The infusion of opioids during terminal withdrawal of mechanical ventilation in the medical intensive care unit

Abstract

Context: Most deaths in intensive care units occur after limitation or withdrawal of life-sustaining therapies. Often these patients require opioids to assuage suffering; yet, little has been documented concerning their use in the medical intensive care unit.

Objectives: To determine the dose and factors influencing the use of opioids in patients undergoing terminal withdrawal of mechanical ventilation in this setting.

Methods: Data were prospectively collected from 74 consecutive patients expected to die soon after extubation. The doses of morphine, effect on time to death, and relation of dose to diagnostic categories were analyzed.

Results: The mean (±standard deviation) dose of morphine given to patients during the last hour of mechanical ventilation was 5.3mg/hour. Patients dying after extubation received 10.6 mg/hour just before death. Immediately before extubation, the dose correlated directly with chronic medical opioid use and sepsis with respiratory failure and inversely with coma after cardiopulmonary resuscitation or a primary neurological event. After terminal extubation, the final morphine dose correlated directly with the presence of sepsis with respiratory failure and chronic pulmonary disease. The mean time to death after terminal extubation was 152.7 ± 229.5 minutes without correlation with premorbid diagnoses. After extubation, each 1mg/hour increment of morphine infused during the last hour of life was associated with a delay of death by 7.9 minutes (P = 0.011).

Conclusion: Premorbid conditions may influence the dose of morphine given to patients undergoing terminal withdrawal of mechanical ventilation. Higher doses of morphine are associated with a longer time to death.