Lung Ultrasound–Guided Dry Weight Assessment and Echocardiographic Measures in Hypertensive Hemodialysis Patients: A Randomized Controlled Study

Changes in right ventricular dimensions, function, and pulmonary circulation loading according to the degree of interdialytic weight gain in maintenance hemodialysis patients

INTRODUCTION

The aim of this study was to investigate changes in echocardiographic right ventricular (RV) indices in relation to the degree of fluid accumulation between hemodialysis sessions, evaluated according to the recommended threshold of interdialytic-weight-gain corrected for dry weight (IDWG%).

METHODS

A post-hoc analysis was performed using data from 41 maintenance hemodialysis patients. Patients were divided into a higher (>4.5%) and a lower (<4.5%) IDWG% group and underwent an echocardiographic assessment at the start and the end of the 3-day and the 2-day interdialytic interval.

RESULTS

RV systolic pressure (RVSP) increments were more pronounced in the higher compared to the lower IDWG% group (16.43 ± 5.37 vs. 14.11 ± 13.38 mm Hg respectively, p = 0.015) over the 3-day interval, while changes in RV filling pressures, did not differ significantly between the groups (p = 0.84).

CONCLUSIONS

During the 3-day interdialytic interval, pulmonary circulation is particularly overloaded in patients with fluid accumulation higher than the recommended thresholds, as evidenced by higher RVSP elevations.

Different Interdialytic Intervals and Cardiorespiratory Fitness in Patients Undergoing Hemodialysis

Key Points

Background

Long interdialytic interval in thrice-weekly hemodialysis is associated with excess cardiovascular and all-cause mortality risk. Impaired cardiorespiratory fitness is a strong predictor of mortality in hemodialysis. This study investigated differences in cardiorespiratory fitness assessed with cardiopulmonary exercise testing (CPET) between the end of the 2-day and the 3-day interdialytic interval.

Methods

A total of 28 hemodialysis patients, randomized in two different sequences of evaluation, underwent CPET and spirometry examination at the end of the 2-day and the 3-day intervals. The primary outcome was the difference in oxygen uptake at peak exercise (VO2peak [ml/kg per minute]) assessed with CPET. Volume status was assessed with interdialytic weight gain, lung ultrasound, bioimpedance spectroscopy, and inferior vena cava measurements. A total of 14 age-matched and sex-matched controls were also evaluated. Comparisons of changes in parameters of interest were performed with paired or independent t-tests or relevant nonparametric tests, as appropriate. Bivariate correlation analyses and generalized linear mixed models were used to examine associations between changes in CPET parameters and volume indices.

Results

Hemodialysis patients at the end of both 2-day and 3-day intervals presented lower values in all major CPET parameters than controls. VO2peak (ml/kg per minute) was significantly higher at the end of the 2-day than the 3-day interval (15.2±4.2 versus 13.6±2.8; P < 0.001); the results were similar for VO2peak (ml/min) (1188±257 versus 1074±224; P < 0.001) and VO2peak (% predicted) (58.9±9.2 versus 52.3±8.6; P < 0.001). Numerical but no statistically significant differences were detected in VO2 anaerobic threshold (ml/kg per minute) and VO2 anaerobic threshold (ml/min) between the two time points. Maximal work load (90.1±23.2 versus 79.3±25.1; P < 0.001), exercise duration, heart rate at peak exercise, and oxygen pulse also showed lower values at the end of the 3-day interval. Forced expiratory volume in 1-second levels were similar between the two evaluations. Generalized linear mixed model analysis, including interdialytic weight gain as random covariate, attenuated the observed differences in VO2peak (ml/kg per minute). Changes in bioimpedance spectroscopy–derived overhydration indexes were moderately correlated with changes of VO2peak (ml/kg per minute).

Conclusions

The 3-day interval was associated with further impairment of VO2 at peak exercise. This effect was predominantly driven by excess fluid accumulation during the extra interdialytic day.

On Whether Ca-125 Is the Answer for Diagnosing Overhydration, Particularly in End-Stage Kidney Disease Patients-A Systematic Review

Overhydration (OH) is a prevalent medical problem that occurs in patients with kidney failure, but a specific marker has still not been found. Patients requiring kidney replacement therapy suffer from a water imbalance, which is correlated with mortality rates in this population. Currently, clinicians employ techniques such as bioimpedance spectroscopy (BIS) and ultrasound (USG) markers of overhydration or markers of heart and kidney function, namely NT-pro-BNP, GFR, or creatinine levels. New serum markers, including but not limited to Ca-125, galectin-3 (Gal-3), adrenomedullin (AMD), and urocortin-2 (UCN-2), are presently under research and have displayed promising results. Ca-125, which is a protein mainly used in ovarian cancer diagnoses, holds great potential to become an OH marker. It is currently being investigated by cardiologists as it corresponds to the volume status in heart failure (HF) and ventricular hypertrophy, which are also associated with OH. The need to ascertain a more precise marker of overhydration is urgent mainly because physical examinations are exceptionally inaccurate. The signs and symptoms of overhydration, such as edema or a gradual increase in body mass, are not always present, notably in patients with chronic kidney disease. Metabolic disruptions and cachexia can give a false picture of the hydration status. This review paper summarizes the existing knowledge on the assessment of a patient's hydration status, focusing specifically on kidney diseases and the role of Ca-125.

Lung Ultrasound and Bioelectrical Impedance Analysis for Fluid Status Assessing Patients Undergoing Maintenance Hemodialysis

Background

Volume overload is a fatal complication for people undergoing hemodialysis. Therefore, regulating a patient's "dry weight" based on their fluid status is imperative. Clinical experiences are too subjective to accurately judge a patient's fluid status, but techniques have emerged for improved fluid control in the two decades. Specifically, lung ultrasonography (LUS) uses a unique aspect of ultrasound images, the B-lines, to evaluate extravascular lung water, which has increasingly attracted attention. However, the role of B-line quantification in predicting short-mid-term death and/or cardiovascular complications is unclear.

Methods

Patients undergoing MHD at the hemodialysis center of Zhejiang Provincial People's Hospital from October 1, 2020, to February 28, 2021, were examined using LUS and a bioelectrical impedance analysis before and after dialysis, and related clinical data were collected. All patients were followed up for one year after the examination, and deaths and first cardiovascular events (e.g., stroke, myocardial infarction, and heart failure) during this period were recorded.

