Safety and efficacy of percutaneous renal biopsy by physicians-in-training in an academic teaching setting.

OBJECTIVES: The safety and efficacy of percutaneous renal biopsy (PKB) are relatively little studied in a training setting. We sought to review our recent experience with bedside PKB in our training program. METHODS: We performed a retrospective cohort review of our consecutive 2.5-year renal biopsy experience (May 2007-November 2009) at the University of Mississippi Nephrology Fellowship. All of the biopsies were performed exclusively by renal fellows using real-time ultrasound (US) visualization within the framework of a structured US-PKB training course. RESULTS: A total of 64 patients underwent PKB during the index period; 50 (78.1%) of these procedures were performed on native kidneys. Participant age was 39.8 ± 13.7 years, blood pressures measured 140.1/85.3 ± 21.5/14.9 mm Hg, serum creatinine was 3.05 ± 3.15 mg/dL, and median random urine protein:creatinine ratio was 2.38 (25%-75% interquartile range 0.49-7.32). The biopsied kidneys measured 11.8 (±1.6) cm. We recovered 18.8 ± 11.5 glomeruli per procedure; two biopsies were unsuccessful. Focal glomerular sclerosis and lupus nephritis (22% and 25%, respectively) predominated among the specimens. Only three specimens returned with no diagnostic changes. There was a close correlation between preceding history and recovered diagnoses of diabetic changes and lupus nephritis (r 0.605 and 0.842; P < 0.0001 for both). Initial hemoglobin of 10.8 ± 1.8 g/dL dropped to 10.2 (1.9) g/dL after the procedure (P < 0.0001). Five (7.8%) patients needed transfusion; one patient experienced persistent urine leakage; however, none of the patients needed surgical or radiological intervention or died. CONCLUSIONS: In the setting of a well-structured training environment, US-guided PKB is a reasonably safe and valuable component of renal fellowship training.

Which fluid space is affected by ultrafiltration during hemodiafiltration?

Ultrafiltration (UF) is a common procedure performed during almost all dialysis sessions. During UF, several liters of fluid are removed; however, what proportion of this fluid is removed from which fluid space could not be clinically measured easily until now; we designed this study to evaluate the fluid spaces most affected by UF. This is a prospective cohort study of 40 prevalent chronic hemodialysis patients receiving thrice weekly hemodiafiltration (HDF). We measured the patients' fluid spaces using a whole-body bioimpedance apparatus to evaluate the changes of fluid spaces before and immediately after the HDF sessions. We recorded the data on fluid spaces, UF volume, and blood pressures. The cohort consisted of 40 prevalent HDF patients, aged 60.0 ± 5.2 years (37.5% men; 27.5% people with diabetes), and body weight 71.03 ± 15.48 kg. Achieved UF was 2.38 ± 0.98 L on HDF (measured fluid overload: 2.35 ± 1.44 L). The extracellular fluid (EC) volume decreased from 16.84 ± 3.52 to 14.89 ± 3.06 L (P < 0.0001) and intracellular fluid (IC) volume from 16.88 ± 4.40 to 16.55 ± 4.48 L (P = 0.45). Although urea volume of distribution remained effectively unchanged (31.38 ± 7.28 vs. 30.70 ± 7.32 L; P = 0.45), the degree of EC volume overload decreased from 13.60% ± 7.30% to 3.83% ± 8.32% (P < 0.0001). The mean arterial pressure also decreased from 122.95 ± 19.02 to 108.50 ± 13.91 mmHg (P < 0.0001). We conclude that source of net fluid loss by ultrafiltration is almost exclusively the EC fluid space. The intracellular fluid space is not significantly affected immediately after HDF.