Yan M. Zhang

Spray-as-you-go airway topical anesthesia in patients with a difficult airway: a randomized, double-blind comparison of 2% and 4% lidocaine.

BACKGROUND: We designed this randomized, double-blind clinical study to compare the safety and efficacy of 2% and 4% lidocaine during airway topical anesthesia with a spray-as-you-go technique via the fiberoptic bronchoscope. METHODS: Fifty-two adult patients with a difficult airway were randomly assigned to 1 of 2 study groups to receive 2% (Group 1) or 4% lidocaine (Group 2) by a spray-as-you-go technique with the fiberoptic bronchoscope, in a double-blind manner. After airway topical anesthesia, awake fiberoptic orotracheal intubation (FOI) was performed. Level of sedation, time for each lidocaine spray in different targeted areas, total times for airway sprays, total dosages of lidocaine used for airway sprays, intubation times, and number of intubation attempts were noted. An independent investigator scored patients’ comfort during airway topical anesthesia, patients’ reaction, coughing severity, and intubating condition during awake FOI, and observed changes of arterial blood pressure and heart rate during each stage in the airway manipulation process. Serial blood samples were obtained for analysis of plasma lidocaine concentrations. RESULTS: Except for the total dosages and plasma concentrations of lidocaine, there were no significant differences in any of the observed variables between groups. All patients exhibited excellent or acceptable intubating conditions. The total dosages of lidocaine were significantly smaller in Group 1 (3.4 ± 0.6 mg/kg) than in Group 2 (7.1 ± 2.1 mg/kg). The plasma lidocaine concentrations in all observed points after the supraglottic sprays were larger in Group 2 than in Group 1. CONCLUSIONS: Both 2% and 4% lidocaine administered topically by a spray-as-you-go technique can provide clinically acceptable intubating conditions for awake FOI in sedated patients with a difficult airway. As compared with 4% lidocaine, however, 2% lidocaine requires a smaller dosage and results in lower plasma concentrations.

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.

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.

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).

A comparative study of the dose-response and time course of action of rocuronium and vecuronium in anesthetized adult patients

STUDY OBJECTIVES (1) To compare the dose-response relations of rocuronium and vecuronium in healthy adult patients anesthetized with nitrous oxide-oxygen-fentanyl-thiopental; and (2) to evaluate the time-course of action of two drugs following equipotent doses. DESIGN Prospective, randomized, clinical comparison. SETTING Operating room, Plastic Surgery Hospital of the Chinese Academy of Medical Sciences and Peking Union Medical College. PATIENTS 60 ASA physical status I patients, aged 17-51 years, scheduled for elective plastic surgery. INTERVENTIONS All patients were randomly assigned to either the rocuronium or vecuronium group. General anesthesia was induced with thiopental 4 to 6 mg/kg and fentanyl 2 to 4 micrograms/kg intravenously (i.v.), and maintained with 60% nitrous oxide (N2O) in oxygen. Further increments of thiopental or fentanyl were given as required. The dose-response relations of rocuronium and vecuronium were determined by the cumulative dose-response technique. MEASUREMENTS AND MAIN RESULTS Neuromuscular function was assessed mechanomyographically with train-of-four (TOF) stimulation at the wrist every 12 seconds. The percentage depression of first twitch (T1) was used as the study parameter. The cumulative dose-response curve of vecuronium was shifted to the left in a parallel fashion compared with that of rocuronium. As assessed by linear regression, the potency ratio of vecuronium: rocuronium was 1:7.2. There were significant differences in the ED50, ED90, and ED95 between the two drugs. After i.v. administration of equipotent doses of both drugs (2 x ED90), the duration of peak effect, clinical duration, recovery index, and total duration were not significantly different between the two drugs. CONCLUSIONS Compared with vecuronium, rocuronium is a low-potency, nondepolarizing relaxant, and its neuromuscular blocking potency is approximately 15% that of vecuronium in adult patients anesthetized with N2O and fentanyl. Following equipotent doses, the time-course of recovery for rocuronium is similar to that of vecuronium.

Intraoral Fixation of Endotracheal Tubes Using a Suture in Edentulous Patients Undergoing Maxillofacial Surgery

Securing an endotracheal tube in completely edentulous patients undergoing maxillofacial surgery can pose difficulties. In this report, a readily available and easy method of securing the endotracheal tube to gums of the teeth using the suture in such a circumstance is described. This technique has been used successfully in more than 100 patients at our institutions. Our experience suggests that it can provide reliable tube fixation and does not hinder surgical access.