Results

98 patients were enrolled and divided into three groups in relation to their mild (<16 B-lines), moderate (16-30 B-lines), or severe (>30 B-lines) hypervolemia, defined by the number of B-lines. The long-term survival rate was significantly lower in the severe group than in the mild and moderate groups. LUS and bioelectrical impedance-related parameters (e.g., extracellular water-to-water ratio) were closely related to cardiac ultrasound parameters (left ventricular ejection fraction) (P < 0.001). The optimal B-line cutoff value on LUS for predicting fluid overload (defined clinically) in patients on hemodialysis was 11.5 lines (AUC = 0.840, 95% confidence interval 0.735-0.945, P < 0.001), and the diagnostic sensitivity and specificity were both 76.5%. During the one-year follow-up period, ten deaths and six cardiovascular events occurred. The survival rate was significantly lower in the severe group than in the mild group (log-rank test χ2 = 10.050, P=0.002) but did not differ between the severe and moderate groups (χ2 = 2.629, P=0.105).

Conclusion

LUS is a cheap, noninvasive, simple, and repeatable volume-monitoring method that can assist with individualized fluid volume management in patients undergoing MHD. LUS results may also help to predict the short-mid-term survival rate of patients to a certain extent.

Volume Status Assessment by Lung Ultrasound in End-Stage Kidney Disease: A Systematic Review

Purpose of review

Lung ultrasound is a noninvasive bedside technique that can accurately assess pulmonary congestion by evaluating extravascular lung water. This technique is expanding and is easily available. Our primary outcome was to compare the efficacy of volume status assessment by lung ultrasound with clinical evaluation, echocardiography, bioimpedance, or biomarkers. The secondary outcomes were all-cause mortality and cardiovascular events.

Sources of information

We conducted a MEDLINE literature search for observational and randomized studies with lung ultrasound in patients on maintenance dialysis.

Methods

From a total of 2363 articles, we included 28 studies (25 observational and 3 randomized). The correlation coefficients were pooled for each variable of interest using the generic inverse variance method with a random effects model. Among the clinical parameters, New York Heart Association Functional Classification of Heart Failure status and lung auscultation showed the highest correlation with the number of B-lines on ultrasound, with a pooled r correlation coefficient of .57 and .36, respectively. Among echocardiographic parameters, left ventricular ejection fraction and inferior vena cava index had the strongest correlation with the number of B-lines, with a pooled r coefficient of .35 and .31, respectively. Three randomized studies compared a lung ultrasound-guided approach with standard of care on hard clinical endpoints. Although patients in the lung ultrasound group achieved better decongestion and blood pressure control, there was no difference between the 2 management strategies with respect to death from any cause or major adverse cardiovascular events.

Key findings

Lung ultrasound may be considered for the identification of patients with subclinical volume overload. Trials did not show differences in clinically important outcomes. The number of studies was small and many were of suboptimal quality.

Limitations

The included studies were heterogeneous and of relatively limited quality.

Seeing through the myths: Practical aspects of diagnostic point-of-care ultrasound in nephrology

Point of care ultrasonography (POCUS) is emerging as an invaluable tool for guiding patient care at the bedside, providing real-time diagnostic information to clinicians. Today, POCUS is recognized as the fifth pillar of bedside clinical examination, alongside inspection, palpation, percussion, and auscultation. In spite of growing interest, the adoption of diagnostic POCUS in nephrology remains limited, and comprehensive training beyond kidney ultrasound is offered in only a few fellowship programs. Moreover, several misconceptions and barriers surround the integration of POCUS into day-to-day nephrology practice. These include myths about its scope, utility, impact on patient outcomes and legal implications. In this minireview, we address some of these issues to encourage wider and proper utilization of POCUS.

Conduction System Pacing: Have We Finally Found the Holy Grail of Physiological Pacing?

The late fifties are considered a high point in the history of cardiac pacing, since this era is marked by the first pacemaker implantation, which has since evolved into life-saving therapy. Right ventricular apical and biventricular pacing are the classic techniques that are recommended as first-l ine approaches for most indications in current guidelines. However, conduction system pacing has emerged as being able to deliver a more physiological form of pacing and is becoming mainstream practice in a growing number of centres. In this review, we aim to compare traditional pacing methods with conduction system pacing.

A Personalized Approach to the Management of Congestion in Acute Heart Failure

Heart failure (HF) is the common final pathway of several conditions and is characterized by hyperactivation of numerous neurohumoral pathways. Cardiorenal interaction plays an essential role in the progression of the disease, and the use of diuretics is a cornerstone in the treatment of hypervolemic patients, especially in acute decompensated HF (ADHF). The management of congestion is complex and, to avoid misinterpretations and errors, one must understand the interface between the heart and the kidneys in ADHF. Congestion itself may impair renal function and must be treated aggressively. Transitory elevations in serum creatinine during decongestion is not associated with worse outcomes and diuretics should be maintained in patients with clear hypervolemia. Monitoring urinary sodium after diuretic administration seems to improve the response to diuretics as it allows for adjustments in doses and a personalized approach. Adequate assessment of volemia and the introduction and titration of guideline-directed medical therapy are mandatory before discharge. An early visit after discharge is highly recommended, to assess for residual congestion and thus avoid readmissions.

The Role of Pre- and Post-Transplant Hydration Status in Kidney Graft Recovery and One-Year Function

Background and Objectives: Early improvements to graft function are crucial for good outcomes in kidney transplantation (kTx). Various factors can influence early graft function. This study aimed to evaluate the pre- and post-transplant hydration statuses of kTx recipients using bioimpedance analysis (BIA) and lung ultrasonography (LUS) and to investigate the hydration status' relationship with the function of the transplanted kidney during the first year after transplantation. Materials and Methods: This observational prospective cohort study included deceased kidney recipients transplanted in the Hospital of the Lithuanian University of Health Sciences between September 2016 and January 2023. BIA and LUS were performed before transplantation, on days 3 and 7, and at discharge. Data on recipient and donor clinical characteristics were collected. Graft function was evaluated according to the serum creatinine reduction ratio and the need for dialysis. Hydration status was evaluated by calculating B-lines (BL) on LUS and the ratio of extracellular/total body water on BIA. Results: Ninety-eight kTx recipients were included in the study. Patients with immediate graft function (IGF) were compared to those with slow or delayed graft function (SGF + DGF). Recipients in the SGF + DGF group had a higher sum of BL on LUS before transplantation. After transplantation in early postoperative follow-up, both groups showed hyperhydration as determined by BIA and LUS. After one year, recipients with no BL before transplantation had better graft function than those with BL. Logistic regression analysis showed that having more than one BL in LUS was associated with a 2.5 times higher risk of SGF or DGF after transplantation. Conclusions: This study found that lung congestion detected by LUS before kTx was associated with slower graft recovery and worse kidney function after 1 year. Meanwhile, the hyperhydration status detected by BIA analysis did not correlate with the function of the transplanted kidney.

