Pulmonary Hypertension in Various Stages of Chronic Kidney Disease in Indian Patients

Chronic kidney disease and pulmonary hypertension: Progress in diagnosis and treatment

Pulmonary hypertension (PH) is a medical condition characterized by elevated pulmonary vascular resistance and pressure, resulting from different diseases. Due to their high occurrence of PH, intricate hemodynamic classification, and frequently multifactorial cause and mechanism, individuals suffering from chronic kidney disease (CKD) are categorized as the fifth primary group of PH. Based on both domestic and international research, this article provides information on the epidemiology, risk factors, pathogenesis, and targeted drug treatment of PH associated with CKD.

The impact of vascular access location on pulmonary arterial pressure in chronic kidney disease patients undergoing hemodialysis

BACKGROUND AND AIM

It is feared that among chronic kidney disease patients undergoing hemodialysis, arteriovenous fistula (AVF) itself could contribute to pulmonary hypertension (PH). The impact of AVF location on PH is yet to be assessed. We hypothesize that patients with proximal AVF have higher access blood flow and hence higher pulmonary arterial systolic pressure (PASP) than those with distal AVF. We aimed to compare the PASP between patients with proximal and distal AVF.

METHODS

In this cross-sectional study, PASP was estimated using Doppler echocardiography and blood flow in the AVF was assessed by Doppler ultrasound. PASP was modeled by multivariate linear regression. AVF location was the primary exposure of interest.

RESULTS

Out of 89 patients undergoing hemodialysis, 72 (81%) had PH defined as PASP >35 mmHg. The mean blood flow in proximal and distal AVF was, respectively, 1240 and 783 mL/min (mean difference 457 mL/min, p < 0.001). Mean PASP in patients with proximal AVF was 16.6 mmHg higher than those with distal AVF (p < 0.001, 95% CI 8.3-24.9). There was a positive correlation between access blood flow and PASP (r = 0.28, p = 0.007). If access blood flow was included as a covariate in the multivariate model, the association between AVF location and PASP ceased to exist.

CONCLUSION

Patients with proximal AVF have a significantly higher PASP than those with distal AVF, and this could be attributed to the higher blood flow in proximal AVF compared to distal AVF.

Pulmonary Manifestations at Different Stages in the Chronic Kidney Disease: An Observational Study

INTRODUCTION

By a variety of pathogenic pathways, kidney diseases can have a direct negative impact on the lungs and worsen the prognosis for those with chronic renal disease. Chronic kidney disease (CKD) is a public health concern throughout the world. The relationship between the kidneys and lungs is crucial for maintaining acid-base balance, fluid homeostasis, and blood pressure control. These patients have a higher prevalence of lung dysfunction regardless of the disease's stage, including sleep apnea syndrome, pulmonary hypertension, and chronic obstructive pulmonary disease (COPD). The chance of getting a pulmonary consequence increases with the severity of kidney disease. In individuals with chronic renal disease, this study looked at the prevalence of several respiratory disorders.

MATERIALS AND METHODS

From February 2021 to October 2021, 70 CKD patients who were receiving care at the Saveetha Medical College and Hospital were taken into consideration for the study. Clinical assessment and pertinent tests, such as a pulmonary function test, chest radiography, CT chest, sputum analysis, and pleural fluid analysis were performed. To evaluate left ventricular function, echocardiography was performed. Selected patients underwent polysomnography.

RESULTS

The study's population had a mean age of 50 years. There was a 20:50 sex ratio (M:F). Seventy percent of them had respiratory conditions, the most frequent of which was pleural effusion (70%), followed by pulmonary edema (52%). The pleural effusion was primarily transudative and right sided. Both tuberculous pleural effusion and pulmonary tuberculosis were detected in 2% of the population. Seven percent of them developed pneumonia. 10% of patients had thickening of the pleura. Using chest CT and x-ray, 3% of patients had pulmonary calcification visible. In 12 (60%) out of the 20 patients who were studied, sleep apnea was observed. Two patients with tuberculosis and pneumonia lacked the typical signs.

CONCLUSIONS

In our research study, CKD patients have a much higher preponderance of respiratory illnesses, which has negative effects on patient care.

Risk Factors of Pulmonary Hypertension in Patients on Hemodialysis: A Single Center Study

Introduction

Pulmonary hypertension (PH) is an underestimated cardiovascular consequence and a mortality predictor in patients on hemodialysis (HD). Thus, we studied its prevalence, risk factors, association with inflammation/oxidative stress, and cardiac changes in HD patients.

