STONE DISEASE

Forced Versus Minimal Intravenous Hydration in the Management of Acute Renal Colic: A Randomized Trial
Springhart WP, Marguet CG, Sur RL, Norris RD, Delvecchio FC, Young MD, Sprague P, Gerardo CA, Albala DM, Preminger GM
Comprehensive Kidney Stone Center, Duke University Medical Center, Durham, North Carolina, USA
J Endourol. 2006; 20: 713-6

• Background and Purpose: The management of acute renal colic is a problem commonly encountered by both urologists and emergency medicine physicians. The classic approach to managing uncomplicated acute renal colic involves hydration, along with imaging and pain control. Previous studies have suggested that hydration has a significant impact on patient comfort, as well as spontaneous stone passage. This study evaluated the effects of maintenance vs forced hydration and its effect on the pain experienced from renal colic.
• Patients and Methods: Forty male and 18 female patients with a mean age of 41 years suspected to have acute renal colic were identified in the emergency department. After screening and informed consent, the patients were enrolled in the study, and 43 patients were eventually available for analysis. Patients received intravenous (IV) analgesia, imaging with a noncontrast CT scan of abdomen and pelvis, and assignment to either forced IV hydration with 2 L of normal saline over 2 hours (N = 20) or minimal IV hydration at 20 mL of normal saline per hour (N = 23). A visual analog pain scale was completed hourly for a total of 4 hours. Demographic information, laboratory and imaging results, narcotic use in morphine equivalents (ME), and pain scores were recorded and compared. Spontaneous stone passage rates were also calculated by careful patient follow-up. Results were considered statistically significant at p < 0.05.
• Results: Stone size was equivalent in the two treatment groups (p > 0.05). There was no difference in the narcotic requirement in ME (p = 0.644) between the two groups. Similarly, there was no difference in hourly pain score or stone-passage rates between the groups (p > 0.05).
• Conclusions: Treatment of uncomplicated renal colic has traditionally included vigorous intravenous hydration, as well as medications for the control of pain and nausea. Our data suggest that maintenance intravenous fluids are as efficacious as forced hydration with regard to patient pain perception and narcotic use. Moreover, it appears the state of hydration has little impact on stone passage.
  
  
• Editorial Comment
  This study demonstrates that in the emergency room (ER) setting, forced hydration for acute renal colic does not impact pain or stone passage. However, it is important to note that this study evaluates hydration only in the acute ER setting. It is common practice for patients to be instructed to force oral hydration after discharge from the emergency room. Compliance with this recommendation and its impact on subsequent stone passage was not evaluated in this study, and may be worthwhile of further investigation. While the study relies on chart review and self-reporting to document stone passage, other studies have suggested that self-reporting of stone passage may be inaccurate in a significant proportion of patients. The authors do not report the duration of follow-up or time to stone passage, though the 30% spontaneous stone passage rate is lower than one might expect in relation to the mean stone size. Location of ureteral calculi was not reported, and could be a confounding variable in the equation. In addition, the utility of forced hydration may depend on the fluid status of the patient and the time from onset of pain to presentation to the ER. As renal hemodynamics adapt to obstruction within the first 24 hours, the impact of hydration may diminish with delayed presentation. It may be useful to evaluate response to hydration based on the presence of volume depletion (BUN/CR ratio) and the time to presentation (< or > 24 hours from onset of pain).

Dr. Manoj Monga
Professor, Department of Urology
University of Minnesota
Edina, Minnesota, USA