Lung Ultrasound Estimates the Overhydration and Benefits Blood Pressure Control in Normal or Mild Symptomatic Hemodialysis Patients

Introduction

Lung ultrasound (LUS) is used for dry weight guidance by assessment of pulmonary congestion in hemodialysis (HD) patients. The aim of this study was to estimate amounts of accumulated fluid by total LUS scores (TLUSS), which were scarcely reported in HD patients who were normal or had a mild functional abnormality. In addition, the correlations between the LUS score of each area and TLUSS were determined to suggest fewer specific areas valuable to shorten the examination time of LUS.

Methods

This cohort study was conducted in adult HD patients who have New York Heart Association Classes I-II. LUS and multifrequency bioimpedance (BIA) were performed at baseline and the individual prescribed dry weight was set. Then each LUS was conducted at 28 areas of bilateral intercostal spaces and calculated as TLUSS weekly for eight weeks in which dry weight was adjusted. The second BIA was also measured at week eight. The difference of pre-HD weight and target weight (weight gain; WG) represented the amount of fluid accumulation.

Results

Twenty patients with a mean age of 62.2±14.0 years were enrolled. One hundred and sixty-six LUS were performed in which forty episodes of them were simultaneously measured with BIA. Optimum dry weight adjusted by TLUSS which benefited in mean reductions of blood pressure, and cardiothoracic ratios. WG amounts were significantly correlated with TLUSS (r=0.38), and with extracellular fluid (r=0.35) and overhydration fluid (r=0.39) assessed by BIA. Estimations of mean fluid overload were 2.18 (TLUSS ≤15), 2.72 (TLUSS 16-24), 3.17 (TLUSS 25-33), 3.65 (TLUSS 34-38) and 5.03 (TLUSS ≥39) in liters. The cut-off points of sum scores of 12 specific lung areas represented the none-mild were <8, moderate at 8-16, and severe pulmonary congestions were >16.

Conclusion

TLUSS estimated accumulated fluid useful for volume and blood pressure controls. Performance of LUS in 12 specific lung areas may reduce spending time and support routine uses of LUS in clinical practice.

Left ventricular dysfunction with preserved ejection fraction: the most common left ventricular disorder in chronic kidney disease patients

Chronic kidney disease (CKD) is a risk factor for premature cardiovascular disease. As kidney function declines, the presence of left ventricular abnormalities increases such that by the time kidney replacement therapy is required with dialysis or kidney transplantation, more than two-thirds of patients have left ventricular hypertrophy. Historically, much research in nephrology has focussed on the structural and functional aspects of cardiac disease in CKD, particularly using echocardiography to describe these abnormalities. There is a need to translate knowledge around these imaging findings to clinical outcomes such as unplanned hospital admission with heart failure and premature cardiovascular death. Left ventricular hypertrophy and cardiac fibrosis, which are common in CKD, predispose to the clinical syndrome of heart failure with preserved left ventricular ejection fraction (HFpEF). There is a bidirectional relationship between CKD and HFpEF, whereby CKD is a risk factor for HFpEF and CKD impacts outcomes for patients with HFpEF. There have been major improvements in outcomes for patients with heart failure and reduced left ventricular ejection fraction as a result of several large randomized controlled trials. Finding therapy for HFpEF has been more elusive, although recent data suggest that sodium-glucose cotransporter 2 inhibition offers a novel evidence-based class of therapy that improves outcomes in HFpEF. These observations have emerged as this class of drugs has also become the standard of care for many patients with proteinuric CKD, suggesting that there is now hope for addressing the combination of HFpEF and CKD in parallel. In this review we summarize the epidemiology, pathophysiology, diagnostic strategies and treatment of HFpEF with a focus on patients with CKD.

Pre-Dialysis B-Line Quantification at Lung Ultrasound Is a Useful Method for Evaluating the Dry Weight and Predicting the Risk of Intradialytic Hypotension

Intradialytic hypotension (IDH) is a frequent and well-known complication of hemodialysis, occurring in about one third of patients. An integrated approach with different methods is needed to minimize IDH episodes and their complications. In this prospective observational study, recruited patients underwent a multiparametric evaluation of fluid status through a lung ultrasound (LUS) with the quantification of B-lines, a physical examination, blood pressure, NT-proBNP and chest X-rays. The evaluation took place immediately before and at the end of the dialysis session, and the patients were divided into IDH and no-IDH groups. We recruited a total of 107 patients. A pre-dialysis B-line number ≥ 15 showed a high sensitivity in fluid overload diagnosis (94.5%), even higher than a chest X-ray (78%) or physical examination (72%) alone. The identification at the beginning of dialysis of <8 B-lines in the overall cohort or <20 B-lines in patients with NYHA 3−4 class are optimal thresholds for identifying those patients at higher risk of experiencing an IDH episode. In the multivariable analysis, the NYHA class, a low pre-dialysis systolic BP and a low pre-dialysis B-line number were independent risk factors for IDH. At the beginning of dialysis, the B-line quantification at LUS is a valuable and reliable method for evaluating fluid status and predicting IDH episodes. A post-dialysis B-line number <5 may allow for an understanding of whether the IDH episode was caused by dehydration, probably due to due to an overestimation of the dry weight.

