Time to consider supraglottic airway device oropharyngeal leak pressure measurement more objectively

We have compared four tests for assessing airway sealing pressure with the laryngeal mask airway (LMA) to test the hypothesis that airway sealing pressure and inter-observer reliability differ between tests. We studied 80 paralysed, anaesthetized adult patients. Four different airway sealing pressure tests were performed in random order on each patient by two observers blinded to each other's measurements: test 1 involved detection of an audible noise; test 2 was detection of end-tidal carbon dioxide in the oral cavity; test 3 was observation of the aneroid manometer dial as the pressure increased to note the airway pressure at which the dial reached stability; and test 4 was detection of an audible noise by neck auscultation. Mean airway sealing pressure ranged from 19.5 to 21.3 cm H2O and intra-class correlation coefficient was 0.95-0.99. Inter-observer reliability of all tests was classed as excellent. The manometric stability test had a higher mean airway sealing pressure (P < 0.0001) and better inter-observer reliability (P < 0.0001) compared with the three other tests. We conclude that for clinical purposes all four tests are excellent, but that the manometric stability test may be more appropriate for researchers comparing airway sealing pressures.

Research defining optimal methods of intubation has been limited by the lack of a validated outcome measure to assess airway visualization. The objective of this study was to develop a reliable scale for the assessment of airway visualization during endotracheal intubation. This prospective study was performed to assess the intra- and interphysician reliabilities of emergency physicians (EPs) for estimating the percentage of glottic opening (POGO) that is visualized during direct laryngoscopy. Using video images of laryngeal views obtained from a commercially available videotape, still slide images were prepared representing glottic openings ranging from 0% to 100%. Five EPs, blinded to study objective, reviewed 25 pairs of airway slides (50 slides total). For each slide, the physicians recorded the POGO and their scores using a modified Cormack-Lehane (MCL) scale, where grade I is a view of the full glottic opening, MCL grade II is a partial view of the glottic opening, and MCL grade III is a view of the epiglottis only. Inter- and intraphysician reliabilities were assessed using the kappa statistic (K) for MCL grade and intraclass correlation coefficient for the POGO scores. For the POGO score, the degree of intrarater reliability was very good, with an intraphysician correlation of 0.85 and an interphysician correlation of 0.74. For the MCL score, the intraphysician concordance had a K of 0.71, and interphysician concordance was also good, with a kappa of 0.59. Both the modified version of the Cormack-Lehane grading classification and the POGO score have good interphysician and intraphysician reliabilities. Because the POGO score can distinguish patients with large and small degrees of partial glottic visibility, it might provide a better outcome for assessing the difference between various intubation techniques.