Leonard M. Pott

Review of video laryngoscopy and rigid fiberoptic laryngoscopy.

Purpose of review Recent advances in fiberoptic systems and video technology have resulted in the development of new intubation devices and techniques. A defining characteristic of rigid fiberoptic and videolaryngoscopic techniques is that glottic opening is viewed indirectly in place of direct line-of-sight. Various issues common to all instruments in this group are highlighted, and a few recently released tools are described. The aim of this article is to review material published since January 2007. Recent findings Indirect laryngoscopic techniques seemed to be easy to learn by both novice and experienced intubators, and can be used to teach both direct laryngoscopy and fiberoptic intubation. An adequate glottic view is generally easily obtained, which is frequently superior to that obtained by direct laryngoscopy. However, endotracheal tube insertion may be problematic, and various techniques have been developed to facilitate this procedure. Indirect laryngoscopic techniques are proving useful in situations of both anticipated and unanticipated difficult intubations, and therefore challenge the preeminence of flexible fiberoptic intubation. Summary As indirect laryngoscopic tools become more available, and clinicians become more facile in their use, the management of (potentially) difficult intubations is likely to change. Further technological advances are likely to lead to the development of even more new instruments.

A survey of airway training among U.S. and Canadian Anesthesiology residency programs

STUDY OBJECTIVE To determine the current trends in airway education in academic programs. DESIGN Survey instrument. SETTING American academic medical center. SUBJECTS 147 directors of American and Canadian anesthesiology residency programs. MEASUREMENTS An invitation to complete an online questionnaire was sent. Non-responding institutions were contacted repeatedly by email and telephone to ensure a reasonable response rate. MAIN RESULTS 88 of the 147 (60%) programs completed the survey. Forty-three respondents (49%) reported that they had formal airway rotations, and 39 respondents said that a designated titled faculty member was responsible for airway training. Didactic lecture and manikin instruction were used by more than two thirds of the programs. Documentation of supervised airway experience was recorded in 71 (82%) programs. The majority of the programs (81%) had videolaryngoscopes. A fiberoptic bronchoscope was nearly universally available, and approximately one third (34%) of graduating residents were estimated to have performed more than 25 awake fiberoptic intubations. For most techniques, the estimates of the required number of procedures to ensure competence varied widely. CONCLUSIONS The number of programs with a formal airway management program continues to increase, and programs are incorporating newer intubation techniques. The criteria for competence have not been established.

The prediction of difficult intubation in obese patients using mirror indirect laryngoscopy: A prospective pilot study.

Background: The incidence of difficult laryngoscopy and intubation in obese patients is higher than in the general population. Classical predictors of difficult laryngoscopy and intubation have been shown to be unreliable. We prospectively evaluated indirect mirror laryngoscopy as a predictor of difficult laryngoscopy in obese patients. Materials and Methods: 60 patients with a body mass index (BMI) greater than 30, scheduled to undergo general anesthesia, were enrolled. Indirect mirror laryngoscopy was performed and was graded 1-4 according to Cormack and Lehane. A view of grade 3-4 was classified as predicting difficult laryngoscopy. Additional assessments for comparison were the Samsoon and Young modification of the Mallampati airway classification, Wilson Risk Sum Score, neck circumference, and BMI. The view obtained upon direct laryngoscopy after induction of general anesthesia was classified according to Cormack and Lehane as grade 1-4. Results: Sixty patients met the inclusion criteria; however, 8 (13.3%) patients had an excessive gag reflex, and examination of the larynx was not possible. 15.4% of patients who underwent direct laryngoscopy had a Cormack and Lehane grade 3 or 4 view and were classified as difficult. Mirror laryngoscopy had a tendency toward statistical significance in predicting difficult laryngoscopy in these patients. Conclusions: This study is consistent with previous studies, which have demonstrated that no one individual traditional test has proven to be adequate in predicting difficult airways in the obese population. However, the new application of an old test - indirect mirror laryngoscopy - could be a useful additional test to predict difficult laryngoscopy in obese patients.

An avoidable reintubation.

To the Editor: Additional hydrostatic pressure accounts for an increase in measured blood pressure (BP), as systemic BP is assessed at a site lower than the heart in patients placed in a non-level position [1]. For the same reason, BP at the level of the head in patients having surgery in a sitting or modified sitting position may become insufficient for adequate cerebral perfusion, with potentially devastating neurological consequences [2,3]. When BP is measured with an arterial catheter, a common method of ensuring adequate cerebral BP is to place the transducer at the level of the head. No such mechanical method is available for a measurement with oscillometric BP cuffs, and clinicians may be easily misled by seemingly adequate systemic BPs if one does not compensate for the hydrostatic pressure difference between the patients head and the cuffs location. We have devised a simple, easy-to-remember way for clinicians to estimate cerebral BP in patients placed in a non-level position. The densities of mercury and blood are approximately 13.53 g/cm3 and 1.05 g/cm3, respectively [4,5]. Each millimeter of vertical difference between the measurement site and the patients head will therefore result in a 1.05/ 13.53 mmHg change in BP. This ratio yields a 0.07758 mmHg change per mm height difference. Although this and similar numbers can be found in some textbooks [1,6] and publications [2,7,8], it is difficult to remember accurately, more so when one is used to thinking and measuring in inches. However, this conversion to inches (by multiplying 0.07758 mmHg/mm by 25.4 mm/inch) results in a 1.97 mmHg or – rounded up – 2 mmHg pressure difference per inch. For example, if a BP cuff is attached to a patients arm, and this position places the head 12 inches above the BP cuff, the pressure difference is 12 × 2 = 24 mmHg less than the pressure measured by the cuff. Nevertheless, one should keep in mind that this calculation refers only to the hydrostatic gradient and does not incorporate unrelated factors such as the peripheral enhancement of pulse pressure [1] or obstructions to flow from vascular stenoses.