Fluid Overload and Tissue Sodium Accumulation as Main Drivers of Protein Energy Malnutrition in Dialysis Patients

Protein energy malnutrition is recognized as a leading cause of morbidity and mortality in dialysis patients. Protein-energy-wasting process is observed in about 45% of the dialysis population using common biomarkers worldwide. Although several factors are implicated in protein energy wasting, inflammation and oxidative stress mechanisms play a central role in this pathogenic process. In this in-depth review, we analyzed the implication of sodium and water accumulation, as well as the role of fluid overload and fluid management, as major contributors to protein-energy-wasting process. Fluid overload and fluid depletion mimic a tide up and down phenomenon that contributes to inducing hypercatabolism and stimulates oxidation phosphorylation mechanisms at the cellular level in particular muscles. This endogenous metabolic water production may contribute to hyponatremia. In addition, salt tissue accumulation likely contributes to hypercatabolic state through locally inflammatory and immune-mediated mechanisms but also contributes to the perturbation of hormone receptors (i.e., insulin or growth hormone resistance). It is time to act more precisely on sodium and fluid imbalance to mitigate both nutritional and cardiovascular risks. Personalized management of sodium and fluid, using available tools including sodium management tool, has the potential to more adequately restore sodium and water homeostasis and to improve nutritional status and outcomes of dialysis patients.

Sodium First Approach, to Reset Our Mind for Improving Management of Sodium, Water, Volume and Pressure in Hemodialysis Patients, and to Reduce Cardiovascular Burden and Improve Outcomes

New physiologic findings related to sodium homeostasis and pathophysiologic associations require a new vision for sodium, fluid and blood pressure management in dialysis-dependent chronic kidney disease patients. The traditional dry weight probing approach that has prevailed for many years must be reviewed in light of these findings and enriched by availability of new tools for monitoring and handling sodium and water imbalances. A comprehensive and integrated approach is needed to improve further cardiac health in hemodialysis (HD) patients. Adequate management of sodium, water, volume and hemodynamic control of HD patients relies on a stepwise approach: the first entails assessment and monitoring of fluid status and relies on clinical judgement supported by specific tools that are online embedded in the HD machine or devices used offline; the second consists of acting on correcting fluid imbalance mainly through dialysis prescription (treatment time, active tools embedded on HD machine) but also on guidance related to diet and thirst management; the third consist of fine tuning treatment prescription to patient responses and tolerance with the support of innovative tools such as artificial intelligence and remote pervasive health trackers. It is time to come back to sodium and water imbalance as the root cause of the problem and not to act primarily on their consequences (fluid overload, hypertension) or organ damage (heart; atherosclerosis, brain). We know the problem and have the tools to assess and manage in a more precise way sodium and fluid in HD patients. We strongly call for a sodium first approach to reduce disease burden and improve cardiac health in dialysis-dependent chronic kidney disease patients.

Hidden risks associated with conventional short intermittent hemodialysis: A call for action to mitigate cardiovascular risk and morbidity

The development of maintenance hemodialysis (HD) for end stage kidney disease patients is a success story that continues to save many lives. Nevertheless, intermittent renal replacement therapy is also a source of recurrent stress for patients. Conventional thrice weekly short HD is an imperfect treatment that only partially corrects uremic abnormalities, increases cardiovascular risk, and exacerbates disease burden. Altering cycles of fluid loading associated with cardiac stretching (interdialytic phase) and then fluid unloading (intradialytic phase) likely contribute to cardiac and vascular damage. This unphysiologic treatment profile combined with cyclic disturbances including osmotic and electrolytic shifts may contribute to morbidity in dialysis patients and augment the health burden of treatment. As such, HD patients are exposed to multiple stressors including cardiocirculatory, inflammatory, biologic, hypoxemic, and nutritional. This cascade of events can be termed the dialysis stress storm and sickness syndrome. Mitigating cardiovascular risk and morbidity associated with conventional intermittent HD appears to be a priority for improving patient experience and reducing disease burden. In this in-depth review, we summarize the hidden effects of intermittent HD therapy, and call for action to improve delivered HD and develop treatment schedules that are better tolerated and associated with fewer adverse effects.

Detecting and Treating Lung Congestion with Kidney Failure

Fluid overload is a common complication in patients with CKD, particularly patients with kidney failure, a population with a very high risk for pulmonary edema. Lung ultrasound is now a well-validated technique that allows for reliable estimates of lung water in clinical practice. Several studies in patients with kidney failure documented a high prevalence of asymptomatic lung congestion of moderate to severe degree in this population, and this alteration was only weakly related with fluid excess as measured by bioimpedance spectroscopy. Furthermore, in these studies, lung congestion correlated in a dose-dependent fashion with death risk. In the Lung Water by Ultra-Sound Guided Treatment to Prevent Death and Cardiovascular Complications in High Risk Kidney Failure Patients with Cardiomyopathy (LUST) trial, a treatment strategy guided by lung ultrasound safely relieved lung congestion but failed to significantly reduce the risk for a combined end point including death, nonfatal myocardial infarction, and decompensated heart failure. However, in line with three trials in patients with heart failure, a post hoc analysis of the LUST trial showed that the use of lung ultrasound reduces the risk for repeated episodes of acute heart failure and repeated cardiovascular events. Given the high cardiovascular risk of pulmonary edema in patients with predialysis CKD, defining the epidemiology of lung congestion in this population is a public health priority. Specific trials in this population and additional trials in patients with kidney failure will establish whether targeting lung congestion at an asymptomatic phase may improve the severe cardiovascular prognosis of both patients predialysis and patients on dialysis.

Quantitative Lung Ultrasonography for the Nephrologist: Applications in Dialysis and Heart Failure

Volume overload, and its attendant increase in acute care utilization and cardiovascular morbidity and mortality, represents a critical challenge for the practicing nephrologist. This is particularly true among patients with ESKD on HD, where predialysis volume overload and intradialytic and postdialytic hypovolemia account for almost a third of all cost for the Medicare dialysis benefit. Quantitative lung ultrasound is a tool for assessing the extent of extravascular lung water that outperforms physical exam and plain chest radiography. B-lines are vertical hyperechoic artifacts present in patients with increased extravascular lung water. B-lines have been shown to decrease dynamically during the hemodialysis treatment in proportion to ultrafiltration volume. Among patients with chronic heart failure, titration of diuretics on the basis of the extent of pulmonary congestion noted on lung ultrasonography has been shown to decrease recurrent acute care utilization. Early data from randomized controlled trials of lung ultrasound-guided ultrafiltration therapy among patients with ESKD on HD have shown promise for potential reduction in recurrent episodes of decompensated heart failure and cardiovascular events. Ultimately, lung ultrasound may predict those who are ultrafiltration tolerant and could be used to decrease acute care utilization and, thus, cost in this population.

