Factors related to paradoxical reactions during propofol-induced sedated endoscopy.

Objective: The factors related to paradoxical excitement during propofol-induced sedation remain unclear. We aimed to investigate this issue during sedated upper endoscopy. Material and methods: Among the health examinees scheduled for sedated upper endoscopy from June 2017 to December 2017, 421 participated in the study. Endoscopists were blinded to the information about the examinees and evaluated the development of paradoxical reactions. Propofol was exclusively used as the sedative agent via intermittent bolus injection. A multiple logistic regression analysis was performed to investigate the factors associated with paradoxical reactions. Results: The incidence of paradoxical reactions was 16.1%. Anxiety (adjusted odds ratio: 2.76; 95% confidence interval: 1.46 - 5.27; p = .002) and age (odds ratio: 0.92; 95% confidence interval: 0.89 - 0.96; p < .001) were significantly associated with paradoxical reactions. Of the nine items of the anxiety questionnaire, four had independent and significant associations with paradoxical reactions (i.e., excess worry, sleeping problems, somatic symptoms, and health concerns; odds ratios: 2.38, 2.71, 2.27 and 2.39, respectively). Conclusion: Propofol-induced paradoxical reactions tend to occur when an individual has anxiety and is of a young age. Further large population-based studies should be performed to confirm this phenomenon.

Comparison of topical ropivacaine with and without ketamine on post-surgical pain in children undergoing tonsillectomy: a randomized controlled double-blind study.

PURPOSE: Tonsillectomy in pediatric patients may cause severe postoperative pain. Topical local anesthetics are an easy and safe way to control post-tonsillectomy pain, but there is no benefit during the early postoperative stage. Topical ketamine shows a good effect on early stage postoperative pain. We compared the effect of topical ropivacaine with and without ketamine on post-tonsillectomy pain. METHODS: Patients aged 3-7 years undergoing tonsillectomy were selected to participate in the study. Our study was performed in a randomized, placebo-controlled, double-blind manner. Patients were randomly assigned to one of two groups using computer-generated random numbers. The researchers who assessed the pain score, the caregivers, and the patient were blinded to group assignment. One group received topical ropivacaine with saline (RS group) and the other group received topical ropivacaine with 20 mg ketamine (RK group) on the tonsillar bed. Pain scores using the modified Children's Hospital of Eastern Ontario Pain Scale (mCHEOPS) at 15 min and 30 min, and at 1, 2, 4, 8, 16 and 24 h were recorded. Rescue analgesic requirement and complications were also recorded. RESULTS: A total of 66 patients were randomly assigned to the RS group (n = 33) and the RK group (n = 33). The mCHEOPS scores were significantly lower in the RK group at 15 min (P = 0.046). The mCHEOPS scores of the two groups decreased with time, but there was no intergroup interaction. The RS group received more analgesics until 1 h after surgery and the RK group received more analgesics during 1-24 h after surgery. There were no differences in adverse outcomes. CONCLUSIONS: Topical ropivacaine with ketamine can reduce immediate postoperative pain and analgesic requirement better than ropivacaine alone.

2-Sulfonamidopyridine C-region analogs of 2-(3-fluoro-4-methylsulfonamidophenyl)propanamides as potent TRPV1 antagonists.

A series of 2-sulfonamidopyridine C-region derivatives of 2-(3-fluoro-4-methylsulfonamidophenyl)propanamide were investigated as hTRPV1 ligands. Systematic modification on the 2-sulfonamido group provided highly potent TRPV1 antagonists. The N-benzyl phenylsulfonamide derivatives 12 and 23 in particular showed higher affinities than that of lead compound 1. Compound 12 exhibited strong analgesic activity in the formalin pain model. Docking analysis of its chiral S-form 12S in our hTRPV1 homology model indicated that its high affinity might arise from additional hydrophobic interactions not present in lead compound 1S.

Enhanced astroglial GABA uptake attenuates tonic GABAA inhibition of the presympathetic hypothalamic paraventricular nucleus neurons in heart failure.

