Median effective dose of remifentanil for awake laryngoscopy and intubation / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>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.</p>

Clinical assessment of awake endotracheal intubation using the lightwand technique alone in patients with difficult airways / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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%.</p><p><b>CONCLUSION</b>Alone use of the lightwand technique can achieve effective, safe and successful awake ETI in patients with difficult airways.</p>

Comparison of bolus remifentanil versus bolus fentanyl for blunting cardiovascular intubation responses in children: a randomized, double-blind study / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>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.</p>

Clinical experience of airway management and tracheal intubation under general anesthesia in patients with scar contracture of the neck / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Because patients with scar contracture of the neck are at a high risk of loss of the airway control after anesthesia induction, awake intubation is usually recommended. This retrospective clinical study was designed to evaluate the possibility, safety and efficacy of airway management and tracheal intubation under general anesthesia in such patients.</p><p><b>METHODS</b>This retrospective study included 1683 patients from January 1994 to December 2006 with scar contracture of the neck, aged 1.5 - 67.0 years, who were scheduled for elective plastic surgery under general anesthesia in Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College. Based on the results of the preoperative airway assessment, the patients were classified into group 1 (including 1375 patients with the atlanto-occipital extension of > 20 degrees and the Mallampatti's grade I or II) and group 2 (containing 308 patients with the atlanto-occipital extension of < 20 degrees and the Mallampatti's grade III or IV. In group 1, the intravenous induction and maintenance of anesthesia and succinylcholine for muscle relaxation were used. The intubation was done using a modified Macintosh technique. In group 2, the total intravenous anesthesia (TIVA) or the sevoflurane inhalation anesthesia was chosen and the spontaneous breathing was reserved during anesthesia. The intubation was performed by a fiberoptic stylet laryngoscope (FOSL). The number of intubation attempts, intubation time and relative complications were observed and recorded in all patients.</p><p><b>RESULTS</b>In group 1, the intubation was accomplished during the first attempt in 1279 cases (93%) and the intubation time was < 3 minutes in 1304 cases (95%). In group 2, the intubation was completed by the first attempt in 114 patients (37%) and 123 patients had an intubation time of < 3 minutes (40%). Tracheal intubation was successful by the second or third attempt in 96 patients in group 1 and 156 patients in group 2. Thirty-eight patients required four or more attempts which only occurred in group 2. The incidence of traumatic complication was 2.6% and 9.7% with one intubation attempt in groups 1 and 2, respectively, 12.5% and 17.0% with multiple intubation attempts (one vs multiple attempts in both groups, P < 0.001). All non-traumatic complications occurred in group 2 and laryngospasm and hypoxemia were more common in patients using the TIVA compared to those using the sevoflurane inhalational anesthesia (P < 0.001).</p><p><b>CONCLUSIONS</b>This study demonstrated that with a precise airway evaluation, an adequate preoperative preparation and a pre-planned failed intubation strategy, the anesthetist who was experienced in the difficult airway management could safely perform airway control and tracheal intubation under general anesthesia in patients with scar contracture of the neck. We believe that this technique may be very valuable for the management of a known difficult airway because it is comfortable for the patient and saves time for the anesthetist.</p>

Inductions and intubating conditions with sevoflurane and different doses of remifentanil without muscle relaxant in children / 中国医学科学院学报

<p><b>OBJECTIVE</b>To observe the clinical effectiveness of inductions and tracheal intubating conditions with 3% sevoflurane and different doses of remifentanil without muscle relaxant in children.</p><p><b>METHODS</b>Totally 120 peadiatric patients (aged 4-10 years, American Society of Anesthesiologists grade I for inhalational induction) were randomly allocated into group I (remifentanil 1 microg/kg), group II (remifentanil 2 microg/kg), group III (remifentanil 3 microg/kg), and control group (vecuronium bromide 0.1 mg/kg). After inhalational induction with 3% sevoflurane and 60% nitrous oxide in 40% oxygen for 2 minutes, remifentanil 1 microg/kg, 2 microg/ kg, and 3 microg/kg were intravenously injected over 1 minute into patients in group I , group II, and group III, respectively. After remifentanil administration and manual ventilation for 1 minute, the trachea was intubated. In the control group, 2 minutes after intravenous administration of vecuronium bromide 0.1 mg/kg, tracheal intubation was attempted. Agitation, intubating satisfactoriness, and the circulation changes after tracheal intubation and anesthesia induction were observed.</p><p><b>RESULTS</b>In these four groups, agitation occurred in 37.5% of patients during sevoflurane induction. Satisfactory intubation rate was 70.0% in group I, 86.7% in group II, 90.0% in group III, and 93.3% in the control group. Compared with the control group, the impact of tracheal intubation on the circulatory system was smaller in group I , II , and III.</p><p><b>CONCLUSIONS</b>Induction with 3% sevoflurane combined with remifentanil can be smoothly performed, followed by the successful tracheal intubation. The intubating conditions are more satisfactory with 3% sevoflurane combined with remifentanil 2 microg/kg or 3 microg/kg.</p>

