Median effective dose of remifentanil for awake laryngoscopy and intubation.

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.

Clinical assessment of awake endotracheal intubation using the lightwand technique alone in patients with difficult airways.

BACKGROUND: There is few study to determine whether the use of the lightwand technique alone could achieve effective, safe and successful awake endotracheal intubation (ETI), therefore we designed a prospective clinical study to systematically evaluate the feasibility, safety and efficacy of awake ETI using the lightwand alone in patients with difficult airways. METHODS: Seventy adult patients with difficult airways were enrolled in this study. After the desired sedation with fentanyl and midazolam, airway topical anesthesia was performed with 9 ml of 2% lidocaine, which were in order sprayed in three aliquots at 5 minutes intervals into the supraglottic (two doses) and laryngotracheal areas (one dose) using a combined unit of the lightwand and MADgic atomizer. After airway topical anesthesia, awake ETI was performed using a Lightwand. Subjective assessments by patients and operators using the visual analogue scores (VAS), and objective assessments by an independent investigator using patients' tolerance and reaction scores, coughing severity, intubating conditions and cardiovascular variables were taken as the observed parameters. RESULTS: Of 210 airway sprays, 197 (93.8%) were successfully completed on the first attempt. The total time for airway spray was (14.6 +/- 1.5) minutes. During airway topical anesthesia, the average patients' tolerance scores were 1.7 - 2.3. After airway topical anesthesia, the mean VAS for discomfort levels that the patients reported was 6.5. Also airway topical anesthesia procedure was rated as acceptable and no discomfort by 94.3% of patients. The lightwand-guided awake ETI was successfully completed on first attempt within 29 seconds in all patients. During awake ETI, patients' reaction and coughing scores were 1.9 and 1.6, respectively. All patients exhibited excellent or acceptable intubating conditions. Cardiovascular monitoring revealed that changes of systolic blood pressure and heart rate at each stage of airway manipulations were less than 20% of baseline values. The postoperative follow-up showed that 95.7% of patients had no recall or slight memories of all airway instrumentation. The incidence of postoperative mild airway complications was 38.6%. CONCLUSION: Alone use of the lightwand technique can achieve effective, safe and successful awake ETI in patients with difficult airways.

Comparison of bolus remifentanil versus bolus fentanyl for blunting cardiovascular intubation responses in children: a randomized, double-blind study.

BACKGROUND: The authors found no study to compare the efficacy of bolus dose fentanyl and remifentanil blunting the cardiovascular intubation response in children, so they designed this randomized, double-blind clinical study to assess the effects of remifentanil 2 microg/kg and fentanyl 2 microg/kg by bolus injection on the cardiovascular intubation response in healthy children. METHODS: One hundred and two children, the American Society of Anesthesiologists (ASA) physical status 1-2 and scheduled for elective plastic surgery under general anesthesia, were randomly divided into one of two groups to receive the following treatments in a double blind manner: remifentanil 2 microg/kg (Group R) and fentanyl 2 microg/kg (Group F) when anesthesia was induced with propofol and vecuronium. The orotracheal intubation was performed using a direct laryngoscope. Blood pressure (BP) and heart rate (HR) were recorded before anesthesia induction (baseline values), immediately before intubation, at intubation and every minute for 5 minutes after intubation. The percent changes of systolic blood pressure (SBP) and HR relative to baseline values and the rate pressure product (RPP) at every observing point were calculated. The incidences of SBP and HR percent changes >30% of baseline values and RPP >22,000 during the observation were recorded. RESULTS: There were no significant differences between groups in the demographic data, baseline values of BP and HR and the intubation time. As compared to baseline values, BP, HR and RPP at intubation and their maximum values during observation increased significantly in Group F, but they all decreased significantly in Group R. BP, HR and RPP at all observed points, and their maximum values during the observation, were significantly different between groups. There were also significant differences between groups in the percent change of SBP and HR relative to baseline values at all observed points and their maximum percent changes during the observation. The incidences of SBP and HR percent increased >30% of the baseline values and RPP >22,000 during the observation, were significantly higher in Group F than in Group R, but the incidences of SBP and HR percent decreased >30% of baseline values were significantly lower in Group F compared with Group R. CONCLUSIONS: When used as part of routine anesthesia induction with propofol and vecuronium in children, fentanyl 2 microg/kg by bolus injection fails to effectively depress the cardiovascular intubation response. Remifentanil 2 microg/kg by bolus injection can completely abolish the cardiovascular intubation response, but also cause more adverse complications of temporary significant cardiovascular depression.

Bolus dose remifentanil and sufentanil blunting cardiovascular intubation responses in children: a randomized, double-blind comparison.

BACKGROUND AND OBJECTIVE: The present randomized controlled study was designed to compare the efficacy of remifentanil 2 microg kg(-1) and sufentanil 0.2 microg kg(-1) by bolus injection on the cardiovascular response to intubation in healthy children. METHODS: One hundred and five children, ASA 1-2 and scheduled for elective plastic surgery under general anaesthesia, were randomly divided into one of two study groups to receive the following treatments in a double-blind manner: remifentanil 2 microg kg(-1) (group R) and sufentanil 0.2 microg kg(-1) (group S). Blood pressure and heart rate (HR) were recorded before anaesthesia induction (baseline values), immediately before intubation (postinduction values), at intubation and every minute for 5 min after intubation. The percentage changes in systolic blood pressure (SBP) and HR relative to baseline values were calculated. The incidences of SBP and HR percentage changes of more than 30% of baseline values during the observation were recorded. RESULTS: As compared with baseline values, blood pressure and HR at intubation and their maximum values during the observation increased significantly in group S, but decreased significantly in group R. Blood pressure and HR at intubation and their maximum values during the observation were significantly different between the groups. There were significant differences between the groups in the percentage changes of SBP and HR relative to baseline values and their maximum percentage changes during the observation. The incidences of SBP and HR percentage increases of more than 30% of baseline values were not significantly different between the groups, but the incidences of SBP and HR percentage decreases of more than 30% of baseline values were significantly higher in group R than in group S. CONCLUSION: In combination with propofol for anaesthesia induction in children, sufentanil 0.2 microg kg(-1) by bolus injection fails to depress the cardiovascular intubation response. Remifentanil 2 microg kg(-1) by bolus injection can completely abolish the cardiovascular intubation response, but causes more adverse cardiovascular depression.