Constant pressure perfusion: a method to determine obstruction in the upper urinary tract

Area of Science:

• Urology
• Physiology
• Medical Devices

Background:

• Assessing upper urinary tract obstruction is crucial for patient management.
• Current methods like constant flow perfusion may lack sensitivity in detecting partial obstructions.
• A more physiological approach is needed to accurately diagnose urinary tract obstruction.

Purpose of the Study:

• To evaluate constant pressure perfusion as a more physiological method for diagnosing upper urinary tract obstruction.
• To compare the efficacy of constant pressure perfusion against constant flow perfusion in canine and porcine models.
• To determine the sensitivity and discriminatory power of constant pressure perfusion in identifying partial obstructions.

Main Methods:

• Constant pressure perfusion technique was studied in canine and porcine models.
• This method involves low, fixed pressures (7-12 cm water) in the renal pelvis.
• Flow rates from the upper tracts were measured and analyzed.

Main Results:

• Constant pressure perfusion demonstrated increased sensitivity and better discrimination of normal versus obstructed systems compared to constant flow.
• Non-obstructed systems showed low renal pelvic pressures (<8 cm water) with normal flow rates.
• Partial distal ureteral obstructions were identified by low or no flow at renal pelvic pressures of 7-12 cm water, unlike constant flow which required higher pressures (>15-20 cm water).

Conclusions:

• Constant pressure perfusion is a more sensitive and discriminatory method for diagnosing upper urinary tract obstruction.
• The technique is independent of upper tract compliance and utilizes physiological pressures.
• Constant pressure perfusion shows clear clinical applicability for improved obstruction diagnosis.