Fentanyl-induced chest wall rigidity and laryngospasm in preterm and term infants

Objective: To assess the occurrence of muscle rigidity after fentanyl administration in premature and term neonates. Design: Prospective case series, observational study. Setting: A university hospital neonatal intensive care unit. Patients: 8/89 preterm end term infants (25-40 wks gestational age) who received fentanyl for perioperative analgesia and sedation or intensive care procedures. Interventions: Mechanical or bag mask ventilation and antagonization with naloxone. Measurements and Main Results: We observed chest wall rigidity in 8 patients after low dosage of fentanyl (3-5 mu g/kg body weight). All patients presented with respiratory distress, hypercapnia, and hypoxemia leading to bradycardia. In two patients, laryngospasm was noted and associated with muscle rigidity, thus making intubation impossible. Naloxone (20-40 mu g/kg body weight) reversed the laryngospasm and muscle rigidity immediately, allowing restitution within 1 min. In our patient population, we found fentanyl-induced chest wall rigidity in 4% of neonates after fentanyl administration. Conclusion: Even low doses of fentanyl can lead to thoracic rigidity in neonates. Additionally, we observed laryngospasm in two patients and speculate that it might be a variant of muscle rigidity.