Effect of spontaneous breathing on umbilical venous blood flow and during delayed cord clamping in preterm lambs

Emma Brouwer, Arjan B. Te Pas, Graeme R. Polglase, Erin V. McGillick, Stefan Böhringer, Kelly J. Crossley, Karyn Rodgers, Douglas Blank, Shigeo Yamaoka, Andrew William Gill, Martin Kluckow, Stuart B. Hooper

Research output: Contribution to journalArticleResearchpeer-review

1 Citation (Scopus)

Abstract

Introduction: During delayed umbilical cord clamping, the factors underpinning placental transfusion remain unknown. We hypothesised that reductions in thoracic pressure during inspiration would enhance placental transfusion in spontaneously breathing preterm lambs. Objective: Investigate the effect of spontaneous breathing on umbilical venous flow and body weight in preterm lambs. Methods: Pregnant sheep were instrumented at 132-133 days gestational age to measure fetal common umbilical venous, pulmonary and cerebral blood flows as well as arterial and intrapleural (IP) pressures. At delivery, doxapram and caffeine were administered to promote breathing. Lamb body weights were measured continuously and breathing was assessed by IP pressure changes. Results: In 6 lambs, 491 out of 1117 breaths were analysed for change in body weight. Weight increased in 46.6% and decreased in 47.5% of breaths. An overall mean increase of 0.02±2.5 g per breath was calculated, and no net placental transfusion was observed prior to cord clamping (median difference in body weight 52.3 [-54.9-166.1] g, p=0.418). Umbilical venous (UV) flow transiently decreased with each inspiration, and in some cases ceased, before UV flow normalised during expiration. The reduction in UV flow was positively correlated with the standardised reduction in (IP) pressure, increasing by 109 mL/min for every SD reduction in IP pressure. Thus, the reduction in UV flow was closely related to inspiratory depth. Conclusions: Spontaneous breathing had no net effect on body weight in preterm lambs at birth. UV blood flow decreased as inspiratory effort increased, possibly due to constriction of the inferior vena cava caused by diaphragmatic contraction, as previously observed in human fetuses.

Original languageEnglish
Number of pages7
JournalArchives of Disease in Childhood: Fetal and Neonatal Edition
DOIs
Publication statusAccepted/In press - 2 Apr 2019

Keywords

  • animal research
  • neonatology
  • physiology
  • placental transfusion
  • resuscitation

Cite this

@article{37575871bd1d46e78608ea200b81adae,
title = "Effect of spontaneous breathing on umbilical venous blood flow and during delayed cord clamping in preterm lambs",
abstract = "Introduction: During delayed umbilical cord clamping, the factors underpinning placental transfusion remain unknown. We hypothesised that reductions in thoracic pressure during inspiration would enhance placental transfusion in spontaneously breathing preterm lambs. Objective: Investigate the effect of spontaneous breathing on umbilical venous flow and body weight in preterm lambs. Methods: Pregnant sheep were instrumented at 132-133 days gestational age to measure fetal common umbilical venous, pulmonary and cerebral blood flows as well as arterial and intrapleural (IP) pressures. At delivery, doxapram and caffeine were administered to promote breathing. Lamb body weights were measured continuously and breathing was assessed by IP pressure changes. Results: In 6 lambs, 491 out of 1117 breaths were analysed for change in body weight. Weight increased in 46.6{\%} and decreased in 47.5{\%} of breaths. An overall mean increase of 0.02±2.5 g per breath was calculated, and no net placental transfusion was observed prior to cord clamping (median difference in body weight 52.3 [-54.9-166.1] g, p=0.418). Umbilical venous (UV) flow transiently decreased with each inspiration, and in some cases ceased, before UV flow normalised during expiration. The reduction in UV flow was positively correlated with the standardised reduction in (IP) pressure, increasing by 109 mL/min for every SD reduction in IP pressure. Thus, the reduction in UV flow was closely related to inspiratory depth. Conclusions: Spontaneous breathing had no net effect on body weight in preterm lambs at birth. UV blood flow decreased as inspiratory effort increased, possibly due to constriction of the inferior vena cava caused by diaphragmatic contraction, as previously observed in human fetuses.",
keywords = "animal research, neonatology, physiology, placental transfusion, resuscitation",
author = "Emma Brouwer and {Te Pas}, {Arjan B.} and Polglase, {Graeme R.} and McGillick, {Erin V.} and Stefan B{\"o}hringer and Crossley, {Kelly J.} and Karyn Rodgers and Douglas Blank and Shigeo Yamaoka and Gill, {Andrew William} and Martin Kluckow and Hooper, {Stuart B.}",
year = "2019",
month = "4",
day = "2",
doi = "10.1136/archdischild-2018-316044",
language = "English",
journal = "Archives of Disease in Childhood: Fetal and Neonatal Edition",
issn = "1359-2998",
publisher = "BMJ Group",

}

Effect of spontaneous breathing on umbilical venous blood flow and during delayed cord clamping in preterm lambs. / Brouwer, Emma; Te Pas, Arjan B.; Polglase, Graeme R.; McGillick, Erin V.; Böhringer, Stefan; Crossley, Kelly J.; Rodgers, Karyn; Blank, Douglas; Yamaoka, Shigeo; Gill, Andrew William; Kluckow, Martin; Hooper, Stuart B.

