Prevalence and risk factors of hemodynamic instability associated with preload-dependence during continuous renal replacement therapy in a prospective observational cohort of critically ill patients

Abstract

Background Hemodynamic instability is a frequent complication of continuous renal replacement therapy (CRRT). Postural tests (i.e., passive leg raising in the supine position or Trendelenburg maneuver in the prone position) combined with measurement of cardiac output are highly reliable to identify preload-dependence and may provide new insights into the mechanisms involved in hemodynamic instability related to CRRT (HIRRT). We aimed to assess the prevalence and risk factors of HIRRT associated with preload-dependence in ICU patients. We conducted a single-center prospective observational cohort study in ICU patients with acute kidney injury KDIGO 3, started on CRRT in the last 24 h, and monitored with a PiCCO® device. The primary endpoint was the rate of HIRRT episodes associated with preload-dependence during the first 7 days after inclusion. HIRRT was defined as the occurrence of a mean arterial pressure below 65 mmHg requiring therapeutic intervention. Preload-dependence was assessed by postural tests every 4 h, and during each HIRRT episode. Data are expressed in median [1st quartile–3rd quartile], unless stated otherwise. Results 42 patients (62% male, age 69 [59–77] year, SAPS-2 65 [49–76]) were included 6 [1–16] h after CRRT initiation and studied continuously for 121 [60–147] h. A median of 5 [3–8] HIRRT episodes occurred per patient, for a pooled total of 243 episodes. 131 episodes (54% [CI95% 48–60%]) were associated with preload-dependence, 108 (44%, [CI95% 38–51%]) without preload-dependence, and 4 were unclassified. Multivariate analysis (using variables collected prior to HIRRT) identified the following variables as risk factors for the occurrence of HIRRT associated with preload-dependence: preload-dependence before HIRRT [odds ratio (OR) = 3.82, p < 0.001], delay since last HIRRT episode > 8 h (OR = 0.56, p < 0.05), lactate (OR = 1.21 per 1-mmol L−1 increase, p < 0.05), cardiac index (OR = 0.47 per 1-L min−1 m−2 increase, p < 0.001) and SOFA at ICU admission (OR = 0.91 per 1-point increase, p < 0.001). None of the CRRT settings was identified as risk factor for HIRRT. Conclusions In this single-center study, HIRRT associated with preload-dependence was slightly more frequent than HIRRT without preload-dependence in ICU patients undergoing CRRT. Testing for preload-dependence could help avoiding unnecessary decrease of fluid removal in preload-independent HIRRT during CRRT.

Fluid balance neutralization secured by hemodynamic monitoring versus protocolized standard of care in critically ill patients requiring continuous renal replacement therapy: study protocol of the GO NEUTRAL randomized controlled trial

“…The current study has been preceded by two observational studies led by the coordinating center, whose conclusions have led the investigators to identify a lower than expected rate of preload-dependent hemodynamic instability episodes in the critically ill population and to test the hypothesis that UF NET may be secured if a protocolized hemodynamic monitoring is performed thoroughly, aiming to individualize care and optimize fluid balance control [ 9 , 31 ].…”

“…All have experience in advanced hemodynamic monitoring, used in routine care by the nursing staff. The application of the hemodynamic assessment and determination of profiles takes less than 5 min every 4 h. Also, in an observational study assessing the causes of hypotension in critically ill patients requiring CRRT, the enrollment rate of the coordinating center was between 1 and 2 per month over the study period (12 to 24 enrolled patients per year) [ 9 ].…”

“…However, disproportionate net ultrafiltration may induce a state of preload dependence and decreased cardiac output, which will in turn impair organ perfusion and potentially patient outcome [ 7 , 8 ]. Indeed, hemodynamic instability episodes are frequent in this population; yet, in a single-center observational study performed in patients treated with continuous renal replacement therapy (CRRT), approximately 50% of the hemodynamic instability episodes were not associated with a preload dependent status (i.e., were not related to a decrease in cardiac preload), as identified by a positive postural maneuver (passive leg raising or Trendelenburg maneuver) [ 9 ]. Also, a positive preload dependence test at RRT start was associated with an increased risk of arterial hypotension during intermittent RRT [ 10 ].…”

Proceedings of the 2022 UAB CRRT Academy: Non-Invasive Hemodynamic Monitoring to Guide Fluid Removal with CRRT and Proliferation of Extracorporeal Blood Purification Devices

“…Adding to the complexity of this delicate balance, the pathophysiology of hypotension during RRT is complex, with only a subset of the hypotensive episodes that occur during RRT being due to preload dependence [66, 67], suggesting that some patients may benefit from ongoing volume removal with RRT despite hypotension and underscoring the need for accurate individualized measures of volume status (Fig. 3).…”

Practice Variation in the Prescription of Volume Removal with Acute KRT

“…The pathophysiology of intradialytic hypotension in critically ill patients is complicated, with mechanistic studies suggesting that only some hypotensive episodes are caused by volume removal. 6 This implies that some patients may benefit from ongoing net ultrafiltration despite experiencing intradialytic hypotension. Without prospective data to guide clinicians on the optimal approach to ultrafiltration in the ICU, the best way to remove excess fluid with KRT in critically ill patients remains unclear.…”