Jian H. Liu

Dose-response and time course of effect of rocuronium in male and female anesthetized patients

To determine differences from dose-response and time-course of rocuronium between male and female patients, 60 adult patients (30 male and 30 female), ASA grade I, aged 17-52 yr, undergoing elective plastic surgery were studied. Anesthesia was maintained with 60% nitrous oxide in oxygen, thiopental, and incremental doses of fentanyl as required. Neuromuscular function was assessed mechanomyographically with train-of-four (TOF) stimulation at the wrist every 12 s, and the percentage depression of the T1 response was used as the study variable. The dose-response relationship of rocuronium was determined by a cumulative dose-response technique. The results showed that the dose-response curve of rocuronium in the men was shifted to the right, indicating a decrease in the sensitivity to rocuronium-induced neuromuscular block versus the women. The 50%, 90%, and 95% effective doses of rocuronium were 178.4 +/- 53.7, 358.7 +/- 101.3, and 386.2 +/- 113.4 micro g/kg, respectively, in male patients, and 128.8 +/- 42.5, 252.8 +/- 51.7, and 274.4 +/- 59.4 micro g/kg in female patients. After an intravenous administration of total dose of 400 micro g/kg rocuronium, neuromuscular block was significantly longer in the men than in the women. The duration of peak effect, clinical duration, and total duration were 6.5 +/- 3.0,12.5 +/- 4.9, and 33.6 +/- 8.7 min, respectively, in male patients, and 11.8 +/- 2.7, 18.5 +/- 5.3, and 46.8 +/- 9.6 min in female patients. We conclude that women were approximately 30% more sensitive to rocuronium compared with men. Implications: The authors found that women were 30% more sensitive to rocuronium than men. This suggests that the routine dose of rocuronium should be reduced in women compared with men. (Anesth Analg 1997;85:667-71)

The influence of surgical sites on early postoperative hypoxemia in adults undergoing elective surgery.

UNLABELLED To determine the influence of the surgical sites on early postoperative hypoxemia, we studied postoperative hypoxemia in 994 patients, ASA physical status I or II, aged 18-68 yr, scheduled for various types of elective surgery. Patients were divided into three groups on the basis of the surgical sites: Group 1 = elective superficial plastic surgery (n = 288); Group 2 = upper abdominal surgery (n = 452); and Group 3 = thoracoabdominal surgery (n = 254). Anesthesia was maintained with 1%-2% enflurane and 67% nitrous oxide in oxygen; thiopental or fentanyl was given IV as required. SpO2 levels were recorded while patients breathed room air shortly after arrival in the recovery room (0 min) and 5, 10, 15, 20, 30, 40, 50, 60, 120, and 180 min thereafter. The results showed that during the early postoperative period, the degree of arterial desaturation and the incidences of hypoxemia (SpO2 86%-90%) and severe hypoxemia (SpO2 85%) were closely related to the operative sites and were greatest for thoracoabdominal operations, less for the upper abdominal operation, and least for the peripheral surgery. The incidence of hypoxemia and severe hypoxemia in the recovery room was 7% and 0.7%, respectively, in Group 1, 38% and 3% in Group 2, and 52% and 20% in Group 3. Mild airway obstruction and hypothermia in the postanesthesia recovery unit (PAR) were the predictive factors of early postoperative hypoxemia. We conclude that during the early postoperative period, there were significant differences in SpO2 levels and incidences of hypoxemia and severe hypoxemia among the three groups. IMPLICATIONS We found that the severity of arterial desaturation and the incidence of hypoxemia during the early postoperative period are closely related to the surgical sites and are strongest for thoracoabdominal surgery, less for upper abdominal surgery, and least for peripheral surgery.