In: Archives of Disease in Childhood: Fetal and Neonatal Edition, 02.04.2019.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Effect of spontaneous breathing on umbilical venous blood flow and during delayed cord clamping in preterm lambs

AU - Brouwer, Emma

AU - Te Pas, Arjan B.

AU - Polglase, Graeme R.

AU - McGillick, Erin V.

AU - Böhringer, Stefan

AU - Crossley, Kelly J.

AU - Rodgers, Karyn

AU - Blank, Douglas

AU - Yamaoka, Shigeo

AU - Gill, Andrew William

AU - Kluckow, Martin

AU - Hooper, Stuart B.

PY - 2019/4/2

Y1 - 2019/4/2

N2 - Introduction: During delayed umbilical cord clamping, the factors underpinning placental transfusion remain unknown. We hypothesised that reductions in thoracic pressure during inspiration would enhance placental transfusion in spontaneously breathing preterm lambs. Objective: Investigate the effect of spontaneous breathing on umbilical venous flow and body weight in preterm lambs. Methods: Pregnant sheep were instrumented at 132-133 days gestational age to measure fetal common umbilical venous, pulmonary and cerebral blood flows as well as arterial and intrapleural (IP) pressures. At delivery, doxapram and caffeine were administered to promote breathing. Lamb body weights were measured continuously and breathing was assessed by IP pressure changes. Results: In 6 lambs, 491 out of 1117 breaths were analysed for change in body weight. Weight increased in 46.6% and decreased in 47.5% of breaths. An overall mean increase of 0.02±2.5 g per breath was calculated, and no net placental transfusion was observed prior to cord clamping (median difference in body weight 52.3 [-54.9-166.1] g, p=0.418). Umbilical venous (UV) flow transiently decreased with each inspiration, and in some cases ceased, before UV flow normalised during expiration. The reduction in UV flow was positively correlated with the standardised reduction in (IP) pressure, increasing by 109 mL/min for every SD reduction in IP pressure. Thus, the reduction in UV flow was closely related to inspiratory depth. Conclusions: Spontaneous breathing had no net effect on body weight in preterm lambs at birth. UV blood flow decreased as inspiratory effort increased, possibly due to constriction of the inferior vena cava caused by diaphragmatic contraction, as previously observed in human fetuses.

AB - Introduction: During delayed umbilical cord clamping, the factors underpinning placental transfusion remain unknown. We hypothesised that reductions in thoracic pressure during inspiration would enhance placental transfusion in spontaneously breathing preterm lambs. Objective: Investigate the effect of spontaneous breathing on umbilical venous flow and body weight in preterm lambs. Methods: Pregnant sheep were instrumented at 132-133 days gestational age to measure fetal common umbilical venous, pulmonary and cerebral blood flows as well as arterial and intrapleural (IP) pressures. At delivery, doxapram and caffeine were administered to promote breathing. Lamb body weights were measured continuously and breathing was assessed by IP pressure changes. Results: In 6 lambs, 491 out of 1117 breaths were analysed for change in body weight. Weight increased in 46.6% and decreased in 47.5% of breaths. An overall mean increase of 0.02±2.5 g per breath was calculated, and no net placental transfusion was observed prior to cord clamping (median difference in body weight 52.3 [-54.9-166.1] g, p=0.418). Umbilical venous (UV) flow transiently decreased with each inspiration, and in some cases ceased, before UV flow normalised during expiration. The reduction in UV flow was positively correlated with the standardised reduction in (IP) pressure, increasing by 109 mL/min for every SD reduction in IP pressure. Thus, the reduction in UV flow was closely related to inspiratory depth. Conclusions: Spontaneous breathing had no net effect on body weight in preterm lambs at birth. UV blood flow decreased as inspiratory effort increased, possibly due to constriction of the inferior vena cava caused by diaphragmatic contraction, as previously observed in human fetuses.

KW - animal research

KW - neonatology

KW - physiology

KW - placental transfusion

KW - resuscitation

UR - http://www.scopus.com/inward/record.url?scp=85065789383&partnerID=8YFLogxK

U2 - 10.1136/archdischild-2018-316044

DO - 10.1136/archdischild-2018-316044

M3 - Article

JO - Archives of Disease in Childhood: Fetal and Neonatal Edition

JF - Archives of Disease in Childhood: Fetal and Neonatal Edition

SN - 1359-2998

ER -