Differences in decline in GFR with age between males and females. Reference data on clearances of inulin and PAH in potential kidney donors. (25/67)

BACKGROUND: To ensure that potential kidney donors have no renal impairment, it is extremely important to have accurate methods for evaluating the glomerular filtration rate (GFR). The golden standard, clearance of inulin, has been used in the present study. The aim was to evaluate the effects of age and sex on renal function and present reference data. METHODS: A total of 122 potential kidney donors, 62 females, aged 21-67 years, were investigated with the GFR and effective renal plasma flow (ERPF) determined by clearances of inulin and para-amino hippurate. RESULTS: The mean +/- SD GFR and ERPF were 105 +/- 13 and 545 +/- 108 ml/min/1.73 m(2), respectively, and we found no difference between the males and females. When relating GFR and ERPF to age, however, a significant decline was found in GFR and ERPF in males, but not in females in the age range of 20-50 years. GFR fell by a mean of 8.7 ml/min/1.73 m(2) and ERPF by 90 ml/min/1.73 m(2) per decade in male donors. CONCLUSION: With adequate methods for determining GFR and ERPF, a clear difference in the effect of age was seen between the sexes. Males showed a significant decrease between 20 and 50 years of age, which was not seen in females. Females seem to be protected in the pre-menopausal period probably by oestrogens. These results confirm clinically those found in rats.  (+info)

Impact of pre-dilution and flushing on continuous renal replacement therapy. (26/67)

INTRODUCTION: Infusing the replacement solution before the filter (pre-dilution) and regular flushing have not been accounted for in conventional mathematical equations. Their effects on various continuous renal replacement therapy (CRRT) parameters, such as ultrafiltration fraction and urea clearance, have not been well studied. We incorporated these parameters into mathematical equations to help in understanding and prescribing CRRT. METHODS: We built a mathematical model to evaluate the plasma flow rate, filter fluid inflow rate with pre- and post-dilution and ultrafiltration rate, plasma clearance of urea, and ultrafiltration fraction. RESULTS: In pre-dilutional therapy, the volume of replacement needed to be increased in order to achieve the target plasma clearance rate. The extra volume needed increased exponentially with higher target plasma clearance rate. The higher the targeted plasma clearance in relation to blood flow rate (Qb), the greater the increase. Increasing blood flow rate reduced the ultrafiltration fraction for both pre- and post-dilution therapy. It had no effect on plasma clearance with post-dilution therapy but significantly improved the clearance in pre-dilution therapy. Higher haematocrit resulted in higher ultrafiltration fraction in both pre- and post-dilution therapy. Higher haematocrit had no effect on plasma clearance with post-dilution therapy but slightly reduced clearance in pre-dilution therapy. For a given total volume of ultrafiltration, flushing reduced plasma clearance with both pre- and post-dilution therapy. Flushing slightly reduced ultrafiltration fraction of post-dilution therapy but minimally increased the ultrafiltration fraction of pre-dilution therapy. This mathematical model could be utilised in prescribing Qb and replacement rate based on targeted plasma clearance, ultrafiltration fraction, fluid removal rate and haematocrit. There was close approximation of predicted and measured urea plasma clearance. CONCLUSION: Pre-dilution therapy reduced urea clearance significantly and this needed to be compensated for by increasing the volume of ultrafiltration or Qb. Flushing was of limited benefit and may reduce urea clearance. In prescribing haemofiltration, Qb and replacement rate could be determined with this model.  (+info)

Dual-head lithotripsy in synchronous mode: acute effect on renal function and morphology in the pig. (27/67)

