Fluid overload, pulse wave velocity, and ratio of brachial pre-ejection period to ejection time in diabetic and non-diabetic chronic kidney disease

Inter- and intradialytic fluid volume changes and vascular stiffness parameters in patients on hemodialysis

Background

Whether fluid overload is associated with vascular stiffness parameters in hemodialysis (HD) patients has not been fully elucidated. We hypothesized that interdialytic fluid accumulation increases vascular stiffness parameters, which improves with intradialytic ultrafiltration.

Methods

Fluid overload and vascular stiffness parameters were assessed in 39 HD patients (20 with and 19 without fluid overload) and compared to 26 healthy controls. Fluid status was assessed 15 minutes before the mid-week HD session by bio-impedance spectroscopy. Following this, ambulatory pulse wave velocity (PWV) and augmentation index (AIx) were measured for 24 hours before another mid-week HD session and then for 5 hours starting 30 minutes before and ending 30 minutes after the session.

Results

HD patients had significant fluid overload compared to healthy controls (2.0±2.4 vs. -0.2±0.6 L; P<0.001) and baseline PWV was higher (10.3±1.7 vs. 8.8±1.4 m/s; P<0.001). There was no significant difference between PWV and AIx in fluid overloaded and non-fluid overloaded HD patients prior to, or during the HD session. AIx of non-fluid overloaded HD patients improved after the HD session (P = 0.04). Average 24-hour AIx was higher in fluid overloaded HD patients (P<0.001).

Conclusions

Inter- and intradialytic changes in fluid volume were only weakly related to vascular stiffness parameters in HD patients. Although there was a modest reduction in AIx in non-fluid overloaded HD patients after the dialysis session, fluid removal did not improve vascular stiffness parameters during the HD session. We speculate that the effect of fluid overload correction on vascular stiffness parameters requires long-term adjustments in the vasculature.

Extracellular fluid volume expansion, arterial stiffness and uncontrolled hypertension in patients with chronic kidney disease

BACKGROUND

Hypertension is prevalent in patients with chronic kidney disease (CKD) and is related to extracellular fluid volume (ECFV) expansion. Arterial stiffening is another implication of CKD that can be caused by ECFV expansion. In this study, we hypothesized that CKD patients with uncontrolled hypertension are more likely to be fluid volume expanded than normotensive patients, which in turn is associated with increased arterial stiffness.

METHODS

Adult hypertensive patients with mild-severe CKD (n = 82) were recruited. ECFV was assessed using multifrequency bioimpedance and arterial stiffness by applanation tonometry and oscillometry.

RESULTS

Patients with uncontrolled hypertension had fluid volume expansion compared with controls (1.0 ± 1.5 versus 0.0 ± 1.6 L, P < 0.001), and had a higher augmentation index (AIx) and pulse wave velocity. Fluid volume expansion was more prevalent in patients with uncontrolled hypertension (58%) than patients who were at target (27%). Fluid volume expansion was correlated with age, AIx and systolic blood pressure. In a binary logistic regression analysis, AIx, age and fluid volume status were independent predictors of uncontrolled hypertension in both univariate and multivariate models.

DISCUSSION

In summary, uncontrolled hypertension among hypertensive CKD patients is associated with ECFV expansion. Our data suggest a relationship between ECFV expansion, increased arterial stiffness and uncontrolled hypertension.

Effect of high-salt diet on blood pressure and body fluid composition in patients with type 1 diabetes: randomized controlled intervention trial

INTRODUCTION

Patients with type 1 diabetes are susceptible to hypertension, possibly resulting from increased salt sensitivity and accompanied changes in body fluid composition. We examined the effect of a high-salt diet (HSD) in type 1 diabetes on hemodynamics, including blood pressure (BP) and body fluid composition.

RESEARCH DESIGN AND METHODS

We studied eight male patients with type 1 diabetes and 12 matched healthy controls with normal BP, body mass index, and renal function. All subjects adhered to a low-salt diet and HSD for eight days in randomized order. On day 8 of each diet, extracellular fluid volume (ECFV) and plasma volume were calculated with the use of iohexol and 125I-albumin distribution. Hemodynamic measurements included BP, cardiac output (CO), and systemic vascular resistance.

