Document Detail

Hemodynamics of fetal breathing movements: the inferior vena cava.
MedLine Citation:
PMID:  21425196     Owner:  NLM     Status:  Publisher    
OBJECTIVES: Based on the hypothesis that fetal breathing movements (FBM) enhance sections of the circulation to meet the needs of gas transport, we studied the effects on the fetal inferior vena cava (IVC), which transports blood with the lowest oxygen saturation in the fetal body. METHODS: One-hundred and ten women with low-risk singleton pregnancies were included in a longitudinal study during the second half of pregnancy. Inner diameter, peak systolic velocities and time-average maximum blood velocities were measured in the IVC below the ductus venosus outlet during rest and FBM. Volume flow and pressure gradient were estimated in 55 observations of forced inspiratory movements at 36 weeks of gestation. Results are presented with means and 95% CI of the mean. RESULTS: Based on 585 observations obtained during fetal rest and FBM, we found no difference in diameter, 0.42 cm (0.41-0.42) vs. 0.41 (0.39-0.42), respectively, apart from during high-amplitude inspiratory movement, 0.15 (0.13-0.17). The peak systolic velocity was different during rest and FBM, 34.0 cm/s (32.7-35.3) vs. 81.5 (76.2-87.5), respectively, and correspondingly for time-averaged maximum velocity, 19.7 cm/s (18.9-20.5) vs. 37.2 (34.9-39.9), respectively. Forced inspiratory movements at 36 weeks significantly reduced flow in the IVC compared with rest, 63.6 mL/min (44.4-88.1) vs. 188.8 (149.3-235.2), respectively. The pressure gradient increased 14-fold from 0.64 to 8.76 mmHg during forced inspiration. CONCLUSIONS: High-amplitude fetal inspiration substantially constricts the abdominal IVC and creates a negative pressure in the chest. The IVC constriction withholds abdominal blood thus temporarily giving way to other flows. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
M K Nyberg; S L Johnsen; S Rasmussen; T Kiserud
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-3-21
Journal Detail:
Title:  Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology     Volume:  -     ISSN:  1469-0705     ISO Abbreviation:  -     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-3-22     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9108340     Medline TA:  Ultrasound Obstet Gynecol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Department of Clinical Medicine, University of Bergen, Bergen, Norway.
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