Evidence-Based Review of Physiologic Effects of

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Kangaroo Care's effects on preterm infant heart rate, bradycardia, respiratory rate, apnea, oxygen ..... involution, and shorter length of postpartum stay) was.
Current Women’s Health Reviews, 2011, 7, 000-000

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Evidence-Based Review of Physiologic Effects of Kangaroo Care Susan M. Ludington-Hoe* Pediatric Nursing, Bolton School of Nursing, Case Western Reserve University, Cleveland, OH, USA Abstract: A comprehensive review of the evidence documenting preterm infant physiologic responses to Kangaroo Care (KC – intermittent skin-to-skin contact) and Kangaroo Mother Care (KMC – 24/7 skin-to-skin contact) has been conducted. Kangaroo Care’s effects on preterm infant heart rate, bradycardia, respiratory rate, apnea, oxygen saturation, cerebral oxygenation, supplemental oxygen needs, oxygen consumption, desaturation episodes, temperature, rewarming, blood glucose, serum bilirubin, cholecystokinin, gastrin, somatostatin, weight gain or change, sleep and crying, brain maturation and complexity, infection, stress, and pain are reviewed, as are KC’s effects with congenital heart defect infants. Documented effects of KC on prevention and amelioration of maternal depression, swifter delivery of the placenta and involution, and decreased likelihood of postpartal anemia are presented. Guidelines based on dosage (duration and frequency) of KC are provided, as is a summary of actual and potential benefits of KC, including use at end-of-life. Kangaroo Care’s role in moving to the new paradigms of non-separation of the infant and mother during hospitalization and parents as primary providers of neonatal care concludes the manuscript.

Keywords: ????? INTRODUCTION Each preterm infant and mother have a particular level of maturation and manner of responding to environmental stimuli and care-giving activities in the neonatal intensive care unit, creating variability in their physiologic responses to the stimuli that are generic to neonatal intensive care. Surprisingly, variability in response to Kangaroo Care, another multi-sensory stimulus encountered by preterm infants, is quite diminished, making prediction of infant responses possible. Variation in responses, mostly minimal, have been documented in over 425 formal research studies of KC effects on preterm infants [1]. The purpose of this manuscript is to discuss the biologic basis for practicing KC with preterm infants and their families by summarizing physiologic effects of KC, identifying type and magnitude of variations in specific responses, reviewing the wide variation in dosages of KC and what is known in relation to the predominantlypracticed dosages, to relate infant tolerance to KC, and to conclude with known and potential benefits of the unique treatment known as Kangaroo Care. Kangaroo Care is not just a “cuddling, soft, warm thing to do for the baby and mother,” but is a therapy that accomplishes several benefits. Kangaroo Care prevents some diseases and ameliorates others, promotes physiologic stability, facilitates adaptation to the stresses of prematurity, helps the infant’s brain mature and develop, and is the epitome of a wellness, and naturalistic, orientation to the care of premature infants. PHYSIOLOGIC EFFECTS A review of physiologic effects of KC on preterm infants follows. Because many types of studies have been conducted, distinguishing between the types of studies is included, *Address correspondence to this author at the Pediatric Nursing, Bolton School of Nursing, Case Western Reserve University, Cleveland, OH, USA; Tel: ???????????; Fax: ???????????; E-mail: [email protected] 1573-4048/11 $58.00+.00

identifying descriptive (qualitative, evaluative, comparative, correlational, and regression analyses) and experimental (randomized controlled trials, quasi-experiments, and metaanalyses) studies per se. The strongest evidence comes from randomized controlled trials and meta-analyses. Infant Heart Rate Effects Heart rate (HR) increases when the infant is moved from horizontal to inclined [2], from supine to the prone [2], and from head down to head up [3] position as occurs when moved from an incubator into KC. These positional effects on HR occur as do changes in response to the warming that the infant immediately experiences as maternal breasts heat up to provide a neutral thermal zone for the infant [4, 5]. According to randomized controlled trials, during KC HR increases minimally, usually remaining within normal limits and demonstrating greater stability than when in an incubator [6, 7], in a crib [8], and in swaddled holding [9, 10]. Heart rate stability has also been seen during twin [5, 10-12]and triplet KC [13, 14], so all mothers can safely offer KC. Cardiorespiratory status is more stable when mothers are available to provide KC during transport to and from the NICU, eliminating the need for transport incubators [15]. Given that neonates often die during transport between hospitals, especially transports longer than 30-59 minutes [16], the cardiorespiratory stability seen during KC transport could help save neonatal lives. One mechanism by which KC can save newborn lives is by improvements in autonomic control of heart rate, called heart rate variability. Heart rate variability is more stable during KC than during incubator periods and shows increased in sympathetic activity (needed for response to life-threatening events) [17-20] and a predominance of control by the parasympathetic [relaxation, calm) system [18, 20]. More rapid maturation of vagal tone, another indicator of autonomic control of heart rate, occurs during KC than incubator care [21]. Accelerated maturation © 2011 Bentham Science Publishers Ltd.

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of vagal tone is a major physiologic benefit of KC because maturation fosters cardiorespiratory stability [22, 23]. In relation to bradycardia, no randomized controlled trials were found, but pretest-test-posttest trials within one group have been reported [24, 25]. In these trials isolated bradycardic events did not occur during KC, but bradycardia coupled with apnea did, increasing from 2.2 per hour in the incubator to 3.0 per hour in KC. A clinical observation report notes that bradycardia rarely occurred during KC in stable preterm infants, even in some smaller and sicker infants [26], most likely due to the positional changes inherent in KC. Mothers and fathers are encouraged to hold even the smallest ventilated infants in KC to minimize apnea, bradycardia, and hypoxemia that can accompany bolus gavage feedings [27, 28]. Bradycardia is common during transfusions, did not occur at all during transfusions given in KC in a time series study (before and after initiating KMC in a Neonatal Intensive Care Unit) of 622 smaller (