Ketamine for procedural pain relief in newborn infants.
OBJECTIVE
To assess the suitability of ketamine for relief of pain caused by tracheal suction during ventilator treatment in newborn infants.


METHODS
In a randomised, double blind, cross over trial, 16 newborn infants received placebo or 0.5, 1, or 2 mg/kg ketamine as two minute infusions in random order five minutes before four separate endotracheal suctions, with intervals of at least 12 hours.


RESULTS
Mean (SD) plasma ketamine concentration increased linearly with the dose (103 (49), 189 (75), and 379 (97) ng/ml after 0.5, 1, and 2 mg/kg respectively). Heart rate decreased significantly only after 2 mg/kg ketamine (-7 (10) beats/min, p = 0.029 v placebo). The increases in heart rate, arterial blood pressure, and pain score in response to tracheal suction during the placebo phase (11 (23) beats/min, p = 0.065; 6 (7) mm Hg, p = 0.004; 3.5 (interquartile range (IQR) 2.75-5) points, p = 0.001) were not attenuated by 0.5 or 2 mg/kg ketamine. However, 1 mg/kg ketamine attenuated the increase in pain score (1 (IQR 0.75-4.25) points, p = 0.043 v placebo), but not in heart rate (7 (23) beats/min) or blood pressure (7 (9) mm Hg).


CONCLUSIONS
None of the doses of ketamine attenuated the changes in heart rate or blood pressure caused by suction, and only with a dose of 1 mg/kg was the suction induced pain moderately reduced. Thus infusion of ketamine at the doses used appears to be an ineffective method of relieving the pain caused by endotracheal suction.
Saarenmaa
E
E
Hospital for Children and Adolescents, University of Helsinki, PB 281, 00029 Huch, Finland. elina.saarenmaa@hus.fi
Neuvonen
P J
PJ
Huttunen
P
P
Fellman
V
V
D000700:Analgesics / Q000493:pharmacokinetics / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007231:Infant, Newborn; D007442:Intubation, Intratracheal / Q000379:methods*; D007649:Ketamine / Q000493:pharmacokinetics / Q000627:therapeutic use*; D008297:Male; D010146:Pain / Q000517:prevention & control*; D010147:Pain Measurement; D018709:Statistics, Nonparametric; D013396:Suction / Q000379:methods; D016896:Treatment Outcome
D000700:Analgesics; D007649:Ketamine