TY - JOUR
T1 - Do β-Adrenergic Blockade and Sleep State Affect Cardiorespiratory Control in Neonatal Lambs?
T2 - Multivariate Autoregressive Modeling Approach
AU - Grönlund, Juhani
AU - Kalli, Seppo
AU - Siimes, Anja
AU - Sydänmaa, Matti
AU - Antila, Kari
AU - Välimäki, Ilkka
PY - 1991
Y1 - 1991
N2 - β-Blockers are used in pregnancy-associated hypertension and in
postnatal cardiac arrhythmias, and the neonate may get them in breast
milk. We therefore studied the effects of β-adrenergic medication on
interrelations between heart rate (HR), respiration, and arterial blood
pressure (aBP) in newborn lambs. The influence of sleep state on these
cardiorespiratory interrelations was also examined. HR, aBP, and
respiration (based on transthorack electrical impedance) were recorded
and the sleep state was visually documented in five healthy chronically
instrumented newborn lambs before the age of 30 d. Propranolol was given
(1 mg/kg). Two-min stationary segments of the three signals were
analyzed using a multivariate autoregressive model, which yields
oscillations of the signals and intersignal relationships as source
contributions. The variabilities of aBP and HR were greatest at the low
frequencies (<0.25 Hz) and so were their intersignal relationships
(including baroreflex). The respiratory variability was greatest at the
frequencies corresponding to the respiratory rate. Daring quiet sleep,
the variabilities in HR, aBP, and respiration were lowest. The impact of
respiratory oscillations on other signals increased but the impact of
aBP variability decreased during quiet sleep. β-Blockade and sleep state
affected separately the cardiovascular and respiratory variables and
their interrelations. β-Blockade reduced HR and increased pulse
pressure. The overall heart rate variability and the respiratory
low-frequency contribution to heart rate variability decreased due to
the β-blockade. We postulate that the β-adrenergic system is an
important regulator of HR and HR variability IB neonatal lambs and also
of the low-frequency components of the respiratory sinus arrhythmia.
However, inasmuch as the interrelations between HR and aBP were not
altered by the β-blockade, even high doses of propranolol do not seem
hazardous for the cardiovascular system in neonatal lambs.
AB - β-Blockers are used in pregnancy-associated hypertension and in
postnatal cardiac arrhythmias, and the neonate may get them in breast
milk. We therefore studied the effects of β-adrenergic medication on
interrelations between heart rate (HR), respiration, and arterial blood
pressure (aBP) in newborn lambs. The influence of sleep state on these
cardiorespiratory interrelations was also examined. HR, aBP, and
respiration (based on transthorack electrical impedance) were recorded
and the sleep state was visually documented in five healthy chronically
instrumented newborn lambs before the age of 30 d. Propranolol was given
(1 mg/kg). Two-min stationary segments of the three signals were
analyzed using a multivariate autoregressive model, which yields
oscillations of the signals and intersignal relationships as source
contributions. The variabilities of aBP and HR were greatest at the low
frequencies (<0.25 Hz) and so were their intersignal relationships
(including baroreflex). The respiratory variability was greatest at the
frequencies corresponding to the respiratory rate. Daring quiet sleep,
the variabilities in HR, aBP, and respiration were lowest. The impact of
respiratory oscillations on other signals increased but the impact of
aBP variability decreased during quiet sleep. β-Blockade and sleep state
affected separately the cardiovascular and respiratory variables and
their interrelations. β-Blockade reduced HR and increased pulse
pressure. The overall heart rate variability and the respiratory
low-frequency contribution to heart rate variability decreased due to
the β-blockade. We postulate that the β-adrenergic system is an
important regulator of HR and HR variability IB neonatal lambs and also
of the low-frequency components of the respiratory sinus arrhythmia.
However, inasmuch as the interrelations between HR and aBP were not
altered by the β-blockade, even high doses of propranolol do not seem
hazardous for the cardiovascular system in neonatal lambs.
U2 - 10.1203/00006450-199103000-00010
DO - 10.1203/00006450-199103000-00010
M3 - Article
SN - 0031-3998
VL - 29
SP - 272
EP - 277
JO - Pediatric Research
JF - Pediatric Research
IS - 3
ER -