Determinants of Premature Infant Pain Responses to Heel Sticks

Lina Kurdahi Badr; Bahia Abdallah; Mirvat Hawari; Saadieh Sidani; May Kassar; Pascale Nakad; Julianna Breidi

Disclosures

Pediatr Nurs. 2010;36(3):129-137. 

In This Article

Abstract and Introduction

Abstract

The exposure of premature infants to stressors, such as pain intended to ensure their survival, may instead alter their brain development and contribute to several learning and behavioral difficulties observed in later childhood. The objective of this descriptive, cross-sectional study was to compare the pain responses of 72 preterm infants to a heel stick procedure taking into consideration a variety of factors, including the use of opioids and sedatives. The pain scores assessed on the Preterm Infant Pain Profile (PIPP) scale were highest for the lowest gestational age (GA) group. Multiple linear regression analysis with the four predictor variables noted to be correlated with the PIPP scores (GA, type of needle, severity of illness, and behavioral state) indicated a significant overall relationship (F [5/66] = 5.62, p < 0.01) and accounted for 44% of the variance. All but severity of illness did not add significantly to the variance. Gender, postnatal age, amount, opioids, and sedatives used were not correlated to the PIPP scores. It was concluded that sick premature infants and those who have been exposed to a variety of painful procedures may not manifest behavioral or physiological signs of pain, but may be the most to benefit from precise pain assessment and prudent management.

Introduction

Preterm infants emerge from a safe uterine environment to a noisy, chaotic, stressful, and painful environment. Whereas the mature infant is better equipped to handle stressful experiences, the preterm infant lacks the autonomic and functional maturity to do so. The exposure to stressors and noxious stimuli intended to ensure the survival of preterm infants may instead alter their brain development and contribute to several learning and behavioral difficulties observed in later childhood (Abdulkader, Freer, Garry, Fleetwood-Walker, & McIntosh, 2007; Anand, 2000; Grunau, Oberlander, Whitfield, Fitzgerald, & Lee, 2001; Grunau, Holtsi, & Peters, 2006; Mainous & Looney, 2007). A recent study in France reported that on average, infants in the neonatal intensive care unit (NICU) experience 115 painful procedures in a two-week period (Lenclen & Carbajal, 2007). Researchers have noted that premature infants exposed to repeated painful experiences may either manifest more heightened responses to pain or may be desensitized to pain (Anand et al., 2005; Grunau, Whitfield, & Petrie, 1998). Whether responses of preterm infants are heightened or desensitized, there seems to be an agreement among researchers that there are permanent adverse consequences to pain due to an altered hypothalamic-pituitaryadrenal axis (Grunau et al., 2005).

Several studies over the last decade have contributed to the satisfactory, albeit not the precise, assessment of pain in the premature infant (Abu-Saad, Bours, Stevens, & Hamers, 1998; Anand, 2007a; Hummel, Lawlor-Klean, & Weiss, 2009). The appraisal of factors that could increase or decrease premature infants' response to pain has also been a subject of great interest (Holsti, Grunau, Whitfield, Oberlander, & Lindh, 2006; Johnston et al., 1999). Despite growing scientific evidence, several gaps in the research remain. For example, it is not yet clear whether repeated exposure to pain in preterm infants intensifies or diminishes their behavioral and physiologic responses, nor is it ascertained which factors heighten or dampen their responses. It is thus imperative to consider all possible contextual factors that could modulate the infant's responses to pain.

The effect of contextual factors in the responses to pain has been documented by several research studies (Ahn, 2006; Bartocci, Bergqvist, Lagercrantz, & Anand, 2006; Johnston et al., 1999) and are based on a hypothesis by Melzack and Wall (1970) – responses to painful stimuli vary in the context in which they are experienced. Therefore, the aims of this study were to compare preterm infant responses to a heel stick procedure taking into consideration a variety of factors: gestational age (GA), postnatal age at time of study, newborn complications, type of needle used, state of the infant before the procedure, gender, and the administration of opioids, sedatives, and steroids.

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