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Background: Awake intubation requires an anesthetic management that provides sufficient patient safety and comfort, adequate intubating conditions, and stable hemodynamics. In this prospective clinical study, our aim was to determine the median effective dose (ED(50)) of remifentanil in combination with midazolam and airway topical anesthesia for awake laryngoscopy and intubation., Methods: Thirty-six female adult patients, scheduled for elective plastic surgery under general anesthesia requiring orotracheal intubation were included in this study. Ten minutes after intravenous administration of midazolam 0.1 mg/kg, patients were assigned to receive remifentanil in bolus, followed by a continuous infusion. The bolus dose and infusion rate of remifentanil were adjusted by a modified Dixon's up-and-down method. Patient's reaction score at laryngoscopy and an Observer's Assessment of Alertness/Sedation Scale (OAA/S) were used to determine whether the remifentanil dosage regimen was accepted. During laryngoscopy, 2% lidocaine was sprayed into the airway to provide the topical anesthesia. ED(50) of remifentanil was calculated by the modified Dixon up-and-down method, and the probit analysis was then used to confirm the results obtained from the modified Dixon's up-and-down method. In the patients who were scored as "accept", patient's OAA/S and reaction scores at different observed points, intubating condition score and patient's tolerance to the endotracheal tube after intubation were evaluated and recorded. Blood pressure and heart rate at different measuring points were also noted., Results: ED(50) of remifentanil for awake laryngoscopy and intubation obtained by the modified Dixon's up-and-down method was (0.62 +/- 0.02) microg/kg. Using probit analysis, ED(50) and ED(95) of remifentanil were 0.63 microg/kg (95% CI, 0.54 - 0.70) and 0.83 microg/kg (95% CI, 0.73 - 2.59), respectively. Nineteen patients who were scored as "accept" had an OAA/S of > 15 and tolerated well laryngoscopy without significant discomfort or gagging. The mean intubating condition score was 1.8 +/- 0.8. The endotracheal tube was well tolerated. During awake laryngoscopy and intubation, blood pressure and heart rate were also kept stable. The postoperative follow up showed that no patient recalled discomfort and pain for airway manipulation., Conclusions: When combined with midazolam 0.1 mg/kg and airway topical anesthesia, ED(50) of remifentanil for successful awake laryngoscopy and intubation is 0.62 microg/kg in bolus followed by continuous infusion of 0.062 microg*kg(-1)*min(-1). This sedation and analgesia regimen can provide patient safety and comfort, ensure adequate intubating conditions, maintain hemodynamic stability, and prevent negative recall of the airway procedure.

Background: The authors found no study assessing the efficacy of small-dose narcotics on the cardiovascular response from intubation in children, so they observed the effects of fentanyl 2 microg x kg(-1) and sufentanil 0.2 microg x kg(-1) on the cardiovascular changes during laryngoscopy and intubation in children., Methods: Ninety-three children aged 3-9 years were randomized to one of three groups to receive the following treatments in a double-blind manner: normal saline (group C), fentanyl 2 microg x kg(-1) (group F) and sufentanil 0.2 microg x kg(-1) (group S) 2 min before induction. Noninvasive blood pressure (BP) and heart rate (HR) were recorded before anesthesia induction (baseline value), immediately before intubation (postinduction values), at intubation and 5 min after intubation at 1-min interval., Results: Tracheal intubation caused significant increases in BP and HR in the three groups compared with baseline values. BP and HR at intubation and after intubation and their maximum values during observation were significantly lower in groups F and S than in group C (P < 0.05). The mean percent increases of systolic blood pressure (SBP) and HR at intubation were significantly lower in group S, 7% and 10%, than in group F, 17% and 25% (P < 0.05). The increases in SBP and HR of more than 30% of baseline values during the observation period were significantly higher in group F, 27% and 43%, than in group S, 0% and 3% (P < 0.05)., Conclusions: When used as part of anesthesia induction with propofol in children, sufentanil 0.2 microg x kg(-1) 2 min before induction is more effective in attenuating the cardiovascular intubation response than fentanyl 2 microg x kg(-1).

Objective: To evaluate the safety and efficacy of oral endotracheal intubation in the patients with difficult laryngoscopy undergoing general anesthesia., Methods: A total of 1 683 patients with difficult laryngoscopy, aged 1.5-67 yr, and scheduled for the elective plastic surgery were observed in this study from 1989-1997. All these patients were at American Society of Anesthesiologist physical status I. According to the preoperative predictive results for difficult laryngoscopy, we classified these patients into two groups: Group I included 1 375 patients, whose epiglottis could be viewed (laryngoscopic view grades II and III); and Group II, included 308 patients, whose epiglottis could not be viewed (laryngoscopic view grade IV). For group I, anesthesia was induced with thiopentone 4-5 mg/kg and succinylcholine 1 mg/kg; Laryngoscopy was carried out using modified Macintosh method. For Group II, anesthesia was induced with a total intravenous anesthesia or inhaled anesthesia; anesthetic depth was required to effectively inhibit laryngeal reflexes with reservation of spontaneous breathing. Tracheal intubation was performed by fiberoptic stylet laryngoscope (FOSL). During anesthesia induction and tracheal intubation procedures, electrocardiogram, arterial pressure, heart rate and pulse oxygen saturation (SpO2) were continuously monitored. Complications of intubation (arrhythmia, and so on) were observed and recorded. Immediately after laryngoscopy and successful intubation, patients were examined for any traumatic injuries at teeth, lips, tongue, and oropharyngeal tissues., Results: In group I, tracheal intubation was accomplished by the first attempt in 1 279 cases (93.0%) and the intubation time was less than 3 min in 1 304 cases (94.8%). In group II, tracheal intubation was accomplished by the first attempt in 114 patients (37.0%), and 123 patients (39.9%) had the intubation time of less than 3 min. Tracheal intubation was successful by the second or third attempt in 96 patients of group I and 156 patients of group II, respectively. Thirty-eight patients required four or more attempts, which only occurred in group II. Of all the complications of tracheal intubation, the traumatic complications were most common. The incidences of traumatic complications in the patients with laryngoscopic view grade II, III (group I ) and IV (group II) were 0.7%, 3.9% and 14.3%, respectively. Other complications such as respiratory depression were only seen in group II. A pooled incidence of the intubation complications was 6.7% (113/1 683)., Conclusion: An anesthesiologist who is skillful in difficult airway management may safely manage the airway in the patients with difficult laryngoscopy under general anesthesia.