RESULTS

After HSD, patients with type 1 diabetes showed a BP increase (mean arterial pressure: 85 (5) mm Hg vs 80 (3) mm Hg; p<0.05), while BP in controls did not rise (78 (5) mm Hg vs 78 (5) mm Hg). Plasma volume increased after HSD in patients with type 1 diabetes (p<0.05) and not in controls (p=0.23). There was no significant difference in ECFV between diets, while HSD significantly increased CO, heart rate (HR) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in type 1 diabetes but not in controls. There were no significant differences in systemic vascular resistance, although there was a trend towards an HSD-induced decrease in controls (p=0.09).

CONCLUSIONS

In the present study, patients with type 1 diabetes show a salt-sensitive BP rise to HSD, which is accompanied by significant increases in plasma volume, CO, HR, and NT-proBNP. Underlying mechanisms for these responses need further research in order to unravel the increased susceptibility to hypertension and cardiovascular disease in diabetes.

TRIAL REGISTRATION NUMBERS

NTR4095 and NTR4788.

Investigation of Acoustic Cardiographic Parameters before and after Hemodialysis

Patients with end-stage renal disease are at an increased risk of cardiovascular diseases and associated mortality. Acoustic cardiography is a technique in which cardiac acoustic data is synchronized with electric information to detect and characterize heart sounds and detect heart failure early. The aim of this study was to investigate acoustic cardiographic parameters before and after hemodialysis (HD) and their correlations with ankle-brachial index (ABI), brachial-ankle pulse wave velocity (baPWV), and ratio of brachial preejection period to ejection time (bPEP/bET) obtained from an ABI-form device in HD patients. This study enrolled 162 HD patients between October 2016 and April 2018. Demographic, medical, and laboratory data were collected. Acoustic cardiography was performed before and after HD to assess parameters including third heart sound (S3), fourth heart sound (S4), systolic dysfunction index (SDI), electromechanical activation time (EMAT), and left ventricular systolic time (LVST). The mean age of the enrolled patients was 60.4 ± 10.9 years, and 86 (53.1%) patients were male. S4 (p < 0.001) and LVST (p < 0.001) significantly decreased after HD, but EMAT (p < 0.001) increased. Multivariate forward linear regression analysis showed that EMAT/LVST before HD was negatively associated with albumin (unstandardized coefficient β = ‐0.076; p = 0.004) and ABI (unstandardized coefficient β = ‐0.115; p = 0.011) and positively associated with bPEP/bET (unstandardized coefficient β = 0.278; p = 0.003). Screening HD patients with acoustic cardiography may help to identify patients at a high risk of malnutrition, peripheral artery disease, and left ventricular systolic dysfunction.

Increased Aortic Arch Calcification and Cardiomegaly is Associated with Rapid Renal Progression and Increased Cardiovascular Mortality in Chronic Kidney Disease

Vascular calcification and cardiomegaly are highly prevalent in chronic kidney disease (CKD) patients. However, the association of the combination of aortic arch calcification (AoAC) and cardio-thoracic ratio (CTR) with clinical outcomes in patients with CKD is not well investigated. This study investigated whether the combination of AoAC and CTR is associated with poor clinical outcomes in CKD stages 3–5 patients. We enrolled 568 CKD patients, and AoAC and CTR were determined by chest radiography at enrollment. Rapid renal progression was defined as estimated glomerular filtration rate (eGFR) decline over 3 ml/min/1.73 m² per year. Both AoAC score and CTR were significantly associated with rapid renal progression. High CTR was correlated with increased risk for cardiovascular mortality. We stratified the patients into four groups according to the median AoAC score of 4 and CTR of 50%. Those with AoAC ≥ 4 and CTR ≥ 50% (vs. AoAC score < 4 and CTR < 50%) were associated with eGFR decline over 3 ml/min/1.73 m²/year and cardiovascular mortality. AoAC and CTR were independently associated with eGFR slope. In conclusion, the combination of increased AoAC and cardiomegaly was associated with rapid renal progression and increased cardiovascular mortality in patients with CKD stage 3–5 patients. We suggest that evaluating AoAC and CTR on chest plain radiography may be a simple and inexpensive method for detecting CKD patients at high risk for adverse clinical outcomes.

