1685 EFFECT OF MULTIPLE ACCESS TRACTS DURING PCNL ON RENAL FUNCTION: BASELINE CREATININE AND GLOMERULAR FILTRATION RATE ARE IMPORTANT PREDICTORS

Abstract

INTRODUCTION AND OBJECTIVES: To assess the impact of multiple access tracts during percutaneous nephrolithotomy (PCNL) on renal function, and to determine risk factors predicting renal function deterioration and/or recovery in patients undergoing this procedure. METHODS: Patients undergoing PCNL with multiple punctures between July 2009 and February 2011 were prospectively enrolled. Preoperative evaluation included DMSA and DTPA renography. Patients were classified according to baseline renal function into patients with normal ( 1.4 mg/dL) serum creatinine (group A) and patients with elevated ( 1.4 mg/dL) serum creatinine (group B). Patients were followed postoperatively with serial serum creatinine measurements and a repeat renography at 12 months. Factors evaluated for possible impact on renal function included age, preoperative serum creatinine, preoperative GFR, hypertension, and diabetes. Paired t-test and General Linear Model (GLM) Repeated Measures procedure were used as appropriate. RESULTS: One hundred and two patients aged 21 to 62 years (mean 39.9) underwent PCNL with multiple (2-4) access tracts. Mean ( SD) preoperative serum creatinine for the whole cohort was 1.66 ( 0.71) mg/dL and Mean ( SD) GFR (of the involved renal unit) was 48.7 ( 12.9) mL/min. Fifty patients had normal preoperative serum creatinine (group A) and had no significant change in serum creatinine after PCNL (1.02 ( 0.19) preoperatively to 1.01 ( 0.13) post-operatively), while there was a small decline in GFR (57.9 ( 11.1) to 53.8 ( 11.4)). Fifty two patients had baseline renal impairment (group B), and they experienced a significant worsening of serum creatinine (2.30 ( 0.36) preop. to 2.65 ( 0.42) at 12 months) (p 0.001) and a more important decline in GFR (39.4 ( 6.0) preop. to 32.9 ( 6.3) at 12 months)(p 0.001). Patients with diabetes and/or hypertension had a larger rise in serum creatinine (1.90 ( 0.52) preoperatively to 2.24 ( 0.76) at 12 months) and a larger drop in GFR (45.4 ( 13.1) to 38.1 ( 14.1)), compared to patients without these comorbidities (creatinine from 1.52 ( 0.65) to 1.58 ( 0.81) and GFR from 50.4 ( 12.5) to 46.0 ( 13.3), p 002). CONCLUSIONS: PCNL with multiple access tracts carries a risk of affecting renal function. Patients with preoperative baseline renal impairment are particularly susceptible to renal function deterioration after the procedure, and so are patients with diabetes and hypertension. Alternatives to multiple tracts PCNL (flexible or combined retrograde/antegrade approaches) may be preferable in these patients.