Objective:To determine physician and nurse adherence with sedative, analgesic, and neuromuscular blocking agent guidelines in the management of mechanically ventilated patients in a medical intensive care unit.Design:Prospective cohort study.Subjects:One hundred consecutively admitted patients to a medical intensive care unit who required mechanical ventilatory support. A sample of 29 nurses, residents, and attending physicians were interviewed regarding their attitudes and perceptions of the guidelines.Measurement:Data were collected from concurrent medical records and included the following: demographic characteristics; clinical variables; physician prescriptions of sedative, analgesic, and/or neuromuscular blocking agents; nurse administration of these medications; documentation of monitoring; and assessment of patient hemodynamic status and behaviors. A semistructured interview was elicited from both nurses and physicians about their rationale for the use or nonuse of the guidelines.Results:Patients ranged in age from 24 to 87 yrs, mean 60.7 (±15.3) yrs. Admission Acute Physiology and Chronic Health Evaluation III scores ranged from 36 to 192, mean 93.8 (±30.5) and median 88. Length of mechanical ventilatory support ranged from 1 to 112 days, mean 14.8 (±20.0) days, and median 8 days; medical intensive care unit length of stay ranged from 1 to 46 days, with a mean of 9.8 (±8.1) days and a median of 8 days. Of the 100 patients, 47% died, 28% returned home, and 25% were discharged to a nursing facility. Eighty-five patients were administered one or more sedative, analgesic, and/or neuromuscular blocking agent, range 1-9 drugs, mean 2.5 (±1.5) drugs. Physicians prescribed 14 different medications; the most commonly administered drug was lorazepam (n = 71), followed by morphine (n = 39). Physicians and nurses had partial or total adherence to the guidelines in 58% of patients. The initial choice of the drug followed the guidelines in 60% of patients; the overall guideline was followed in 23% of patients. The most common rationales for nonadherence to the guidelines stated by both physicians and nurses were patient-specific factors, resident guideline learning curve, and physician medication preferences.Conclusion:Most patients required treatment for agitated behaviors. The majority of treatment regimens partially or totally adhered to the guidelines. Factors such as patient-specific disease states, resident guideline learning curve, and physician preferences of medications may have decreased adherence. Improving adherence to the guidelines is essential to assess their effectiveness in improving clinical outcomes.