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This study was performed to examine whether applying triamcinolone acetonide paste as a lubricant to endotracheal tubes (ETTs) reduces the incidence and severity of postoperative sore throat (POST) more effectively than applying chlorhexidine gluconate jelly.This was a randomized controlled clinical trial. Patients enrolled in the study were ages 20 to 70 yr, American Society of Anesthesiologists' physical status I and II, and scheduled for elective laparoscopic cholecystectomy. The patients were divided randomly into two groups, the chlorhexidine group and the triamcinolone group. Prior to endotracheal intubation, ETTs in the chlorhexidine group were lubricated with 0.1% chlorhexidine gluconate jelly, whereas the ETTs in the triamcinolone group were lubricated with 0.1% triamcinolone acetonide paste 0.5 mg. During the 24 hr after the operation, we recorded the incidence and severity of POST and the incidence of cough, hoarseness, dysphagia, nausea, and dry throat.Of the 150 patients initially enrolled, 143 patients were included in the study. The incidence of POST was significantly lower in the triamcinolone group compared with the chlorhexidine group (difference = 52.4%; 95% confidence interval, 36.8% to 64.2%; P0.001). The severity score for the triamcinolone group was significantly lower than that for the chlorhexidine group. The frequencies of coughing, hoarseness, dysphagia, nausea, and dry throat were similar in the two groups for the first 24 hr after surgery.Triamcinolone acetonide paste applied along the length of the ETT resulted in clinically important and statistically significant decreases in the incidence and severity of POST compared with the application of chlorhexidine jelly. (ClinicalTrials.gov number, NCT00908817).

The aim of this study was to investigate the influence of nitroglycerin- and nicardipine-induced hypotension on regional cerebral oxygen saturation (rSO(2)) and postoperative cognitive function in patients undergoing orthognathic surgery.Sixty adult patients scheduled for orthognathic surgery were randomly assigned to either the nitroglycerin group (group 1) or nicardipine group (group 2). After induction of anesthesia, hypotension was induced with continuous infusion of nitroglycerin or nicardipine. Mean arterial pressure (MAP), heart rate (HR), and rSO(2) were measured at the following time points: before induction of anesthesia, immediately before commencing induced hypotension, at 30 and 60 minutes after induced hypotension, and immediately before the end of surgery. Cerebral desaturation was defined as a reduction of rSO(2) less than 75% of baseline foror = 15 seconds. The Mini Mental State Examination (MMSE) was conducted before surgery and then repeated after 1 week.Baseline rSO(2) values were similar in the 2 groups. There were no significant differences in rSO(2) values between the 2 groups. Cerebral desaturation was not observed in any of the patients. Both nitroglycerin and nicardipine reduced MAP and increased HR during induced hypotension as compared with the baseline values (P.05). No differences in MAP and HR during baseline and induced hypotension were observed between the 2 groups. Decreased MMSE scores were not observed in any of the patients.Cerebral oxygen saturation and postoperative cognitive function were not impaired during nitroglycerin- and nicardipine-induced hypotension in patients undergoing orthognathic surgery.

Background: It is well known that sevoflurane anesthesia is associated with emergence agitation (EA) in children, and that fentanyl may reduce its incidence. However, in case of midazolam, there have been conflicting reports. Therefore, we measured the effect of midazolam on EA after sevoflurane anesthesia and compared it with that of fentanyl. Methods: Sixty pediatric patients receiving sevoflurane anesthesia for tonsillectomy was assigned to 3 groups. Saline 0.1 ml/kg (group P), midazolam 0.1 mg/kg (group M), or fentanyl 1/kg (group F) was administered intravenously 10 minutes before the end of surgery. The incidences of over-sedation (OS) and EA were checked three times at the postanesthesia care unit. Results: Group M had a tendency to show a high incidence of OS, but its incidence of EA was not different from the other groups. In group F, OS and EA were less frequent than in groups P and M. Conclusions: After sevoflurane anesthesia for tonsillectomy, fentanyl effectively prevented EA, but midazolam elicited OS and was ineffective at preventing EA.

