LA-area values and intubation times were compared with repeated measures analysis of variance, followed by Scheffé test as appropriate. IDS scores were compared with Friedman’s exact test. Significance was set at P < 0.05. Data are presented as mean ± sd or median (interquartile range).
The data from 10 patients (7 male, 3 female; age, 66 ± 14 yr; body mass index, 23.8 ± 1.6 kg/m2) were analyzed. Relative to conventional/balloon/McCoy laryngoscopies, McCoy-balloon laryngoscopy resulted in larger LA exposure and lower IDS score (P < 0.001-0.05). Relative to conventional laryngoscopy, balloon and McCoy laryngoscopies resulted in larger LA exposure and lower IDS score (P = 0.002-0.007). Balloon and McCoy laryngoscopies provided similar laryngoscopic/intubating conditions. Individual LA-area data and IDS scores are provided in Table 2 and Table 3, respectively. Representative laryngoscopic images are provided in Figure 3. Time to intubation confirmation was longest with conventional laryngoscopy (36 ± 4 s), intermediate/similar with balloon and McCoy laryngoscopies (18 ± 7 and 21 ± 8 s, respectively) and shortest with McCoy-balloon laryngoscopy (11 ± 2 s) (P < 0.001-0.05).
Our main findings are that in patients with moderate-to-major intubation difficulty (2), combined McCoy-balloon laryngoscopy results in superior laryngoscopic/intubating conditions relative to the conventional/balloon/McCoy laryngoscopic techniques. In patients with difficult conventional laryngoscopy-guided intubation, the Macintosh blade contour may not adequately conform to an abnormal upper airway contour (9,12,13). Thus, the hyoid/tongue base and epiglottis cannot be lifted and the LA cannot be visualized (7). The McCoy-balloon blade is a balloon-tipped McCoy blade-modification (8,9). By combining an inflatable balloon with a hinged tip (4,8,9), this blade exhibits enhanced contour adjustability compared with all the other three laryngoscope blades we used. Consequently, the probability of blade contour conformation to upper airway contour and of effective epiglottis lifting/LA exposure is maximized.
The number of supplementary attempts at intubation (N1) was a major determinant of the differences in IDS scores/intubation times. Each supplementary attempt generated the need for use of OTT guide, or external laryngeal pressure, or (subjectively) (2) increased lifting force. The sums of individual N1s were 28, 9, 12, and 1 with conventional, balloon, McCoy, and McCoy-balloon laryngoscopies, respectively, reflecting successful intubation after an average of 3.8, 1.9, 2.2, and 1.1 attempts, respectively.
Fewer supplementary attempts and shorter intubation times indicate reduced probability of upper airway trauma (7,14). More rapid intubation indicates reduced time of airway management-related apnea and associated hypoxemia risk. Thus, McCoy-balloon laryngoscopy may be particularly useful in patients with acute respiratory failure (ARF) who require emergency ventilatory support.
Study participants were intubated 4 times for no therapeutic purpose. However, study results (Table 3) indicated that any future emergency/elective McCoy-balloon laryngoscopy-guided orotracheal intubation would most likely be ideal and, consequently, safer. Also, seven patients were admitted for ARF as a result of obstructive lung disease exacerbation; in such patients, severe disease exacerbations necessitating ventilatory support recur frequently after ICU/hospital discharge (15–19).
In conclusion, McCoy-balloon laryngoscopy substantially facilitates orotracheal intubation in patients with high IDS scores. Consequently, we recommend the use of McCoy-balloon laryngoscopy in difficult airway management.
The authors thank physiotherapist Mr. C. Gregoriades for his valuable help with the laryngeal view recordings.
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