Assessment of fluid unresponsiveness guided by lung ultrasound in abdominal surgery: a prospective cohort study

A fluid challenge can generate an infraclinical interstitial syndrome that may be detected by the appearance of B-lines by lung ultrasound. Our objective was to evaluate the appearance of B-lines as a diagnostic marker of preload unresponsiveness and postoperative complications in the operating theater. We conducted a prospective, bicentric, observational study. Adult patients undergoing abdominal surgery were included. Stroke volume (SV) was determined before and after a fluid challenge with 250 mL crystalloids (Delta-SV) using esophageal Doppler monitoring. Responders were defined by an increase of Delta-SV > 10% after fluid challenge. B-lines were collected at four bilateral predefined zones (right and left anterior and lateral). Delta-B-line was defined as the number of newly appearing B-lines after a fluid challenge. Postoperative pulmonary complications were prospectively recorded according to European guidelines. In total, 197 patients were analyzed. After a first fluid challenge, 67% of patients were responders and 33% were non-responders. Delta-B-line was significantly higher in non-responders than responders [4 (2–7) vs 1 (0–3), p < 0.0001]. Delta-B-line was able to diagnose fluid non-responders with an area under the curve of 0.74 (95% CI 0.67–0.80, p < 0.0001). The best threshold was two B-lines with a sensitivity of 80% and a specificity of 57%. The final Delta-B-line could predict postoperative pulmonary complications with an area under the curve of 0.74 (95% CI 0.67–0.80, p = 0.0004). Delta-B-line of two or more detected in four lung ultrasound zones can be considered to be a marker of preload unresponsiveness after a fluid challenge in abdominal surgery.

The objectives and procedures of the study were registered at Clinicaltrials.gov (NCT03502460; Principal investigator: Stéphane BAR, date of registration: April 18, 2018).

Protocol of a pilot-scale, single-arm, observational study to assess the utility and acceptability of a wearable hydration monitor in haemodialysis patients

Background

Fluid overload has a high prevalence in haemodialysis patients and is an important risk factor for excess mortality and hospitalisations. Despite the risks associated with chronic fluid overload, it is clinically difficult to assess and maintain fluid status adequately. Current methods of fluid status assessment are either imprecise or time intensive. In particular, to date, no method exists to accurately assess fluid status during the interdialytic interval.

Objectives

This pilot study aimed to evaluate whether a prototype wearable hydration monitor can accurately and reproducibly detect fluid overload in the haemodialysis population when compared to haemodialysis and bioimpedance data.

Methods

A prospective, open-label, single-arm observational trial of 20 patients commenced in January 2021 in a single haemodialysis centre in Ireland, with a wearable hydration monitor, the Sixty device. The Sixty device uses diffuse reflectance spectroscopy to measure fluid levels at the level of the subdermis and uses machine learning to develop an algorithm that can determine fluid status. The Sixty device was worn at every dialysis session and nocturnally over a three-week observational period. Haemodialysis parameters including interdialytic weight gain, ultrafiltration volume, blood pressure, and relative blood volume were collected from each session, and bioimpedance measurements using the Fresenius body composition monitor were performed on 4 occasions as a comparator. The primary objective of this trial was to determine the accuracy and reproducibility of the Sixty device compared to bioimpedance measurements.

Conclusion

If the accuracy of the wearable hydration monitor is validated, further studies will be conducted to integrate the device output into a multi-parameter machine learning algorithm that can provide patients with actionable insights to manage fluid overload in the interdialytic period.

Trial registration

www.clinicaltrials.govNCT04623281. Registered November 10th, 2020.

Increased Right Ventricular Pressure as a Predictor of Acute Decompensated Heart Failure in End-Stage Renal Disease Patients on Maintenance Hemodialysis

Background and Objectives

Many patients with end-stage renal disease (ESRD) on hemodialysis (HD) have reduced vascular compliance and are likely to develop heart failure (HF). This study aimed to determine the factors associated with acute decompensation events among ESRD patients undergoing HD.

Methods

We retrospectively investigated ESRD patients on HD using a medical record review. We divided the patients into those admitted to hospital due to acute decompensated heart failure (ADHF) and those who were not. We compared the medical histories, electrocardiograms, and echocardiographic and laboratory data between the two groups.

Results

Of the 188 ESRD patients on HD, 87 were excluded, and 101 were enrolled (mean age: 63.7 years; 52.1% male). Thirty patients (29.7%) were admitted due to ADHF. These patients exhibited similar left ventricular ejection fraction (LVEF), left ventricular (LV) mass index, and E/E′ values compared to the non-ADHF group. However, the ADHF group exhibited significantly higher tricuspid regurgitation (TR) jet velocity (2.9±0.6 vs. 2.5±0.4 m/s; p=0.004) and right ventricular systolic pressure (RVSP) (43.5±17.2 vs. 34.2±9.9 mmHg; p=0.009) than the non-ADHF group, respectively. A multivariate logistic regression analysis demonstrated that the TR jet velocity (odds ratio, 8.356; 95% confidence interval, 1.806–38.658; p=0.007) was an independent predictor of ADHF after adjusting for age and sex, while the LVEF and E/E′ were not.

Conclusions

Our data showed that an increased TR jet velocity was an independent predictor of ADHF events in ESRD patients on HD, but the LVEF and E/E′ were not.

Lung ultrasound guided dry-weight reduction and echocardiographic changes in clinically euvolemic hypertensive hemodialysis patients: 12-month results of a randomized controlled trial

BACKGROUND

Left ventricular hypertrophy (LVH) and dysfunction are highly prevalent in hemodialysis patients and independently associated with adverse outcomes. This study examines the long-term effects of dry-weight reduction with a standardized lung-ultrasound (US)-guided strategy on echocardiographic indexes of left ventricular (LV) mass and function in hemodialysis patients.

METHODS

Seventy-one clinically euvolemic, hemodialysis patients with hypertension were randomized to dry-weight reduction guided by pre-hemodialysis lung US (n=35) or standard-of-care treatment (n=36) and were followed-up for 12 months. Two-dimensional and tissue-Doppler echocardiography (TDI) were performed at baseline and study-end.

