Abstract
In this issue, Boonyapalanant et al. present data on operative outcomes of different irrigation systems in endoscopic combined intrarenal surgery (ECIRS) between 2016 and 2021 at their university hospital. 294 well-matched patients were divided between two irrigation systems for flexible ureteroscopy. In the manual and gravity irrigation group, a 2 L saline bag was suspended 60 cm above the patient and attached to a continuous-flow single-action pumping system, whereas for the automated irrigation group, an automatic system was set to a pump pressure of 90 mmHg. In both cases, gravity irrigation was used for the percutaneous nephrolithotomy. Patients received either culture-directed perioperative antibiotics or Ancef if no culture data was available. The study, “Effect of Using Automated Irrigation Systems on the Risk of Infectious Complications after Endoscopic Combined Intrarenal Surgery: A Retrospective Cohort Study,” concludes that using an automated irrigation system for flexible ureteroscopy in ECIRS is associated with a reduction in the incidence of postoperative fever and a shorter operative time.
It is worthwhile to consider the researchers’ use of postoperative fever, defined as an axillary temperature greater than 38°C, as the primary outcome measure. Conventional teaching is that postoperative fever occurring within the first 24 hours is often due to surgical tissue trauma and the release of pro-inflammatory cytokine mediators (e.g., IL-6 and TNF). 1 Rates of postoperative fever among patients undergoing percutaneous nephrolithotomy are as high as 39.8%. 2 This may reflect a transient bacteremia related to stone fragmentation that does not ultimately portend worse patient outcomes. Notably, the rate of sepsis (4%) was equal between the two different irrigation systems. A positive preoperative urine culture was shown to be significantly associated with both fever and sepsis, suggesting that true infectious complications might be better attributed to other case factors.
While this study is an interesting comparison of irrigation systems and serves as an important reminder to consider the impact of increased renal pressure on infection risk, its results should be cautiously generalized. In the absence of other clinical benefits (and possibly the ability to not only set an external pressure but also measure and control the intrarenal pressure), a lower rate of postoperative fever may not be sufficiently convincing to request a $20,000 automated irrigation machine at the next department meeting. 3