Sandra L. Smith, PhD, APRN, NNP-BC Associate Professor University of Louisville, School of Nursing

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 slsmit51@louisville.edu

Consequences of Neonatal Stress 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 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; Diegoet al., 2003, 2007; Field et al., 2006)

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

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

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

Procedures and Testing Schema • Medically stable 29-32 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

Infant Characteristics Smith et al., J.Perinatol., 2012

HRV • 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 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 (0.02-0.2 Hz) Parasympathetic nervous system (>0.2 – 2.0 Hz) LF/HF ratio Higher = Sympathetic Lower = Parasympathetic .02 2.0 0.2 Hertz

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

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

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

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 unpublished data

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

Acknowledgements • 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

Sandra L. Smith, PhD, APRN, NNP-BC Associate Professor University of Louisville, School of Nursing