Comparison Between Two Shock Wave Regimens for Treating Urinary Stones
Condition: Urinary (Renal or Ureteral) Stones
MeSH terms: Urinary Calculi; Urolithiasis
Study type: Interventional

Summary: 
      In order to check if a reduction in the frequency and total number of shocks delivered during
      extracorporeal shockwave lithotripsy (SWL) results in a great number of stone-free
      patients,the investigators compared two different ways of treating urinary stones using SWL.
    

Detailed description: 
      Purpose: Two different regimens of SWL delivery for treating urinary stones were compared.

      Methods: After informed consent, patients with previously untreated renal and ureteric stones
      were admitted for an initial treatment by SWL between June 2008 and May 2009. Patients were
      randomly divided into two groups; one group received 3000 impulses at a rate of 60 impulses
      per minute, and the other received 4000 impulses at a rate of 90 impulses per minute.
      Patients submitted to re-treatment of the same stone were excluded. All treatments were done
      using the Dornier Compact Delta lithotripter. Stones were located by x-ray or ultrasound.
      Prior to treatment, patients were submitted to laboratory tests and a cardiologic evaluation
      when indicated. Urinary infections were treated prior to the SWL session. All procedures were
      performed under general anesthesia. Briefly, Tramadol 1-2 mg/kg associated to Propofol
      2.5-3.0 mg/kg and scopolamine were employed in the majority of the procedures. Patients
      received 50-100 mg of diluted Tramadol and 20 mg of scopolamine just before the beginning of
      the SWL session and Propofol was maintained on continuous bomb infusion during the treatment
      and interrupted three minutes before the end of the session. All patients were maintained
      under spontaneous breathing, and a facial or a laryngeal oxygen mask was used according to
      the anesthesiologist's judgment. The potency of the lithotripter was increased progressively
      by 300 shocks until reaching the final stage, which occurred at a mean of 1500 shocks. The
      maximum potency employed was level 4 (equivalent to 14 kV) for renal stones and level 6 (16
      kV) for ureteric stones.

      All patients were treated on an outpatient basis and were discharged from the hospital six
      hours after treatment. All patients received non-steroidal anti-inflammatory drugs (NSAIDs)
      and Dipyrone in combination with to Hyoscine for three days postoperatively unless
      contraindicated and were instructed to come to the emergency department in case of severe
      pain, fever or hematuria.

      The final results for each patient were assessed with a kidney and urinary bladder scan (KUB)
      plus an abdominal ultrasound three months after the procedure. Success was defined as
      stone-free status or the detection of residual fragments ≤ 3 mm on final evaluation. Partial
      fragmentation was considered to have occurred if a significant reduction in the stone burden
      was observed but residual fragments bigger than 3 mm remained.

      We evaluated overall stone-free rates, the incidence of unchanged stones and the occurrence
      of partial fragmentation as well as the occurrence of significant complications in both
      groups.

      The sample size required was based on the assumption that the estimated success rate would be
      70% in the 3000 impulses at 60 impulses per minute group and 50% in the 4000 impulses at 90
      impulses per minute group, with a type I error of 0.05 and a type II error of 0.05 (power of
      80%). This yielded a projected sample size of 93 stones in each group.

      Data were analyzed using the Fischer's exact, Chi-square and Mann-Whitney tests; a level of
      significance of 5% was adopted.
    

Intervention name(s): extracorporeal shockwave lithotripsy (SWL)
Intervention type(s): Procedure
Intervention description(s): patients were submitted to one session SWL at a Dornier Compact Delta lithotripter under general anesthesia under supervision of an anesthesiologist and an urologist.
Other intervention name(s): lithotripsy; shock waves
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: kidney calculi; urolithiasis; urologic surgical procedures; extracorporeal shockwave lithotripsy