Figure 1.

First-pass success (%) over time among control or reference groups of studies on patients in intensive care units or medical wards undergoing emergency endotracheal intubation. Retrospective and prospective cohort studies as well as randomized controlled trials were included. Studies were excluded if the target population was patients with cardiac arrest. Trendline was added to demonstrate increasing first-pass success over time period examined. The Spearman correlation coefficient between first-pass success and month of study publication was 0.64 (P < 0.05) (1, 3–5, 7–10, 12–27).