Assessment of airway visualization: validation of the percentage of glottic opening (POGO) scale.

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Airway management and direct laryngoscopy. A review and update.

Direct laryngoscopy is the direct visualization of the larynx while using a rigid laryngoscope to distract the structures of the upper airway. This article reviews the anatomy relevant to laryngoscopy and then presents a stepwise approach to the procedure. Alternative intubation techniques, positioning, laryngoscopy blades, and stylets are then covered. Pharmacologic adjuncts are discussed briefly as they relate to the difficult airway and incorporation into overall airway management.

Bridges to establish an emergency airway and alternate intubating techniques.

In this article, a number of alternatives to direct laryngoscopy are examined. These alternatives include the laryngeal mask airway (LMA; LMA North America, San Diego, CA), cuffed oropharyngeal airway (COPA; Mallinckrodt, St. Louis, MO), and Combitube (Kendall-Sheridan, Mansfield, MA), that have been designed to act as bridges to establish an airway. Other devices, such as rigid stylets, the lightwand (a blind technique) and indirect fiberoptic rigid stylets, such as the Bullard scope, Upsher scope, and Wu scope are also briefly discussed.

Augmented fiberoptic intubation.

Patients who are difficult to intubate are randomly encountered. Patients who are in the postoperative period or who have suffered trauma have a greater chance of being difficult to intubate. The ability to quickly mobilize trained personnel and advanced equipment provides the best chance for a good outcome for these patients. Practice in placement of and intubation with LMAs is an important step toward providing an extensive safety net for patients needing intubation.

A videographic analysis of laryngeal exposure comparing the articulating laryngoscope and external laryngeal manipulation.

Activation of the articulating laryngoscope and external laryngeal manipulation (ELM) improve laryngeal exposure during direct laryngoscopy. We used a head-mounted direct laryngoscopy imaging system and a previously validated scoring system for assessing laryngeal view (the percentage of glottic opening or POGO score) on 33 adult patients undergoing laryngoscopy. On each patient, we videotaped the initial laryngeal exposure (blade not activated), the view with activation of the blade, and the view with operator-directed external laryngeal manipulation. The video recordings were reviewed and the laryngeal view assessed with POGO scores. POGO scores improved with blade activation in 9/33 (27%) of patients vs 28/33 (85%) of patients with ELM. In nearly half of patients studied (16/33, 48%) POGO scores decreased with blade activation. We conclude that ELM is superior to articulating laryngoscope blade activation in improving POGO scores during laryngoscopy on adult patients in standard sniffing position. Using recordings from a direct laryngoscopy video system, we compared laryngeal views in 33 patients with a special articulating laryngoscope blade to views achieved by external laryngeal manipulation (pressing on the patient's neck). Laryngeal exposure, which is important for placement of tracheal tubes, was better with external laryngeal manipulation.

Use of the intubating laryngeal mask airway by medical and nonmedical personnel.

The intubating laryngeal mask airway (ILMA) is a newly available device designed to allow for blind endotracheal intubation and treatment of patients with difficult airways. We studied the intubation success rates and speed with initial use of this device on an intubation manikin to determine whether this device might be easily used by trained and untrained personnel. Rapid and successful intubation with a device requiring limited or no training could have widespread implications for both health care providers and laypersons. The study consisted of 2 parts. In part 1, health care providers with intubation experience, health care providers without prior intubation experience, and nonmedical personnel were instructed to enter a room and intubate a manikin using the ILMA. A single page set of schematic directions was provided within the ILMA setup. The main outcomes were the intubation success rate and the time required for successful ventilation and intubation. In part 2, participants were retested after a standardized <60 second device demonstration. The 111 participants in the study included 44 emergency physicians (40%), 21 anesthesiologists (19%), and 46 other medical or nonmedical personnel (41%). On first attempted use of the device, and with no prior training, 59% of all participants successfully intubated the manikin. Attending and resident physicians had an 83% initial success rate. The median time to ventilation was 47 seconds, and the median time from ventilation until intubation was 29 seconds. Following the <60 second demonstration, 108 of 111 (97%) participants achieved success, with the median time to ventilation 18 seconds, and the median time from ventilation until intubation 17 seconds. All attending and resident physicians succeeded in intubation following the demonstration. Success rates on first attempt correlated with level of training, prior intubation experience, and prior LMA use (all P < .001). After a <60 second demonstration, medical and nonmedical personnel with and without prior intubation training can successfully use the ILMA to rapidly establish an airway in a manikin model. The ILMA should be further studied to determine if it may permit endotracheal intubation by first responders, paramedical personnel, and other medical staff with limited or no laryngoscopy skills.

Assessment of laryngeal view: percentage of glottic opening score vs Cormack and Lehane grading.

PURPOSE: To examine the intra- and inter-rater reliability of two methods that categorize laryngeal view during direct laryngoscopy, the Cormack-Lehane grading system and a new scale, the percentage of glottic opening (POGO) scale. METHODS: Seven anesthesiologists from the University of Pennsylvania Health System viewed 25 identical pairs of slides of laryngeal views during direct laryngoscopy. Each anesthesiologist rated the 50 slides for both Cormack-Lehane grades and POGO scores. The latter CL replaces grades 1 and 2 C-L grades with a percentage of glottic opening: the POGO score. Inter and intra-physician reliability for the Cormack-Lehane grades were determined using the kappa statistic analysis, comparison of POGO scores was performed using the intraclass correlation coefficients (rI). RESULTS: The POGO score had a better inter and intra-physician reliability than the Cormack-Lehane grading system. The intra-physician reliability for the POGO score was very good with an average interclass rI value of 0.88. The inter-physician score was good with a rI of 0.73. The Cormack-Lehane grading system had excellent intra-physician concordance (average kappa = 0.83.) but the inter-physician reliability was poor (kappa = 0.16.) CONCLUSION: The Cormack-Lehane grading system has very poor inter-physician reliability. The lack of inter-physician reliability with Cormack-Lehane grading calls into question the results of previous studies in which different laryngoscopists used this method to assess laryngeal view. The POGO score appears to have good intra and inter-rater reliability. It has several theoretical advantages and may prove to be more useful for research studies in direct laryngoscopy.