Critical Illness Myopathy and Trajectory of Recovery in AKI Requiring CRRT

Critical Illness Myopathy and Trajectory of Recovery in Acute Kidney Injury (AKI) Requiring Continuous Renal Replacement Therapy (CRRT): A Prospective Observational Trial

The purpose of this study is to determine whether patients with acute kidney injury requiring renal replacement therapy have a higher incidence of muscle wasting than controls and whether the course of recovery is longer compared to controls.

Acute kidney injury (AKI), the abrupt loss of kidney function, is a common complication that affects more than half of all intensive care unit (ICU) admissions, and it is associated with substantially higher rates of morbidity and mortality in both the short- and the long-term. This is especially true in patients with AKI requiring renal replacement therapy (AKI-RRT), also known as dialysis. An understudied mechanism by which AKI-RRT may contribute to poor clinical outcomes, both in the hospital and after discharge, is through its impact on muscle mass and muscle function. AKI of any severity is known to alter tissue utilization of amino acids, and preliminary data suggest that RRT in the ICU may exacerbate muscle dysfunction through the removal of large quantities of amino acids from the patient's plasma. This study will determine whether patients with AKI-RRT have greater lean muscle loss over 1 week than historical critically ill controls, whether patients with AKI-RRT have diminished recovery of muscle mass and function at 1-3 months following discharge compared to controls, and whether changes in plasma levels of amino acids during hospitalization correlate with loss of muscle function or lack of recovery.

Inclusion Criteria:

• >18 years old
• AKI requiring CRRT, with enrollment within 48 hours of CRRT initiation

Exclusion Criteria:

• ICU admission for >7 days
• RRT of any kind at any time prior to ICU admission
• Chronic kidney disease (CKD) with estimated glomerular filtration rate <20 mL/min/1.73 m2 as calculated by the 2021 CKD-EPI equation
• underlying muscle disorders or muscle atrophy such as quadriplegia or hemiplegia, stroke with residual motor deficits, end-stage liver disease, active alcohol use disorder, active malignancy (other than non-melanoma skin cancer) within 1 year, burns, or other baseline neuromuscular disease
• pregnancy
• concomitant use of other extracorporeal support devices such as ventricular assist devices or extracorporeal membrane oxygenation
• anticipated inability to engage in weight-bearing testing after discharge (e.g., trauma or orthopedic surgery)
• subjects will be ineligible for outpatient testing if they remain on RRT in the week prior to the research appointment