Whether IRRT or CRRT influences clinical outcomes remains the subject of debate. Even though the worldwide standard RRT in the ICU is IHD, survey evidence has consistently shown considerable variation in RRT practice patterns. In recent years, the use of SLED has risen and is mainly driven by its convenience and lower cost compared to CRRT.
Several nonrandomized studies have suggested that CRRT may contribute to improved survival and a higher rate of renal recovery; however, other similar studies have failed to show any additional benefit with CRRT. The first randomized controlled trial (RCT) was done in 2001 by Mehta et al.2 IHD was averaged 5 days/week for 3 to 4 hours per session. Univariate intention-to-treat analysis revealed a higher mortality among patients receiving CRRT. However, multivariate analysis revealed no impact of RRT modality on all-cause mortality or recovery of renal function. Because Mehta et al, there have been 8 RCTs, comparing CRRT and IRRT (Table 71–1) (IHD,3,4,5,6,7,8 SLED9,10). There is significant variation among these RCTs in terms of study population (exclusion of chronic kidney disease, illness severity, and etiology of AKI), methods of RRT (criteria for RRT, device/technique, doses, and membrane material). Serious concerns have been identified in some trials due to unbalanced baseline characteristics, inappropriate sample size, and significant crossover between dialytic modalities.11 Most studies3,4,5,7,8 used IHD 3 times per week; however, recently, Lins et al6 performed a multicenter prospective RCT comparing IHD (7 days/week, 4-6 hours per session) with CVVH, with a higher sample size, and better control of the severity of illness of the study population. Lins et al reported that after AKI, the modality of RRT had no impact on ICU outcome. However, the dose of IHD (42 hours/week) was far greater than the typical 9 to 12 hours of IHD being delivered in the ICU setting. To date, none of the RCTs and meta-analyses11,12,13,14 has demonstrated any significant difference in mortality between modalities. However, there are other important factors for selecting the RRT modality (Table 71–2).