title: Cardiorespiratory responses to bidirectional tilts in infants.
abstract: Prior research in newborns has shown that head-up and head-down tilting elicits sustained increases and decreases in heart rate, respectively. Other studies in older infants have suggested that the pattern of heart rate responses to head-up tilting varies with risk for sudden infant death syndrome (SIDS). In this study, heart and respiratory rate changes following bidirectional tilting were recorded in sleeping infants on Day 1 or 2 of life, and during the period of maximum risk for SIDS, at 2 and 4 months of age. Newborns show increases in heart rate following 30 degrees head-up tilts and decreases in heart rate to 300 head-down tilting. Respiratory rates decreased to head-up tilting but did not change significantly to head-down tilting. While respiratory rate changes at 2 and 4 months of age are comparable to those of newborns, and decreases in heart rate to head-down tilting are similar across ages, sustained elevations in heart rate following head-up tilting are no longer apparent at the older ages. These results are consistent with the hypothesis that, during the period of maximum risk for SIDS, infants may have reduced ability to compensate for challenges that lead to decreases in blood pressure.
authors.affiliation: New York State Psychiatric Institute and Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York 10032, USA. wpfl@columbia.edu
authors.forename: W P
authors.initials: WP
authors.lastname: Fifer
authors.forename: M
authors.initials: M
authors.lastname: Greene
authors.forename: A
authors.initials: A
authors.lastname: Hurtado
authors.forename: M M
authors.initials: MM
authors.lastname: Myers
mesh_terms: D000367:Age Factors; D004562:Electrocardiography; D018475:Head-Down Tilt / Q000009:adverse effects / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D012119:Respiration; D012307:Risk Factors; D012890:Sleep / Q000502:physiology; D013398:Sudden Infant Death / Q000209:etiology* / Q000517:prevention & control