Comparison of various surrogate markers for venous congestion in predicting acute kidney injury following cardiac surgery: A cohort study

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.

Venous excess ultrasound score association with acute kidney injury in critically ill patients: a systematic review and meta-analysis of observational studies

BACKGROUND

Systemic venous congestion assessed by the venous excess ultrasound score (VExUS), has been associated with acute kidney injury (AKI) in patients undergoing cardiac surgery. However, there is a lack of evidence of this association in the general critically ill patients.

STUDY DESIGN AND METHODS

PubMed, Embase, and Cochrane databases were searched for observational prospective studies that included critically ill patients and analyzed VExUS score on the first day of admission to the ICU. The main outcome was occurrence of AKI. Secondary outcome was all-cause mortality. Statistical analysis was performed using Review Manager 5.4.1. Odds ratios (OR) with 95% confidence interval were pooled using a random-effects model. The Quality in Prognosis Studies (QUIPS) tool was used to assess risk of bias. Publication bias was assessed via funnel plot and heterogeneity was examined with I2 statistics.

RESULTS

Our analysis included 1036 patients from nine studies, of whom 17.4% presented venous congestion according to VExUS definition. In critically ill patients presenting with venous congestion (VExUS score ≥ 2), the incidence of AKI was significantly higher as compared with those without congestion (OR 2.63, 95% CI 1.06-6.54; p = 0.04; I2 = 74%). The association was notably stronger in cardiac surgery patients (OR 3.86, 95% CI 2.32-6.42; p < 0.00001; i2 = 0%). There was no significant association between venous congestion and all-cause mortality (OR 1.25, 95% CI 0.71-2.19; p = 0.44; i2 = 8%).

CONCLUSIONS

These findings suggest that VExUS score may correlate with an elevation in the incidence AKI in critically ill patients, with a more pronounced effect observed within the subgroup of patients undergoing cardiac surgery. There was no statistically significant association between VExUS score and all-cause mortality.

CLINICAL TRIAL REGISTRATION

PROSPERO under protocol number CRD535513.

Central Venous Pressure as a Predictor of Acute Kidney Injury in Cardiac Surgery: A Systematic Review of Observational Studies

Background/Objectives: Acute kidney injury (AKI) is a syndrome characterized by impaired kidney function, which is associated with reduced survival and increased morbidity. Central venous pressure (CVP) is a widely used hemodynamic parameter for assessing the volume status of patients and evaluating their response to fluid resuscitation. This systematic review aims to analyze various prospective and retrospective observational and controlled trials to determine the association between CVP and the risk of developing AKI in patients undergoing cardiac surgery. Additionally, it examines whether elevated CVP serves as an accurate predictor of AKI in this patient population. Methods: A systematic review was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, using PubMed as the primary database. The search focused on studies published after 2014 that included adult patients undergoing cardiac surgery with reported measurements of CVP and kidney function assessment. Studies conducted on animals, pediatric populations, those published before 2014, or in languages other than English were excluded from the review. Results: Through the analysis of 21 studies, a clear association between higher CVP and increased AKI risk emerged. The most critical CVP thresholds identified were 10 mmHg, 12 mmHg, 14 mmHg, and 20 mmHg, with risk increasing progressively beyond these values. CVP ≥ 10 mmHg was the most commonly reported cutoff for elevated AKI risk, showing 1.42 to 4.53 times increased odds. CVP ≥ 12 mmHg further amplified the risk, while CVP ≥ 14 mmHg was consistently associated with severe AKI and the need for RRT. The highest threshold (CVP ≥ 20 mmHg) showed the greatest risk escalation, linked to fluid overload, right heart failure, and mortality. Studies also suggest an optimal CVP range of 6-8 mmHg to minimize AKI incidence. Conclusions: Elevated CVP is an independent risk factor for the development of AKI in patients undergoing cardiac surgery. These findings suggest that CVP monitoring can play a significant role in predicting AKI and guiding perioperative management strategies.

Inferior vena cava distensibility during pressure support ventilation: a prospective study evaluating interchangeability of subcostal and trans‑hepatic views, with both M‑mode and automatic border tracing

The Inferior Vena Cava (IVC) is commonly utilized to evaluate fluid status in the Intensive Care Unit (ICU),with more recent emphasis on the study of venous congestion. It is predominantly measured via subcostal approach (SC) or trans-hepatic (TH) views, and automated border tracking (ABT) software has been introduced to facilitate its assessment. Prospective observational study on patients ventilated in pressure support ventilation (PSV) with 2 × 2 factorial design. Primary outcome was to evaluate interchangeability of measurements of the IVC and the distensibility index (DI) obtained using both M-mode and ABT, across both SC and TH. Statistical analyses comprised Bland-Altman assessments for mean bias, limits of agreement (LoA), and the Spearman correlation coefficients. IVC visualization was 100% successful via SC, while TH view was unattainable in 17.4% of cases. As compared to the M-mode, the IVC-DI obtained through ABT approach showed divergences in both SC (mean bias 5.9%, LoA -18.4% to 30.2%, ICC = 0.52) and TH window (mean bias 6.2%, LoA -8.0% to 20.4%, ICC = 0.67). When comparing the IVC-DI measures obtained in the two anatomical sites, accuracy improved with a mean bias of 1.9% (M-mode) and 1.1% (ABT), but LoA remained wide (M-mode: -13.7% to 17.5%; AI: -19.6% to 21.9%). Correlation was generally suboptimal (r = 0.43 to 0.60). In PSV ventilated patients, we found that IVC-DI calculated with M-mode is not interchangeable with ABT measurements. Moreover, the IVC-DI gathered from SC or TH view produces not comparable results, mainly in terms of precision.

