Determination of renal blood flow by thermodilution method

Area of Science:

• Nephrology
• Cardiovascular Physiology
• Medical Imaging

Background:

• Accurate measurement of renal vein blood flow is crucial for understanding renal hemodynamics.
• Existing methods may be complex or invasive, limiting their utility for repeated assessments.

Purpose of the Study:

• To evaluate the accuracy and reliability of the single bolus thermodilution method for measuring renal vein blood flow.
• To compare thermodilution with established methods in both experimental models and human subjects.

Main Methods:

• Model experiments comparing thermodilution with graduated cylinder measurements (50-1050 ml/min).
• Duplicate measurements in thirty-one renal veins across eighteen patients.
• Bilateral renal vein blood flow measurements in twelve patients compared with para-aminohippuric acid (PAH) clearance.

Main Results:

• Excellent correlation (r=0.98) between thermodilution and graduated cylinder measurements, with a 5.2% mean difference.
• Very high correlation (r=0.99) for duplicate thermodilution measurements within 3 minutes.
• Good correlation (r=0.98) between total renal blood flow measured by thermodilution and PAH clearance.

Conclusions:

• The single bolus thermodilution method provides simple, inexpensive, and reliable renal vein blood flow measurements.
• This technique is particularly advantageous for studies requiring repeated assessments of renal hemodynamics.
• Catheterization of renal veins is necessary, but the method's overall practicality is high.