Ziaee SA et al, 2011: Impact of Sleep Position on Stone Clearance after Shock Wave Lithotripsy in Renal Calculi
Ziaee SA, Hosseini SR, Kashi AH, Samzadeh M.
Shahid Labbafinejad Medical Center and Urology and Nephrology Research Center (UNRC), Shahid Beheshti University, M.C. (SBMU), Tehran, Iran
Objectives: We evaluated the impact of sleep position on the effectiveness of shock wave lithotripsy (SWL) in renal calculi.
Patients and Methods: Patients (n = 120) with a single radiopaque renal stone who were candidates for SWL were enrolled. For studying patients' position during sleep, a novel sleep position recorder was designed. Group 1 (n = 60) consisted of patients who slept preferentially on the ipsilateral side of the stone; group 2 (n = 60) comprised patients who slept preferentially on the contralateral side. Treatment effectiveness was defined as the absence of residual stones >3 mm up to 3 months after SWL.
Results: The mean (range) percent of sleep on the ipsilateral side of the stone was 61.5% (51-78) and on the contralateral side it was 62.4% (51-81) in groups 1 and 2, respectively (p > 0.05). The overall success rate of SWL was 88.3% (77.4-95.2) and 70.0% (56.8-81.2) in groups 1 and 2, respectively (p = 0.01). Stone clearance increased with an increasing percent of total sleep time on the ipsilateral side of the kidney stone (p = 0.045).
Conclusions: The percent of stone-free patients was higher in the group of patients who slept ipsilaterally relative to the kidney stone compared with patients who slept on the contralateral side.
Copyright © 2011 S. Karger AG, Basel.
Urol Int. 2011;87(1):70-4. doi: 10.1159/000325881. Epub 2011 Jun 16
PMID: 21677418 [PubMed - as supplied by publisher]
The role of kidney position during sleep has been a matter of interest for stone/fragment clearance as well as for explaining why many patients only form stones in one kidney. In this report fragment clearance after ESWL was examined and compared with the sleeping position as evaluated in a sleeping laboratory. The conclusion was that the percentage of stone-free kidneys was higher in those patients who had most of their sleeping time on the same side as the treated stone in comparison with patients who preferentially slept on the opposite side.
The explanation provided was that the renal perfusion and diuresis theoretically would be better in the kidney on the sleeping side. Measurements to support that assumption were, however, not carried out. Moreover, the authors defined patients as stone-free if the remaining fragments were 3 mm or smaller. It would indeed have been interesting to know how easy the smallest fragments were eliminated as a result of the assumed increased diuresis.
The observation is of interest and should stimulate to further similar studies in order to get methods with the aim of improving fragment clearance after ESWL.