KDIGO Clinical Practice Guideline for Acute Kidney Injury
Hemodynamically unstable patients: Recommendations and Rationale

• 5.6.2: We suggest using CRRT, rather than standard intermittent RRT, for hemodynamically unstable patients. (2B)

Rationale

Many clinicians prefer CRRT in critically ill AKI patients with severe hemodynamic instability, because of better hemodynamic tolerance due to the slower fluid removal and the absence of fluid shifts induced by rapid solute removal. The Cochrane meta-analysis could not establish a difference in the number of patients with (however poorly defined) hemodynamic instability (RR 0.48; 95% CI 0.10–2.28; n = 205) nor with (variably defined) hypotension (RR 0.92; 95% CI 0.72–1.16; n = 514). On the other hand, the mean arterial pressure at the end of the treatment was significantly higher with CRRT than with IHD (mean deviation 5.35; 95% CI 1.41–9.29; n = 112) and the number of patients requiring escalation of vasopressor therapy was significantly lower with CRRT compared to IHD (RR 0.49; 95% CI 0.27–0.87; n = 149).⁷¹³ In general, the number of patients included in these analyses of the hemodynamic tolerance of RRT remains limited, and none of the RCTs has specifically looked at the effect of different modalities of RRT in patients with shock.

SLED has been proposed as an alternative to other forms of RRT and is used in many centers worldwide for logistical reasons. A recent review⁷²³ summarizes the results obtained with SLED in several studies and discusses in detail the technical aspects of this dialysis method. However, randomized trials comparing IHD with SLED have not been performed. Also, clinical experience is far more limited with SLED compared to CRRT, and very few randomized studies have compared SLED to CRRT. A first small trial in 39 AKI patients did not find any difference in hemodynamics, and less need for anticoagulation with SLED compared to CRRT.⁷²⁴ An (even smaller) Australian study showed similar control of urea, creatinine, and electrolytes, but a better control of acidosis and less hypotension during the first hours of the treatment with CRRT.^725,726 A recent retrospective analysis examined the mortality data from three general ICUs in different countries that have switched their predominant therapeutic dialysis approach from CRRT to SLED. This change was not associated with a change in mortality.⁷²⁷ In addition, Fieghen et al.⁷²⁸ examined the relative hemodynamic tolerability of SLED and CRRT in critically ill patients with AKI. This study also compared the feasibility of SLED administration with that of CRRT and IHD. Relatively small cohorts of critically ill AKI patients in four critical-care units included 30 patients treated with CRRT, 13 patients with SLED, and 34 patients with IHD. Hemodynamic instability occurred during 22 (56.4%) SLED and 43 (50.0%) CRRT sessions (P = 0.51). In a multivariable analysis that accounted for clustering of multiple sessions within the same patient, the OR for hemodynamic instability with SLED was 1.20 (95% CI 0.58–2.47) compared to CRRT. Significant session interruptions occurred in 16 (16.3%), 30 (34.9%), and 11 (28.2%) of IHD, CRRT, and SLED therapies, respectively. This study concluded that, in critically ill patients with AKI, the administration of SLED is feasible and provides hemodynamic control comparable to CRRT.

In conclusion, in the presence of hemodynamic instability in patients with AKI, CRRT is preferable to standard IHD. SLED may also be tolerated in hemodynamically unstable patients with AKI in settings where other forms of CRRT are not available, but data on comparative efficacy and harm are limited. Once hemodynamic stability is achieved, treatment may be switched to standard IHD.