OBJECTIVE: To assess the effect of dual-head lithotripsy on renal function and morphology in a pig model of shockwave (SW) injury, as lithotripters with two shock heads are now available for treating patients, but little information is available with which to judge the safety of treatment with dual pulses. MATERIALS AND METHODS: A dual-head electrohydraulic lithotripter (Duet, Direx Corp., Natick, MA, USA) was used to treat the lower renal pole of anaesthetized pigs with a clinical dose of SWs (2400 dual SWs; 10 kidneys) delivered in synchronous mode, i.e. both heads fired simultaneously. For comparison, pigs were treated with either 2400 SWs (12 kidneys) or 4800 SWs (eight) with a conventional electrohydraulic lithotripter (HM3, Dornier, Wessling, Germany). RESULTS: Dual-pulse SW treatment with the Duet lithotripter caused a decline in the mean (sd) glomerular filtration rate (GFR) of 4.1 (1.9) mL/min, with a trend for the effective renal plasma flow (RPF), at 31 (19) mL/min, to also decrease. These changes in renal haemodynamics were similar to the decreases in GFR and RPF in response to treatment with the HM3 lithotripter with 2400 SWs, at 4.8 (0.8) and 32 (10) mL/min, respectively, or 4800 SWs, at 5.4 (1.0) and 68 (14) mL/min, respectively. Linear association analysis showed that the functional response to dual-pulse SWs was more variable than with conventional SWs. Morphological quantification of kidney damage (expressed as a percentage of functional renal volume, FRV) showed that tissue injury with 2400 paired SWs with the Duet, at 0.96 (0.39)% FRV, was similar to injury produced by either 2400 single SWs, at 1.08 (0.38)% FRV, or 4800 single SWs, at 2.71 (1.02)% FRV, with the HM3. However, morphological damage was less consistent with the Duet (measurable in only five of eight kidneys) than that with the HM3 (measurable in all 12 kidneys). Acoustic output and the timing of dual SWs in synchronous mode increased in variability as the electrodes aged, affecting the amplitude and targeting of focal pressures. CONCLUSION: With the caveat that variability in the timing of dual SWs will unpredictably alter the distribution of SW energy within the kidney, this study shows that a clinical dose of dual-head SWs delivered in synchronous mode elicits a renal response similar to, but more variable than, that with a clinical dose of SWs from a conventional electrohydraulic lithotripter.  (+info)

Effects of statins on renal sodium and water handling: acute and short-term effects of atorvastatin on renal haemodynamics, tubular function, vasoactive hormones, blood pressure and pulse rate in healthy, normocholesterolemic humans. (28/67)

BACKGROUND: Statins have a beneficial effect on cardiovascular morbidity and mortality due to a reduction in plasma cholesterol. However, statins seem to have effects beyond the lowering of plasma cholesterol. We hypothesize that these effects are caused by an effect on renal function. METHODS: We measured the effects of atorvastatin (AS) on renal function in two randomized, placebo-controlled, double-blinded and crossover studies in healthy man. In an acute trial (Study 1), 19 subjects received either 80 mg AS as a single dose or placebo. In a short-term trial (Study 2), 20 subjects received either 80 mg AS or placebo daily for 4 weeks. In both studies glomerular filtration rate (GFR), renal plasma flow (RPF), plasma concentrations of angiotensin II (Ang II), renin (PRC), atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), aldosterone (Aldo), vasopressin (AVP) and blood pressure (BP) were determined. RESULTS: In Study 1 AS decreased fractional excretion of sodium (FE(Na)) significantly (P = 0.035), but very modestly, and reduced diastolic BP (P = 0.024). Apart from this, we found no significant differences in GFR, RPF, tubular function and vasoactive hormones in either Study 1 or 2. CONCLUSIONS: An acute dose of AS decreased FE(Na) and DBP in healthy humans. The reduction in fractional urinary sodium excretion was very modest and transitory, and most likely secondary to the fall in diastolic blood pressure (DBP). However, renal haemodynamics, tubular function, vasoactive hormones and blood pressure were unchanged during short-term statin treatment in healthy man.  (+info)

Functional assessment of the kidney from magnetic resonance and computed tomography renography: impulse retention approach to a multicompartment model. (29/67)

 (+info)

Changes in glomerular filtration rate after cardiac surgery with cardiopulmonary bypass in patients with mild preoperative renal dysfunction. (30/67)

 (+info)

Renal and hormonal responses to direct renin inhibition with aliskiren in healthy humans. (31/67)

 (+info)

Obesity-induced glomerular hyperfiltration: its involvement in the pathogenesis of tubular sodium reabsorption. (32/67)

 (+info)