Our understanding of how and why important practice variations exist is incomplete, and the topic is understudied. In a systematic review of sedative drug regimens to facilitate mechanical ventilation in the pediatric ICU, Hartman and colleagues reviewed 39 published studies describing 39 different sedative drug regimens and concluded that high-quality evidence to guide clinical practice remains limited. Similarly,jackson and colleagues found considerable variation in the definition and assessment of opimal sedation in a systematic review of 82 studies (75 primary studies). They concluded an overall poor quality of epidemiological data concerning current sedation practices.