Procedural pain reducing methods and pain assessment in newborns

• Our knowledge of pain in neonates has increased significantly during the last fifteen years.We now have an improved understanding of the pain system and of the negative effects of untreated pain. Advances in neonatal care have increased the nwnber of preterm and severely ill infants who are treated in neonatal intensive care units (NICU). These infants are subjected to a variety of painful procedures as part of their management. Sufficient pain relief is needed and for this, valid pain assessment is one prerequisite.The aim of this research was to improve the management of procedural pain and to examine the assessment of neonatal pain in clinical practice.In an earlier study, oral glucose was found to reduce pain during blood sampling. To further evaluate the pain-reducing effect of oral glucose and to compare this effect with different blood sampling techniques, a trial was performed. The pain score was lower and crying time shorter in the venipuncture group than in the heel stick group when no glucose was given. When glucose was administered, the pain score was lower in both glucose groups than in the groups not receiving glucose (paper I).In a randomized, controlled study, the effect of oral glucose was compared with that of a topical local anaesthetic, EMLA, during venipuncture. The pain scores were found to be lower in the glucose group and fewer infants were scored as having pain. Crying time was also shorter in the glucose group (paper II).To compare the pain-reducing effect of oral glucose with that of breast-feeding shortly before venipuncture, a new trial was performed. The pain score was significantly lower in the infants receiving glucose than in those not given glucose. There was no significant difference in pain score between the infants who were fed and the fasting infants (paper III).In a previous study we found an increase in heart rate in newboms when they received glucose as pain relief. We therefore investigated whether oral glucose in itself could cause an increase in heart rate in healthy infants. In a trial, infants were randomized to receive oral glucose or placebo without undergoing any painful procedure. The heart rate was significantly higher in the glucose than in the placebo group (paper IV).Activation of endogenous opioids is suggested as one possible mechanism underlying the pain-reducing effect of oral glucose. We therefore investigated whether administration of an opioid antagonist would reduce the effect of oral glucose at heel stick in full-term newboms. There were no significant differences in pain score or crying between the group receiving an opioid antagonist before oral glucose and the group receiving placebo before oral glucose during heel stick (paper V).To document whether pain is assessed in Swedish neonatal units and by what methods, a questionnaire was distributed to all neonatal wards in Sweden in 1993, and again in 1998. Only a small proportion of neonatal units in Sweden attempted to assess pain. There was a minor increase in the nwnber of wards that used a structured method for pain scoring. Docwnentation of pain is still inadequate and needs to be improved (paper VI). We compared parental assessment during blood sampling with measurement of the pain score with a multidimensional tool and crying. There was low agreement between these variables during the procedure (paper III).In conclusion, we found that oral glucose reduces signs of pain from both heel stick and venipuncture blood sampling. Oral glucose reduces pain better than does EMLA cream and better than if the infant is breast-fed shortly before the procedure. Oral glucose increases the heart rate in infants and the pain-reducing effect of oral glucose in newboms was not diminished by injection of an opioid antagonist. Parental assessment of an infant's pain cannot replace measurement by pain scores. The pain assessment at neonatal units in Sweden needs to be improved.

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