RESULTS

During follow-up, dry-weight reduction took place in more patients in the active than in the control arm of the trial (71.4% vs 22.2%; p<0.001). Left atrial (LA) surface (-1.37±4.50 vs 1.28±5.00 cm²; P=0.006) and LA volume index (-3.22±11.82 vs 4.76±12.83 ml/m²; P=0.009) decreased in the active and increased in the control group. LV end-diastolic volume (-0.94±11.45 vs 6.58±13.92 ml/m²; P=0.015) decreased only in the active group. LV mass index was unchanged in the active (134.21±44.75 vs 133.57±45.51; P=0.844) and marginally increased in the control group (134.21±40.96 vs 143.77±50.04 g/m²; P=0.089). LV E/e' wave ratio was unchanged in the active (12.45±4.69 vs 12.56±4.89; P=0.521) and increased in the usual-care group (10.91±4.97 vs12.36±6.43; P=0.003). LV systolic function did not differ among the two study arms across the trial.

CONCLUSIONS

Over 12 months, lung-US-guided dry-weight reduction is associated with reverse LV and LA remodeling, myocardial hypertrophy regression and improved LV diastolic filling properties.

Peritoneal-Membrane Characteristics and Hypervolemia Management in Peritoneal Dialysis: A Randomized Control Trial

Excessive bodily-fluid retention is the major cause of hypertension and congestive heart failure in patients with end-stage renal disease. Compared to hemodialysis, peritoneal dialysis (PD) uses the abdominal peritoneum as a semipermeable dialysis membrane, providing continuous therapy as natural kidneys, and having fewer hemodynamic changes. One major challenge of PD treatment is to determine the dry weight, especially considering that the speed of small solutes and fluid across the peritoneal membrane varies among individuals; considerable between-patient variability is expected in both solute transportation and ultrafiltration capacity. This study explores the influence of peritoneal-membrane characteristics in the hydration status in patients on PD. A randomized control trial compares the bioimpedance-assessed dry weight with clinical judgment alone. A high peritoneal membrane D/P ratio was associated with the extracellular/total body water ratio, dialysate protein loss, and poor nutritional status in patients on PD. After a six-month intervention, patients with monthly bioimpedance analysis (BIA) assistance had better fluid (−1.2 ± 0.4 vs. 0.1 ± 0.4 kg, p = 0.014) and blood-pressure (124.7 ± 2.7 vs. 136.8 ± 2.8 mmHg, p < 0.001) control; however, hydration status and blood pressure returned to the baseline after we prolonged BIA assistance to a 3-month interval. The dry-weight reduction process had no negative effect on residual renal function or peritoneal-membrane function. We concluded that peritoneal-membrane characteristics affect fluid and nutritional status in patients on PD, and BIA is a helpful objective technique for fluid assessment for PD.

Cardiac geometry, function, and remodeling patterns in patients under maintenance hemodialysis and peritoneal dialysis treatment

Cardiovascular disease is the leading cause of mortality in patients with end-stage-kidney disease. Evidence on the possible echocardiographic differences between hemodialysis and peritoneal dialysis (PD) is scarce. This study aimed to evaluate differences in left (LA) and right atrial (RA), left (LV) and right ventricular (RV) geometry, systolic and diastolic function in hemodialysis, and PD patients. Thirty-eight hemodialysis and 38 PD patients were matched for age, sex, and dialysis vintage. Two-dimensional and tissue-Doppler echocardiography, and lung ultrasound were performed during an interdialytic day in hemodialysis and before a programmed follow-up visit in PD patients. Vena cava diameter (11.09 ± 4.53 vs. 14.91 ± 4.30 mm; p < 0.001) was significantly lower in hemodialysis patients. Indices of LA, RA, LV, and RV dimensions were similar between the two groups. LVMi (116.91 [38.56] vs. 122.83 [52.33] g/m² ; p = 0.767) was similar, but relative wall thickness was marginally (0.40 [0.14] vs. 0.45 [0.15] cm; p = 0.055) lower in hemodialysis patients. LV hypertrophy prevalence was similar between groups (73.7% vs. 71.1%; p = 0.798), but hemodialysis patients presented eccentric and PD patients concentric LVH. Regarding ventricular systolic function, stroke volume (p = 0.030) and cardiac output (p = 0.036) were higher in hemodialysis, while RV systolic pressure (RVSP) (20.37 [22.54] vs. 27.68 [14.32] mm Hg; p = 0.009) was higher in PD. No significant differences were evidenced in diastolic function indices and lung water excess between the two groups. A moderate association was noted between ultrasound B-lines score and LA volume index (r = 0.465, p < 0.001), RVSP (r = 0.431, p < 0.001), and E/e' ratio (r = 0.304, p = 0.009). Hemodialysis and PD patients present largely similar echocardiographic indices reflecting cardiac geometry, systolic, and diastolic function, but different patterns of abnormal LV remodeling.

POCUS for Nephrologists: Basic Principles and a General Approach

Point-of-care ultrasonography (POCUS) has evolved as a valuable adjunct to physical examination in the recent past and various medical specialties have embraced it. However, POCUS training and scope of practice remain relatively undefined in nephrology. The utility of diagnostic POCUS beyond kidney and vascular access is under-recognized. Assessment of fluid status is a frequent dilemma faced by nephrologists in day-to-day practice where multiorgan POCUS can enhance the sensitivity of conventional physical examination. POCUS also reduces fragmentation of care, facilitates timely diagnosis, and expedites management. Although the need for further imaging studies is obviated in selected patients, POCUS is not meant to serve as an alternative to consultative imaging. In addition, the utility of POCUS depends on the skills and experience of the operator, which in turn depend on the quality of training. In this review, we discuss the rationale behind nephrologists performing POCUS, discuss patient examples to illustrate the basic principles of focused ultrasonography, and share our experience-based opinion about developing a POCUS training program at the institutional level.