Dose–response and time‐course of the effect of rocuronium bromide during sevoflurane anaesthesia

To evaluate the influence of sevoflurane on the dose–response relationship and on the time‐course of the effect of rocuronium, 60 adult patients undergoing elective plastic surgery were randomly allocated to either the control or the sevoflurane group. Anaesthesia was maintained with 60% nitrous oxide in oxygen and thiopentone in the control group and with 60% nitrous oxide in oxygen and an end‐tidal concentration of 1.75% sevoflurane in the sevoflurane group. Neuromuscular function was assessed mechanomyographically with train‐of‐four stimulation at the wrist every 12 s and the percentage depression of the first twitch of the train‐of‐four was used as the study parameter. The dose–response relationship of rocuronium in the two groups was determined by the cumulative dose–response technique. The dose–response curve of rocuronium in the sevoflurane group was shifted to the left compared to the control group, indicating a potentiation of rocuronium‐induced neuromuscular block. The effective doses of rocuronium required to produce 50%, 90% and 95% twitch depression in the sevoflurane group were decreased by 30.5%, 26.7% and 25.2%, respectively, compared to the control group. Following the administration of a total dose of rocuronium of 400 μgkg−1, the duration of action of, and the recovery from, rocuronium were both significantly prolonged by sevoflurane. There were significant differences in the duration of peak effect, clinical duration, recovery index and the total duration of action between the control and the sevoflurane groups.

More maneuvers to facilitate endotracheal intubation using the Airtraq® laryngoscope in children with difficult airways

Surgical repair of the atresia auris congenita was performed successfully, and the tracheal tube was removed without adverse sequelae. The AOL provides a high-grade, indirect, close proximity view of the glottis without the need for alignment of the oral, pharyngeal, and laryngeal axes. The oropharyngeal airwayshaped blade allows laryngeal exposure with ease even in patients with difficult airways (1–5). In addition, the AOL has a guiding channel that directs the tracheal tube through the glottis; and hence, it facilitates tracheal tube insertion once the glottis is aligned with the center of the laryngeal inlet on the view field. The infant AOL accepts tracheal tube with an internal diameter between 2.5 and 3.5 mm; while the pediatric one accepts tube with an internal diameter between 3.5 and 5.5 mm. The pediatric AOL easily provided a full view of the glottic opening in our patient with Treacher Collins syndrome, in whom the Macintosh laryngoscopy failed to expose the glottis. Anesthesia resident completed tracheal intubation without difficulty within 40 s. The small-size AOL seems suitable for difficult airways in small children.

Influences of age and gender on dose response and time course of effect of atracurium in anesthetized adult patients.

STUDY OBJECTIVE To determine the influences of age and gender on the dose response and the time course of effect of atracurium. DESIGN Prospective, nonrandomized, clinical comparison. SETTING Operating room, Plastic Surgery Hospital of the Chinese Academy of Medical Sciences and Peking Union Medical College. PATIENTS 72 adult ASA physical status I patients (38 male and 34 female), aged 15 to 59 years, scheduled for elective plastic surgery. INTERVENTIONS Patients were divided into the three groups on the basis of age: Group 1, patients aged 15-29 years (n = 32); Group 2, patients aged 30-40 years (n = 21); and Group 3, patients aged 41-59 years (n = 19). Anesthesia was maintained with 60% nitrous oxide in oxygen, thiopental, and incremental doses of fentanyl as required. The dose-response relationship of atracurium was determined by a cumulative dose-response technique. MEASUREMENTS AND MAIN RESULTS Neuromuscular function was assessed mechanomyographically with train-of-four stimulation at the wrist every 12 seconds and the percentage depression of first twitch (T1) response was used as the study variable. Age and gender significantly affected the dose-response relationship and time course of recovery of atracurium. Advancing age was associated with a reduced effective doses (ED50, ED90, and ED95) of atracurium and a longer duration of action. The effective doses of atracurium were greater, and its duration of action was shorter in men than in women. There were significant differences in the 50%, 90%, and 95% effective dose (ED50, ED90, and ED95) of atracurium, and clinical duration and total duration following administration of atracurium 400 micrograms/kg among the three age groups, and between men and women. CONCLUSIONS Age and gender have significant effects on the dose response and time course of effect of atracurium. Older patients and women are more sensitive to atracurium-induced neuromuscular block than are young patients and men.

