Document Detail

Preexisting hypoxia is associated with a delayed but more sustained rise in T/QRS ratio during prolonged umbilical cord occlusion in near-term fetal sheep.
MedLine Citation:
PMID:  17652358     Owner:  NLM     Status:  MEDLINE    
There is limited information about whether preexisting fetal hypoxia alters hemodynamic responses and changes in T/QRS ratio and ST waveform shape during subsequent severe asphyxia. Chronically instrumented near-term sheep fetuses (124 +/- 1 days) were identified as either normoxic Pa(O(2)) > 17 mmHg (n = 9) or hypoxic Pa(O(2)) < or = 17 mmHg (n = 5); then they received complete occlusion of the umbilical cord for 15 min. Umbilical cord occlusion led to sustained bradycardia, severe acidosis, and transient hypertension followed by profound hypotension in both groups. Preexisting hypoxia did not affect changes in mean arterial blood pressure but was associated with a more rapid initial fall in femoral blood flow and vascular conductance and with transiently higher fetal heart rate at 2 min and from 9 to 11 min of occlusion compared with previously normoxic fetuses. Occlusion was associated with a significant but transient rise in T/QRS ratio; preexisting hypoxia was associated with a significant delay in this rise (maxima 3.7 +/- 0.4 vs. 6.2 +/- 0.5 min), but a slower rate of fall. There was a similar elevation in troponin-T levels 6 h after occlusion in the two groups [median (range) 0.43 (0.08, 1.32) vs. 0.55 (0.16, 2.32) microg/l, not significant]. In conclusion, mild preexisting hypoxia in normally grown singleton fetal sheep is associated with more rapid centralization of circulation after umbilical cord occlusion and delayed elevation of the ST waveform and slower fall, suggesting that chronic hypoxia alters myocardial dynamics during asphyxia.
Bert Wibbens; Laura Bennet; Jenny A Westgate; Harmen H De Haan; Guido Wassink; Alistair J Gunn
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-07-25
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  293     ISSN:  0363-6119     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2007 Sep 
Date Detail:
Created Date:  2007-08-31     Completed Date:  2007-10-17     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  R1287-93     Citation Subset:  IM    
Department of Physiology, The University of Auckland, Auckland, New Zealand.
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MeSH Terms
Amniotic Fluid / physiology
Anoxia / physiopathology
Blood Gas Analysis
Blood Glucose / metabolism
Blood Pressure / physiology
Carotid Arteries / physiology
Data Interpretation, Statistical
Femoral Artery / physiology
Fetal Hypoxia / physiopathology*
Heart Rate, Fetal / physiology*
Hypertension / physiopathology
Lactic Acid / blood
Regional Blood Flow / physiology
Troponin T / blood
Umbilical Cord / physiology*
Reg. No./Substance:
0/Blood Glucose; 0/Troponin T; 50-21-5/Lactic Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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