An increase in permeability of microvessels will cause a loss of intravascular fluid and may therefore partially explain the large fluid requirements of patients in shock. It will also favour the development of oedema, which is often found in septic patients. We propose that changes in Kf are useful indices of microvascular malfunction and that VCP allows the non-invasive assessment of these parameters.

Duplex Doppler ultrasound (DDU) was used to study the blood flow characteristics of the renal interlobar artery in 20 subjects with acute renal failure (ARF), 14 subjects with transient impairment of renal function and 23 control subjects with normal function. Renovascular resistance was assessed by pulsatility index (PI) and change in flow velocity by change in mean frequency shift (delta f). The 99% confidence intervals for PI in the three groups were 3.32-5.46, 1.58-2.34 and 0.99-1.33 respectively. Values for delta f were 0.2-0.38, 0.5-0.62 and 0.7-1.02 kHz respectively. Ten ARF patients recovered function, 99% confidence intervals for PI just prior to recovery were 0.9-1.48 and for delta f 0.52-1.02 kHz. There was increased renovascular resistance and reduced intrarenal blood flow velocity at the onset of ARF. These changes persisted during ARF; recovery of function occurred after they returned to normal. Similar, but less marked, changes were found in patients with a transient impairment of function.

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To determine appropriate doses of cefuroxime and ceftazidime for septic patients with acute renal failure (ARF) treated by continuous arteriovenous haemodialysis (CAVHD), we performed pharmacokinetic studies in patients receiving these antibiotics. All patients were treated by CAVHD using Hospal AN69S 0.43 m2 filters and Fresenius 1.5% peritoneal dialysis fluid at dialysate flow rates (Qd) of 1 and 2 l/h. Patients received cefuroxime 500 mg (n = 11) or 750 mg (n = 1), or ceftazidime 500 mg (n = 9) i.v. 12-hourly and all studies were done at steady-state. For cefuroxime, volume of distribution (Vdarea) was 22.8 +/- 3.5 l, terminal elimination half-life (t1/2) 12.6 +/- 2.2 h and total body clearance (TBC) 22.3 +/- 3.0 ml/min (mean +/- SEM). Mean sieving coefficient (SC) was 0.90 +/- 0.12 and filter clearances at Qd 1 and 2 l/h were 14.0 +/- 2.3 and 16.2 +/- 3.4 ml/min respectively. For ceftazidime, Vdarea was 31.1 +/- 6.5 l, t1/2 14.7 +/- 3.3 h, and TBC 24.8 +/- 0.8 ml/min. Mean SC was 0.86 +/- 0.03, and filter clearances at Qd 1 and 2 l/h 13.1 +/- 1.2 and 15.2 +/- 1.5 ml/min. Satisfactory plasma concentrations of both antibiotics were maintained in all patients during treatment. These data suggest that cefuroxime 500-750 mg and ceftazidime 500 mg 12-hourly are suitable doses for patients with ARF treated by CAVHD.