Methods

This was a single-center cross-sectional observational study conducted at a tertiary care hospital. Patients aged >18 years on hemodialysis for at least three months were included and divided into those with and without PH; patients with secondary causes for PH were excluded. Clinical characteristics, HD-related factors, lab parameters (C-reactive protein and malondialdehyde with thiol assay were used as markers of inflammation and oxidative stress, respectively), and echocardiography details were compared. PH was defined as a mean pulmonary artery pressure of >25 mmHg at rest, and it was further divided as mild (25–40 mmHg), moderate (40–60 mmHg), and severe (>60 mmHg).

Results

Of 52 patients, 28 patients had PH (mild 24, moderate 4, and none had severe PH) with prevalence of 54%. No difference was found in clinical characteristics, dialysis-related factors, biochemical parameters including inflammation (C-reactive protein; p=0.76), or oxidative stress (thiol; p=0.36 and MDA; p=0.46) between the groups. When compared to individuals without PH, HD patients with PH exhibited significantly more mitral regurgitation (p=0.002).

Conclusion

Hemodialysis patients have a high prevalence of PH. PH was significantly associated with the presence of mitral regurgitation on echocardiography. Our study did not find differences in traditional risk factors, HD-related factors, and inflammation/oxidative markers between the groups with and without PH.

Novel Prognostic Predictor for Primary Pulmonary Hypertension: Focus on Blood Urea Nitrogen

Background: Primary pulmonary hypertension (PPH) is a life-threatening disease associated with increased mortality. The urea cycle pathway plays a major role in PPH severity and treatment response. Little is known about the association of the blood urea nitrogen (BUN) and PPH prognosis.

Methods: Clinical data were extracted from the Medical Information Mart for Intensive Care III (MIMIC-III) database. Adult patients (≥18 years) patients with primary pulmonary hypertension (PPH) in the database were enrolled. Spearman correlation was used to analyze the association of BUN with length of hospital and intensive care unit (ICU) stays. The chi-square test was used to analyze the association of BUN with mortality rate. Survival curves were estimated using the Kaplan-Meier method and compared by the log-rank test. Multivariable logistic regression was used to identify the BUN as an independent prognostic factor of mortality. Receiver operating characteristic (ROC) curves and the area under the curve (AUC) were used to analyze the sensitivity and specificity for mortality.

Results: In total, 263 patients who met the selection criteria were enrolled. BUN was significantly positively associated with length of hospital stay and ICU stay (hospital stay: ρ = 0.282, ICU stay: ρ = 0.276; all P < 0.001). Higher hospital, 90-day and 4-year mortality rates were observed in the higher BUN quartile of PPH patients (hospital: P = 0.002; 90-day: P = 0.025; 4-year: P < 0.001). The Kaplan-Meier survival curves showed that patients in higher BUN quartile tended to have lower 4-year survival (Q1:7.65%, Q2: 10.71%; Q3: 14.80%, Q4: 16.84%; P < 0.0001). Logistic regression analyses found a significant association of BUN and mortality (hospital: OR = 1.05, 95% CI = 1.02–1.08, P = 0.001; 90-day: OR = 1.02, 95% CI = 1.00–1.05, P = 0.027; 4-year: OR = 1.05, 95% CI = 1.02–1.08, P = 0.001). Results of ROC and AUC showed that the diagnostic performance of BUN for mortality was moderately good.

Conclusion: BUN was positively correlated with the length of hospital stay and ICU stay of PPH patients. Higher BUN was associated with higher hospital, 90-day and 4-year mortality and lower 4-year survival of PPH patients. These findings indicate that BUN can be a novel potential prognostic predictor for PPH.

Association of Pulmonary Hypertension With Inflammatory Markers and Volume Status in Hemodialysis Patients of End-Stage Renal Disease

Background and objectives

Pulmonary hypertension (PH) is an independent risk factor for increased mortality, especially in patients undergoing hemodialysis (HD), but the mechanism of its development is unknown. This study aimed at evaluating volume overload and inflammation as potential variables to cause its development in patients undergoing maintenance hemodialysis.