Small intra-individual variability of the pre-ejection period justifies the use of pulse transit time as approximation of the vascular transit

Background

Vascular transit time (VTT) is the propagation time of a pulse wave through an artery; it is a measure for arterial stiffness. Because reliable non-invasive VTT measurements are difficult, as an alternative we measure pulse transit time (PTT). PTT is defined as the time between the R-wave on electrocardiogram and arrival of the resulting pulse wave in a distal location measured with photoplethysmography (PPG). The time between electrical activation of the ventricles and the resulting pulse wave after opening of the aortic valve is called the pre-ejection period (PEP), a component of PTT. The aim of this study was to estimate the variability of PEP at rest, to establish how accurate PTT is as approximation of VTT.

Methods

PTT was measured and PEP was assessed with echocardiography (gold standard) in three groups of 20 volunteers: 1) a control group without cardiovascular disease aged <50 years and 2) aged >50 years, and 3) a group with cardiovascular risk factors, defined as arterial hypertension, dyslipidemia, kidney failure and diabetes mellitus.

Results

Per group, the mean PEP was: 1) 58.5 ± 13.0 ms, 2) 52.4 ± 11.9 ms, and 3) 57.6 ± 11.6 ms. However, per individual the standard deviation was much smaller, i.e. 1) 2.0–5.9 ms, 2) 2.8–5.1 ms, and 3) 1.6–12.0 ms, respectively. There was no significant difference in the mean PEP of the 3 groups (p = 0.236).

Conclusion

In conclusion, the intra-individual variability of PEP is small. A change in PTT in a person at rest is most probably the result of a change in VTT rather than of PEP. Thus, PTT at rest is an easy, non-invasive and accurate approximation of VTT for monitoring arterial stiffness.

Effect of Strict Volume Control on Renal Progression and Mortality in Non-Dialysis-Dependent Chronic Kidney Disease Patients: A Prospective Interventional Study

OBJECTIVE

The aim of this study was to examine the effect of volume status on the progressions of renal disease in normovolemic and hypervolemic patients with advanced non-dialysis-dependent chronic kidney disease (CKD) who were apparently normovolemic in conventional physical exam-ination.

MATERIALS AND METHODS

This was a prospective interventional study performed in a group of stage 3-5 CKD patients followed up for 1 year. Three measurements were made for volume and renal status for every patient. The fluid status was assessed by a bioimpedance spectroscopy method. A blood pressure (BP) value > 130/80 mm Hg prompted the initiation or dose increment of diuretic treatment in normovolemic patients.

RESULT

Forty-eight patients (48%) were hypervolemic. At the end of the 1-year follow-up, hypervolemic patients were found to have a significantly lower estimated glomerular filtration rate and higher systolic BP compared to baseline. Hypervolemia was associated with an increased incidence of death.

CONCLUSION

We have shown that maintenance of normovolemia with diuretic therapy in normovolemic patients was able to slow down and even improve the progression of renal disease. Volume overload leads to an increased risk for dialysis initiation and a decrease in renal function in advanced CKD. Volume overload exhibits a stronger association with mortality in CKD patients.

Ejection time: influence of hemodynamics and site of measurement in the arterial tree

The left ventricular ejection time is routinely measured from a peripheral arterial waveform. However, the arterial waveform undergoes constant transformation as the pulse wave propagates along the arterial tree. Our goal was to determine if the left ventricular ejection time measured peripherally in the arterial tree accurately reflected the ejection time measured through the aortic valve. Moreover, we examined/accessed the modulating influence of hemodynamics on ejection time measurements. Continuous wave Doppler waveform images through the aortic valve and the simultaneously obtained radial artery pressure waveforms were analyzed to determine central and peripheral ejection times, respectively. The peripheral ejection time was significantly longer than the simultaneously measured central ejection time (174.5±25.2 ms vs. 120.7±14.4 ms; P<0.0001; 17.4±8.7% increase). Moreover, the ejection time prolongation was accentuated at lower blood pressures, lower heart rate and lower pulse wave velocity. The time difference between centrally and peripherally measured ejection times likely reflects intrinsic vascular characteristics. Moreover, given that the ejection time also depends on blood pressure, heart rate and pulse wave velocity, peripherally measured ejection times might need to be adjusted to account for changes in these variables.