High-frequency Jet Ventilation is Beneficial During Shock Wave Lithotripsy Utilizing a Newer Unit with a Narrower Focal Zone

Introduction: High-frequency jet ventilation (HFJV) during shock wave lithotripsy (SWL) has been reported using older lithotripsy units with larger focal zones. We investigated how HFJV affects the clinical parameters of SWL using a newer lithotripsy unit with a smaller focal zone.

Methods: We reviewed all patients who underwent SWL by a single surgeon (KVA) from July 2006 until December 2007 with the Siemens Lithostar Modularis (Siemens AG, Erlangen, Germany). Either HFJV or conventional anesthetic techniques were used based on the anesthesiologists' preference. Preoperative imaging was reviewed for stone size, number and location. Total operating room time, procedure time, number of shocks and total energy delivery were analyzed. Postoperative imaging was reviewed for stone-free rates.

Results: A total of 112 patients underwent SWL with 80 undergoing conventional anesthesia, and 32 with HFJV. Age, body mass index, preoperative stone size and number were not significantly different between the groups. The HFJV group required significantly less total shocks (3358 vs. 3754, p = 0.0015) and total energy (115.8 joules vs. 137.2 joules, p = 0.0015). Total operating room time, SWL procedure time and postoperative stone-free rates were not significantly different.

Conclusions: Previous studies using older SWL units with larger focal zones have demonstrated that HFJV can be effective in reducing total shocks and total energy. Our data is consistent with these studies, but also shows benefit with newer units that have narrower focal zones.