This is a retrospective study of patients whose tracheas were impossible to intubate on a previous occasion. There is a correlation between the degree of difficulty and the anatomy of the oropharynx in the same patient. The study was initially on obstetric patients but was extended to nonobstetric surgical patients in order to increase the number of cases investigated. The incidence of failed intubations in the obstetric group over a 3-year period was seven out of 1980 cases, whereas in the surgical group the results were six out of 13,380 patients. Any screening test which adds to our ability to predict difficulty in intubation must be welcomed, as failure to intubate can potentially lead to fatality.

Difficult tracheal intubation: A retrospective study

Purpose
To review the current literature and generate recommendations on the role of newer technology in the management of the unanticipated difficult airway.

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The unanticipated difficult airway with recommendations for management

Background. The GlideScope® Video Laryngoscope is a new intubating device. It was designed to provide a view of the glottis without alignment of the oral, pharyngeal and tracheal axes. The aim of the study was to describe the use of the GlideScope® in comparison with direct laryngoscopy for elective surgical patients requiring tracheal intubation. Methods. Two hundred patients were randomly assigned to intubation by direct laryngoscopy using a Macintosh size 3 blade (DL, n=100) or intubation using the GlideScope® (GS, n=100). Prior to intubation all patients were given a Cormack and Lehane (C&L) grade by a separate anaesthetist using a Macintosh size 3 blade. The patient was then intubated, using direct laryngoscopy or the GlideScope®, by a different anaesthetist during which the larynx was inspected and given a laryngoscopy score. Time to intubate was measured. Results. In the GS group, laryngoscopy grade was improved in the majority (28/41) of patients with C&L grade >1 and in all but one of patients who were grade 3 laryngoscopy (P Conclusion. In most patients, the GlideScope® provided a laryngoscopic view equal to or better than that of direct laryngoscopy, but it took an additional 16 s (average) for tracheal intubation. It has potential advantages over standard direct laryngoscopy for difficult intubations.

The GlideScope® Video Laryngoscope: randomized clinical trial in 200 patients

Prediction of difficult laryngoscopy in obese patients is challenging. In 50 morbidly obese patients, we quantified the neck soft tissue from skin to anterior aspect of trachea at the vocal cords using ultrasound. Thyromental distance 2, abnormal upper teeth, neck circumference >45 cm, and sleep apnoea were considered predictors of difficult laryngoscopy. Of the nine (18%) difficult laryngoscopy cases, seven had obstructive sleep apnoea history; whereas, only 2 of the 41 easy laryngoscopy patients did (P<0.001). Difficult laryngoscopy patients had larger neck circumference [50 (3.8) vs. 43.5 (2.2) cm; P<0.001] and more pre-tracheal soft tissue [28 (2.7) mm vs. 17.5 (1.8) mm; P<0.001] [mean (SD)]. Soft tissue values completely separated difficult and easy laryngoscopies. None of the other predictors correlated with difficult laryngoscopy. Thus, an abundance of pretracheal soft tissue at the level of vocal cords is a good predictor of difficult laryngoscopy in obese patients.

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Prediction of difficult laryngoscopy in obese patients by ultrasound quantification of anterior neck soft tissue

A modified version of the Cormack and Lehane scoring system was prospectively evaluated in 663 patients requiring tracheal intubation. In the modified system, grade 2 (only part of the glottis visible) was divided into 2a (part of the cords visible) and 2b (only the arytenoids or the very posterior origin of the cords visible). One hundred and sixty-two intubations (24.4%) were scored as grade 2a and 43 (6.5%) as grade 2b, of which seven (4.3%) and 29 (67.4%), respectively, were difficult, defined as requiring more than one laryngoscopy or the use of specialist equipment. Grade 2b denotes a laryngoscopic view that is relatively common and is often associated with difficulty passing a tracheal tube. The modified scoring system thus provides more information than the original Cormack and Lehane system and its use should be considered when recording the ease of tracheal intubation in the anaesthetic record or in studies of tracheal intubation.

Evaluation of an improved scoring system for the grading of direct laryngoscopy.

The displacement of the larynx in the three specific directions (a) posteriorly against the cervical vertebrae, (b) superiorly as possible, and (c) slightly laterally to the right have been reported and named the “BURP” maneuver. We evaluated the efficacy of the BURP maneuver in improving visualization of the larynx. Six hundred thirty patients without obvious malformation of the head and neck participated in this study. We divided the degree of visualization of the larynx using laryngoscopy into five grades and compared the visualization of the larynx using the BURP maneuver with that of laryngoscopy with and without simple laryngeal pressure (“Back”). The maneuver of Back and BURP significantly improved the laryngoscopic visualization from initial inspection. The BURP maneuver also significantly improved the visualization compared with the Back maneuver. We concluded that the BURP maneuver improved the visualization of the larynx more easily than simple back pressure on the larynx. (Anesth Analg 1997;84:419-21)

Hideki Matsumoto

Papers

The Efficacy of the "BURP" Maneuver During a Difficult Laryngoscopy