Cardiovascular autonomic regulation in preterm infants: the effect of atropine.
To study cardiovascular autonomic control, we assessed the effect of atropine on heart rate (HR) and blood pressure (BP) variability in 12 preterm infants (range 26-32 wk) before intubation for respiratory insufficiency. Spectral power analysis of R-R interval and systolic BP (SBP) series were estimated in a low-frequency (LF; 0.04-0.15 Hz) and high-frequency (HF; 0.4-1.5 Hz) band and evaluated for a 10-min period before and a 10-min period after atropine sulfate (0.01 mg/kg). Baroreceptor reflex (BR) functioning was estimated using transfer function analysis at LF (coherence, gain, and phase). Atropine resulted in a significant 12% increase in steady-state HR (p < 0.01) and unchanged SBP. For R-R interval series, the total spectral power decreased 6-fold (p < 0.01), which was predominantly due to a reduction in the LF band (16-fold; p < 0.01). In contrast, we observed a significant increase (25%; p < 0.05) in total spectral power of SBP series partly as a result of an increase in HF power. The LF power of SBP series was not altered. The median LF transfer gain (BR sensitivity) between SBP and R-R interval decreased from 4.2 to 1.4 ms/mm Hg (p < 0.01) after atropine. The LF phase relationship (BP leads R-R interval fluctuations by approximately 4 s) was not changed after atropine. In conclusion, even in preterm infants in distress, atropine modulates HR and BP variability, suggesting that BR-mediated parasympathetic control of heart rate is of significance for cardiovascular control at that age.
Andriessen
Peter
P
Máxima Medical Center, Neonatal Intensive Care Unit, Veldhoven, P.O. Box 7777, 5500 MB, The Netherlands. P.Andriessen@mmc.nl
Janssen
Ben J A
BJ
Berendsen
Ralph C M
RC
Oetomo
S Bambang
SB
Wijn
Pieter F F
PF
Blanco
Carlos E
CE
D001285:Atropine / Q000008:administration & dosage*; D001341:Autonomic Nervous System / Q000187:drug effects* / Q000502:physiology*; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D018727:Muscarinic Antagonists / Q000008:administration & dosage*; D015656:Respiratory Mechanics / Q000187:drug effects / Q000502:physiology
D018727:Muscarinic Antagonists; D001285:Atropine