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Background Cerebral blood flow (CBF) may decrease during intermittent hemodialysis (IHD). Patients with acute kidney injury (AKI) may be more vulnerable to cerebral hypoperfusion than patients with end-stage renal disease (ESRD), due to concomitant critical illness and hemodynamic instability. Methods In this observational, prospective study, we measured mean flow velocity at the level of the middle cerebral artery by transcranial Doppler at the start, after 2 h and at the end of a hemodialysis session in 15 consecutive patients with AKI and critical illness referred to the nephrological intensive care unit of a university hospital and in 12 patients with ESRD on regular treatment thrice weekly, who served as controls. We compared end-dialysis changes from baseline in mean flow velocity between the study groups and examined the correlation between this change and that of other relevant clinical parameters. Results Mean flow velocity decreased significantly at end-dialysis in the patients with AKI, but not in those with ESRD (P = 0.02). This difference persisted after adjusting for baseline mean flow velocity and net ultrafiltration volume. No significant correlations were found in either group between changes in mean flow velocity and changes in mean blood pressure (AKI: r = −0.27, P = 0.34; ESRD: r = 0.15, P = 0.68), SUN (AKI: r = −0.33, P = 0.25; ESRD: r = 0.06, P = 0.85), plasma HCO3− (AKI: r = −0.52, P = 0.24; ESRD: r = −0.18, P = 0.59), hematocrit (AKI: r = 0.08, P = 0.71; ESRD: r = −0.19, P = 0.65) or arterial oxygen content (AKI: r = −0.17, P = 0.36; ESRD: r = −0.33, P = 0.43). Conclusions Our data suggest that AKI patients may be more vulnerable than ESRD patients to cerebral hypoperfusion during IHD. Our findings do not support a clear-cut role of rapid changes in blood osmolarity, rheological properties or vasoreactivity of the cerebral circulation to O2 supply in modulating CBF during hemodialysis. [ABSTRACT FROM PUBLISHER]

Background In patients admitted to the Intensive Care Unit (ICU), Kidney Replacement Therapy (KRT) is an important risk factor for hypophosphataemia. However, studies addressing the development of hypophosphatemia during prolonged intermittent KRT modalities are lacking. Thus, we evaluated the incidence of hypophosphatemia during Sustained Low-Efficiency Dialysis (SLED) in ICU patients; we also examined the determinants of post-SLED serum phosphate level (s-P) and the relation between s-P and phosphate supplementation and ICU mortality. Methods We conducted a retrospective analysis on a cohort of critically ill patients with severe renal failure and KRT need, who underwent at least three consecutive SLED sessions at 24–72 h time intervals with daily monitoring of s-P concentration. SLED with Regional Citrate Anticoagulation (RCA) was performed with either conventional dialysis machines or continuous-KRT monitors and standard dialysis solutions. When deemed necessary by the attending physician, intravenous phosphate supplementation was provided by sodium glycerophosphate pentahydrate. We used mixed-effect models to examine the determinants of s-P and Cox proportional hazards regression models with time-varying covariates to examine the adjusted relation between s-P, intravenous phosphate supplementation and ICU mortality. Results We included 65 patients [mean age 68 years (SD 10.0); mean Acute Physiology and Chronic Health Evaluation II score 25 (range 9–40)] who underwent 195 SLED sessions. The mean s-P before the start of the first SLED session (baseline s-P) was 5.6 ± 2.1 mg/dL (range 1.5–12.3). Serum phosphate levels at the end of each SLED decreased with increasing age, SLED duration and number of SLED sessions (P  < .05 for all). The frequency of hypophosphatemia increased after the first through the third SLED session (P  = .012). Intravenous phosphate supplementation was scheduled after 12/45 (26.7%) SLED sessions complicated by hypophosphataemia. The overall ICU mortality was 23.1% (15/65). In Cox regression models, after adjusting for potential confounders and for current s-P, intravenous phosphate supplementation was associated with a decrease in ICU mortality [adjusted hazard ratio: 0.24 (95% confidence interval: 0.06 to 0.89; P = 0.033)]. Conclusions Hypophosphatemia is a frequent complication in critically ill patients undergoing SLED with standard dialysis solutions, that worsens with increasing SLED treatment intensity. In patients undergoing daily SLED, phosphate supplementation is strongly associated with reduced ICU mortality. [ABSTRACT FROM AUTHOR]

Background. Prolonged intermittent renal replacement therapy (PIRRT) is a dialysis modality for critically ill patients that in theory combines the superior detoxification and haemodynamic stability of the continuous renal replacement therapy (CRRT) with the operational convenience, reduced haemorrhagic risk and low cost of conventional intermittent haemodialysis. However, the extent to which PIRRT should replace these other modalities is uncertain because comparative studies of mortality are lacking. We retrospectively examined the mortality data from three general intensive care units (ICUs) in different countries that have switched their predominant therapeutic approach from CRRT to PIRRT. We assessed whether this practice change was associated with a change in mortality rate.Methods. Data were analysed from ICUs in New Zealand, Australia and Italy. The study population comprised all patients requiring renal replacement therapy from 1 January 1995 to 31 December 2005 (n = 1347), the period of time spanning the change from CRRT to PIRRT in each unit. Poisson regression models were used to estimate the incident rate ratio (IRR) for death, comparing the periods before and after change to PIRRT in each unit. Estimates were adjusted for patient illness severity (APACHE II score) and for the underlying time trend in mortality rate over time.Results. The change from CRRT to PIRRT was not associated with any increase in mortality rate, with an adjusted IRR of 1.02 (0.61–1.71). The IRR was virtually identical in the three ICUs (P-value = 0.63 for the difference in the IRR between ICUs).Conclusions. Switching from CRRT to PIRRT was not associated with a change in mortality rate. Pending the results of a randomized trial, our study provides evidence that PIRRT might be equivalent to CRRT in the general ICU patient. [ABSTRACT FROM AUTHOR]