Evaluation of global cardiac systolic performance and diastolic filling in central hypovolumia by lower body negative pressure with Doppler echocardiography

Abstract

Objective To overall evaluate the change of global cardiac systolic performance and diastolic filling in hypovoleamia by LBNP. Methods 10 healthy male subjects were placed in a standard LBNP chamber. Baseline haemodynamic and echocardiographic measure- ments were made after a period of least 10 min resting supine within the chamber. Pressure was then decreased to -10,-20 and -30 mmHg, with each pressure maintained for 15 min. The indices offour transvalvular and SVC flow were measured using Doppler echocardiography. Results The results showed that S wave, Re wave, and VTI of SVC progressively decreased with increasing LBNP. At -30 mmHg stage, S wave decreased by 35.4 %(change of 0.21+0.03 m/s, P < 0.001). This reduction in pre-load was associated with a progressive decrease in SV(by 21.5 ± 4.5 ml at −30 mmHg, P < 0.001), decrease in CO(by 1.2 ±0.2 L min −1 at -30 mmHg LBNP, P < 0.001). The diastolic filling of mitral and tricuspid flow also reduced significantly. At -30 mmHg stage, the E wave of MVF and TVF decreased 31% and 32% respectively(change of 0.23 ± 0.05 m/s, P <0.001 and 0.18 ± 0.01 m/s, P < 0.001). VTI of MVF and TVF decreased 27% and 27.7% respectively(change of 5.55 ± 1.41cm, P < 0.01 and 4.25 ± 0.44 cm, P < 0.01). A wave of both sides did not change significantly. Conclusion Doppler indices changes in different LBNP stage can roughly reflect the degree of hypovoleamia caused by blood volume redistribution. The indices of Doppler echocardiography are more sensitive than traditional physiological indexes in evaluating cardiovascular responses of LBNP. Echocardiography techniques overall can evaluate the global cardiac function including systolic performance and diastolic filling.