Acute withdrawal from opioids

Acute withdrawal from opioids: Reports on dexmedetomidine use for opioid withdrawal are limited to case studies and retrospective reviews involving a total of 20 paediatric patients.[19] When bolus doses are used, strategies described in published reports entail a loading dose of 0.5–1.0 microgram/kg administered over 5–10 minutes, followed by a continuous infusion at 0.1–1.4 microgram/kg/hour for a period of 1–16 days. Reported adverse effects include hypotension and bradycardia. (LOE IV)
Prevention of postoperative junctional ectopic tachycardia in children after congenital heart surgery: In an RCT [20] in 90 children who underwent elective cardiac surgery for congenital heart diseases randomised to dexmedetomidine 0.5 microgram/kg intravenously over 20 minutes completed 10 minutes before induction, followed by 0.5 microgram/kg/hour infusion for 48 hours postoperatively versus placebo group. The incidence of junctional ectopic tachycardia was significantly reduced in the dexmedetomidine group (3.3%) compared with placebo (16.7%) with P<0.005. Heart rate while coming off cardiopulmonary bypass was significantly lower in the dexmedetomidine group, and ventilation time, mean duration of intensive care unit and hospital stay (days) were significantly shorter. There was no difference between the 2 groups with regards to mortality, bradycardia, or hypotension. Conclusion: Prophylactic use of dexmedetomidine is associated with significantly decreased incidence of postoperative junctional ectopic tachycardia in children after congenital heart surgery without significant side effects. [LOE II GOR B]
Safety
When used for long-term sedation during mechanical ventilation in critically ill patients, dexmedetomidine doubled the incidence of bradycardia, with heterogeneous other effects compared to other agents including hypotension, hypertension, tachycardia, first degree heart block, hyperglycaemia and hypoglycaemia. [7]
In animal studies, there was no histological neurological injury associated with dexmedetomidine when administered by itself, and 13 of 16 studies reported beneficial neuroprotective effects of dexmedetomidine when administrated with other anaesthetics. [1] However, studies are lacking about the long‐term neurobehavioral effects when administered in children for sedation or anaesthesia. A RCT to determine the long‐term neurobehavioral effects of dexmedetomidine in children (compared to currently used neurotoxic anaesthetics), with the ultimate aim to find a safer alternative to the currently used neurotoxic anaesthetics in children is needed. [1]
Limited observational studies in newborn infants have reported dexmedetomidine to be generally well-tolerated and safe, although not without side effects particularly with use of bolus doses. [3, 11, 15, 17] In a dose escalation study in 42 newborns receiving mechanical ventilation, inadequate analgaesia was reported in 17 (40%) and inadequate sedation in 4 (10%), with 3 (5%) adverse events attributed to dexmedetomidine. [3] A report of use of dexmedetomidine for induction of anaesthesia in newborns reported 4 infants experiencing bradycardia which responded to atropine, resulting in a change in the induction protocol. [16] In postoperative neonatal surgical patients receiving prolonged infusion, dexmedetomidine resulted in a significant decrease in the cumulative dose of opioid but was associated with more episodes of bradycardia (12.8% versus 5.1%) than opioids alone. Hypothermia has been reported in newborns receiving dexmedetomidine for perioperative sedation. [16, 21] There is a case report of a newborn infant with electrical seizures during administration of dexmedetomidine which ceased following discontinuation. [22] In a RCT in 104 infants (75% born premature), allocated to dexmedetomidine sedation with caudal block versus general sevoflurane anaesthesia with tracheal intubation and caudal block for elective bilateral inguinal hernia surgery, infants in the dexmedetomidine group had significantly lower heart rates and higher mean arterial pressures intraoperatively, and 9.8% required additional anaesthetic agents or conversion to general anaesthesia. [18]
Withdrawal from prolonged dexmedetomidine infusion (>72 hours) was reported to result in increased heart rate and blood pressure, reduced COMFORT scores, and 30%, whether weaned or abruptly stopped, had withdrawal symptoms including agitation, tremor and decreased sleep. [23]
Dexmedetomidine has been reported to be safe in paediatric patients with congenital heart disease and is not associated with any significant ECG interval abnormalities other than a trend towards lower heart rate. [24] The therapeutic use of dexmedetomidine has been reported for acute termination of re-entrant supraventricular tachycardia (SVT) in 15 infants aged 6 to 16 days. Twenty seven doses of dexmedetomidine (mean dose 0.7 +/- 0.3 microgram/kg) for a total of 27 episodes of SVT. [25]
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