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Autonomic Reflexes in Preterm Infants
Author(s) -
LAGERCRANTZ H.,
EDWARDS D.,
HENDERSONSMART D.,
HERTZBERG T.,
JEFFERY H.
Publication year - 1990
Publication title -
acta pædiatrica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 115
eISSN - 1651-2227
pISSN - 0803-5253
DOI - 10.1111/j.1651-2227.1990.tb11546.x
Subject(s) - medicine , bradycardia , heart rate , reflex , apnea , anesthesia , autonomic nervous system , sympathetic nervous system , gestational age , vascular resistance , parasympathetic nervous system , blood pressure , hemodynamics , pregnancy , biology , genetics
. Some autonomic nervous reflexes often tested in adult medicine have been studied in 21 preterm infants (25‐37 gestational weeks). The aim was to develop such tests for preterm infants and see if there were any differences in babies with recurrent apnea and bradycardia and babies who had been exposed to sympathicolytic drugs before birth. To test sympathetic nervous activity the peripheral vascular resistance was measured before and during 45° of head‐up tilting. To test parasympathetic nervous activity the degree of bradycardia was measured in response to cold face test (application of an ice‐cube on the fore‐head) and laryngeal stimulation with saline. Finally the heart rate changes after a sudden noise (85 dB) were studied as an indicator of both sympathetic and vagal activity. The peripheral resistance was found to be relatively low in these preterm infants, particularly in some infants tested at the postnatal age of about two months. Heart rate and mean blood pressure did not change during tilting, while the peripheral resistance increased significantly mainly due to lowered limb blood flow. The median decrease of the heart rate during the cold face test was 20.0% and during laryngcal receptor stimulation 23.7%. The sudden noise usually caused a biphasic heart rate response. An autonomic nervous reflex score was calculated and found to be negative (parasympathetic) in infants with recurrent prolonged apnea and bradycardia and positive in infants with clinical signs of increased sympathetic nervous activity.