The exponential relationship between raised intrarenal pressure and bacteraemia

Area of Science:

• Urology
• Nephrology
• Surgical Innovation

Background:

• Ureterorenoscopy (URS) is a common procedure for treating kidney stones.
• Elevated intrarenal pressures (IRPs) during URS may lead to complications.
• Understanding fluid and bacterial dynamics at varying IRPs is crucial for patient safety.

Purpose of the Study:

• To quantify the absorption of irrigation fluid and bacteria into the venous system.
• To investigate the relationship between intrarenal pressures (IRPs) and pyelovenous backflow.
• To determine the threshold IRP for bacterial translocation during URS.

Main Methods:

• In vivo porcine kidney models under general anesthesia to simulate URS at increased IRPs.
• Ex vivo porcine kidney models perfused with saline and inoculated with E. coli or acetic acid.
• Serial measurement of venous effluent for electrolyte concentration and E. coli colony-forming units (CFUs).

Main Results:

• Pyelovenous backflow of fluid and E. coli showed an exponential increase with rising IRP.
• Bacteremia was detected in vivo at IRPs as low as 30 mmHg, with incidence increasing with pressure.
• Ex vivo studies confirmed exponential increases in E. coli CFUs with rising IRP, particularly above 60 mmHg.

Conclusions:

• Pyelovenous backflow escalates exponentially beyond 60 mmHg IRP.
• Bacteremia is a risk during URS at IRPs between 30 and 120 mmHg.
• These findings highlight the importance of managing IRP during URS to prevent complications.