The clinical application of HFPPV on the extracorporeal shock wave lithotripsy

The efficiency of HFPPV with respiratory rates, 100 and 150/min

Abstract

High frequency positive pressure ventilation (HFPPV) was used with thirty-four patients to minimize the movement of kidney or ureter stones during the extracorporeal shock wave lithotripsy (ESWL) under enflurane anesthesia. The patients were subdivided into four groups according to settings of HFPPV for respiratory rate(RR) and tidal volume (V_T): Group 1, RR 100/min and V_T2.5ml/kg; Group 2, 100/min and 3.0ml/kg; Group 3, 150/min and 2.0ml/kg; Group 4, 150/min and 2.5ml/kg. The range of stone movement during HFPPV averaged 0.7 to 1.1mm in the four groups, which was significantly less than 7.6 to 9.3mm during intermittent positive pressure ventilation (IPPV). The Paco₂ level during HFPPV in Groups 1, 2 and 4 was lower than before anesthesia. The peak airway pressure significantly increased in Group 4 during HFPPV with the increase in the end-expiratory pressure. The settings 2.5 or 3.0ml/kg tidal volume, with 100/min respiratory rate (Groups 1 and 2), produced minimum stone movement and adequate ventilation.