title: QRS-activated ventilation during general anesthesia for extracorporeal shock wave lithotripsy.
abstract: High frequency ventilation has been claimed to improve the efficiency of extracorporeal shock wave lithotripsy (ESWL) by minimizing the movement of urinary stones during the procedure. A ventilatory mode, QRS-activated ventilation, was developed in which the stones remain motionless during the delivery of shock waves. As the shock wave is triggered to occur approximately 20 milliseconds after the R wave of the QRS complex, the mechanical breath was synchronized to occur approximately 150 ms later. QRS-activated ventilation is used in 16 patients undergoing ESWL under general anesthesia. Tidal volume was set at 3 ml/kg (234 +/- 36 ml; mean +/- SD) at a rate that equaled the heart rate (71 +/- 9 beats/min). The time between the R wave and the initiation of mechanical breath (T1) was 124 +/- 25 ms, time of mechanical breath itself (T2) was 431 +/- 67 ms, and time between end of T2 and next R wave (T3) was 264 +/- 84 ms. End-tidal CO2 measured by the large breath technique was 28.1 +/- 4.8 mmHg. During the clinical use of QRS-activated ventilation and during earlier studies using an EKG simulator and a test lung, the shock wave occurred invariably at end-expiration even at high heart rates.
authors.affiliation: Department of Anesthesiology, Sheba Medical Center, Tel-Hashomer, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Perel
authors.forename: E
authors.initials: E
authors.lastname: Segal
authors.forename: R
authors.initials: R
authors.lastname: Pizov
authors.forename: Z
authors.initials: Z
authors.lastname: Lenkovskey
authors.forename: Y
authors.initials: Y
authors.lastname: Mahler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000768:Anesthesia, General; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008096:Lithotripsy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012121:Respiration, Artificial / Q000295:instrumentation*