Extravascular Absorption of Irrigating Fluid during TURP. The Role of Transmural Bladder Pressure as the Driving Pressure Gradient

Abstract

The critical intravesical pressure range for extravascular absorption of irrigating fluid (EVA) during transurethral resection of the prostate (TURP) is determined by the pressure in the perivesical tissue. This means that the transmural bladder pressure (detrusor pressure), calculated by deducting perivesical pressure from intravesical pressure during cystometry, is the pressure gradient behind EVA. The transmural pressure in 6 patients undergoing TURP has been studied both before and during epidural anaesthesia, using both conventional medium-fast fill cystometry and "free-flow" cystometry through the resectoscope. Epidural block does not influence the transmural pressure response on filling the bladder and neither does the type of infusion. A positive transmural pressure, and thereby a pressure gradient for EVA, exists already during the very early phase of bladder filling. Incomplete perforation of the prostatic capsule and clotting, as well as the accumulation of irrigating fluid in the perivesical tissue, probably moderate the rate of absorption.

Intravesical Pressure during Irrigating Fluid Absorption in Transurethral Resection of the Prostate

“…The length of time during which the pressure exceeds this limit expresses the patient's exposure to the risk of massive fluid absorption. The critical pressure for absorption by the extravascular indirect route is lower (12) and seems to equal the transmural bladder pressure (20). In the present report, however, the number of extravascular absorption events was quite small, which is consistent with findings from a large consecutive series of TURP patients (21).…”

Fluid absorption in endoscopic surgery

“…The fluid pressure only needs to exceed the intra-abdominal pressure of %0.5 kPa for extravasation to occur. 67 Extravasation is more common during renal stone surgery, 24 115 while direct intravascular absorption is the more common during TURP 31 34 45 48 and TCRE. 89…”

Effects of Bladder Capacity and Height of Fluid Bag on Intravesical Pressure during Transurethral Resection of the Prostate

“…extravascular absorption is even lower [6,7], However, there seems to be practically no information concerning another key factor in the possible relationship between bag height and fluid absorption, e.g. the intravesical pres sure that actually results from placing the fluid bag at a particular height above the operating table.…”