Upper urinary tract pressures in endourology: A systematic review of range, variables and implications.

Abstract

To systematically review the literature, ascertaining upper tract pressures generated during endourology, relevant influencing variables and clinical implications. A systematic review of MEDLINE/Scopus/Cochrane databases was performed by two authors independently (SC,ND). Studies reporting ureteric or intrarenal pressures during semi-rigid ureteroscopy(URS)/flexible ureterorenoscopy(FURS)/percutaneous nephrolithotomy(PCNL)/miniaturised PCNL(mPCNL);1950-2021 were identified. Both in vitro and in vivo studies were considered for inclusion. Findings were independently screened for eligibility based on content, with disagreements resolved by author consensus. Data were assessed for bias and compiled based upon predefined variables. Fifty-two studies met inclusion criteria. Mean IRP appears to frequently exceed a previously proposed threshold of 40cmH2 O. Semi-rigid ureteroscopy with low-pressure irrigation (gravity <1m) resulted in a wide mean IRP range (lowest reported 6.9 cmH2 O, highest mean 149.5±6.2cmH2 O; animal models). FURS without an ureteric access sheath (UAS) was associated with lowest mean IRP 47.6±4.1, with maximum peak IRP 557.4cmH2 O (in vivo human data). UAS placement significantly reduces IRP during FURS; however does not guarantee pressure control with hand-operated pump/syringe irrigation. Miniaturisation of PCNL sheaths is associated with increased IRP; however a wide mean human IRP range has been recorded with both mPCNL (lowest -6.8±2.2cmH2 O(suction sheath); highest 41.2±5.3cmH2 O) and standard PCNL (lowest 6.5cmH2 O; highest 41.2cmH2 O). Use of continuous suction in mPCNL results in greater control of mean IRP, although short pressure peaks >40cmH2 O are not entirely prevented. Definitive conclusions are limited by heterogeneity in study design and results. Postoperative pain and pyrexia may be correlated with increased IRP, however few in vivo studies correlate clinical outcome with measured IRP. Intrarenal pressure generated during upper tract endoscopy often exceeds 40cmH2 O. IRP is multifactorial in origin, with contributory variables discussed. Larger, prospective human in vivo studies are required to further our understanding of IRP thresholds and clinical sequelae.