The Effect of Mechanical Tactile Stimulation on Autonomic Nervous System Function in Preterm Infants Sandra L. Smith, PhD, APRN, NNP-BC Associate Professor University of Louisville, School of Nursing

Environmental Sources of Neonatal Stress  Painful procedures  Noise and lighting  Maternal separation  Temperature fluctuation  Hypoxia and hyperoxia  Glucocorticoids  Oxygen consumption  Energy expenditure  Temperature fluctuations  Hypoxemia Consequences of Neonatal Stress The stress response is meant to be limited and of short duration Massage may improve vagal activity, sleep, and growth by attenuating the stress response (Arora et al., 2005; Diego et al., 2003, 2007; Field et al., 2006)

STRESS Hypothalamus Pituitary Adrenal Medulla Cortex CatecholaminesGlucocorticoids Sympathetic ‘fight or flight’ Parasympathetic ‘rest & recovery’ ++ GC, Catecholamines, Overriding SNS response -- GC, Catecholamines, SNS/PNS balance PHYSIOLOGIC INSTABILITY ↑ HR, RR, BP PHYSIOLOGIC STABILITY Normal HR, RR, BP HPA AXIS

LOUISVILLE.EDU Hypothesis In preterm infants, twice daily mechanical tactile stimulation (MTS) will promote autonomic nervous system function as measured by heart rate variability (HRV)

LOUISVILLE.EDU Screened N=175 Ineligible N=44 Eligible N=131 Enrolled N=52 MTS N=27 Incomplete Data N=10 Control N=25 Incomplete Data N=5 Control N=20 MTS N=17

Procedures and Testing Schema Medically stable week preterms Randomized to MTS or Control MTS: 20 minute prescribed compression and manipulation of soft tissues followed by joint flexion/extension Masked to HCP and Parents LMTs provided MTS and Control

LOUISVILLE.EDU Infant Characteristics MTSControl Gender 8F/9M11F/9M Ethnicity 47% Hispanic 53% White 13% Hispanic 7% White Birth PMA (wk) 31.6 ± ± 0.9 Entry PMA (wk) 32.7 ± ± 0.7 Birth Weight (g) 1522 ± ± 277 Entry Weight (g) 1522 ± ± 272 Study End 2186 ± ±337 Smith et al., J.Perinatol., 2012

Cyclical change in R-R interval mediated by the ANS – The interaction and adaptability of SNS and PNS ECG data were acquired continuously prior to, during, and post MTS or CTL – Pre, during, and post session epochs were extracted for analysis – HRV measures were calculated from the ECG Fast Fourier Transform (FFT) analysis – Estimates cardiac modulation by ANS – Regions are specific to the SNS and PNS HRV Burr, 1992; David et al., 2007; Malik & Camm, 1993; Longin et al., 2006; Ori et al., 1992; Patural et al., 2004; Sanhi et al., 2000

HRV Regions of ANS Activity Sympathetic nervous system ( Hz) Parasympathetic nervous system (>0.2 – 2.0 Hz) LF/HF ratio Higher = Sympathetic Lower = Parasympathetic Hertz

MTS Control LF:HF Ratio (SEM) * ‡ * Males (n = 18) Females (n = 19) *p < 0.5 between MTS & CTL at wk 3 and 4 ‡p < 0.05 MTS & CTL baseline to wk 4 J.Perinatol. (2012) PRE SESSION

LF:HF Ratio (SEM) MTS Control Males (n = 18) Females (n = 19) J.Perinatol. (2012)NS between groups by sex MTS or CTL SESSION

LF:HF Ratio (SEM) MTS Control Males (n = 18) Females (n = 19) * *p < 0.5 between MTS & CTL at wk 3 (J.Perinatol., 2012) POST SESSION

HRV 6 HOURS POST SESSION WEEK 2 Males (4 MTS, 4 CONTROL) LF:HF Ratio (SEM) Smith, et al. unpublished data

LOUISVILLE.EDU Conclusions Twice daily MTS promoted improved HRV in preterm male infants The trajectory of LF:HF ratio in MTS males approximates those of the term infant reported by Patural et al. (2008) The MTS intervention did not increase LF:HF ratio; thus MTS appears non-stressful A well delivered intervention may improve male infant’s adaptation to stressful events The long term effects of MTS on preterm infant adaptation to daily stressors is unknown

LOUISVILLE.EDU Laurie Moyer-Mileur, PhD Shannon Haley, PhD, LMT and team of LMTs Hillarie Slater, BS Robert Lux, PhD Nancy Allen, ECG technician Funding – NIH NCCAM R 21 (LMM, PI) – University of Utah Interdisciplinary Research Grant, College of Nursing, and Department of Pediatrics Acknowledgements