γ-Aminobutyric acid (GABA) generates persistent tonic inhibitory currents (Itonic) and conventional inhibitory postsynaptic currents in the hypothalamic paraventricular nucleus (PVN) via activation of GABAA receptors (GABAARs). We investigated the pathophysiological significance of astroglial GABA uptake in the regulation of Itonic in the PVN neurons projecting to the rostral ventrolateral medulla (PVN-RVLM). The Itonic of PVN-RVLM neurons were significantly reduced in heart failure (HF) compared with sham-operated (SHAM) rats. Reduced Itonic sensitivity to THIP argued for the decreased function of GABAAR δ subunits in HF, whereas similar Itonic sensitivity to benzodiazepines argued against the difference of γ2 subunit-containing GABAARs in SHAM and HF rats. HF Itonic attenuation was reversed by a nonselective GABA transporter (GAT) blocker (nipecotic acid, NPA) and a GAT-3 selective blocker, but not by a GAT-1 blocker, suggesting that astroglial GABA clearance increased in HF. Similar and minimal Itonic responses to bestrophin-1 blockade in SHAM and HF neurons further argued against a role for astroglial GABA release in HF Itonic attenuation. Finally, the NPA-induced inhibition of spontaneous firing was greater in HF than in SHAM PVN-RVLM neurons, whereas diazepam induced less inhibition of spontaneous firing in HF than in SHAM neurons. Overall, our results showed that combined with reduced GABAARs function, the enhanced astroglial GABA uptake-induced attenuation of Itonic in HF PVN-RVLM neurons explains the deficit in tonic GABAergic inhibition and increased sympathetic outflow from the PVN during heart failure.

[Types of Perception Toward Quarantine Measures among Patients Infected with COVID-19].

PURPOSE: This study was conducted to identify the types of perception toward quarantine measures at hospitals or community treatment centers among patients infected with COVID-19. METHODS: This study applied Q-methodology. Two hundred and nineteen Q populations were constructed based on related literature and in-depth interviews with 5 adults infected with COVID-19 and who experienced quarantine and hospitalization. Interviews were performed from November 14 to 29, 2020. A total of 45 Q samples were extracted and Q sorting was performed using a 9-point scale for 30 adult subjects who experienced quarantine at hospitals and community treatment centers. The data were analyzed using the PC-QUANL program. RESULTS: The perception of subjects toward quarantine measures was classified into the following six types: 'passive acceptance', 'social stigma perception', 'appreciation of daily life through awareness of the realities of illness', 'why me?', 'fearful perception', and 'positive meaning'. CONCLUSION: The perception of quarantine measure among patients with COVID-19 is identified as six types with positive and negative emotional characteristics. This result will contribute to the development of individualized strategies to address psychosocial health problems among patients with infectious diseases.

Pretreatment with nafamostat mesilate, a kallikrein inhibitor, to decrease withdrawal response associated with rocuronium.

PURPOSE: This randomized, double-blind, placebo-controlled study was conducted to examine the preventive effect of nafamostat mesilate, a kallikrein inhibitor, on the withdrawal response associated with rocuronium injection. METHODS: Ninety American Society of Anesthesiology (ASA) physical status I or II patients, aged 18-65 years, were randomly divided into two groups that received either a 1.5-ml solution containing 1.5 mg nafamostat mesilate diluted in a 5% glucose solution or a 1.5-ml 5% glucose solution. Anesthesia was induced by 5 mg/kg 2.5% thiopental. After confirming loss of consciousness, a tourniquet was applied to the mid forearm and tightened to block venous flow. The test solution was then administered, 1 min after which the tourniquet was removed and 0.6 mg/kg rocuronium was administered. Each patient's response to rocuronium injection was graded on a four-point scale in a double-blind manner. Activated coagulation time and plasma potassium concentration were measured before and 5 and 10 min after nafamostat administration. RESULTS: The incidence of withdrawal response was 68.9% in the control group and 24.4% in the nafamostat group (P < 0.001). The number of patients showing generalized movement (response 4) with the rocuronium injection was significantly lower in nafamostat group [1 (2.2%)] than the control group [15 (33.3%)], P < 0.001. Five and 10 min after nafamostat administration, measured potassium and activated coagulation time were similar to baseline values. CONCLUSION: Pretreatment with 1.5 mg nafamostat mesilate decreased withdrawal response associated with rocuronium injection.

Theracurmin (Highly Bioavailable Curcumin) Prevents High Fat Diet-Induced Hepatic Steatosis Development in Mice.

