Neonatal Analgesia: a Neglected Issue in the Tropics
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REVIEW ARTICLE Neonatal analgesia: A neglected issue in the tropics Herbert A. Obu, Josephat M. Chinawa Department of Pediatrics, College of Medicine, University of Nigeria, University of Nigeria Teaching Hospital, Ituku- Ozalla, Enugu, Nigeria ABSTRACT Pain control in newborns is poorly understood and often neglected in neonatal practice in many settings in our environment. Managing pain among newborns can be quite challenging and the effectiveness of various interventions used to ameliorate pain in this category of patients are either unknown or poorly understood by many a people engaged in the care of newborns in one way or the other. A search for published works on neonatal analgesia was performed using Google and PubMed. The Cochrane Database of Systematic Reviews was also searched. The areas of focus were definition, pathophysiology and management of pain in neonates. Relevant information was extracted and processed. Contrary to what is widely believed in Address for correspondence: many quarters, howbeit erroneously, there is compelling evidence that newborns do indeed Dr. Josephat M. Chinawa, feel pain. Supportive care, comprising of use of sucrose, glucose, breastfeeding, kangaroo Department of Paediatrics, mother care are worthwhile measures in ameliorating pain in the newborn. Novel therapies University of Nigeria Teaching (such as sensorial saturation and swaddling) have been evaluated and proven useful. The use Hospital, Enugu 01129, Nigeria. of sedation did not show any beneficial results. E-mail: josephat.chinawa@ unn.edu.ng Key words: Control, neonates, pain INTRODUCTION any form of analgesia. These procedures include ear piercing, circumcision, ligation of extra digits, heel Pain is defined as an unpleasant sensory and/or emotional lancing, venepuncture, lumbar puncture, chest tube 1 experience associated with possible tissue damage. It is insertions, intravenous catheter insertion, endotracheal also defined as localised physical suffering associated with tube suctioning, surgery, etc. Some of these procedures a bodily disorder (disease or injury) or as a basic bodily are repeated severally, especially for sick neonates and sensation induced by a noxious stimulus, received by naked preterm babies. Indeed, a longitudinal study showed that nerve endings, characterised by physical discomfort (as the youngest pre-term neonates had an average of 750 pricking, throbbing, or aching), and typically leading to procedures during their hospital stay.2 It is noted that evasive action (Merriam-Webster’s English Dictionary, premature infants in Canadian neonatal intensive care units Merriam-Webster Inc, 2013). (NICUs) were subjected to an average of two and up to eight Verbalisation of nociceptive sensation is the gold standard painful procedures per day. For these infants, analgesic 3 for assessment of pain.1 Since neonates cannot verbalise agents were provided in only 6.8% of all procedures. their pain, the recognition and management of pain in Moreover, a recent cohort study showed that less than 10% this category of children has left much to be desired, both of the sickest NICU infants received opioids compared with in hospital settings, including neonatal intensive care 22-33% of those at lesser risk for neurologic impairment.3 units, and in the general population. It is often felt, and There is increasing evidence that newborns indeed most erroneously so, that newborns do not feel pain or experience pain and that these early pain experiences may have not yet developed the capacity to feel pain and as have long-term consequences. Following extensive work a result are exposed to a variety of painful procedures in the 1980s and 1990s, the fact that neonates experience both in hospital settings and in the community without pain and mount a stress response was established and appreciated. Even premature neonates undergoing surgery Access this article online can mount a clinically significant stress response, as Quick Response Code: measured by hormonal and metabolic indicators. Stress Website: indicators include plasma adrenaline, noradrenaline, www.nigeriamedj.com glucagon, insulin and cortisol levels as well as blood glucose, lactate, pyruvate and alanine concentrations.1 DOI: The mounting of a stress response results in catabolic 10.4103/0300-1652.132034 responses, including glycogenolysis, gluconeogenesis and lipolysis. These catabolic responses, when un-modulated Nigerian Medical Journal | Vol. 55 | Issue 3 | May-June | 2014 Page | 183 Obu and Chinawa: Neonatal analgesia: A neglected issue in the tropics by medical intervention, may have a detrimental effect on 27-32 weeks, where heel lancing was restricted to one the clinical course of a neonatal