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Estimation of Intraglomerular Pressure Using Invasive Renal Arterial Pressure and Flow Velocity Measurements in
Didier Collard1, Peter M van Brussel2, Lennart van de Velde1,3
1Department of Vascular Medicine, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands.
Insights
A new model estimates glomerular pressure (Pglom) in humans using renal arterial pressure and flow. This method aids in understanding chronic kidney disease (CKD) hemodynamics and offers a novel research technique.
Area of Science:
- Nephrology
- Cardiovascular Physiology
- Medical Engineering
Background:
- Elevated glomerular pressure (Pglom) drives glomerular hyperfiltration, a key factor in chronic kidney disease (CKD).
- Current methods lack direct Pglom assessment feasibility in human subjects.
- A novel model is needed to estimate Pglom non-invasively.
Purpose of the Study:
- To develop and validate a model for estimating glomerular pressure (Pglom) in human patients.
- To assess the hemodynamic changes associated with hyperemia in the renal vasculature.
- To identify factors influencing baseline Pglom in a patient cohort.
Main Methods:
- Hemodynamic measurements were performed in 34 patients undergoing angiography.
- An adapted three-element Windkessel model was fitted to renal arterial pressure and flow data.
- Hyperemia was induced using intrarenal dopamine infusion to evaluate dynamic hemodynamic responses.
Main Results:
- The model successfully analyzed data from 28 patients, with a mean baseline Pglom of 48.0 mm Hg.
- Renal hyperemia significantly increased flow and afferent compliance, while decreasing Pglom.
- Diabetes, BMI, and renal perfusion pressure were positively associated with baseline Pglom.
Conclusions:
- A novel model estimates glomerular pressure, afferent, and efferent resistance using proximal renal arterial pressure and flow velocity.
- This technique offers a new research tool for evaluating CKD hemodynamics.
- Direct pressure and flow measurements provide valuable insights into renal pathophysiology.
Background:
Glomerular hyperfiltration resulting from an elevated intraglomerular pressure (Pglom) is an important cause of CKD, but there is no feasible method to directly assess Pglom in humans. We developed a model to estimate Pglom in patients from combined renal arterial pressure and flow measurements.
Methods:
We performed hemodynamic measurements in 34 patients undergoing renal or cardiac angiography under baseline conditions and during hyperemia induced by intrarenal dopamine infusion (30 μg/kg). For each participant during baseline and hyperemia, we fitted an adapted three-element Windkessel model that consisted of characteristic impedance, compliance, afferent resistance, and Pglom.
Results:
We successfully analyzed data from 28 (82%) patients. Median age was 58 years (IQR, 52-65), median eGFR was 95 ml/min per 1.73 m2 (IQR, 74-100) using the CKD-EPI formula, 30% had microalbuminuria, and 32% had diabetes. The model showed a mean Pglom of 48.0 mm Hg (SD=10.1) at baseline. Under hyperemia, flow increased by 88% (95% CI, 68% to 111%). This resulted in a 165% (95% CI, 79% to 294%) increase in afferent compliance and a 13.1-mm Hg (95% CI, 10.0 to 16.3) decrease in Pglom. In multiple linear regression analysis, diabetes (coefficient, 10.1; 95% CI, 5.1 to 15.1), BMI (0.99 per kg/m2; 95% CI, 0.38 to 1.59), and renal perfusion pressure (0.42 per mm Hg; 95% CI, 0.25 to 0.59) were significantly positively associated with baseline Pglom.
Conclusions:
We constructed a model on the basis of proximal renal arterial pressure and flow velocity measurements that provides an overall estimate of glomerular pressure and afferent and efferent resistance in humans. The model provides a novel research technique to evaluate the hemodynamics of CKD on the basis of direct pressure and flow measurements.
Clinical Trial Registry Name And Registration Number:
Functional HEmodynamics in patients with and without Renal Artery stenosis (HERA), NL40795.018.12 at the Dutch national trial registry (toetsingonline.nl).
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