Curcumin, a hydrophobic polyphenol isolated from the Curcuma longa L. plant, has many pharmacological properties, including antioxidant, anti-inflammatory, and chemo-preventive activities. Curcumin has been shown to have potential in preventing nonalcoholic fatty liver disease (NAFLD). However, the low bioavailability of curcumin has proven to be a major limiting factor in its clinical adoption. Theracurmin, a highly bioavailable curcumin that utilizes micronized technology showed improved biological absorbability in vivo. The aim of this study was to investigate the role of theracurmin in modulating hepatic lipid metabolism in vivo. A fatty liver mouse model was produced by feeding mice a high fat diet (HFD; 60% fat) for 12 weeks. We found that treatment for 12 weeks with theracurmin significantly lowered plasma triacylglycerol (TG) levels and reduced HFD-induced liver fat accumulation. Theracurmin treatment lowered hepatic TG and total cholesterol (T-CHO) levels in HFD-fed mice compared to controls. In addition, theracurmin administration significantly reduced lipid peroxidation and cellular damage caused by reactive oxygen species in HFD-fed mice. Overall, these results suggest that theracurmin has the ability to control lipid metabolism and can potentially serve as an effective therapeutic remedy for the prevention of fatty liver.

The effect of magnesium sulfate concentration on the effective concentration of rocuronium, and sugammadex-mediated reversal, in isolated left phrenic nerve hemi-diaphragm preparations from the rat.

BACKGROUND: Perioperative magnesium sulfate (MgSO4) is used for analgesic, anti-arrhythmic, and obstetric purposes. The effects of MgSO4 on the neuromuscular blockade (NMB) induced by rocuronium, and the sugammadex reversal thereof, have not been clearly quantified. We investigated the effect of various MgSO4 concentrations on the NMB by rocuronium, and sugammadex reversal, in isolated left phrenic nerve hemi-diaphragm (PNHD) preparations from the rat. METHODS: Rat PNHD preparations were randomly allocated to one of four groups varying in terms of MgSO4 concentration (1, 2, 3, and 4 mM, each n = 10, in Krebs solution). The train-of-four (TOF) and twitch height responses were recorded mechanomyographically. The preparations were treated with incrementally increasing doses of rocuronium and each group's effective concentration (EC)50, EC90, and EC95 of rocuronium were calculated via nonlinear regression. Then, sugammadex was administered in doses equimolar to rocuronium. The recovery index, time to T1 height > 95% of control, and the time to a TOF ratio > 0.9 after sugammadex administration were measured. RESULTS: The EC50, EC90, and EC95 of rocuronium fell significantly as the magnesium level increased. The EC50, EC90, and EC95 of rocuronium did not differ between the 3 and 4 mM groups. The recovery index, time to T1 height > 95% of control, and time to a TOF ratio > 0.9 after sugammadex administration did not differ among the four groups. CONCLUSIONS: Increases in the magnesium concentration in rat PNHD preparations proportionally enhanced the NMB induced by rocuronium but did not affect reversal by equimolar amounts of sugammadex.

Effect of an epinephrine mixture for interscalene block on hemodynamic changes after the beach chair position under general anesthesia: a retrospective study.

BACKGROUND: The beach chair position (BCP) can cause significant hypotension. Epinephrine is used to prolong the duration of local anesthetics; it is also absorbed into blood and can exert systemic effects. This study determined the effects of epinephrine mixed with ropivacaine for an interscalene block (ISB) on hemodynamic changes related to BCP. METHODS: Patient data collected from March 2013 to August 2014 were used retrospectively. We divided the patients into three groups: 1) ISB only, 2) I+G (general anesthesia after ISB without epinephrine), and 3) I+E+G (general anesthesia after ISB with epinephrine). Mean blood pressure (MBP) and heart rate (HR) were measured for 30 minutes at 5-minute intervals. RESULTS: The study analyzed data from 431 patients. MBP tended to decrease gradually in the groups I+G and I+E+G. There were significant differences in MBP between the groups I+G and I, and between the groups I+G and I+E+G. Group I+E+G showed a significant increase in HR compared with the other two groups. CONCLUSIONS: ISB with an epinephrine mixture did not prevent hypotension caused by the BCP after general anesthesia. HR increased only in response to the epinephrine mixture. A well-planned prospective study is required to compare hemodynamic changes in that context.

Association Between Exposure to Environmental Tobacco Smoke at the Workplace and Risk for Developing a Colorectal Adenoma: A Cross-Sectional Study.

