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Background: Oral sodium phosphate solution (OSPS) preparations are preferred cleansing agents for colonoscopy because of ease of use and excellent preparation quality. Besides causing acute renal failure in some patients, the high phosphorus content can potentially cause chronic kidney damage to patients undergoing colonoscopy. Methods: We carried out a retrospective study on patients with creatinine levels in the normal range who had undergone colonoscopy or flexible sigmoidoscopy using OSPS preparation from January 1998 to February 2005 and followed them for 1 year to determine its effects on their renal function. A control group of patients with similar comorbidities during this period were chosen to assess agerelated decline in renal function in this population. Results: A total of 286 patients were selected in the study group, and 125 patients were selected in the control group. Both groups had similar baseline characteristics. The base-line glomerular filtration rate (GFR) in the study group was 79 mL/min/1.73 m 2 , which declined to 73 mL/min/ 1.73 m 2 at 6 months after exposure to OSPS preparation. This finding was significantly different from the control group, in whom the baseline GFR was 76 mL/min/ 1.73 m 2 and remained stable at 6 months. Linear regression analysis showed that use of angiotensinconverting enzyme inhibitors and/or angiotensin receptor blockers and the presence of diabetes were significant determinants of the fall in GFR after use of OSPS preparation. Conclusions: Oral sodium phosphate solution preparation is associated with decline in GFR in elderly patients with creatinine levels in the normal range. Its routine use for elective and screening procedures should be discouraged in the elderly population.

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The validity of four indicators to predict successful duodenal feeding tube placement was evaluated in a prospective trial. Data were collected on each indicator at prepyloric (< or = 65 cm) and postpyloric (> or = 75 cm) feeding tube lengths. Feeding tubes were placed in 106 patients. Eighteen feeding tubes were located in the stomach, and 88 were in the duodenum. Auscultation (progression of loudest sound locations from the left to the right abdomen) had a positive predictive value of 85% (negative predictive value, 31%). The vacuum effect (a change from 40 mL of aspirated air to < or = 10 mL after 60 mL of air instillation) had a positive predictive value of 86% (negative predictive value, 45%) and was significantly correlated with duodenal placement (p = .02). Aspirate was present at prepyloric and postpyloric lengths in 35 cases. Ten of these 35 cases had the defined change in pH from < or = 4.0 to > or = 6.0 (positive predictive value, 100%; negative predictive value, 28%). The positive predictive value of color (a change to yellow) was also 100% (n = 11); the negative predictive value was 29%. The low negative predictive values of the indicators suggest that the absence of defined changes is of no assistance in discriminating between stomach and duodenal placement. A positive auscultation or vacuum effect test is not conclusive for duodenal placement. A positive pH or color change test may obviate the need for a confirmatory radiograph.(ABSTRACT TRUNCATED AT 250 WORDS)