Introduction: Adequate analgesia in mechanically ventilated patients is crucial to reduce sedation requirements and minimize risk of ICU delirium. Fentanyl is typically used due to its favorable kinetics, but recent shortages have required use of morphine despite concerns for excessive sedation. Few studies have compared these drugs in the ICU, but evidence suggests associations between opioid choice and clinical outcomes (Casamento et al., Am J Respir Crit Care Med. 2021). We hypothesized that morphine use for ventilator analgesia would be associated with worse clinical outcomes compared to fentanyl. Methods: This was a single-center, retrospective observational study of intubated patients (≥18 years) admitted to the ICU of an urban hospital in Japan between January and March 2025 and received continuous infusion of either fentanyl or morphine. Patients with do-not-resuscitate orders or who died within 24 hours of admission were excluded. Primary outcomes were ventilator-free days (VFDs), ICU length of stay (LOS), and 28-day mortality. Secondary outcomes included total opioid (morphine-equivalent) dose and enteral nutrition volume during ICU stay. Data were analyzed via Mann–Whitney U and chi-square tests; p< 0.05 was used for statistical significance. Results: A total of 75 patients were included; 20 received fentanyl, 55 received morphine. No significant differences were observed in baseline characteristics (age, gender, or SOFA scores), LOS or mortality between groups (fentanyl, morphine; respectively: LOS: 3.0 v. 7.0 days, p = 0.23; mortality: 15.0% v. 20.0%, 95% CI: 0.38–6.82, p = 0.62).Total opioid dose and enteral nutrition volume also showed no significant differences between fentanyl or morphine respectively (52.3 v. 60.2 mg; p=0.97; 956.5 v. 1200.0 kcal; p=0.75). However, VFDs were significantly greater in the fentanyl group (24.5 v. 20.0 days; p=0.04). Conclusions: In mechanically ventilated ICU patients, morphine was not associated with differences in mortality or ICU stay compared to fentanyl but was associated with significantly fewer ventilator-free days, suggesting potential implications for recovery. Caution is warranted if morphine use in this setting continues.
Masuyama et al. (Sun,) studied this question.