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Changes in parathyroid hormone (PTH) during hemodialysis have been explained by the influence of ionized calcium changes on PTH secretion. In this study we have investigated the influence of dialysis membranes of different permeability on PTH changes during hemodialysis. Five chronic renal failure patients underwent three consecutive hemodialysis sessions with cuprophane (CUP) polysulfone (PS) and polyacrylonitrile (PAN). Two hours of isolated ultrafiltration were followed by 3 h dialysis. A significant decrease in carboxy terminal PTH (COOH PTH) was observed with PAN (p < 0.05) but not with CUP or PS. Intact PTH decreased (p < 0.001) with all three membranes, following a significant increase in ionized calcium (p < 0.001). Sieving coefficients for COOH PTH were significantly lower with CUP than with PS (p < 0.05) or PAN (p < 0.001). Intact PTH sieving coefficients were near zero for all three membranes. COOH PTH and intact PTH clearance rates were significantly higher with PAN (p < 0.001) than with PS or CUP, either in isolated ultrafiltration or with dialysis fluid. Thus PTH changes during hemodialysis do not only depend on the increase in calcium but also on the nature of the dialysis membrane. Adsorption of PTH to the PAN membrane surface explain the high PTH clearance rates achieved with this filter.

IntroductionWe compare open pyeloplasty (OP) versus laparoscopic pyeloplasty (LP) in children in a multicenter, prospective, case–control study.Materials and methodsFrom May 2007 to March 2009, a program was established at Hospital Garrahan, the reference center, to perform LP with a mentoring surgeon that would attend the institution once a month. Every new case of ureteropelvic junction obstruction (UPJO) diagnosed in the reference institution was offered to participate in the study. If the patient was enrolled, it was scheduled for LP. The following patient diagnosed with UPJO was operated on with open technique and served as a case–control. In three other facilities, patients were only offered LP and had a matched control open case at the reference institution. The first end point of the study was patient recovery: analgesia requirement and length of hospitalization (LOH). The second end point of the study was resolution of UPJO in long-term follow-up for the two techniques. Demographic data, surgical time, perioperative complications, analgesia requirement, analgesia score during hospitalization, LOH, and outcome were recorded. Both groups received the same postoperative indications for pain control. Parents were asked to assess pain in their children every 4 h postoperatively and to complete a pain scale chart to which the nurses were blinded.ResultsFifteen OP and 15 LP were compared. Groups were similar with regard to sex, age, weight, and laterality. Mean surgical time was longer in LP than in OP group (mean 188 versus 65 min) (p < 0.01). Hospitalization was shorter for LP group with a mean of 1.9 versus 2.5 days for OP group (p < 0.05). Postoperative analgesia requirement was significantly higher in the OP group with a mean use of morphine of 1.7 versus 0.06 mg/kg in the LP group (p < 0.05). Pain scores were similar in both the groups. At a mean follow-up of 58 months there were no failures.ConclusionIn this prospective comparative cohort, LP was a longer procedure than OP. Both procedures had the same efficacy and complication rates, but patients undergoing LP needed fewer narcotics for pain control and had a shorter hospitalization.

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