Topical anesthesia of the airway using fibreoptic bronchoscope and the MADgic atomizer in patients with predicted difficult intubation.

To the Editor: Whenever difficulty in ventilation and laryngoscopic intubation is anticipated, awake fibreoptic intubation is often the safest option.1 However, effective local anesthesia of the airway is mandatory for patient comfort and subsequent successful instrumentation.2 The “spray as you go” technique using fibreoptic bronchoscope (FOB) provides flexibility in selectively anesthetizing respiratory passages, but cannot provide topical anesthesia as effectively as transtracheal injection of lidocaine.3 This may be related to the fact that local anesthetic injected by the working channel of FOB or epidural catheter cannot be reduced to extremely fine cloud-like particles. The MADgic® atomizer (Wolfe Tory Medical Inc., Salt Lake City, UT, USA) is a new device that has the ability to provide atomized topical solution directly to the airway mucosa.4 One of its disadvantages is the requirement for direct laryngoscopy to provide access to the pharynx, larynx and trachea, which may cause airway stimulation that the awake patient cannot well tolerate. In contrast, exposure of the airway structures using a FOB can attenuate or even avoid direct airway stimuli. We have successfully combined a FOB (Olympus LF-DP or LF-TP, Tokyo, Japan) and a MADgic® atomizer to provide topical anesthesia of the hypopharynx, larynx and trachea before tracheal intubation. This combined technique requires an elastic 5 mm lactoprene tube 3 cm in length. The lumen of the lactoprene tube is well lubricated using a watersoluble lubricant. Both the distal bending section of the FOB and the applicator portion of the MADgic® atomizer are inserted into the lactoprene tube until their tips protrude just beyond the distal end of lactoprene tube (Figure). With local Ethics Committee approval, 15 patients scheduled for elective surgery who had a predicted difficult intubation gave written informed consent to participate in a clinical evaluation of this combined technique. Of the 15 patients, three had limited mouth opening (inter-incisor distance of 18–22 mm), 11 had limited extension of the head, and one patient had micrognathia (thyromental distance of 4.2 cm). Following topical anesthesia of the oropharynx with traditional spray techniques, fentanyl 1.5 μg·kg–1 was administered intravenously and midazolam (dose range 1–8 mg iv) was titrated to the desired level of sedation, with the patient calm, falling asleep if undisturbed, but still able to respond to verbal commands or gentle stimulation. An airway intubator was inserted into the oropharynx, and a jaw thrust or gentle forward pull of the tongue was performed by an assistant. The operator introduced the FOBMADgic® unit through the airway intubator into the hypopharynx. By gentle rotation of the body of the FOB and manipulations of the tip control lever, the tip of the FOB-MADgic® unit was positioned near the bilateral piriform recess and epiglottic vallecula. Then the assistant used the MADgic® atomizer to spray 3 mL of 2% lidocaine in three aliquots onto these targeted areas. After three minutes, the FOBMADgic® unit was again inserted and positioned above the vocal cords. Two percent lidocaine (1 mL) was sprayed onto the vocal cords. This procedure was repeated two to three times until adequate anesthesia of the vocal cords was observed, as evidenced by cessation of the laryngeal response to further lidocaine administration. The FOB-MADgic® unit was then advanced into the trachea and its tip was positioned 2 cm below the vocal cords. Two percent lidocaine 2 mL was sprayed into trachea during inspiration. In five patients requiring nasotracheal intubation, the nasal mucosa of both nostrils was also prepared with lidocaine gel and vasoconstrictor before intubation. The fibreoptic intubation was started five minutes after the tracheal spray of lidocaine. In all patients the FOB-MADgic® unit was successfully directed to the different targeted areas using one CORRESPONDENCE 951

Cuff inflation as an aid to nasotracheal intubation using the Airtraq laryngoscope.

