Evaluation of extravascular lung water and cardiac function in normal vaginal delivery by intrapartum bedside ultrasound

Abstract

Background: Healthy parturients may experience pulmonary edema and disturbed cardiac function during labor. We aimed to evaluate the extravascular lung water (EVLW), intravascular volume, and cardiac function of normal parturients during spontaneous vaginal delivery by bedside ultrasound. And to explore the correlation between EVLW and intravascular volume, cardiac function.

Methods: This was a prospective observational study including 30 singleton-term pregnant women undergoing spontaneous vaginal delivery. Bedside ultrasound was performed at the early labor, the end of the second stage of labor, 2 and 24 h postpartum, and 120 scanning results were recorded. EVLW was evaluated by the echo comet score (ECS) obtained by the 28-rib interspaces technique. Inferior vena cava collapsibility index (IVC-CI), left ventricle ejection fraction, right ventricle fractional area change, left and right ventricular E/A ratio, and left and right ventricular index of myocardial performance (LIMP and RIMP) were measured. Measurements among different time points were compared, and the correlations between ECS and other measurements were analyzed.

Results: During the spontaneous vaginal delivery of healthy pregnant women, 2 had a mild EVLW increase at the early labor, 8 at the end of the second stage of labor, 13 at 2 h postpartum, and 4 at 24 h postpartum (P < 0.001). From the early labor to 24 h postpartum, ECS first increased and then decreased, reaching its peak at 2 h postpartum (P < 0.001). IVC-CI first decreased and then increased, reaching its minimum at the end of the second stage of labor (P < 0.001). RIMP exceeded the cut-off value of 0.43 at the end of the second stage of labor. ECS was weakly correlated with IVC-CI (r=-0.373, P < 0.001), LIMP (r = 0.298, P = 0.022) and RIMP (r = 0.211, P = 0.021).

Conclusions: During spontaneous vaginal delivery, the most vital period of perinatal care is between the end of the second stage of labor and 2 h postpartum, because the risk of pulmonary edema is higher and the right ventricle function may decline. IVC-CI can be used to evaluate maternal intravascular volume. The increase in EVLW may be related to the increase in intravascular volume and the decrease in ventricular function.

Keywords: Cardiac function; Echocardiography; Labor; Lung ultrasound; Pulmonary edema.

Fig. 1

Flow chart of recruitment

Fig. 2

Box plot of ECS during and after labor. ECS: echo comet score. In the abscissa, A: the early labor, B: the end of the second stage of labor, C: 2 h postpartum, D: 24 h postpartum respectively

Fig. 3

Box plot of IVEe (A), IVCi (B), and IVC-CI (C) during and after labor. IVCe: the diameter of the inferior vena cava at the end of expiration, IVCi: the diameter of the inferior vena cava at the end of inspiration, IVC-CI: inferior vena cava collapsibility index. In the abscissa, A: the early labor, B: the end of the second stage of labor, C: 2 h postpartum, D: 24 h postpartum respectively

Fig. 4

Box plot of LVEF (A), LV E/A (B), LIMP (C), RVFAC (D), RV E/A(E), RIMP (F) during and after labor. LVEF: left ventricle ejection fraction, LV E/A: left ventricular E/A ratio, LIMP: left ventricular index of myocardial performance, RVFAC: right ventricle fractional area change, RV E/A: right ventricular E/A ratio, RIMP: right ventricular index of myocardial performance. In the abscissa, A: the early labor, B: the end of the second stage of labor, C: 2 h postpartum, D: 24 h postpartum respectively