Low-frequency blood pressure oscillations and inotrope treatment failure in premature infants

Abstract

The underlying mechanism as to why some hypotensive preterm infants do not respond to inotropic medications remains unclear. For these infants, we hypothesize that impaired vasomotor function is a significant factor and is manifested through a decrease in low-frequency blood pressure variability across regulatory components of vascular tone. Infants born ≤28 wk estimated gestational age underwent prospective recording of mean arterial blood pressure for 72 h after birth. After error correction, root-mean-square spectral power was calculated for each valid 10-min data frame across each of four frequency bands (, 0.005-0.0095 Hz; , 0.0095-0.02 Hz;, 0.02-0.06 Hz; and , 0.06-0.16) corresponding to different components of vasomotion control. Forty infants (twenty-nine normotensive control and eleven inotrope-exposed) were included with a mean ± SD estimated gestational age of 25.2 ± 1.6 wk and birth weight 790 ± 211 g. 9.7/11.8 Million (82%) data points were error-free and used for analysis. Spectral power across all frequency bands increased with time, although the magnitude was 20% less in the inotrope-exposed infants. A statistically significant increase in spectral power in response to inotrope initiation was noted across all frequency bands. Infants with robust blood pressure response to inotropes had a greater increase compared with those who had limited or no blood pressure response. In this study, hypotensive infants who require inotropes have decreased low-frequency variability at baseline compared with normotensive infants, which increases after inotrope initiation. Low-frequency spectral power does not change for those with inotrope treatment failure, suggesting dysfunctional regulation of vascular tone as a potential mechanism of treatment failure. In this study, we examine patterns of low-frequency oscillations in blood pressure variability across regulatory components of vascular tone in normotensive and hypotensive infants exposed to inotropic medications. We found that hypotensive infants who require inotropes have decreased low-frequency variability at baseline, which increases after inotrope initiation. Low-frequency spectral power does not change for those with inotrope treatment failure, suggesting dysfunctional regulation of vascular tone as a potential mechanism of treatment failure.

Low Variability of Blood Pressure Predicts Abnormal Electroencephalogram in Infants with Hypoxic Ischemic Encephalopathy

“…Total spectral power calculations were made in each of the four frequency bands (A-D) described in a previous publication. 23 Bands C (20-60 mHz) and D (60-160 mHz) were the strongest discriminators, with slightly better performance in band D (AUC ¼ 0.66, p ¼ 0.03). Slight modification of the frequency band limits to encompass regions of both bands C and D (25-65 mHz) resulted in significant improvement in model performance (AUC ¼ 0.73, p < 0.01).…”

“…Using the same 3-hour time periods (18-21, 21-24, and 24-27 hours) as the time-series analysis, the total spectral power in four different candidate frequency bands was calculated using frequencies similar to those previously published by previous authors 23,24 and are listed in ►Supplementary Table S1 (available in the online version). As there were missing data introduced by the cleaning process, unequally spaced samples, the Lomb-Scargle method for spectral density estimation was used.…”

Coupling between mean blood pressure and EEG in preterm neonates is associated with reduced illness severity scores

“…BP is known to be a slowly evolving signal ( Fig 3 ) and all important frequency components are within the 0–0.5 Hz band. Low frequency components of MAP were previously investigated for premature infants (0.005 Hz to 0.16 Hz) in [ 20 ] and adult population [ 21 ]. An example of a data segment is shown in Fig 3 .…”

Advanced analyses of physiological signals in the neonatal intensive care unit

“…Currently, no treatment for IVH exists, though studies identifying risk factors and pathophysiology help to guide clinical care for prevention. One such study identified a strong association between improvements in blood pressure and increased in low-frequency variability in blood pressure within infants exposed to inotropes, often administered to improve mean arterial blood pressure (Vesoulis et al 2017). This variability was quantified using spectral analysis of certain low-frequency (0.005-0.16 Hz) components of the blood pressure signal and may be used as an adjunctive measure of response to these medications and potentially mitigating risk of hypertension-induced IVH (Bel et al 1987) through more optimal titration (Vesoulis et al 2017).…”