Maternal Hemodynamics by Thoracic Impedance Cardiography for Normal Pregnancy and the Postpartum Period

Morris, Rachael; Sunesara, Imran; Rush, Laura; Anderson, Belinda; Blake, Pamela G.; Darby, Marie; Sawardecker, Sandip; Novotny, Sarah; Bofill, James A.; Martin, James N.

doi:10.1097/aog.0000000000000104

Cited by 23 publications

(15 citation statements)

References 26 publications

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“…Our LVOT VTI , HR, SV and CO values were comparable to published echocardiography values in similar gestation women [ 19 , 20 ]. ICG-derived mean values for SV and CO in the current paper were also comparable to those previously published in similar gestation women [ 21 ]. At 6.5 ± 2.5%, the echocardiography CoV in the current study is lower than previously reported 8.8% for cardiac output [ 22 ].…”

Section: Discussionsupporting

confidence: 88%

Validation of thoracic impedance cardiography by echocardiography in healthy late pregnancy

McIntyre

Ellyett

Mitchell

et al. 2015

BMC Pregnancy Childbirth

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BackgroundAssessment of stroke volume (SV) is often necessary in clinical and research settings. The clinically established method for SV assessment in pregnancy is echocardiography, but given its limitations, it is not always an appropriate measurement tool. Thoracic impedance cardiography (ICG) allows continuous, non-invasive SV assessment. However, SV determination relies on assumptions regarding the thoracic shape that may mean the algorithm is not valid in pregnancy. The available data regarding the validity of ICG against an established reference standard using modern SV algorithms are both limited and conflicting. We aimed to test the validity of ICG in a clinically realistic setting in late pregnancy using echocardiography.MethodsTwenty-nine women in late pregnancy underwent standard echocardiography assessments with simultaneous ICG measurement. Agreement between devices was tested using Bland-Altman analysis.ResultsBland-Altman analysis of the relationship between ICG and echocardiography demonstrated that the 95% limits of agreement exceeded acceptable or expected ranges. Measures of maternal and fetal anthropometry do not account for the lack of agreement.ConclusionsAbsolute values of SV as determined by ICG are not valid in pregnancy. Further work is required to examine the ability of ICG to assess relative changes in maternal haemodynamics in late pregnancy.

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Section: Discussionsupporting

confidence: 88%

Validation of thoracic impedance cardiography by echocardiography in healthy late pregnancy

McIntyre

Ellyett

Mitchell

et al. 2015

BMC Pregnancy Childbirth

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“…Compared with echocardiography, ICG is able directly to evaluate myocardial pump function, SV and thoracic fluid content, and changes can be measured instantaneously and monitored continuously. Using ICG, previous studies confirmed that CO increased from the first trimester, peaked by the end of the second trimester and then slightly decreased in the third trimester . Given the concomitant opposite changes in MAP, with a nadir at 20 weeks, SVR decreased in the first half of the pregnancy and then increased until the end of the third trimester.…”

Section: Discussionmentioning

confidence: 82%

Maternal functional hemodynamics in uncomplicated twin pregnancies: A longitudinal study using impedance cardiography

Orabona

Prefumo

Zanardini

et al. 2018

Acta Obstet Gynecol Scand

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Introduction Longitudinal studies of maternal hemodynamics in twin pregnancy are scarce and preload reserve in twin pregnancies has not been studied. Thus, we aimed to investigate serial changes in maternal systemic hemodynamics from the first to third trimester, and cardiovascular response to passive leg raising to evaluate preload reserve using impedance cardiography in a cohort of uncomplicated twin pregnancies. Material and methods This was a prospective longitudinal study of 50 twin pregnancies. Maternal hemodynamics was assessed at baseline and 120 seconds after passive leg raising using impedance cardiography, at five time points during gestation. Women were excluded from the analysis if there were pregnancy complications or fewer than three of five planned assessments were available. Results Data from 37 uncomplicated twin pregnancies were available for analysis. Mean arterial pressure slightly decreased until 17 weeks’ gestation, then increased. Systemic vascular resistance was constant in the first half of pregnancy before rising steadily thereafter, whereas the cardiac output increased from the first trimester, peaked by the end of the second trimester and then decreased in the third trimester. The change in stroke volume and cardiac output following passive leg raising during pregnancy ranged from −2.2% to 1.6% and from −3.7% to 3.2%, respectively. Although passive leg raising caused no significant changes in systemic vascular resistance, cardiac output or heart rate, mean arterial pressure decreased in the first and second trimesters. Conclusions In uncomplicated twin pregnancies, maternal cardiovascular adaptation is evident from the first trimester. Twin pregnancies show a reduced preload reserve in the second half of gestation.

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“…The process involves spiral artery luminal obliteration due to phenomena such as thrombosis, endarteritis and intima thickening 14 , which result in increased local vascular resistance 15 . Although this finding may reflect systemic circulatory changes 16 17 , an immediate cause for the events is the mechanical pressure imposed by the contracted postpartum myometrium, as well as, possibly, local immunological phenomena 18 . As the structural involution of the uterine artery and distal branches occurs, functional changes can be assessed using a computerised analysis of the blood velocity spectrum obtained with Doppler ultrasound.…”

Section: Discussionmentioning

confidence: 95%

Uterine artery impedance during the first eight postpartum weeks

Guedes-Martins

Gaio

Saraiva

et al. 2015

Sci Rep

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The aim of this study was to construct reference ranges for the uterine artery (UtA) mean pulsatility (PI) and resistance (RI) indices from 1–8 weeks postpartum. A prospective, cross-sectional, and observational study was performed with 320 healthy women from week 1 through week 8 postpartum. UtAs were examined transvaginally using colour and pulsed Doppler imaging, and the means of the right and left values of the PI and RI, as well as the presence or absence of a bilateral protodiastolic notch, were recorded. The 5th, 50th and 95th reference percentile curves for the UtA-PI and UtA-RI were derived using regression models. The adjusted reference intervals uncovered a convergence trend at the week 8 time-point, although impedance was lower at the week 1 time-point in multiparous women compared with primiparous women. The notching prevalence was 22.5% (9/40) at week 1 and 95.0% (38/40) at week 8. The study revealed consistent evidence of a progressive increase of postpartum uterine impedance and provided new average UtA-PI and UtA-RI reference charts for weeks 1 through 8. Multiparity does not change the trend but does impart a lower rate of increase, likely as a consequence of previous vascular structural and functional differences.

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Maternal Hemodynamics by Thoracic Impedance Cardiography for Normal Pregnancy and the Postpartum Period

Abstract: III.

Cited by 23 publications

References 26 publications

Validation of thoracic impedance cardiography by echocardiography in healthy late pregnancy

Validation of thoracic impedance cardiography by echocardiography in healthy late pregnancy

Maternal functional hemodynamics in uncomplicated twin pregnancies: A longitudinal study using impedance cardiography

Uterine artery impedance during the first eight postpartum weeks

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