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Preterm Infants' Sympathetic Arousal and Associated Behavioral Responses to Sound Stimuli in the Neonatal Intensive Care Unit

PURPOSETo evaluate the utility of skin conductance (SC) as a measure of autonomic arousal to sound stimuli in preterm infants. DESIGNA pilot cross-sectional, correlations study. SUBJECTSEleven preterm infants with a mean gestational age of 31.6 weeks without anomalies or conditions associated with neurodevelopmental delay composed the sample. METHODSOn days 5–7 of life, the following infant responses were simultaneously recorded in response to naturally occurring sound stimuli in the NICU: real-time measurements of heart rate, respiratory rate, and oxygen saturations; sympathetic-mediated sweating via SC; and behavioral responses using the Newborn Individualized Developmental Care and Assessment Program naturalistic observation. Baseline sound levels (BSL, <55 dBA) and high sound levels (HSL, >65 dBA) were measured to index patterns of response during a nonhandling period preceding care. RESULTSMean heart rate during precare was directly associated with higher SC increases to sound stimuli (r[10] = 0.697, P = .017). The SC during HSL was significantly higher than that during BSL (P < .0001). Males demonstrated higher SC increases to sound stimuli than females (P = .030). Changes in SC induced by increases in sound intensity were associated with lower attention responses (r[10] = −0.92, P < .0001) and lower summated behavioral responses (r[10] = −0.59, P = .054). CONCLUSIONSC provides a noninvasive, sensitive measure of sympathetic arousal that may not be apparent in behavioral cues or states, or determined by standard physiological responses alone.