ResearchObstetricsModelflow: a new method for noninvasive assessment of cardiac output in pregnant women
Section snippets
Subjects
Twenty-one healthy, normotensive primigravid women with a singleton pregnancy and a gestational age of <12 weeks were selected at the outpatient clinic of our hospital. Gestational age was confirmed by crown-rump measurement during the first trimester. They had no medical history of cardiovascular disease, and no subject had vasoactive medication. All of the women had a normal blood pressure (systolic, ≤120 mm Hg; diastolic, ≤80 mm Hg) that was measured by sphygmomanometer.
The Medical Ethical
Results
Twenty-one women were included, but 5 women did not complete all measurements. Four women resigned from participation after the first measurement, and 1 woman was hospitalized for preterm uterus contractions.
Results of 16 women who completed all measurements were used for the analysis. Characteristics are presented in Table 1. The pregnancies were uneventful, and all women were delivered at term of healthy babies with a birth weight of >10th percentile.28 Data on aorta characteristics (PWV and
Comment
Our results indicate that, as expected, Modelflow underestimates SV in pregnant women. We observed that PWV was lower; therefore, aorta compliance was higher during pregnancy than in the nonpregnant state after delivery. However, values at the 3 measurement periods during pregnancy were similar. Our observations on the change in aortic compliance are in accordance with the observations of Poppas et al14 and Slangen et al.15 Assuming that postpartum values were comparable with values before
References (41)
- et al.
Prevention of preeclampsia: a randomized trial of atenolol in hyperdynamic patients before onset of hypertension
Obstet Gynecol
(1999) - et al.
Aortic function during normal human pregnancy
Am J Obstet Gynecol
(1986) - et al.
Computer simulation of arterial flow with applications to arterial and aortic stenoses
J Biomech
(1992) - et al.
The static elastic properties of 45 human thoracic and 20 abdominal aortas in vitro and the parameters of a new model
J Biomech
(1984) - et al.
A comparison of cardiac output derived from the arterial pressure wave against thermodilution in cardiac surgery patients
Br J Anaesth
(2001) - et al.
Comparing methods of measurement: why plotting difference against standard method is misleading
Lancet
(1995) - et al.
Continuous cardiac output by pulse contour analysis?
Br J Anaesth
(2001) - et al.
Comparison of thermodilution bolus cardiac output and Doppler cardiac output in the early post-cardiopulmonary bypass period
J Cardiothorac Vasc Anesth
(2003) - et al.
Cardiac output in normal pregnancy: a critical review
Obstet Gynecol
(1996) - et al.
Early pregnancy changes in hemodynamics and volume homeostasis are consecutive adjustments triggered by a primary fall in systemic vascular tone
Am J Obstet Gynecol
(1993)
A longitudinal study of cardiac output in normal human pregnancy
Am J Obstet Gynecol
Central hemodynamic observations in untreated preeclamptic patients
Hypertension
Measurement of cardiac output during pregnancy: validation of Doppler technique and clinical observations in preeclampsia
Obstet Gynecol
Contribution to the continuous indirect blood pressure measurement
Z Gesamte Inn Med
On the indirect registration of finger blood pressure after Peñáz
Funkt Biol Med
A century of noninvasive arterial pressure measurement: from Marey to Peñáz and Finapres
Homeostasis
Physiocal, calibrating finger vascular physiology for Finapres
Homeostasis
Fifteen years experience with finger arterial pressure monitoring: assessment of the technology
Cardiovasc Res
Comparison of Portapres with standard sphygmomanometry in pregnancy
Hypertens Pregnancy
Computation of aortic flow from pressure in humans using a nonlinear, three-element model
J Appl Physiol
Cited by (30)
The 9-Month Stress Test: Pregnancy and Exercise—Similarities and Interactions
2021, Canadian Journal of CardiologyCitation Excerpt :Its clinical value in pregnancy is well recognized with elevated PWV associated with hypertensive disorders in pregnancy that have immediate and long-term health risks for mother and baby.29 However, the evidence regarding its directional change in healthy pregnancy is conflicting with some showing a nadir reached in the second trimester followed by a gradual increase until term30,31 whereas elsewhere, PWV exhibits no change,32,33 or even a continuous decrease in PWV until term in uncomplicated pregnancies.34 Differential arterial properties including elasticity and muscular composition of the aorta vs peripheral muscular arteries might explain these contrasting findings.35
Alternative Approaches to the Assessment of the Systemic Circulation and Left Ventricular Performance: A Proof-of-Concept Study
2019, CJC OpenCitation Excerpt :The results of this study could form the basis of a new approach to clinical stress testing. CI and systolic pressures might be measured noninvasively, for example, by using the Modelflow method.21-24 CI could be varied by the manipulation of LV preload (eg, lower-body negative pressure or head-up tilt to pool blood peripherally and positive pressure or leg raising to mobilize peripheral blood).
Accuracy and precision of the ultrasound cardiac output monitor (USCOM 1A) in pregnancy: Comparison with three-dimensional transthoracic echocardiography
2014, British Journal of AnaesthesiaCitation Excerpt :Alternative non-invasive monitors include finger pressure and bioreactance devices. The finger pressure device has been found to have an MPD of 40% when compared with Doppler echocardiography in pregnant women.34 Bioreactance devices have been used to study changes in CO in pregnancy, but accuracy data in this group are lacking.
Comparison of noninvasive continuous arterial waveform analysis (Nexfin) with transthoracic Doppler echocardiography for monitoring of cardiac output
2012, Journal of Clinical AnesthesiaCitation Excerpt :As previously mentioned, the Nexfin monitor uses the volume-clamp method of Peńãz in combination with the physiocal criteria of Wesseling et al for the measurement of pressure [4,5]. This earlier developed Modelflow method [11] calculates flow from BP pulsation using a three-element Windkessel model of aortic input impedence, and has been validated in various settings [12-22]. Wesseling et al showed that the model estimated CO with a mean difference of 7%, with an SD of 22%, which was further improved to 2%, with an SD of 8% after single calibration with thermodilution CO [11].
Serial hemodynamic measurement in normal pregnancy, preeclampsia, and intrauterine growth restriction
2008, American Journal of Obstetrics and GynecologyCitation Excerpt :We observed an underestimation of approximately 10% by the former method during pregnancy because of changes in vascular characteristics in pregnancy.23 After adjustment with an algorithm using systolic blood pressure, heart rate, and pulse wave velocity, average measurement results were similar between both measurement techniques, and both methods showed a similar random variation.23 We decided against adjustment in the present study because the observed systematic difference did not change during pregnancy, was proportionally small, and adjustment would not increase the efficacy of the discriminant analysis.
A mathematical model of vascular and hemodynamics changes in early and late forms of preeclampsia
2023, Physiological Reports
Cite this article as: Rang S, de Pablo Lapiedra B, van Montfrans GA, et al. Modelflow, a new method for noninvasive assessment of cardiac output in pregnant women. Am J Obstet Gynecol 2007;196:235.e1-235.e8.