PURPOSE: A colorectal adenoma (CRA) is a well-defined precursor to colorectal cancer (CRC). Additionally, smoking is a potent risk factor for developing a CRA, as well as CRC. However, the association between exposure to environmental tobacco smoke (ETS) and the risk for developing a CRA has not yet been fully evaluated in epidemiologic studies. We performed a cross-sectional analysis on the association between exposure to ETS at the workplace and the risk for developing a CRA. METHODS: The study was conducted on subjects who had undergone a colonoscopy at a health promotion center from January 2012 to December 2012. After descriptive analyses, overall and subgroup analyses by smoking status were performed by using a multivariate logistic regression. RESULTS: Among the 1,129 participants, 300 (26.6%) were diagnosed as having CRAs. Exposure to ETS was found to be associated with CRAs in all subjects (fully adjusted odds ratio [OR], 1.95; 95% confidence interval [CI], 1.08-2.44; P = 0.001). In the subgroup analysis, exposure to ETS in former smokers increased the risk for developing a CRA (fully adjusted OR, 4.44; 95% CI, 2.07-9.51; P < 0.001). CONCLUSION: Exposure to occupational ETS at the workplace, independent of the other factors, was associated with increased risk for developing a CRA in all subjects and in former smokers. Further retrospective studies with large sample sizes may be necessary to clarify the causal effect of this relationship.

Effects of nicardipine on the onset time and intubation conditions of rocuronium-induced neuromuscular blockade.

STUDY OBJECTIVE: The objective of this study was to identify the effects of nicardipine on neuromuscular blockade of rocuronium, such as the onset time and intubation conditions, using a nicardipine dose that attenuates cardiovascular responses during endotracheal intubation. DESIGN: Randomized, double-blinded, placebo-controlled clinical comparison was used as the design of this study SETTING: The study was conducted at the operating room of a university hospital. PATIENTS: Participants of this study comprise 78 American Society of Anesthesiologists physical status 1 and 2 patients, aged 18 to 60 years who were undergoing elective surgery under general anesthesia. INTERVENTIONS: The nicardipine group was given an intravenous bolus of 20 µg/kg nicardipine before tracheal intubation: the control group was given an intravenous bolus of a comparable volume of normal saline before tracheal intubation. MEASUREMENTS: Using a TOF-Watch SX monitor, the time from the end of the injection of rocuronium to maximum depression of T1 (onset time) was measured. Intubation was performed 1 minute after rocuronium administration, and the status of the intubation conditions was assessed. The mean blood pressure and heart rate were each measured after endotracheal intubation. Rate pressure product values were also calculated. MAIN RESULTS: Intubation conditions were clinically acceptable in 37 (94.9%) of 39 patients in group N compared with 29 (74.4%) of 39 in group C (P < .05). The onset time of rocuronium was significantly faster in group N than in group C (P < .05). The mean blood pressure was significantly lower in group N than in group C (P < .05). The heart rate was significantly higher in group N than in group C (P < .05). Rate pressure product values showed no significant difference between the two groups (P > .05). CONCLUSIONS: Pretreatment with 20 µg/kg nicardipine improves intubation conditions, shortens the onset time of rocuronium, and attenuates cardiovascular responses to tracheal intubation.

Comparison of etomidate and propofol on intubating conditions and the onset time associated with cisatracurium administration.

BACKGROUND: This study compared intubating conditions and the onset time associated with administration of cisatracurium, a nondepolarizing neuromuscular blocker with a relatively slow onset, according to prior injection of one of two intravenous anesthetic agents: propofol or etomidate. METHODS: Forty-six female patients, undergoing general anesthesia and endotracheal intubation for elective surgery, were randomized to two groups; group P were administered propofol (2 mg/kg) prior to cisatracurium (0.2 mg/kg); group E were administered etomidate (0.3 mg/kg) prior to cisatracurium (0.2 mg/kg). We measured intubating conditions and the onset time according to the types of intravenous anesthetic administered. Measurements of heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were taken immediately prior to induction; immediately and 1 min after IV anesthetic administration; and immediately and 1, 2, 3, 4, 5, 7, and 15 min after endotracheal intubation. RESULTS: Intubating conditions were superior in group E compared with group P (P = 0.009). The average onset time of cisatracurium was more rapid in group E (155.74 ± 32.92 s vs. 185.26 ± 38.57 s in group P; P = 0.008). There were no group differences in SBP, DBP, and HR following intravenous anesthetic drug injection and endotracheal intubation. However, SBP and DBP were substantially higher in group E after endotracheal intubation. CONCLUSIONS: Etomidate improves intubating conditions and provide a more rapid onset time of cisatracurium during anesthetic induction compared to propofol.

Epiglottic cyst incidentally discovered during screening endoscopy: a case report and review of literature.

