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A longitudinal study of the relationship between maternal cardiac output measured by impedance cardiography and uterine artery blood flow in the second half of pregnancy
Author(s) -
Flo K,
Wilsgaard T,
Vårtun Å,
Acharya G
Publication year - 2010
Publication title -
bjog: an international journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.157
H-Index - 164
eISSN - 1471-0528
pISSN - 1470-0328
DOI - 10.1111/j.1471-0528.2010.02548.x
Subject(s) - impedance cardiography , uterine artery , medicine , hemodynamics , blood flow , pregnancy , cardiology , cardiac output , population , obstetrics , gestation , ejection fraction , stroke volume , heart failure , biology , genetics , environmental health
Please cite this paper as: Flo K, Wilsgaard T, Vårtun Å, Acharya G. A longitudinal study of the relationship between maternal cardiac output measured by impedance cardiography and uterine artery blood flow in the second half of pregnancy. BJOG 2010;117:837–844. Objective To study serial changes in maternal systemic and uterine artery haemodynamics and establish reference ranges for the second half of pregnancy. Design Prospective longitudinal observational study. Setting University hospital in Norway. Population Low‐risk pregnant women. Methods Fifty‐three low‐risk pregnancies were evaluated at approximately 4‐weekly intervals. Maternal systemic haemodynamics was assessed with impedance cardiography. Uterine artery blood velocity and diameter were measured using Doppler ultrasonography and uterine artery volume blood flow ( Q uta ) was calculated as the product of mean velocity and cross‐sectional area of the uterine artery. The fraction of cardiac output (CO) distributed to the uterine circulation was calculated as: Q uta /CO × 100. Main outcome measures CO, Q uta , uterine vascular resistance ( R uta ) and the fraction of CO distributed to the uterine circulation. Results The CO increased ( P = 0.0063) until 34 weeks and remained stable until term. Total Q uta increased from 299 to 673 ml/minute and R uta halved from 0.26 to 0.13 mmHg/ml/minute ( P < 0.0001). The fraction of CO distributed to the uterine circulation increased from 5.6% to 11.7% ( P < 0.0001). Conclusion During the second half of pregnancy, Q uta and the fraction of maternal CO distributed to the uterine circulation increase approximately two‐fold, mainly as a result of decrease in R uta .