Oral Sucrose May Not Provide Effective Analgesia in Neonates

Laurie Barclay, MD

September 01, 2010

September 1, 2010 — Oral sucrose may not provide effective analgesia in neonates, according to the results of a double-blind, randomized controlled trial study published online today in The Lancet.

"Many infants admitted to hospital undergo repeated invasive procedures," write Rebeccah Slater, PhD, from University College London, United Kingdom, and colleagues. "Oral sucrose is frequently given to relieve procedural pain in neonates on the basis of its effect on behavioural and physiological pain scores. We assessed whether sucrose administration reduces pain-specific brain and spinal cord activity after an acute noxious procedure in newborn infants."

Based on a computer-generated randomization code, 59 newborn infants at University College Hospital were allocated to receive 0.5 mL 24% sucrose solution or 0.5 mL sterile water 2 minutes before undergoing a clinically necessary heel lance. The investigators, clinicians, participants, and parents were blinded as to the identity of the solutions. Electroencephalographically determined pain-specific brain activity evoked by 1 time-locked heel lance was the main study endpoint. Secondary outcomes were baseline behavioral and physiological measures, observational pain scores, and spinal nociceptive reflex withdrawal activity.

Per protocol analysis of the main study endpoint included 20 of 29 infants randomly assigned to receive sucrose and 24 of 30 infants randomly assigned to receive sterilized water. The groups had no significant difference in nociceptive brain activity after the noxious heel lance (sucrose: mean, 0.10; 95% confidence interval [CI] .004 - 0.16; sterile water: mean, 0.08; 95% CI, 0.04 - 0.12; P = .46). Similarly, the groups did not differ significantly in magnitude or latency of the spinal nociceptive reflex withdrawal recorded from the biceps femoris of the stimulated leg.

Compared with infants given sterile water, those given sucrose had a significantly lower observational pain score (mean, 5.8 [95% CI, 3.7 - 7.8] vs 8.5 [95% CI, 7.3 - 9.8]; P = .02). After sucrose administration, significantly more infants had no change in facial expression (7 of 20 [35%] vs 0 of 24; P < .0001).

"Our data suggest that oral sucrose does not significantly affect activity in neonatal brain or spinal cord nociceptive circuits, and therefore might not be an effective analgesic drug," the study authors write. "The ability of sucrose to reduce clinical observational scores after noxious events in newborn infants should not be interpreted as pain relief."

Limitations of this study include that it was a single-center trial with a small sample size, which may mean that the trial was not powered for observation of subtle effects that sucrose might have on central nervous system processing.

"Sucrose seems to blunt facial expression activity after painful procedures, but our data suggest that it does not reduce direct nociceptive activity in central sensory circuits, and therefore might not be an effective analgesic drug," the authors conclude. They add that "the absence of evidence for an analgesic action of sucrose in this study, together with uncertainty over the long-term benefits of repeated sucrose administration, suggest that sucrose should not be used routinely for procedural pain in infants without further investigation."

In an accompanying comment, Robert E. Lasky, PhD, from the University of Texas Medical School in Houston, and Wim van Drongelen, PhD, from the University of Chicago, Illinois, note that despite its limitations, this study adds "an important and innovative measurement to evaluating pain management in newborn babies."

"Slater and colleagues characterise the cortical evoked responses that they recorded as a more direct measure than other responses used to measure pain in newborn babies," Dr. Lasky and Dr. Drongelen write. "But it is the wellbeing of the infant that is the definitive outcome in determining the efficacy of medical interventions and not surrogate outcomes, regardless of how central they are hypothesised to be to the pain response in the newborn baby.... [U]ntil we better understand pain pathways and the short-term and long-term sequelae of painful procedures, it seems premature to conclude that sucrose might not be an effective analgesic for newborn babies."

The Medical Research Council supported this study. The study authors and editorialists have disclosed no relevant financial relationships.

Lancet. Published online September 1, 2010.

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