CHANGE IN CARDIOVASCULAR INDEXES WITH POSITION AND ISOMETRIC-EXERCISETHROUGHOUT PREGNANCY - ASSESSMENT BY IMPEDANCE CARDIOGRAPHY AND OSCILLOMETRIC SPHYGMOMANOMETRY

Background: The poor predictive values of the supine presser and isome tric handgrip exercise tests for pregnancy-induced hypertension may re late to interobserver errors associated with mercury column sphygmoman ometry or to the timing of blood pressure measurements relative to pos ition change or isometric exercise. Objective: To evaluate the Bomed N CCOM-3, in combination with oscillometric measurement of mean arterial pressure (MAP), as a means of assessing beat-to-beat changes in hemod ynamic indices at various stages of pregnancy. Setting: The Prince of Wales Hospital, teaching hospital to the Chinese University of Hong Ko ng. Methods: A longitudinal study of 20 normotensive Chinese women to assess the normal hemodynamic responses to changes in posture and isom etric handgrip exercise; cardiac index (CI) obtained from a Bomed NCCO M-3 impedance cardiograph, and MAP from a Finapres digital blood press ure monitor. Results: Position change did not significantly alter CI. Significant changes in MAP and, hence, total peripheral resistance ind ex (TPRI) following position change were observed at all gestational a ges and in the puerperium. Regression analysis shows that the major co ntributing factor to changes in TPRI was change in CI with a variable effect of change in MAP. Isometric handgrip exercise caused significan t decreases in CI in the second and third trimesters and also in the p uerperium, but not in early pregnancy. Increases in TPRI following iso metric exercise were significant at all gestations tested and in the p ostnatal period. Regression analysis shows that the changes are equall y effected by the increase in MAP and the decreases in CI. Conclusions : The combination of impedance cardiography and oscillometric sphygmom anometry provides excellent recordings of beat-to-beat changes in hemo dynamic indices during physiological testing. The changes observed thr oughout normal pregnancy were similar to those reported using Doppler ultrasound with echocardiography, remaining consistent after 20-24 wee ks' gestation, with the exception of a significant rise in TPRI betwee n the second and third trimesters.