Endoluminal isoproterenol reduces renal pelvic pressure during semirigid ureterorenoscopy: a porcine model

Abstract

To investigate the effects on the pressure-flow relation of renal pelvic pressure during semirigid ureterorenoscopy and endoluminal perfusion of isoproterenol (ISO) 0.1 microg/mL, with emphasis on local effects and cardiovascular side-effects, as topically administered ISO effectively and dose-dependently causes relaxation of the upper urinary tract in pigs with no concomitant cardiovascular side-effects. In anaesthetized female pigs (60 kg), 16 macroscopically normal upper urinary tract systems were subjected to ureterorenoscopy. Via a subcostal incision a 6-F catheter was placed in the renal pelvis for pressure measurements, and a semirigid ureteroscope (7.8 F) was inserted retrogradely in the renal pelvis, through which the pelvis was perfused. The blood pressure and heart rate were recorded. The increase in renal pelvic pressure was examined with increasing flow rates (0, 4, 8, 12, 16, 25 and 33 mL/min) with saline alone or saline + ISO 0.1 microg/mL. Perfusion was initiated on the left side, with randomization for adding ISO or not. Thereafter perfusion was done on the right side as a control in each pig. The surgeons were unaware of whether ISO was added or not. The mean (sd) baseline pelvic pressures in the saline and ISO group were 28 (7.1) and 25 (9.8) mmHg, respectively, with no significant difference (P = 0.079). Endoluminal perfusion with ISO significantly inhibited the pelvic pressure increase to perfusion at all perfusion rates. The pressure-flow relation was linear; the maximum relaxation (27%) was obtained at 4 mL/min, from 52 to 38 mmHg during saline alone and ISO 0.1 microg/mL perfusion, respectively. The mean blood pressure did not change significantly (P = 0.330). The mean (sd) heart rate in the saline and ISO group were 109 (4.5) and 97 (2.1) beats/min, respectively (P < 0.001), i.e. a markedly greater rate in the saline than in the ISO group. The pressure-flow relation during semirigid ureterorenoscopy was linear. ISO 0.1 microg/mL in saline significantly reduced the pressure-flow relation during semirigid ureterorenoscopy in this porcine model. ISO might be a potential additive to the irrigation fluid during upper urinary tract endoscopic procedures, minimizing pressure increases due to irrigation and manipulation.