Background: Ondansetron, a receptor antagonist, is widely used for the prevention of postoperative nausea and vomiting. However, the interaction of ondansetron with non-depolarizing muscle relaxants have not been reported until now. Therefore we studied the effects of ondansetron on the neuromuscular block of vecuronium, rocuronium or atracurium in vitro. Methods: A square wave 0.1 Hz supramaximal stimuli was applied to the phrenic nerve-hemidiaphragm preparation of a rat, and the twitch height response was recorded mechanomyographically. We measured cumulative concentration response curves of vecuronium, rocuronium or atracurium alone and after pretreating with ondansetron (1/ml). We also measured the effects of ondansetron. The 's and EC's of these muscle relaxants alone and after pretreatment with ondansetron were calculated using an inhibitory sigmoid Emax model. Results: Ondansetron depressed the twitch height in a dose-dependent manner, and its potency was lower than the muscle relaxants. The and of ondansetron were 14.7/ml and 33.4/ml, respectively. Pretreated ondansetron (1/ml) significantly reduced the EC's and EC's of vecuronium, rocuronium and atracurium (P

Background : Magnesium sulfate (MgSO4) is widely used in the treatment of preeclamptic Hyperreflexia. Eclamptic convulsions are almost always prevented by MgSO4 in plasma concentrations of 4 to 7 mEq/L. It is well known that MgSO4 enhances the effect of nondepolarizing neuromuscular blockade. But the onset time of rocuronium is not shortened by MgSO4. Methods : The effect of magnesium on the onset time of rocuronium-induced neuromuscular blockade was investigated in vitro rat phrenic nerve-hemidiaphragm preparation. The phrenic nerve-hemidiaphragm was dissected and suspended in an organ bath containing modified Krebs' solution and produced single twitch responses under 0.2 ms, 0.1 Hz, electrical stimulation. We added rocuronium until the twitch height decreased more than 95% of the initial level and determined a dose in 95% decrease twitch height as an effective concentration (EC95). After the administration of MgSO4, the onset time of neuromuscular blockade by rocuronium 1 × EC95, 1.5 × EC95, 2 × EC95 was compared with the onset time without MgSO4. Results : EC50 and EC95 of rocuronium was 0.178 and 1.10 mg/dl. After administration of MgSO4, the concentration of Mg2 in the organ bath was 4.38 mEq/L. The onset time of the neuromuscular blockade by 1 × EC95 rocuronium was significantly shortened, but in the case of over 1.5 × EC95, it was not influenced by MgSO4. Conclusions : The concentration of Mg2 was within the therapeutic range for inhibition of uterine contraction. The onset time of rocuronium-induced neuromuscular blockade was shortened by magnesium but because a high dose of rocuronium was administered for intubation due to low potency and high plasma concentration, the effect of magnesium on the onset time of rocuronium seems to be masked. Therefore clinically, the onset time of rocuronium-induced neuromuscular blockade was not shortened by MgSO4. (Korean J Anesthesiol 1999; 37: 467∼471)

Background : This study was designed to determine whether presynaptic receptor blockade could be differentiated from postsynaptic receptor blockade by examining the effect of increasing frequencies of indirect stimulation on partial twitch depression in vitro rat phrenic nerve hemidiaphragm preparations. Methods: After isolating rat phrenic nerve hemidiaphragm preparation, T200/T1 ratio (twitch height of the 200th stimuli divided by that of the 1st stimuli) at frequencies of 0.2, 0.5, 1.0, and 2.0 Hz using a drug concentration which provided approximately 20% twitch depression at 0.1 Hz was calculated. To compare T200/T1 ratios with TOF ratios, 2.0 Hz TOF response was measured immediately after 200th stimuli at either frequency of stimulation. Results : Hexamethonium caused a marked decrease in T200/T1 ratio at 0.5∼2.0 Hz of stimulation, whereas α-bungarotoxin caused no change in T200/T1 ratios at up to 2.0 Hz of stimulation. The T200/T1 ratios produced by d-tubocurarine, vecuronium, mivacurium, and rocuronium located intermediate between α-bungarotoxin and hexamethonium, however significant differences among four drugs were found at 2.0 Hz. The propensity for decrease in T200/T1 ratios at 2.0 Hz might differ from this study: hexamethonium ＞d-tubocurarine ＞rocuronium ＞mivacurium = vecuronium ＞α-bungarotoxin. T200/T1 ratios at 2.0 Hz were not different from TOF ratios. Conclusions : When the observed effects in this study were provided with result of α-bungarotoxin acting predominantly at postsynaptic receptors and hexamethonium acting predominantly at presynaptic receptors, the effects of nondepolarizing muscle relaxants at each binding site could be differentiated by examining the T200/T1 ratios at 2.0 Hz. (Korean J Anesthesiol 1998; 35: 831∼838)

