The Dose Response Multicentre Investigation on Fluid Assessment (DoReMIFA) in critically ill patients.

BACKGROUND: The previously published "Dose Response Multicentre International Collaborative Initiative (DoReMi)" study concluded that the high mortality of critically ill patients with acute kidney injury (AKI) was unlikely to be related to an inadequate dose of renal replacement therapy (RRT) and other factors were contributing. This follow-up study aimed to investigate the impact of daily fluid balance and fluid accumulation on mortality of critically ill patients without AKI (N-AKI), with AKI (AKI) and with AKI on RRT (AKI-RRT) receiving an adequate dose of RRT. METHODS: We prospectively enrolled all consecutive patients admitted to 21 intensive care units (ICUs) from nine countries and collected baseline characteristics, comorbidities, severity of illness, presence of sepsis, daily physiologic parameters and fluid intake-output, AKI stage, need for RRT and survival status. Daily fluid balance was computed and fluid overload (FO) was defined as percentage of admission body weight (BW). Maximum fluid overload (MFO) was the peak value of FO. RESULTS: We analysed 1734 patients. A total of 991 (57 %) had N-AKI, 560 (32 %) had AKI but did not have RRT and 183 (11 %) had AKI-RRT. ICU mortality was 22.3 % in AKI patients and 5.6 % in those without AKI (p < 0.0001). Progressive fluid accumulation was seen in all three groups. Maximum fluid accumulation occurred on day 2 in N-AKI patients (2.8 % of BW), on day 3 in AKI patients not receiving RRT (4.3 % of BW) and on day 5 in AKI-RRT patients (7.9 % of BW). The main findings were: (1) the odds ratio (OR) for hospital mortality increased by 1.075 (95 % confidence interval 1.055-1.095) with every 1 % increase of MFO. When adjusting for severity of illness and AKI status, the OR changed to 1.044. This phenomenon was a continuum and independent of thresholds as previously reported. (2) Multivariate analysis confirmed that the speed of fluid accumulation was independently associated with ICU mortality. (3) Fluid accumulation increased significantly in the 3-day period prior to the diagnosis of AKI and peaked 3 days later. CONCLUSIONS: In critically ill patients, the severity and speed of fluid accumulation are independent risk factors for ICU mortality. Fluid balance abnormality precedes and follows the diagnosis of AKI.

Assessment of efficiency using on-line urea kinetic modeling in hemodiafiltration.

Urea kinetics has recently been re-evaluated using an on-line urea monitoring system applied to hemodiafiltration. This system allows evaluation of different components possibly responsible for the gap between prescribed and delivered dose of dialysis, such as access and cardiopulmonary recirculation, and altered dialysis parameters, such as blood flow and dialysate flow rates. Furthermore, the system allows prediction of postdialysis rebound urea concentrations. The aim of the present study was to apply the on-line urea monitoring system to assess the dialytic efficiency of double chamber hemodiafiltration in different conditions of blood-dialysate flow rates, reinfusion volumes, and dialyzer configurations (high + low flux membranes or high + high flux membranes) in 10 patients (age, 60 +/- 9 years; dry weight, 65 +/- 5 kg). There was a significantly lower Kt/V (K, dialyzer clearance; t, dialysis time; V, urea distribution volume) at equilibrium with the high + high vs high + low flux configuration, possibly because of a higher tendency toward urea compartmentalization. This difference was evident when reinfusion was performed post dilution. These studies support the concept that small molecular weight uremic toxins may be more efficiently removed using low flux membranes in a modified form of hemodiafiltration.

Acid-base balance determination on ultrafiltrate in two-chamber technique hemodiafiltration (PFD).

Correction of the acid-base balance in uremic patients during hemodiafiltration (HFD) may be biased by an inadequate monitoring of pH and blood gases. HDF performed with the two-chamber technique (PFD) generates pure ultrafiltrate (uf) unmixed with dialysate. We carried out 84 determinations of HCO3- levels in 15 different PFD patients by measuring the pH and pCO2 of the uf, then correlated the values with those simultaneously evaluated on arterial blood with standard methods. The mean HCO3- levels (mmol/L) were 23.21 +/- 2.49 in blood samples and 25.54 +/- 3.07 in uf, with a mean difference of -2.33 +/- 1.46. Statistical analysis gave: t = 13.5 (p = O) (one-sample analysis), r = 0.86 (p = 0) (linear regression analysis) and a good agreement between the two clinical measurements (81 out of 84 data points fell within the 95% confidence interval) (Bland-Altman analysis). In conclusion, we suggest that during HDF performed with the two-chamber technique, the patient's HCO3- level can be monitored on the uf without blood sampling.