Portal vein pulsatility is associated with the cumulative fluid balance: A post hoc longitudinal analysis of a prospective, general intensive care unit cohort.

Background: Previous studies have explored tools for evaluating the effects of positive fluid balance, with recent emphasis, and controversies, on venous ultrasound parameters and composite scores. The portal vein pulsatility index and the renal venous pattern have emerged as the most promising indicators of volume-induced venous congestion. But in the general intensive care unit (ICU), numerous factors influence cardiovascular homeostasis, affecting venous function.

Objectives: This study aimed to evaluate the factors associated with portal vein pulsatility index in general ICU patients. Secondary objectives were to examine the correlations between pulsatility index and additional markers of congestion.

Design: This exploratory study was a post hoc analysis of a prospective, multicentric, observational database.

Setting: The data collection was performed in four ICUs in university-affiliated or tertiary hospitals.

Patients: This study included adult patients within 24 h of general ICU admission with an expected ICU length of stay of more than 2 days.

Intervention: Patients underwent clinical, biological, and echocardiographic assessments at several times: ICU admission, day 1, day 2, day 5 and the last day of ICU.

Main outcome measure: The study primary endpoint was the portal vein pulsatility index during the course of the patients' stay on the ICU.

Results: One hundred forty-five patients and 514 haemodynamic evaluations were analysed. The mean age of the patients was 64 ± 15 years, 41% were women, with a median [IQR] admission simplified acute physiology score II of 46 [37 to 59]. The univariable followed by multivariable mixed-effects linear regression analyses demonstrated an association between portal vein pulsatility index, heart rate [estimate -0.002 (95% CI, -0.003 to -0.001), P < 0.001] and the cumulative fluid balance [estimate 0.0007 (95% CI, 0.00007 to 0.001), P = 0.024]. Portal vein pulsatility index showed no agreement with CVP of at least 12 mmHg (kappa correlation -0.008, P = 0.811), negative passive leg raising (kappa correlation -0.036, P = 0.430), mean inferior vena caval (IVC) diameter greater than 2 cm (kappa correlation -0.090, P = 0.025), maximal IVC diameter greater than 2 cm (kappa correlation -0.010, P = 0.835), hepatic vein systolic/diastolic ratio less than 1 (kappa correlation 0.043, P = 0.276), or renal vein pulsatile pattern (kappa correlation -0.243, P < 0.001).

Conclusion: The study findings emphasise the unique sensitivity of portal vein pulsatility index in assessing fluid balance in general ICU patients. The lack of correlation between portal vein pulsatility index and other parameters of venous congestion underscores its potential to provide distinctive insights into venous congestion.