To the Editor, The Airtraq laryngoscope (Prodol Meditec S.A., Biscay, Spain) is a new disposable optical laryngoscope with the ability to provide a full view of the glottis without the necessity to align oral, pharyngeal, and laryngeal axes. This device has been used successfully for orotracheal and nasotracheal intubation (NTI) in an uncomplicated or difficult airway. 1-4 Also, a mannequin study suggests that the Airtraq laryngoscope offers potential advantages over standard direct laryngoscopy for NTI. 5 However, when NTI is performed with the Airtraq laryngoscope, we find that difficulty in directing the tube tip into the visualized glottis is a common problem. Here, we report our experience using a cuff inflation technique to address this issue. After local ethics committee approval and written informed consent, we recruited 72 patients (29 males and 43 females) into the study. The patients, ASA physical status I-II and aged 18 to 51 yr, were scheduled for elective oral and maxillofacial surgery under general anesthesia with NTI to optimize the surgical approach. Exclusion criteria included patients with a known or predicted difficult airway and those with a history of severe nasal trauma and recurrent epistaxis. In this study, we used the Portex polar preformed cuffed nasotracheal tubes with inner diameters of 7.0 and 6.5 mm (Portex, Keene, NH, USA) for male and female patients, respectively. Prior to NTI, the patients’ nasal passages were prepared with vasoconstrictor and water-soluble jelly. All tracheal intubations were performed by an anesthesiologist (F.S.X.) who had been trained on the use of an Airtraq laryngoscope in a shortterm airway management program and who had performed the NTI using this device in more than 20 patients prior to this study. After anesthesia induction and establishing mask ventilation, a nasotracheal tube was inserted via the preselected nostril until the tube tip passed through the posterior naris. Next, an orotracheal Airtraq laryngoscope was passed into the patient’s mouth over the tongue in the midline. After the distal end of the Airtraq laryngoscope was positioned in the vallecula with the glottis in the centre

A simple maneuver to facilitate tracheal intubation using the Airtraq laryngoscope with a reinforced endotracheal tube.

videolaryngoscope (AWS) using straightvs curved reinforced endotracheal tubes (ETTs). It wasshown that tracheal intubation is more difficult withstraight reinforced ETTs than with curved reinforced ETTs.Regardless of using a straight or a curved reinforced ETT,our own clinical experience suggests that a posteriorETT tip location is a common problem during trachealintubation with the Airtraq laryngoscope, a device similarto the AWS. Due to this device’s wide tube conduit, theample space between the ETT and the tip of the Airtraqlaryngoscope is a contributing factor to the problem(Figure 1, Panel A).

Different small-dose sufentanil blunting cardiovascular responses to laryngoscopy and intubation in children: a randomized, double-blind comparison

BACKGROUND Sufentanil is a potent opioid analgesic frequently used in clinical anaesthesia. This prospective, randomized, double-blind study was designed to assess the efficacy of different small-dose sufentanil attenuating the cardiovascular intubation response in healthy children, aiming at determining the optimal dose of sufentanil for this purpose. METHODS A total of 165 children aged 3-9 yr were randomized to one of four groups to receive the following in a double-blind manner: normal saline (Group 1), sufentanil 0.1 microg kg(-1) (Group 2), sufentanil 0.2 microg kg(-1) (Group 3), and sufentanil 0.3 microg kg(-1) (Group 4). Anaesthesia was induced with propofol 2.5 mg kg(-1) and vecuronium 0.1 mg kg(-1). Non-invasive blood pressure (BP) and heart rate (HR) were recorded before induction of anaesthesia (baseline value), at immediately before intubation (post-induction values), at intubation, and at 1 min intervals for 5 min after intubation. The per cent changes of systolic blood pressure (SBP) and HR during the observation were calculated. RESULTS Except for Group 4, tracheal intubation caused significant increases in BP and HR in Groups 1, 2, and 3 compared with baseline values. BP and HR at intubation and their maximum values during the observation were significantly different among the four groups. The maximum per cent increases of SBP and HR during the observation were 20 and 28% of baseline values, respectively, in Group 2, 13 and 13% in Group 3, and 0 and 4% in Group 4 compared with 24 and 37% in Group 1. Except for the Group 3 vs Group 4 comparison, the incidences of SBP and HR per cent increases >30% of baseline values were also significantly different among the four groups. CONCLUSIONS In combination with propofol for induction of anaesthesia in children, the bolus administration of sufentanil can produce a dose-related attenuation of the cardiovascular intubation response and sufentanil 0.3 microg kg(-1) can completely abolish the cardiovascular intubation response.