Clinical observation of Cookgas intubating laryngeal airway in anticipating difficult tracheal intubation / 中国医学科学院学报

<p><b>OBJECTIVE</b>To compare the clinical effects of Cookgas intubating laryngeal airway (CILA) in facilitating fiberoptic bronchoscope (FOB) and Shikani optical stylet (SOS)-guided intubations in anticipating difficult tracheal intubation.</p><p><b>METHODS</b>Totally 60 anticipated difficult tracheal intubation patients undergoing selective plastic surgery under general anesthesia were allocated to FOB group (n = 30) and SOS group (n = 30). After anesthesia induction and CILA insertion, the patients were treated with FOB or SOS-guided intubation via CILA. The time of intubation and CILA removal and the time and the success rate of CILA insertion were recorded. Noninvasive blood pressure and heart rate were recorded before and after anesthesia induction at CILA insertion, at intubation, at CILA removal, and every minute thereafter for 5 minutes.</p><p><b>RESULTS</b>CILA was inserted successfully in all patients. The first intubation attempt succeeded in all but two who succeeded in the second and the third attempt respectively in FOB group. In SOS group, 18 patients were successfully intubated in the first attempt, and 7 patients were successfully intubated in the second attempt; SOS failed in 5 patients with severe cervical scars, and then FOB was successfully used to intubate. The time of the intubation [(60.2 +/- 29.6) vs. (92.4 +/- 47.9)s] and CILA removal [(104.6 +/- 39.9) vs. (130.0 +/- 51.9) s] in SOS group were significantly longer than in FOB group (P < 0.05). Hemodynamic changes during the intubation with CILA in these two groups were minimal.</p><p><b>CONCLUSIONS</b>FOB and SOS-guided tracheal intubation via CILA is safe and effective in anticipating the outcome of difficult airway management. Compare to SOS-guided intubation, the time of FOB-guided intubation is shorter and the success rate is higher.</p>

Hemodynamic responses to orotracheal intubation with upsherscope or Macintosh direct laryngoscope / 中国医学科学院学报

<p><b>OBJECTIVE</b>To compare the hemodynamic responses to orotracheal intubation via Upsher-scope (USSP) or Macintosh direct laryngoscope (MDLS) under general anesthesia.</p><p><b>METHODS</b>Fifty patients with ASA grade I-II and undergoing the elective plastic surgery and requiring orotracheal intubation were randomly allocated to either the USSP (U group) (n=25) or MDLS (M group) (n=25). After standard intravenous anesthetic induction, orotracheal intubation was performed using a USSP or a MDLS. Noninvasive systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were recorded before and after anesthetic induction, at intubation and every minute thereafter for 5 minutes. The time spent in tracheal intubation was recorded. The mean blood pressure (MBP) and rate-pressure product (RPP) were calculated.</p><p><b>RESULTS</b>The intubation time was not significantly different between these two groups (P > 0.05). After anesthetic induction, SBP, DBP, MAP, and RPP in these two groups decreased significantly as compared with preinduction values. The orotracheal intubation caused significant increases in SBP, DBP, MAP, and RPP in these two groups in comparision with postinduction values (P < 0.05), but these hemodynamic changes lasted only 1 to 2 minutes and then decreased gradually to the postinduction level. The blood pressure changes caused by orotracheal intubation did not exceed the preinduction values (P > 0.05). As compared to, the maximal HR values in these two groups during observation (from the beginning of intravenous anesthetic induction to 5 min after intubation) were significantly higher than their preinduction values (P < 0.05). The maximal RPP values in M group during observation were significantly higher than their preinduction values (P < 0.05), but no such significant difference was observed in U group (P > 0.05). The hemodynamic data at each time point during the observation had no significant differences between these two groups. (P > 0.05).</p><p><b>CONCLUSIONS</b>Orotracheal intubation using the USSP and MDLS may result in similar hemodynamic responses. The standard general anaesthesia can effectively inhibit the pressor, but not the tachycardiac responses caused by orotracheal intubation via USSP or MDLS. USSP is not superior than MDLS in palliating the adverse cardiovascular stress responses to orotracheal intubation.</p>