Ambulatory blood pressure changes with lung ultrasound-guided dry-weight reduction in hypertensive hemodialysis patients: 12-month results of a randomized controlled trial

OBJECTIVES

Hypertension is highly prevalent and independently associated with adverse outcomes in patients undergoing hemodialysis. Volume overload is the main mechanism of increased blood pressure (BP) in these individuals. This study examines the long-term effects of dry-weight reduction with a standardized lung-ultrasound (US)-guided strategy on ambulatory BP in hypertensive hemodialysis patients.

METHODS

This is the report of the 12-month follow-up of a randomized controlled trial in 71 clinically euvolemic, hemodialysis patients with hypertension. Patients were randomized to dry-weight reduction guided by prehemodialysis lung ultrasound and to standard care. A 48-h ambulatory BP monitoring (ABPM) was performed in all study participants at baseline and after 12 months.

RESULTS

During follow-up, a greater proportion of patients in the active group underwent dry-weight reduction compared with the control group (71.4% vs. 22.2%; P < 0.001). The number of lung US-B lines (a metric of lung water) reduced in the active (-4.83 ± 13.73) and increased in the control arm (+5.53 ± 16.01; P = 0.005) paralleling dry-weight changes (-1.68 ± 2.38 vs. 0.54 ± 2.32 kg; P < 0.001). At 12 months, 48-h systolic BP (136.19 ± 14.78 vs. 130.31 ± 13.57 mmHg; P = 0.034) and diastolic BP (80.72 ± 9.83 vs. 76.82 ± 8.97 mmHg; P = 0.008) were lower compared to baseline in the active but similar in the control group. Changes in 48-h systolic BP (-7.78 ± 13.29 vs. -0.10 ± 14.75 mmHg; P = 0.021) were significantly greater in the active compared to the control group. The proportion of patients experiencing ≥1 episode of intradialytic hypotension was nominally lower in the active group (71.4% vs. 88.9%, P = 0.065).

CONCLUSIONS

Lung-US-guided dry-weight reduction can effectively and safely decrease ambulatory BP levels in the long-term.

Assessment and Management of Volume Overload Among Patients on Chronic Dialysis

Volume overload is the most common complication in end-stage renal disease (ESRD) patients, being directly related to numerous complications including resistant hypertension, cardiac hypertrophy, congestive heart failure or arterial stiffness, among others. Therefore, volume overload is now considered an important risk factor for hard outcomes, like all-cause or cardiovascular mortality. Relying solely on clinical examination for assessing volume overload in ESRD patients lacks sensitivity and specificity. Numerous efforts have been made to identify new methods that could objectively assess volume status; however, each of them has important limitations. This review aims to discuss the most frequently used methods (biomarkers, inferior vena cava assessment, lung ultrasonography, bioimpedance analysis and blood volume monitoring) and to compare the advantage of each method vs. the overall/ clinical strategy.

Lung Ultrasound to Diagnose Pulmonary Congestion Among Patients on Hemodialysis: Comparison of Full Versus Abbreviated Scanning Protocols

RATIONALE & OBJECTIVE

Pulmonary congestion contributes to morbidity and mortality in patients with kidney failure on hemodialysis, but physical assessment is an insensitive approach to its detection. Lung ultrasound is useful for assessing the presence and severity of pulmonary congestion, but the most widely validated 28-zone study is cumbersome. We sought to compare abbreviated 4-, 6-, and 8-zone studies to 28-zone studies.

STUDY DESIGN

Diagnostic test study.

SETTING & PARTICIPANTS

Convenience sample of 98 patients with kidney failure on hemodialysis presenting to an emergency department in the United States.

TESTS COMPARED

4-, 6-, and 8-zone lung ultrasound studies versus a 28-zone lung ultrasound.

OUTCOME

Prediction of pulmonary congestion and 30-day mortality.

RESULTS

All patients completed a 28-zone lung ultrasound. Correlation coefficients (nonparametric Spearman) between each of the studies were high (all values > 0.84). Bland-Altman analysis showed good agreement. Each of the short-form studies discriminated well with area under the receiver-operator characteristic curve > 0.83 for no-to-mild versus moderate-to-severe pulmonary congestion. During a median follow-up period of 778 days, 46 (47%) died. Patients with moderate-to-severe pulmonary congestion on lung ultrasound had a 30-day mortality rate similar to that observed among patients with no-to-mild pulmonary congestion (OR, 0.95 [95% CI, 0.70-1.29]).

LIMITATIONS

Single-center study conducted in an emergency care setting, convenience sample of patients, and lack of long-term follow-up data.

CONCLUSIONS

Among hemodialysis patients presenting to an emergency department, 4-, 6-, or 8-zone lung ultrasounds were comparable to 28-zone studies for the assessment of pulmonary congestion. The mortality rates did not differ between those with no-to-mild and moderate-to-severe pulmonary congestion.

An Introduction to Point-of-Care Ultrasound: Laennec to Lichtenstein

Point-of-care ultrasonography (POCUS) is rapidly evolving as a noninvasive adjunct to physical examination among various specialties. POCUS increases the sensitivity of conventional physical examination by providing the answers to simple clinical questions at the bedside. As such, it can reduce fragmentation of care and expedite management. In addition, using bedside ultrasound as the first-line investigation may eliminate unnecessary radiation and contrast exposure. The advent of highly portable and affordable ultrasound devices has made the use of POCUS more practical and user-friendly, making it the stethoscope of the 21st century. This review will provide an overview of the rationale for integrating POCUS into nephrology practice. We also discuss the current scope of POCUS practice and state of training.

Lung Ultrasound: A "Biomarker" for Fluid Overload?

Fluid overload is associated with poor outcomes in patients with acute kidney injury as well as end-stage kidney disease. Lung ultrasound (LUS) has been used in many different settings and specialties including the emergency department, intensive care unit, trauma, cardiology, and nephrology. Although LUS has been a valuable tool in assessing pulmonary congestion, LUS findings may not always be pathognomonic for pulmonary congestion. Furthermore, the feasibility of doing an extensive LUS examination as has been done in research studies may be hard to implement within the clinical setting. This review will go over the use of LUS to evaluate for fluid overload, compare LUS with other markers of fluid overload, review limitations of LUS, and suggest potential future directions in the use of LUS in nephrology.