Cardiac Surgery-Associated Acute Kidney Injury

AKI is a common and serious complication of cardiac surgery that has a significant impact on patient morbidity and mortality. The Kidney Disease Improving Global Outcomes definition of AKI is widely used to classify and identify AKI associated with cardiac surgery (cardiac surgery-associated AKI [CSA-AKI]) on the basis of changes in serum creatinine and/or urine output. There are various preoperative, intraoperative, and postoperative risk factors for the development of CSA-AKI which should be recognized and addressed as early as possible to expedite its diagnosis, reduce its occurrence, and prevent or ameliorate its devastating complications. Crucial issues are the inaccuracy of serum creatinine as a surrogate parameter of kidney function in the perioperative setting of cardiothoracic surgery and the necessity to discover more representative markers of the pathophysiology of AKI. However, except for the tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 ratio, other diagnostic biomarkers with an acceptable sensitivity and specificity are still lacking. This article provides a comprehensive review of various aspects of CSA-AKI, including pathogenesis, risk factors, diagnosis, biomarkers, classification, prevention, and treatment management.

Monitoring the venous circulation: novel techniques and applications

PURPOSE OF REVIEW

Venous pressure is an often-unrecognized cause of patient morbidity. However, bedside assessment of PV is challenging. We review the clinical significance of venous pressure measurement, existing techniques, and introduce the Venous Excess Ultrasound (VExUS) Score as a novel approach using doppler ultrasound to assess venous pressure.

RECENT FINDINGS

Studies show clear associations between elevated venous pressure and adverse outcomes in critically ill patients. Current venous pressure measurement techniques include physical examination, right heart catheterization (RHC), two-dimensional ultrasound, and a variety of labor-intensive research-focused physiological maneuvers. Each of these techniques have specific shortcomings, limiting their clinical utility. To address these gaps, Beaubien-Souligny et al. introduced the VExUS Score, a novel doppler ultrasound-based method that integrates IVC diameter with doppler measurements of the hepatic, portal, and renal veins to generate a venous congestion assesment. Studies show strong correlations between VExUS score and RHC measurements, and well as an association between VExUS score and improvement in cardiorenal acute kidney injury, diuretic response, and fluid status shifts. However, studies in noncardiac populations have been small, heterogenous, and inconclusive.

SUMMARY

Early studies evaluating the use of doppler ultrasound to assess venous congestion show promise, but further research is needed in diverse patient populations and clinical settings.

Renal Arterial and Venous Doppler in Cardiorenal Syndrome: Pathophysiological and Clinical Insights

In recent decades, there has been considerable effort in investigating the clinical utility of renal Doppler measurements in both cardiovascular and renal disorders. In particular, a measure of renal arterial resistance, the renal resistive index (RRI), has been demonstrated to predict chronic kidney disease progression and acute kidney injury in different clinical settings. Furthermore, it is linked to a poorer prognosis in individuals suffering from chronic heart failure. Examining the renal venous flow through pulsed Doppler can offer additional insights into renal congestion and cardiovascular outcomes for these patients. This review seeks to summarize the existing data concerning the clinical significance of arterial and venous renal Doppler measurements across various cardiovascular and renal disease contexts.

Venous Doppler flow patterns, venous congestion, heart disease and renal dysfunction: A complex liaison

The World Journal of Cardiology published an article written by Kuwahara et al that we take the pleasure to comment on. We focused our attention on venous congestion. In intensive care settings, it is now widely accepted that venous congestion is an important clinical feature worthy of investigation. Evaluating venous Doppler profile abnormalities at multiple sites could suggest adequate treatment and monitor its efficacy. Renal dysfunction could trigger or worsen fluid overload in heart disease, and cardio-renal syndrome is a well-characterized spectrum of disorders describing the complex interactions between heart and kidney diseases. Fluid overload and venous congestion, including renal venous hypertension, are major determinants of acute and chronic renal dysfunction arising in heart disease. Organ congestion from venous hypertension could be involved in the development of organ injury in several clinical situations, such as critical diseases, congestive heart failure, and chronic kidney disease. Ultrasonography and abnormal Doppler flow patterns diagnose clinically significant systemic venous congestion. Cardiologists and nephrologists might use this valuable, non-invasive, bedside diagnostic tool to establish fluid status and guide clinical choices.