 The first aim of the study was to evaluate the effectiveness of the three competing interventions on the critical care nurses knowledge of, attitudes toward and adherence to 17 ventilator bundle components; the second aim was to determine the effectiveness of adherence to 17 ventilator bundle components with pre-defined ventilator bundle on the psychological factors of critical care nurses including nurses stressors in intensive care unit ICU, perceived stress, trait and state anxieties; the third aim was to evaluate their impact on the clinical outcomes; and the fourth aim was comparing KAP and psychological factors with clinical outcomes. 