Oral sucrose is frequently given to relieve procedural pain in newborn babies subjected to invasive procedures, on the basis of its effect on behavioural and physiological pain scores. But an Article published Online First and in an upcoming Lancet shows that sucrose does not reduce pain activity in the brain or spinal cord, but merely changes facial expressions for some babies giving the false impression that pain is being relieved. However, authors of a linked Comment say that the results are not surprising since they believe the study is not large enough to detect differences in pain response. The Article is by Dr Rebeccah Slater, University College London, UK, and colleagues.
The researchers carried out their study by administering single heel lances (a pricking of the heel with a small metal blade) to the babies--a procedure that was clinically needed to obtain a blood sample. Single heel lances evoke specific pain activity in the brain recorded with neonatal electroencephalography (EEG), and spinal reflexes activity recorded with electromyography (EMG).
In randomised controlled trial, 59 newborn infants at University College London Hospital (London, UK), were randomly assigned to receive 0•5 mL 24% sucrose solution or 0•5 mL sterile water 2 min before undergoing a clinically required heel lance. The primary outcome was pain-specific brain activity evoked by one time-locked heel lance, recorded with electroencephalograph. Secondary measures were baseline behavioural and physiological measures, observational pain scores (PIPP), and spinal reflex withdrawal activity.
29 infants were assigned to receive sucrose and 30 to sterilised water; 20 and 24 infants, respectively, were included in the analysis of the primary outcome measure. Pain activity in the brain after the heel lance did not differ significantly between the two groups. Also, no significant difference in the spinal reflex withdrawal activity was recorded between the sucrose and sterile water groups . Nevertheless, the premature infant pain profile (PIPP) score was significantly lower in infants given sucrose than in those given sterile water (mean 5•8,vs 8•5) and significantly more infants did not change their facial expression after sucrose administration (seven of 20 [35%] vs none of 24).
The authors suggest that sucrose could inhibit facial expression, even while brain activity suggests there is pain. They say: "This notion is especially important in view of the increasing evidence for short-term and long-term adverse effects of infant pain experience on neurodevelopment. 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."
They conclude: "Sucrose seems to blunt facial expression activity after painful procedures, but our data suggest that it does not reduce direct [pain] activity in central sensory circuits, and therefore might not be an effective analgesic drug."
In the linked Comment, Dr Robert E Lasky, University of Texas Medical School at Houston, TX, USA, and Dr Wim van Drongelen, University of Chicago, IL, USA, say that statistically the study has only a one in three chance of detecting a 'medium' effect size difference and only a one in ten chance of detecting a 'small' size difference. They say: "Therefore we should not be surprised that the study failed to detect an effect of sucrose on cortical evoked responses. Small sample sizes also increase concerns that treatment-condition imbalances, despite random allocation, could account for the study's results."
But they add: "Slater and colleagues' study adds an important and innovative measurement to evaluating pain management in newborn babies."
Dr Rebeccah Slater, University College London, UK. E) email@example.com
Alternative contact: Ruth Howells Media Relations Manager, UCL. T) +44 (0)20 7679 9739 / +44 (0)7990 675 947 E) firstname.lastname@example.org
Dr Robert E Lasky, University of Texas Medical School at Houston, TX, USA. E) Robert.email@example.com
For full Article and Comment see: http://press.
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