Xu Liao

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.

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.

The pharmacokinetics of vecuronium in male and female patients

To evaluate the effect of gender on the pharmacokinetics of vecuronium, we studied 30 patients (15 male and 15 female) undergoing elective plastic surgery with anticipated surgical blood loss of <300 mL under general anesthesia.General anesthesia was induced with thiopental 4-6 mg/kg and fentanyl 2-4 [micro sign]g/kg and was maintained with 60% nitrous oxide in oxygen and an end-tidal concentration of 1.5%-2% enflurane. After a 2-min infusion of vecuronium 100 [micro sign]g/kg, a modified fluorometric assay was used to determine the plasma concentrations of vecuronium for 5 h. The results showed that, compared with women, the plasma concentrations of vecuronium in men were significantly lower during the first 20 min and that the disposition kinetics of vecuronium can be best described mathematically by a three-compartment open model in the two groups. The volume of the central compartment and the volume of distribution at steady state were 39.6 +/- 8.6 and 164.8 +/- 29.3 mL/kg, respectively, in women. These values increased significantly to 54.4 +/- 14.4 and 201.4 +/- 75.8 mL/kg in men (P < 0.05). When the data were calculated on the basis of ideal body weight, the volume of distribution of vecuronium was also different between men and women (P < 0.05. The half-lives of fast distribution and distribution, the elimination half-life, mean residual time, area under the plasma-concentration curve, and plasma clearance were not different between the two groups. We conclude that the pharmacokinetics of vecuronium are significantly different between genders and that and men have the greater volume of distribution of vecuronium. Implications: The authors found that, compared with women, men had lower plasma concentrations of vecuronium after the IV administration of vecuronium and a larger volume of distribution of vecuronium. The pharmacokinetic differences may be related to the differences in the sensitivity to vecuronium between genders. (Anesth Analg 1998;86:1322-7)

Study of the safe threshold of apneic period in children during anesthesia induction

STUDY OBJECTIVES (1) To investigate changes in arterial oxygen saturation via pulse oximeter (SpO2) during apnea and after reinstitution of manual ventilation at SpO2 of 95% or 90% following rapid sequence induction of anesthesia in children after 2-minute preoxygenation; (2) to determine whether the setting of a safe threshold of apneic period to an SpO2 of 95% is appropriate in children during anesthetic induction; and (3) to evaluate the influences of age, body weight, and height on the time from the start of apnea to SpO2 of 95%. DESIGN A clinical study of random design and comparison among groups. SETTING Operating room of a plastic surgery hospital of the Chinese Academy of Medical Sciences and Peking Union Medical College. PATIENTS 152 infants and children, ASA physical status 1, aged 3 months to 12 years, scheduled for elective plastic surgery. INTERVENTIONS Patients were divided into three age groups: Group 1-infants 3 months to 1 year (n = 39); Group 2 children 1 to 3 years (n = 41); and Group 3-children 3 to 12 years (n = 72). Patients in each age group were randomly allocated again to Subgroups A and B. After a 2-minute preoxygenation, anesthesia was induced with thiopental 5 mg/kg, fentanyl 5 micrograms/kg and suxamethonium 1.5 mg/kg. Patients were manually ventilated when SpO2 decreased to 90% in Subgroups A and 95% in Subgroups B, respectively, during apnea. MEASUREMENTS AND MAIN RESULTS SpO2 was measured continuously with a Datex pulse oximeter applied to the right index finger. During apnea, the times for SpO2 to decrease to 09% (T99) and 95% (T99) in all children, and 90% (T90) in Subgroups A were recorded. The time for SpO2 to decrease from 95% to 90% (T95-90) in Subgroups A was also measured. After reinstitution of manual ventilation, the time when SpO2 continued to decrease (T1) and the time from the end of apnea to recovery of SpO2 baseline (T2) were determined. In addition, the lowest value of SpO2 after apnea was also recorded. The results showed that younger children were more susceptible than older children to the risk of hypoxemia during apnea. There were significant differences in T99, T95, T90, and T95-90 between the three age groups T1 and T2 were significantly longer in Group 3 than in Groups 1 and 2. There were significant differences in the lowest values of SpO2 following apnea among the three Subgroups A and between Subgroups A and B of each age group. During apnea, heart rate decreased gradually as SpO2 decreased, showing a significant decrease at SpO2 of 95%. Bradycardia was found in three children in Subgroups A. The apnea time to SpO2 of 95% correlated well with age, weight, and height by linear regression analysis. CONCLUSIONS The safe threshold of an apneic period setting to an SpO2 of 95% was appropriate in children during anesthesia induction. Despite the same duration of preoxygenation, younger children were more susceptible than elder ones to the risk of hypoxemia during apnea. The apnea time to SpO2 of 95% correlated with age, body weight, and height using linear regression analysis.

The clinical observation of difficult laryngoscopy and difficult intubation in infants with cleft lip and palate

Background:  The aims of this study were to evaluate the incidence of difficult laryngoscopy in infants with cleft lip and palate and to observe its relationships with age, sites, and degrees of deformities.

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.

Lightwand guided intubation in paediatric patients with a known difficult airway : a report of four cases

The anaesthetic management of children with craniofacial abnormalities often presents unique challenges because soft tissue and bony abnormities can affect the airway and influence airway management. We report four paediatric patients with predicted difficult airways due to craniofacial abnormalities. They all had a laryngeal view of Cormack–Lehane grade IV and were impossible to intubate using direct laryngoscopy. Fibreoptic intubation was also repeatedly attempted but was not successful. All the tracheal intubations were completed using a lightwand on the first attempt in less than 30 s. We consider that lightwand guided intubation technique may be a useful alternative approach to fibreoptic intubation technique in managing the difficult paediatric airway.

Assessment of small-dose fentanyl and sufentanil blunting the cardiovascular responses to laryngoscopy and intubation in children.

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 μg·kg−1 and sufentanil 0.2 μg·kg−1 on the cardiovascular changes during laryngoscopy and intubation in children.