Effects of Lung Ultrasonography-Guided Management on Cumulative Fluid Balance and Other Clinical Outcomes: A Systematic Review

Lung ultrasonography is accurate in detecting pulmonary edema and overcomes most limitations of traditional diagnostic modalities. Whether use of lung ultrasonography-guided management has an effect on cumulative fluid balances and other clinical outcomes remains unclear. In this systematic review, we included 12 studies using ultrasonography guided-management with a total of 2290 patients. Four in-patient studies found a reduced cumulative fluid balance (ranging from -0.3 L to -2.4 L), whereas three out-patient studies found reduction in dialysis dry weight (ranging from -2.6 kg to -0.2 kg) compared with conventionally managed patients. None of the studies found adverse effects related to hypoperfusion. The use of lung ultrasonography-guided management was not associated with other clinical outcomes. This systematic review shows that lung ultrasonography-guided management, exclusively or in concert with other diagnostic modalities, is associated with a reduced cumulative fluid balance. Studies thus far have not shown a consistent effect on clinical outcomes.

Volume overload in hemodialysis: diagnosis, cardiovascular consequences, and management

Volume overload in haemodialysis (HD) patients associates with hypertension and cardiac dysfunction and is a major risk factor for all-cause and cardiovascular mortality in this population. The diagnosis of volume excess and estimation of dry weight is based largely on clinical criteria and has a notoriously poor diagnostic accuracy. The search for accurate and objective methods to evaluate dry weight and to diagnose subclinical volume overload has been intensively pursued over the last 3 decades. Most methods have not been tested in appropriate clinical trials and their usefulness in clinical practice remains uncertain, except for bioimpedance spectroscopy and lung ultrasound (US). Bioimpedance spectroscopy is possibly the most widely used method to subjectively quantify fluid distributions over body compartments and produces reliable and reproducible results. Lung US provides reliable estimates of extravascular water in the lung, a critical parameter of the central circulation that in large part reflects the left ventricular end-diastolic pressure. To maximize cardiovascular tolerance, fluid removal in volume-expanded HD patients should be gradual and distributed over a sufficiently long time window. This review summarizes current knowledge about the diagnosis, prognosis and treatment of volume overload in HD patients.

Management of extracellular volume in patients with end-stage kidney disease and severe hyperglycemia

This commentary addresses volume replacement in hyperglycemic crises in patients with end-stage kidney disease (ESKD). The management of volume issues in this group of patients should not be based on guidelines for management of hyperglycemic crises, but should be individualized and based on directed patient medical history, physical examination, and imaging of the heart and lungs. A scheme for combining information from these three sources is provided.

Assessment of Hydration Status in Peritoneal Dialysis Patients: Validity, Prognostic Value, Strengths, and Limitations of Available Techniques

BACKGROUND

The majority of patients undergoing peritoneal dialysis (PD) suffer from volume overload and this overhydration is associated with increased mortality. Thus, optimal assessment of volume status in PD is an issue of paramount importance. Patient symptoms and physical signs are often unreliable indexes of true hydration status.

SUMMARY

Over the past decades, a quest for a valid, reproducible, and easily applicable technique to assess hydration status is taking place. Among existing techniques, inferior vena cava diameter measurements with echocardiography and natriuretic peptides such as brain natriuretic peptide and N-terminal pro-B-type natriuretic peptide were not extensively examined in PD populations; while having certain advantages, their interpretation are complicated by the underlying cardiac status and are not widely available. Bioelectrical impedance analysis (BIA) techniques are the most studied tool assessing volume overload in PD. Volume overload assessed with BIA has been associated with technique failure and increased mortality in observational studies, but the results of randomized trials on the value of BIA-based strategies to improve volume-related outcomes are contradictory. Lung ultrasound (US) is a recent technique with the ability to identify volume excess in the critical lung area. Preliminary evidence in PD showed that B-lines from lung US correlate with echocardiographic parameters but not with BIA measurements. This review presents the methods currently used to assess fluid status in PD patients and discusses existing data on their validity, applicability, limitations, and associations with intermediate and hard outcomes in this population. Key Message: No method has proved its value as an intervening tool affecting cardiovascular events, technique, and overall survival in PD patients. As BIA and lung US estimate fluid overload in different compartments of the body, they can be complementary tools for volume status assessment.

Lung Ultrasound-Guided Dry-Weight Reduction in Hemodialysis Patients Does Not Affect Short-Term Blood Pressure Variability

BACKGROUND

Increased short-term blood pressure (BP) variability (BPV) in hemodialysis is associated with increased cardiovascular and all-cause mortality. Studies on the impact of BP-lowering interventions on BPV are scarce. This study examined the effect of dry-weight reduction with a lung ultrasound-guided strategy on short-term BPV in hemodialysis patients with hypertension.

METHODS

This is a prespecified analysis of a randomized clinical trial in 71 hemodialysis patients with hypertension, assigned in a 1:1 ratio in the active group, following a strategy for dry-weight reduction guided by pre-hemodialysis lung ultrasound and the control group following standard-of-care treatment. All patients underwent 48-hour ambulatory BP monitoring at baseline and after 8 weeks. BPV was calculated with validated formulas for the 48-hour interval and the 2 daytime and nighttime periods.

RESULTS

Dry-weight changes were -0.71 ± 1.39 in active vs. +0.51 ± 0.98 kg in the control group (P < 0.001), generating a between-group difference of 5.9/3.5 mm Hg (P < 0.05) in 48-hour BP at study end. All brachial BPV indices [SD, weighted SD, coefficient of variation, and average real variability (ARV)] did not change significantly from baseline to study end in the active [systolic blood pressure (SBP)-ARV: 12.58 ± 3.37 vs. 11.91 ± 3.13, P = 0.117; diastolic blood pressure (DBP)-ARV: 9.14 ± 1.47 vs. 8.80 ± 1.96, P = 0.190] or control (SBP-ARV: 11.33 ± 2.76 vs. 11.07 ± 2.51, P = 0.544; DBP-ARV: 8.38 ± 1.50 vs. 8.15 ± 1.49, P = 0.295) group (between-group comparison P = 0.211/0.117). Aortic BPV indices followed a similar pattern. Likewise, no significant changes in BPV indices for the daytime and nighttime periods were noted in both groups during follow-up.

CONCLUSIONS

This study is the first to evaluate the effects of a nonpharmacological intervention on short-term BPV in hemodialysis, showing no effect of dry-weight reduction on BPV, despite BP decrease.