From the endoscopists' point of view, although the main focus of upper gastrointestinal endoscopic examination is the esophagus, stomach, and duodenum (usually bulb and 2nd portion including ampulla of Vater), the portions of the upper airway may also be observed during insertion and withdrawal of the endoscope, such as pharynx and larynx. Thus, a variety of pathologic lesions of the upper airway can be encountered during upper endoscopy. Among these lesions, an epiglottic cyst is relatively uncommon. The cyst has no malignant potential and mostly remains asymptomatic in adults. However, if large enough, epiglottic cysts can compromise the airway and can be potentially life-threatening when an emergency endotracheal intubation is needed. Thus, patients may benefit from early detection and treatment of these relatively asymptomatic lesions. In this report, we present a case of epiglottic cyst in an asymptomatic adult incidentally found by family physician during screening endoscopy, which was successfully removed without complication, using a laryngoscopic carbon dioxide laser.

Lack of Association between Self-reported Saltiness of Eating and Actual Salt Intake.

BACKGROUND: Reducing salt intake is known to be an important factor for lowering blood pressure and preventing cardiovascular disease. Estimating amount of salt intake is a necessary step towards salt intake reduction. Self-reported saltiness of diet is a method most easily used to measure a patient's salt intake. The purpose of this study was to examine the value of self-reported saltiness of diet in measuring salt intake. METHODS: We used data from 681 participants who visited a health center at a university hospital between August 2003 and November 2005. A self-administered questionnaire was used to collect information on self-reported saltiness of diet, other dietary habits and lifestyle factors. Salt intake was estimated on the basis of 24-hour dietary recall with a computer-aided nutritional analysis program (CAN-Pro 2.0, Korean Nutrition Society). RESULTS: There was no statistically significant difference between the mean salt intake of the self-reported salty diet group (13.7 ± 4.8 g/d) and the self-reported unsalty diet group (13.3 ± 4.4 g/d). If we assume calculated salt intake as the gold standard, the sensitivity and specificity of self-reported saltiness were 39.5% and 63.6%, respectively. Salt intake was increased with higher calorie intake, frequency of eating breakfast (≥5 times/wk) and being satiated with usual diet in men, but it was increased only with higher calorie intake in women. Regardless of actual salt intake, the group satiated with a usual diet tended to be in the group of self-reported salty diet. CONCLUSION: Self-reported saltiness of diet was not associated with actual salt intake. Further studies will be needed on the simpler and more objective tools to estimate salt intake.

Major role of GABA(A)-receptor mediated tonic inhibition in propofol suppression of supraoptic magnocellular neurons.

Using slice patch clamp recording, we examined the effects of general anesthetic propofol (2,6-diisoprophlphenol) on dual modality of GABA(A) inhibition in supraoptic nucleus (SON) magnocellular neurosecretory cells (MNCs): conventional quantal synaptic transmission (IPSCs, I(phasic)) and persistent tonic form of inhibitory current (I(tonic)). Propofol (10 µM) enhanced I(tonic) as shown by an inward shift in I(holding) (16.46±2.93 pA, n=27) and RMS increase (from 3.37±0.21 pA to 4.68±0.33 pA, n=27) in SON MNCs. Propofol also prolonged the decay time of IPSCs with decreased IPSCs frequency but no significant changes in IPSCs amplitude. Overall, propofol (1-10 µM) caused much smaller increase in mean I(phasic) than mean I(tonic) at all tested concentrations. In consistent with the enhancement of GABA(A) currents, propofol attenuated ongoing firing activities of SON MNCs by ∼65% of control. Selective inhibition of I(phasic) by a GABA(A) antagonist, gabazine (1 µM), failed to block the propofol suppression of the firing activities, while inhibition of I(tonic) and I(phasic) by bicuculline (20 µM) efficiently blocked the propofol-induced neurodepression in SON MNCs. Taken together, our results showed that propofol facilitated I(tonic) with marginal increase in mean I(phasic), and this could be a mechanism reducing the intrinsic SON MNCs excitability during propofol anesthesia.

Association between low pulmonary function and metabolic risk factors in Korean adults: the Korean National Health and Nutrition Survey.