surgical patient.1 side; periodic flexor reflex threshold testing showed a consistently reduced threshold for the affected heel Before the late nineteenth century, babies were considered compared with the non-injured heel, indicating increased to be more sensitive to pain than adults. Doris Cope quotes pain sensitivity on the side of heel lancing. Compared paediatric surgeon Felix Würtz of Basel, writing in 1656: with untreated and placebo controls, when a group of If a new skin in old people be tender, what is it you think in infants was treated regularly with a topical anaesthetic a newborn Babe? Doth a small thing pain you so much on a beginning 3 days after heel lancing was initiated, flexor finger, how painful is it then to a Child, which is tormented all reflex thresholds between the injured and non-injured the body over, which hath but a tender new grown flesh?.4,5 side became equivalent.12 These findings show that the human neonate is capable of mounting an inflammatory PATHOPHYSIOLOGY OF PAIN response with persisting hyperalgesia, or increased sensitivity to pain, due to early painful experiences — a There have been several recent consensus statements response that can be ameliorated by local anaesthetic concerning neonatal pain.6 These evidences show that: application. Anatomical maturation of nociceptive pathways is complete by mid-to-late second trimester;6,7 and physiological Additional studies in humans have supported the responses in behavioural, cardiovascular, respiratory, suggestion that tissue injury at a young age may have endocrine and metabolic systems are similar to that of long-lasting somatosensory sequelae. First, Andrews 13 pain experienced by adults and older children.7 It is now et al., showed that the indicator of the excitability of the known that these physiological and behavioural responses neonatal spinal cord — a mechanically evoked flexion to painful stimuli can be reduced by analgesia.1 reflex threshold to stimuli applied to the foot and leg — increased with age in normal infants of post conception age The impact of pain may have short (physiological and of 28-42 weeks. However, similar infants with a substantial behavioural) and long-term consequences (increased or leg injury did not exhibit the normal age-related increase decreased behavioural responses to pain),2 even if not in threshold, even when the non-injured leg was tested. expressed as conscious memory.8-10 Memories of pain may This absent development of normally increasing thresholds be recorded biologically and alter brain development and contralateral to the injury reflects substantial ‘secondary’ subsequent behaviour.10 changes in the spinal cord itself and not merely to the injured leg.13 Other mechanism involved in the prevention and management of pain in newborns1,2 include: neuroanatomical Finally, studies reveal that lasting changes in pain sensitivity components and neuroendocrine systems. These are with the early experience of pain have been found in full- sufficiently developed to allow transmission of painful term infants as well. Using a prospective cohort design in stimuli in the term neonate. males, one study found that facial pain-score coding from videotape recordings at 4- or 6-month routine vaccination It is important to note here that four basic concepts was related to circumcision status as well as pain treatment explain the physiology of pain. These include transduction, for the procedure.14 In particular, a significant linear trend transmission, modulation and perception. Although of increasing facial pain scores during immunisation still complex, the science of pain reveals a much more emerged from uncircumcised (lowest) to circumcised ambiguous process, and theories are still continuing to infants with topical lidocaine-prilocaine cream (mid) to evolve. New receptors, pathways and hypotheses are being those who were circumcised with placebo (highest). investigated every day. Genetic variations at the receptor level have been implicated.11 DIAGNOSIS OF PAIN Pain in newborns is often unrecognised and under treated. Most of the signs of pain in babies are quite straight If a procedure is painful in adults it should be considered forward, requiring no special equipment or training. Here, painful in newborns, even if they are pre-term. Compared the baby cries and remains restless when awake, develops with older age groups, newborns may experience a greater a disturbed sleep pattern, feeds poorly and shows a fearful, sensitivity to pain and are more susceptible to the long-term distrustful reaction towards mothers. effects of painful stimulation. Adequate treatment of pain may be associated with decreased clinical complications The cry response is indispensable and researchers are and decreased mortality.11 now able to differentiate between different