title: The neuromuscular response of infants to a continuous infusion of succinylcholine.
abstract: The response of the adductor of the thumb to ulnar nerve stimulation (0.1 Hz) was evaluated during continuous infusion of succinylcholine (SCh) in 20 infants anesthetized with halothane (1%) and N2O2/O2. Train-of-four stimulation (2 Hz for 2 s) was used to differentiate between phase I and phase II block. Some infants were very resistant to the neuromuscular effects of SCh. These infants (Group 1) were younger in age, 57 +/- 15 days (mean +/- SE) and required 24.6 +/- 3.3 mg X kg-1h-1 SCh to achieve more than 90% depression of the twitch. Older infants (Group 2), 188 +/- 33 days, required significantly less (P less than 0.001) SCh (8.7 +/- 0.5 mg X kg-1h-1) to achieve the same degree of twitch suppression. Group 1 infants recovered from the effects of SCh very rapidly. After 10 mg/kg SCh, the train-of-four ratio in Group 1 infants recovered to 75% in 4.7 +/- 0.6 min, whereas it took 34 +/- 10 min in Group 2 infants (P less than 0.01). Tachyphylaxis developed in infants after 3.6 +/- 0.3 mg/kg (mean +/- SE) and phase II block after 5.3 +/- 0.7 mg/kg (P less than 0.05) SCh. Combining the data of infants with that of children from a previous study conducted in a similar fashion resulted in significant correlation (P less than 0.001) between the log age and SCh requirement. The rate of administration of a continuous infusion of SCh in infants should be based upon the response of infants and not on a fixed dose (mg X kg-1 X h-1).
mesh_terms: D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007263:Infusions, Parenteral; D009469:Neuromuscular Junction / Q000187:drug effects*; D013390:Succinylcholine / Q000008:administration & dosage*; D009435:Synaptic Transmission / Q000187:drug effects; D013618:Tachyphylaxis
chemical_list: D013390:Succinylcholine