One hundred and forty studies were included in the review (n=57,132 patients): 117 studies of oral endotracheal intubation (n=54,933 patients) and 23 studies of nasotracheal intubation (n=2,199 patients). The quality of evidence scores (out of 10) ranged from 1 to 10 (mean 5.1) for oral endotracheal intubation studies and from 1 to 7 (mean 4.6) for nasotracheal intubation studies.
Oral endotracheal intubation: The pooled success rate for oral endotracheal intubation was 89.2% (95% CI 87.7% to 90.5%, I2=95%); there was no evidence of publication bias for this outcome. Subgroup analyses indicated little difference in outcome when administered by air medical crews (88.1%) and ground paramedics (87.5%). Success rates were higher in non-trauma patients (88.6%) compared with trauma patients (73.7%) and were higher in cardiac patients (91.2%) compared with non-arrest patients (70.4%).
Nasotracheal intubation: The pooled success rate for nasotracheal intubation was 73.1% (95% CI 67.8% to 77.7%, I2=83%); there was evidence of publication bias for this outcome (p=0.014). Subgroup analyses indicated little difference in outcome when administered by air paramedics (77.9%) and ground paramedics (76.2%).
Rapid-sequence intubation: The pooled success rate for rapid-sequence intubation was 96.1% (95% CI 94.5% to 97.3%, I2=86%); there was evidence of publication bias for this outcome (p=0.007). Subgroup analyses indicated success rates varied from 93.9% for physicians to 97.7% for aircrew.
Drug-facilitated intubation: The pooled success rate for drug-facilitated intubation was 86.2% (95% CI 79.9% to 90.8%; I2 = 83%); there was evidence of publication bias for this outcome (p=0.002).
Subgroup analyses indicated success rates that varied from 65.5% for trauma patients to 94.6% for aircrew. Pooled success rates for non-arrest patients were higher with drug-facilitated intubation (86.8%) and rapid-sequence intubation (96.7%) than for procedures without drugs (69.8%).