Measures to facilitate smooth insertion of an endotracheal tube into the trachea with GlideScope videolaryngoscopy

intraoperative cell salvage and PulseCO hemodynamic monitoring in a Jehovahs Witness with placenta percreta. Int J Obstet Anesth 2008;17:159-63. [13] Dyer RA, Piercy JL, Reed AR, Lombard CJ. Hemodynamic changes associated with spinal anesthesia for Cesarean delivery in severe preeclampsia. Anesthesiology 2008;108:802-11. [14] van Lieshout JJ, Wesseling KH. Continuous cardiac output by pulse contour analysis? Br J Anaesth 2001;86:467-9. [15] Rhodes A, Sunderland R. Arterial pulse power analysis: the LiDCO System. In: Pinsky MR, Payen D, editors. Functional hemodynamic monitoring update in intensive care and emergency medicine 42. Berlin: Springer-Verlag; 2005. p. 183-92. [16] Pearse RM, Ikram K, Barry J. Equipment review: an appraisal of the LiDCO plus method of measuring cardiac output. Crit Care 2004;8:190-5. [17] Cholley BP, Payen D. Noninvasive techniques for measurements of cardiac output. Curr Opin Crit Care 2005;11:424-9. [18] Pittman J, Bar-Yosef S, SumPing J, Sherwood M, Mark J. Continuous cardiac output monitoring with pulse contour analysis: a comparison with lithium indicator dilution cardiac output measurement. Crit Care Med 2005;33:2015-21. [19] Berberian G, Quinn TA, Vigilance DW, et al. Validation study of PulseCO system for continuous cardiac output measurement. ASAIO J 2005;51:37-40. [20] de Wilde RB, Schreuder JJ, van den Berg PC, Jansen JR. An evaluation of cardiac output by five arterial pulse contour techniques during cardiac surgery. Anaesthesia 2007;62:760-8. [21] http://www.finapres.com/index.php. Last accessed November 10, 2008.

A modified technique for lightwand-guided nasotracheal intubation

To the Editor: We read with interest the recent article of Cheng et al. [1], regarding a modified lightwand-guided nasotracheal intubation technique for oromaxillofacial surgical patients. In clinical practice, we often use the TrachlightTM (Laerdal Medical Corp., Wappingers Falls, NY, USA) to perform nasotracheal intubation in patients with normal and difficult airways, during anesthesia or in the awake state [2,3]. Based on our practice, we agree with their view that this modification of lightwand-guided nasotracheal intubation is an efficient technique. However, we suggest that several clinical aspects of this article be clarified. The authors did not describe the cause of the first failed intubation attempt. Our experience suggests that the initial failed intubation attempt is mainly due to the bright light in the lateral aspect of the larynx, which indicates that the nasotracheal tube tip is placed in the pyriform fossae [4] (Fig. 1A). In this situation, the lateral tip location may be managed by ipsilateral movement of the patients head (Fig. 1B) or by maneuvering the larynx in the reverse direction [5] (Fig. 1C). After cuff inflation, a bright, well circumscribed light above the level of the cricothyroid membrane indicates that the nasotracheal tube tip is located at the site distal to the glottis (Fig. 1D). In this situation, the cuff should be deflated, the nasotracheal tube advanced an additional 0.5 to 1.0 cm, and the cuff re-inflated. The frequency of nasal bleeding in the studys lightwand group was zero even when a rigid polyvinyl chloride nasotracheal tube with a thick, high pressure-low volume cuff (RAE Nasal; Mallinckrodt Medical, Athlone, Ireland) was used, and no thermosoftening or lubricating measures taken before use. When the same lubricated RAE nasotracheal tube is used in nasotracheal intubation without first undergoing thermosoftening, the incidence of nasal bleeding is increased to 86% [6]. The authors should explain their results. Intubation time was used as a primary outcome to calculate the sample size. In fact, intubation time might not be the best primary outcome to evaluate the performance and availability of a new airway control technique; a statistically significant difference of several seconds in between the new and standard techniques may not have clinical value. In contrast, a higher success rate of intubation and a lower frequency of airway trauma might be more important considerations, because their success implies fewer failed attempts and a lower risk of bleeding and tissue edema during airway management. Cheng et al. conclude that for patients undergoing oromaxillofacial surgery, this modified lightwand-guided nasotracheal intubation technique is feasible with a RAE nasotracheal tube. However, we found that shortening the proximal part of a nasotracheal tube to fit the Trachlight wand might significantly change its profile, rendering tube fixation more difficult. Furthermore, in head and neck surgery, the shortened distal curve of the device does not allow for convenient placement of the breathing system away from the surgical field without a special connector. We previously reported methods to improve use of RAE nasotracheal tubes during fiberoptic bronchoscope or lightwand-guided nasotracheal intubation [3,7]. We also question the appropriateness of Ref. [8]. In that paper, cuff inflation was not used to facilitate successful nasotracheal intubation. Moreover, a fentanyl dose of two mg/kg during anesthesia induction is, we believe, incorrect. Finally, it must be pointed out that lightwand-guided nasotracheal intubation is a blind technique and should therefore be undertaken gently. The device should not be forced against any resistance it meets. It also cannot be used when there are intrinsic laryngeal abnormalities such as laryngeal stenosis or tumor, extrinsic deviation by infection, vascular abnormality, or when neck anatomy precludes transillumination (eg, morbidly obese patients or patients with neck scarring) [8]. Fu S. Xue MD (Professor) Jian H. Liu MD (Associate Professor) Xu Liao MD (Associate Professor) Yan M. Zhang MD (Associate Professor)