Objective: To evaluate the safety and efficacy of oral endotracheal intubation in the patients with difficult laryngoscopy undergoing general anesthesia.
Methods: A total of 1 683 patients with difficult laryngoscopy, aged 1.5-67 yr, and scheduled for the elective plastic surgery were observed in this study from 1989-1997. All these patients were at American Society of Anesthesiologist physical status I. According to the preoperative predictive results for difficult laryngoscopy, we classified these patients into two groups: Group I included 1 375 patients, whose epiglottis could be viewed (laryngoscopic view grades II and III); and Group II, included 308 patients, whose epiglottis could not be viewed (laryngoscopic view grade IV). For group I, anesthesia was induced with thiopentone 4-5 mg/kg and succinylcholine 1 mg/kg; Laryngoscopy was carried out using modified Macintosh method. For Group II, anesthesia was induced with a total intravenous anesthesia or inhaled anesthesia; anesthetic depth was required to effectively inhibit laryngeal reflexes with reservation of spontaneous breathing. Tracheal intubation was performed by fiberoptic stylet laryngoscope (FOSL). During anesthesia induction and tracheal intubation procedures, electrocardiogram, arterial pressure, heart rate and pulse oxygen saturation (SpO2) were continuously monitored. Complications of intubation (arrhythmia, and so on) were observed and recorded. Immediately after laryngoscopy and successful intubation, patients were examined for any traumatic injuries at teeth, lips, tongue, and oropharyngeal tissues.
Results: In group I, tracheal intubation was accomplished by the first attempt in 1 279 cases (93.0%) and the intubation time was less than 3 min in 1 304 cases (94.8%). In group II, tracheal intubation was accomplished by the first attempt in 114 patients (37.0%), and 123 patients (39.9%) had the intubation time of less than 3 min. Tracheal intubation was successful by the second or third attempt in 96 patients of group I and 156 patients of group II, respectively. Thirty-eight patients required four or more attempts, which only occurred in group II. Of all the complications of tracheal intubation, the traumatic complications were most common. The incidences of traumatic complications in the patients with laryngoscopic view grade II, III (group I ) and IV (group II) were 0.7%, 3.9% and 14.3%, respectively. Other complications such as respiratory depression were only seen in group II. A pooled incidence of the intubation complications was 6.7% (113/1 683).
Conclusion: An anesthesiologist who is skillful in difficult airway management may safely manage the airway in the patients with difficult laryngoscopy under general anesthesia.