Background: Esmolol is rapid hydrolyzed by plasma esterase but may inhibit plasma cholinesterase activity based on its structure. This study was designed to evaluate the interactions between esmolol and succinylcholine or mivacurium which are metabolized by plasma cholinesterase and to determine the inhibitory effect of esmolol on human plasma cholinesterase. Methods: Neuromuscular effects of succinylcholine (1.0 mg/kg) and mivacurium (0.15 mg/kg) with or without esmolol (0.5 mg/kg or 1.0 mg/kg) were compared in 57 adult patients (ASA class I) during O2-N2O-isoflurane anesthesia. Neuromuscular block was monitored by recording the compound electromyogram of the hypothenar muscle resulting from supramaximal train of four stimuli applied to the ulnar nerve. Also plasma cholinesterase activity was measured before and 5, 10 minutes after injection of esmolol. Results: Time from injection to onset of over 95% block, clinical duration from injection to 25% recovery of control twitch, and recovery index defined as from 25% to 75% twitch recovery of succinylcholine or mivacurium were not altered by pretreatment of esmolol. Plasma cholinesterase activity was not decreased after injection of esmolol 0.5 mg/kg, but decreased by 5% after injection of 1.0 mg/kg (p＜0.05). Conclusions: It is unlikely that neuromuscular blocking effects of succinylcholine and mivacurium are prolonged by administration of clinical doses of esmolol (0.5∼1.0 mg/kg) due to inhibition of plasma cholinesterase activity in human. (Korean J Anesthesiol 1998; 35: 908∼913)

The neuromuscular and hem+odynamic effects of mivacurium 0.15 mg/kg and succinylcholine 1 mg/kg were compared in 26 adult patients (ASA I and II) during nitrous oxide-oxygen-propofol-fentanyl anesthesia. Neuromuscular block was monitored by recording the compound electromyogram of the hypothenar muscle resulting from supramaximal train-of-four stimuli applied to the ulnar nerve. Time to onset of over 95% block and duration to 25% recovery of control twitch after injection of mivacurium were significantly longer than for succinylcholine (201 +/- 37.6 vs 54 +/- 5.2 sec and 13.0 +/- 2.2 vs 8.4 +/- 2.1 min; mean +/- SD). Onset of mivacurium with priming technique was shortened (125 +/- 20.7 sec), but was also slower than that of succinylcholine. Although the recovery index during spontaneous recovery was significantly longer for mivacurium than for succinylcholine (6.9 +/- 1.3 vs 5.1 +/- 0.9 min), antagonism with neostigmine at 25% recovery of twitch height sufficiently facilitated the recovery index of mivacurium (4.5 +/- 1.0 min) to a level similar to that of succinylcholine with no statistical difference. The hemodynamic effects of mivacurium were few as compared to those of succinylcholine. In conclusion, mivacurium is considered to have additional advantages for short procedures when succinylcholine is undesirable.

To determine the influence of hypothermia on the neuromuscular transmission, 25 patients were studied during O2-N2O(50%)-enflurane(1-2%) anesthesia without any muscle relaxants. Ventilation was controlled to maintain normocapnia and neuromuscular transmission was monitored by delivering train-of-four(TOF) stimuli to the ulnar nerve at wrist(Accelograph, Biometer) while the circulation to the ipsilateral forearm was occluded by tourniquet for 20 minutes. Regional hypothermia was induced to the isolated arm by intravenous injecton of 20ml normal saline cooled by 10℃ and by surface cooling with ice pack in 15 patients (hypothermia group). To compare the neuromuscular transmission in hypothermia with 10 patients in normothermia whose temperature were maintained at normothermia by intravenous injection of 20ml normal saline of 36℃(normothermia group), TOF response was measured following temperature gone down. The results obtained were as follows. First twitch height of TOF response(T1) was not changed, significantly in normothermia group for 20 minutes. In hypothermia group, T1 was decreased insignificantly until the temperature fell to 32℃, but it began to decrease significantly from below 31℃ as compared to normothermia group, e. g., 82.4±31.2/o(p