Less fentanyl requirement by enteral methadone decreases mechanical ventilation duration and intensive care unit length of stay

Background

Patients exposed to long-term infusion or a high dose of opioids may develop physiological dependence and withdrawal symptoms during its discontinuation. In mechanically ventilated adult patients, the occurrence of fentanyl withdrawal syndrome has been associated with difficulties in discontinuing ventilatory support and with increased length of stay (LOS).

Objective

We tested the hypothesis that enteral methadone can reduce fentanyl requirements and, thereby, decrease mechanical ventilation duration and ICU LOS.

Methods

A prospective, randomized and double-blind study involving patients fulfilling criteria for weaning from mechanical ventilation but under high risk for fentanyl abstinence syndrome (defined as continuous fentanyl for more than 5 days or more than 5 μg/kg/hour during 12 hours). Patients were randomized into two groups, methadone (MET) group and control (CT) group, as follows: for the first 24 hours both groups were given 80% of the original dose of fentanyl and received, additionally, in the MET group enteral methadone (10 mg each 6 hours) or in the CT group enteral placebo. After the first 24 hours, the MET group received enteral methadone and intravenous placebo while the CT group received enteral placebo and intravenous fentanyl. In both groups, the blinded intravenous solutions were reduced by 20% of the original dose, every 24 hours. Any abstinence symptoms were treated with a bolus of fentanyl. The Student t test was used to compare groups in the following criteria: (1) days under mechanical ventilation and (2) ICU LOS.

Results

Sixteen patients were included, seven in the MET group and nine in the CT group. The LOS was significantly lower in the MET group (13 ± 3 vs 27 ± 13 days, P < 0.02). Days under mechanical ventilation were also significantly decreased in patients from the MET group (4 ± 0.8 vs 20 ± 21 days, P < 0.05).

Conclusion

These preliminary data show that, by replacing fentanyl infusion with methadone through the enteral route, it is possible to decrease mechanical ventilation duration as well as the ICU length of stay.