Impaired lung function is a risk factor for cardiovascular events and mortality. In addition, lung function impairment is also associated with insulin resistance and type 2 diabetes mellitus. It is well known that a common mechanism, such as insulin resistance and obesity, underlies metabolic syndrome. Our aim was to evaluate the association between impaired lung function and metabolic risk factors using data from a nationwide survey of chronic obstructive pulmonary disease prevalence in Korea and the Korean National Health and Nutrition Survey in 2001. The study population included 4001 subjects (aged > or =18 years) who underwent spirometry at least twice. We analyzed the association of low pulmonary function with metabolic syndrome components using multiple linear regression and also analyzed the association of metabolic syndrome with restrictive lung disease and obstructive lung disease using multiple logistic regression adjusted for waist to height ratio, sex, age, smoking, and the other covariates. Waist girth, systolic blood pressure, and triglyceride were associated with forced vital capacity (FVC); and only triglyceride was so with forced expiratory volume in 1 second (FEV(1)), but not with FEV(1)/FVC ratio. The odds ratio of metabolic syndrome for restrictive lung disease (FVC <80%, FEV(1)/FVC >0.7) was 1.40 (95% confidence interval, 1.01-1.98), and that for obstructive lung disease (FEV(1)/FVC <0.7) was 0.93 (95% confidence interval, 0.67-1.28) after adjustment for covariates. These results indicate that low pulmonary function in the general population is associated with clustering of metabolic syndrome risk factors and, furthermore, that restrictive lung disease is also related to metabolic syndrome.

Pain management in pediatric day surgery patients at The Maternal and Child Medical Research Center in Mongolia.

BACKGROUND: Pediatric day surgery shortens the hospital stay, reduces the exposure of nosocomial infections and allows for active parental participation. But pain delays the recovery and it increases the morbidity, including nausea and vomiting, and the maladaptive behavioral changes. This study was conducted to compare the effect of rectally administered paracetamol or diclofenac combined with regional nerve block with the traditional pain control method. METHODS: Two hundred forty one randomly selected pediatric patients were allocated into two groups. The empirical pain relief group (the control group, n = 120) included the patients that received intravenous sulpyrin and/or meperidine postoperatively. The patients in the multimodal preemptive pain relief group (the study group, n = 121) received regional nerve blockade with 0.25% bupivacaine combined with preoperative rectally administered paracetamol 45 mg/kg or diclofenac 1 mg/kg 60 min before surgery for cases that were to undergo lower abdominal surgery. But only paracetamol or diclofenac was rectally administered preoperatively in the other surgical cases. RESULTS: The mean time in the recovery room for the study group was shorter than that for the control group. The postoperative pain was hurts even more in 16.7%, worst in 11.8%, a whole lot in 26.5% and no pain in 27.5% of the control group patients. But the pain was hurts little more only in 11%, a little bit in 10.0% and no pain in 88.9% of the study group patients. The average postoperative VAS score was 0.21 +/- 0.6 in the study group and 8.36 +/- 1.7 in the control group, respectively. Vomiting, nausea and fever were more frequently observed in the control group. CONCLUSIONS: The pain intensity of the children who were treated with rectally administered paracetamol or diclofenac combined with regional nerve block before surgery was significantly decreased as compared to that of the children who were treated with the traditional method.

The optimal effect site concentration of remifentanil for tracheal intubation without muscle relaxant during inhalation anesthetic induction using sevoflurane in adult.

BACKGROUND: Sevoflurane has been shown to be suitable for inhalation induction of anesthesia in adults. The addition of remifentanil during sevoflurane induction allows for rapid and smooth tracheal intubation without muscle relaxant. The high concentration of remifentanil can result in improved conditions for tracheal intubation but also caused a cardiovascular instability. We tried to estimate optimal effect site concentration of remifentanil for tracheal intubation without muscle relaxants during inhalation anesthetic induction with 8 vol% sevoflurane and 50% N2O. METHODS: One hundred five ASA I and II patients were randomly allocated to receive an effect site concentration of remifentanil 2, 4, or 6 ng/ml. Trachea was intubated without muscle relaxant after 3 minutes of inhalation induction with 8 vol% sevoflurane and 50% N2O. The intubating conditions for tracheal intubation were assessed and blood pressure and heart rate were recorded at the baseline, before intubation, just after intubation, 1, and 3 minute after intubation. RESULTS: Tracheal intubation was successful in all patients. Clinically acceptable intubation conditions were 60%, 94%, and 100% in 2 ng/ml, 4 ng/ml, and 6 ng/ml group respectively. However, the number of patient who requested rescue medication for bradycardia in 6 ng/ml group was significantly higher than that in the other group (P < 0.05). CONCLUSIONS: We concluded that 4 ng/ml effect site concentration of remifentanil is adequate concentration for tracheal intubation without muscle relaxants during inhalation induction using sevoflurane.