Materials and methods

This was an observational cross-sectional study conducted on patients undergoing hemodialysis at a tertiary hospital in northern India. Patients of end-stage renal disease, aged 18 years or more, on maintenance hemodialysis for over two months were included in the study. The patients were divided into two groups based on the presence or absence of PH, determined by measuring systolic pulmonary arterial pressure (SPAP). The severity of PH was defined as: mild (SPAP 35-45 mmHg), moderate (SPAP 46-55 mmHg), and severe (SPAP> 55mmHg). The two groups were evaluated for demographic variables, type of vascular access, biochemical parameters, and markers of inflammation and fluid overload. Data between the two groups were compared statistically.

Results

This study included a total of 82 patients showing the prevalence of PH to be 25.6% with a men-to-women ratio of 2:1. Out of 21 cases of PH, mild PH was found in seven (33.3%) cases, moderate in 14 (66.7%), and cases with severe PH were none. The two groups differed significantly in ejection fraction and markers of inflammation and volume status. Laboratory data associated with PH were alpha-1-acid glycoprotein (p<0.05) and pro-b-type natriuretic peptide (p <0.05).

Conclusion

The present study showed higher levels of inflammatory markers alpha-1-acid glycoprotein and pro-b-type natriuretic peptide and lower levels of ejection fraction in patients undergoing HD, indicating a significant association with PH.

Clinical impact of pre-kidney transplant pulmonary hypertension on post-transplant outcomes

Outcomes of kidney transplant (KT) patients with pre-transplant pulmonary hypertension (PH) are poorly understood. PH patients are often considered high risk and excluded from KT. We investigated the association of pre-transplant PH with KT recipient's outcomes. A single-center, retrospective study that reviewed all patients transplanted from 2010 to 2016, who had a transthoracic echocardiogram (TTE) before KT and at least one TTE post-KT. The TTE closest to the KT was used for analyses. PH is defined as pulmonary artery systolic pressure (PASP) ≥ 40 mm Hg. Of 204 patients, 61 had PASP ≥ 40 mm Hg (with PH) and 143 had PASP < 40 mm Hg (without PH) prior to KT. No statistically significant differences existed between the two groups in baseline demographics, renal failure etiologies, dialysis access type, and cardiovascular risk factors. The mean difference in pre-KT PASP was 18.1 ± 7 mm Hg (P < 0.001). Patients with PH had a statistically significant decrease in PASP post-KT compared to the patients without PH with a mean change of -7.03 ± 12.28 mm Hg vs. + 3.96 ± 11.98 mm Hg (p < 0.001), respectively. Moderate mitral and moderate-severe tricuspid regurgitation were the only factors found to be independently associated with PH (p = 0.001) on multivariable analysis. No statistically significant difference was notable in patient survival, graft function, and creatinine post-KT in both groups. PH pre-KT particularly mild-moderate PH did not adversely affect intermediate (90-day) and long-term allograft and patient survival. Patients with mild-moderate PH should not be excluded from KT.

The Prevalence of Pulmonary Hypertension Among Maintenance Dialysis Patients With ESRD and Its Associated Factors: A Retrospective Study

Aim: To determine the prevalence of pulmonary hypertension (PH) and its associated factors among end-stage renal disease (ESRD) patients who underwent maintenance dialysis. Methods: A total of 491 patients received echocardiography examinations and underwent pulmonary artery systolic pressure (PASP) assessments. A subgroup of 283 patients were subjected to plasma creatinine (Cr) and blood urea nitrogen concentration (BUN) tests, routine blood examinations and electrolyte analysis. First, we compared the differences in echocardiographic, Cr and BUN, blood routine and electrolyte parameters between PH and non-PH groups. The correlations between PASP and the parameters mentioned above were also analyzed. Furthermore, univariate and adjusted logistic regression analyses were performed to identify the independent associated factors. Results: The incidence of PH among ESRD patients who were treated with maintenance dialysis was 34.6%. Most of the echocardiographic parameters, including end-diastolic internal diameters of the left atrium, left ventricle, right atrium, and pulmonary artery, as well as interventricular septum mobility, left ventricular posterior wall mobility, fractional shortening, stroke volume and left ventricle ejection fraction (LVEF), were associated with PH. Furthermore, Mg²⁺ (p = 0.037) and Cl^- (p = 0.043) were significantly associated with PASP. However, after adjustments were made in the regression analysis, only internal diameters of the left atrium, right atrium, and LVEF were independently associated with PH. Conclusion: PH is prevalent, with a relatively high incidence among ESRD patients who undergo maintenance dialysis. The sizes of the left and right atria as well as LVEF were independently associated with PH, but further cohort and basic mechanistic studies are needed to confirm this finding.