Fifty-seven studies (n=5,176) were included in the review. There were 15 RCTs and 42 case series or correspondence.
In normal patients (n=4,189), the pooled first-time success rates were: Bonfils 96.8% (95% CI 0.92 to 0.99; seven studies, n=125); CTrach 92.9% (95% CI 0.91 to 0.95; seven studies, n=638); and WuScope 84.3% (95% CI 0.77 to 0.90; three studies, n=121). There was no statistically significant heterogeneity. Studies of other devices, including Bullard, Shikani, UpsherScope, Glidescope and McCoy were heterogeneous; the last two showed first-time success rates of over 90%. Individual overall success rates (not pooled) over 95% were reported for Flexiblade, Glidescope, WuScope, CTrach and Bonfils.
Pooled first-time success rates in predicted difficult/known difficult patients (n=987) were: Bonfils 92.5% (95% CI 0.82 to 0.98; four studies, n=53); Glidescope 92.3% (95% CI 0.79 to 0.98; six studies, n=39); and CTrach 90.6% (95% CI 0.75 to 0.98; three studies, n=32). There was no statistically significant heterogeneity. The McCoy showed the highest pooled first-time success rate (96.3%, 95% CI 0.92 to 0.99; nine studies, n=161), but statistically significant heterogeneity was reported (p<0.001). Individual overall success rates (not pooled) over 90% were reported for Flexiblade, McCoy, Bonfils and CTrach.
Comparisons with the Macintosh 3 blade (n=2,124) showed improved laryngeal view from use of non-standard devices (67.7% of patients), but all analyses were based on heterogeneous data (p<0.0001) with the exception in one study (n=566) of known difficult patients and the Macintosh videolaryngoscope (59% net improvement).