Blood pressure extremes and severe IVH in preterm infants

Abstract

Background-The optimal upper and lower limits of blood pressure in preterm infants are not known. Exceeding these thresholds may contribute to intraventricular hemorrhage (IVH).Methods-Preterm infants born ≤30 weeks GA were identified. Infants had continuous measurement of mean arterial blood pressure (MABP) for 7d and cranial ultrasound imaging. IVH was classified as severe IVH (grade 3/4), no severe IVH (no IVH; grade 1/2), or no IVH.Mean±SEM MABP values from hours 1-168 were calculated and sorted into bins 2 mmHg wide. The normalized proportion of each recording spent in each bin was then calculated. Candidate limits were identified by comparison of MABP distribution in those with severe IVH vs. those without severe IVH.Results-85 million measurements were made from 157 infants. Mean EGA was 25.2 weeks; mean BW was 749g; 65/157 female; inotrope use in 59/157; grade 3/4 IVH in 29/157. Infants with severe IVH spent significantly more time with extreme MABP measurements (<23 mmHg or >46mmHg) compared to those without severe IVH (12% vs. 8% of recording, p=0.02). Conclusion-Infants who developed severe IVH had substantially more unstable MABP and spent a significantly greater period of time with MABP outside of the optimal range. Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

Cerebral venous volume changes and pressure autoregulation in critically ill infants: an editorial comment

“…Several studies performed in extremely and very preterm infants, partly already referenced by the authors, confirm that hyperperfusion with or without substantial blood pressure swings was "related" with an increased incidence of PIVH in patients with blood pressure passivity [3][4][5]. Also treatment with positive inotropics for supposed hypotension of prematurity may affect autoregulatory ability of the cerebral vascular bed and hence increase PIVH incidence [6].…”

Assessing key clinical parameters before and after intraventricular hemorrhage in very preterm infants

“…This also supports our research. There is no consensus regarding normal blood pressure in premature neonates [26][27][28]; however, some studies indicate that the neuroprotective mechanism of autoregulation is lost below MAP of 30 mmHg [26]. For example, infants who developed severe IVH have been shown as having substantially more unstable MAP, and therefore, spent significantly more time with extreme MAP values (< 23 mmHg or > 46 mmHg) as compared with those without severe IVH [27].…”

“…The same tendency was observed in our study. Because of the correlation detected between MAP and GA, the threshold values in the present study, as in [27,28], were not fixed, but rather, they were evaluated from the control group for each gestational week. The percentage of extreme MAP values was higher in the affected group than in the control one.…”

Management of Neonatal Hypotension and Shock

“…Lower gestational age (GA), postnatal age, birthweight, and gender all impact BPthus a "one size fits all" approach defining certain absolute BP intervention values is rather limited. BP progressively increases in both term and preterm populations, especially during the first hours and days of life [3][4][5]. These dynamic changes are often neglected, especially in the most commonly used definitions of low BP.…”