 and LD50 of QX-314 and lidocaine. There were four doses for each LD50 determination and 8 animals per dose level. Animals were observed for several hours immediately following drug administration and recorded overt effects and fatalities. Both lidocaine and QX-314 were dissolved in saline. Lidocaine and QX-314 were diluted to 1, 2, 4, 6 and 0.5, 1, 2, 4%, respectively with saline and injected at the same volume to minimized cardiovascular effect. RESULTS: The intravenous CD50 and LD50 were 12.7 and 14.1 mg/kg for QX-314 and 15.7 and 28.8 mg/kg for lidocaine. Electrocardiograms showed intraventricular block (widened QRS complex) at high doses of lidocaine compared to AV block (loss of QRS complex) at high concentrations of QX-314. There are no evidence that CNS toxicity led mouse to death. CONCLUSIONS: QX-314 is about 1.5 times as toxic as lidocaine. Although QX-314 may still be useful clinically as a long-lasting local anesthetic, its safety relative to other available local anesthetics must be considered.

The Change of Bispectral Index in Endotracheal Intubation with Propofol and Remifentanil without Muscle Relaxant

BACKGROUND: There have been conflicting reports about the effect of muscle relaxant to bispectral index during propofol anesthesia. The purpose of this study was to investigate the change of bispectral index (BIS) in endotracheal intubation with propofol and remifentanil without muscle relaxant and to compare with those in endotracheal intubation with muscle relaxant. METHODS: Forty-eight ASA physical status I or II patients were randomly allocated to 2 groups. Each patient were anesthetized with propofol at target effect site concentration of 4.0microg/ml with remifentanil 3.0microg/kg. Saline was injected in Group S and rocuronium 0.6 mg/kg was injected in Group R. Intubation was attempted, and the BIS, intubating condition, mean arterial pressure and heart rate were observed up to 5 minutes after intubation. RESULTS: BIS was elevated after intubation in Group S. BIS after intubation in group S were significantly higher than group R. BIS after injection of rocuronium in group R was significantly decreased. There were no significant differences in hemodynamic datas in two groups. Intubation condition was acceptable in all patients. CONCLUSIONS: The BIS in endotracheal intubation with propofol and remifentanil without muscle relaxantI can be higher than in endotracheal intubation with muscle relaxant.

The Effect of Lesser Palatine Nerve Block on Pain after Elective Pediatric Tonsillectomy / 대한마취과학회지

BACKGROUND: This prospective, double-blind randomized study was performed to evaluate the analgesic effect of lesser palatine nerve block for postoperative pain control after a pediatric tonsillectomy, and to compare the analgesic effects of pre-emptive versus postoperative blocks. METHODS: Forty-eight ASA class 1 children, scheduled for an elective tonsillectomy were randomized into three groups. Patients received lesser palatine nerve blocks, using divided doses of 0.05 ml/kg of 0.2% ropivacaine, 5 min prior to the beginning of tonsillectomy (Pre-block group) or immediately after surgery (Post-block group). Patients allocated into the Control group did not receive any nerve block. Postoperative pain was measured immediately after surgery, 3, 6, 12 and 24 hours following operation using a 0 to 4 points pain scale, based on a facial expression of pain scale ruler. Side effects and the number of analgesic injections were observed for 24 hours postoperatively. RESULTS: No significant differences in the pain scores were observed immediately after surgery and at 3, 6, 12 and 24 hours after operation in the three groups (P > 0.05). The number of analgesic injections was similar in the groups. CONCLUSIONS: The results of this study reveal that the lesser palatine nerve block was not effective for postoperative pain control following pediatric tonsillectomy, and that the pre-emptive block offered no pain control benefit over the postoperative block. Therefore, we do not recommend lesser palatine nerve blocks for the management of postoperative pain after pediatric tonsillectomy.

The Effects of Etomidate on Isolated Tracheal Smooth Muscle in Rat / 대한마취과학회지

BACKGROUND: Etomidate is an intravenous anesthetic which has properties of hemodynamic stability, minimal respiratory depression, and cerebral protection. Also, it is a useful induction agent for patients compromised by asthma and other reactive airway diseases. The aim of this study was to investigate the effect and action mechanism of etomidate on isolated tracheal smooth muscle in rats. METHODS: The rat's trachea was dissected free, cut into rings (2 mm) and mounted for isometric tension in Tris Tyrode solution. Cumulative dose-response curves for etomidate (3 X 10(-7) 3 X 10 (-4) M) were obtained from the tension measurements of acetylcholine (10 (-5)M)-contracted rings. The effects of propranolol, L-NAME and indomethacin on the etomidate induced tracheal response were investigated. Also, the effect of etomidate on the extracellular Ca2+ influx and Ca2+ release from internal stores was investigated. RESULTS: Etomidate produced relaxation of acetylcholine-precontracted trachea in a dose-dependent fashion. Pretreatment with propranolol, L-NAME had no effects on concentration-response curves to acetylcholine. Pretreatment with indomethacin had an effect on the concentration-response curve to acetylcholine. Pretreatment with etomidate inhibited acetylcholine-induced contractions in the absence of extracelluar Ca2+ and the presence of extracellular Ca2+ . CONCLUSIONS: The tracheal smooth muscle relaxation by etomidate is not related with beta-adrenergic activation and NO synthesis but related with prostaglandin production. The relaxation effect of etomidate is induced by a decrease in concentration of intracellular Ca2+ through the blockade of extracellular Ca2+ influx and the simultaneous release of Ca2+ from internal stores.

Effects of Vecuronium and Pancuronium on the Tension of the Smooth Muscle in the Rat Trachea / 대한마취과학회지

BACKGROUND: Vecuronium and Pancuronium have been proven to be associated with nicotinic receptor of skeletal muscle. Generally, nondepolarizing muscle relaxant is associated with contraction of smooth tracheal muscle, but there have been few studies about effects of nondepolarizing muscle relaxant on the smooth tracheal muscle. METHODS: We studied the acetylcholine dose response curve of the tracheal smooth muscle contraction and effects of propranolol, L-NAME after pretreating with vecuronium and pancuronium. RESULTS: Vecuronium shifted the acetylcholine dose-response curve of the tracheal contraction to the left, and pancuronium shifted the curve to the right. Vecuronium and Pancuronium reduced the contraction of smooth tracheal muscle with the use carbachol. Propranolol and L-NAME had no effect on the contraction of smooth tracheal muscle after pretreating with vecuronium and pancuronium. CONCLUSION: We suggest that vecuronium has an anticholinergic effect, while pancuronium has some effect on the muscarinic receptor in addition to its anticholinergic effect.