Conversion from prolonged intravenous fentanyl infusion to enteral methadone in critically ill children

Abstract

AIMTo describe our institutional experience with conversion from intravenous (IV) fentanyl infusion directly to enteral methadone and occurrence of withdrawal in critically ill mechanically ventilated children exposed to prolonged sedation and analgesia.METHODSWith Institutional Review Board approval, we retrospectively studied consecutively admitted invasively mechanically ventilated children (0-18 years) sedated with IV fentanyl infusion > 5 d and subsequently converted directly to enteral methadone. Data were obtained on subject demographics, illness severity, daily IV fentanyl and enteral methadone dosing, time to complete conversion, withdrawal scores (WAT-1), pain scores, and need for rescue opioids. Patients were classified as rapid conversion group (RCG) if completely converted ≤ 48 h and slow conversion group (SCG) if completely converted in > 48 h. Primary outcome was difference in WAT-1 scores at 7 d. Secondary outcomes included differences in overall pain scores, and differences in daily rescue opioids.RESULTSCompared to SCG (n = 21), RCG (n = 21) had lower median WAT-1 scores at 7 d (2.5 vs 5, P = 0.027). Additionally, RCG had lower overall median pain scores (3 vs 6, P = 0.007), and required less median daily rescue opioids (3 vs 12, P = 0.003) than SCG. The starting daily median methadone dose was 2.3 times the daily median fentanyl dose in the RCG, compared to 1.1 times in the SCG (P = 0.049).CONCLUSIONWe observed wide variation in conversion from IV fentanyl infusion directly to enteral methadone and variability in withdrawal in critically ill mechanically ventilated children exposed to prolonged sedation. In those children who converted successfully from IV fentanyl infusion to enteral methadone within a period of 48 h, a methadone:fentanyl dose conversion ratio of approximately 2.5:1 was associated with less withdrawal and reduced need for rescue opioids.

Protocolized Sedative Weaning vs Usual Care in Pediatric Critically Ill Patients: A Pilot Randomized Controlled Trial

“…Methadone, lorazepam, clonidine, or dexmedetomidine are commonly used as an adjunctive therapy for opioid or benzodiazepine withdrawal. 7 , 15 – 23 Our study used methadone and lorazepam as primary medications for weaning therapy. Several prior studies demonstrated various opioid weaning strategies by using methadone to prevent opioid withdrawal.…”

“…Most studies showed that 40 to 80% of patients develop IWS. 6 , 23 Several previous studies reviewed the conversion of intravenous fentanyl to oral methadone. The proposed conversion ratio varied from 1:1 to 1:16.7.…”

“… 21 , 23 A prior retrospective study had the intravenous fentanyl to oral methadone conversion ratio of approximately 1:2.5. 23 The conclusion showed this conversion ratio was associated with less withdrawal and reduced the need for rescue opioids. However, the median WAT-1 score at 48 hours, 72 hours, and 96 hours was greater than 3 (defined as withdrawal syndrome).…”

“…In addition, the initial doses of fentanyl prior to conversion to methadone was high (4 μg/kg/hour). 23 In our study, we used the conversion ratio of intravenous fentanyl to oral methadone was 1:6.5 with the dose of intravenous fentanyl at initiation of enterol methadone was 1–2 μg/kg/hours for safety concern.…”

Shortened Taper Duration after Implementation of a Standardized Protocol for Iatrogenic Benzodiazepine and Opioid Withdrawal in Pediatric Patients: Results of a Cohort Study

“…A recent study evaluated patients who were rapidly converted from intravenous opioids to methadone compared with those who were slowly converted. 27 The patients who had a successful rapid conversion to methadone received a methadone:fentanyl conversion ratio of approximately 2.5:1. Shaheen et al 28 demonstrated that conversion calculations are widely variable and require clinical judgment and patient-specific modifications to be used safely.…”