Airway topical anesthesia using the Airtraq® laryngoscope in patients with difficult airways

To the Editor, The Airtraq laryngoscope (Prodol Meditec S.A., Vizcaya, Spain) is a new disposable optical laryngoscope designed to facilitate orotracheal intubation in an uncomplicated or difficult airway. Its distinctive shape and optical system can provide a full view of the glottis without the need to align oral, pharyngeal, and laryngeal axes. Previous studies have suggested that the device is both effective and easy to use in anesthetized patients with normal and difficult airways. We describe our initial experience with a method of airway topical anesthesia for awake tracheal intubation in adult patients with difficult airways using a combination of an Airtraq laryngoscope and a MADgic laryngotracheal atomizer (MAD-LTA) (Wolfe Tory Medical Inc., Salt Lake City, UT, USA) (Fig. 1). First, the patient’s oral cavity and posterior pharynx were anesthetized with atomized lidocaine in the preoperative holding area. In the operating room, fentanyl 1.5 mg kg and a low dose of midazolam were administered intravenously to achieve the desired level of sedation. A 5-mL Luer-locked syringe prefilled with 2% lidocaine was then connected to the applicator portion of the MAD-LTA. The distal end of the applicator portion was bent anteriorly to an angle of 70–80 to correspond with the distal curvature of the Airtraq laryngoscope. Next, an Airtraq laryngoscope without the endotracheal tube was passed into the patient’s mouth over the tongue in the midline. Once the distal end of the Airtraq laryngoscope was positioned in the vallecula with the glottis in the center of the viewfinder, the curved applicator portion of a MAD-LTA was advanced through the lateral channel of the Airtraq laryngoscope. By adjusting the distant position of the applicator portion under direct vision on the viewfinder, its tip was placed immediately superior to the glottis and the bilateral pyriform recess. Then, 3 mL of 2% lidocaine was sprayed in three aliquots onto these targeted areas with the MAD-LTA. This procedure was repeated within 3–5 min, but the applicator portion was advanced into the trachea with the tip positioned approximately 1 cm below the glottis. During inspiration, 3 mL of 2% lidocaine was sprayed into the trachea. After an additional 3 to 5-min period, awake orotracheal intubation was performed with the Airtraq laryngoscope according to the technique previously described. Based on our preliminary experience in 15 adult patients with known difficult airways (due to micrognathia, a short neck, and/or limited head and neck movement), several advantages appear to exist with this technique. First, because the Airtraq laryngoscope has a wide lateral channel, the applicator portion of the MAD-LTA can well be adapted to the curved blade of the Airtraq laryngoscope. Also, the tip of the MAD-LTA can be directed easily towards the different targeted airway structures by adjusting its distal position under the superior vision of the airway provided by the Airtraq laryngoscope. Second, this approach can provide excellent airway topical anesthesia for awake orotracheal intubation, because the MADLTA can provide effective atomized lidocaine solution to the airway mucosa. Third, this technique is well tolerated by the awake, sedated patient, possibly due to less stimulation of the oropharyngolaryngeal structures during the F. S. Xue, MD (&) J. H. Liu, MD X. Liao, MD Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People’s Republic of China e-mail: fruitxue@yahoo.com.cn