Continuous ultrafiltration with membrane oxygenation can help patients with COVID-19
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COVID-19 infection has resulted in AKI in about 3% to 15% of cases in the United States, and severe infection in about 15% to 50% of cases.
Fluid resuscitation is an important aspect of management in patients with COVID-19 for various reasons, including intravascular volume depletion from fever, nausea, vomiting and diarrhea (experienced by a subset of patients); prerenal AKI and sepsis.
However, there is no clear endpoint for fluid resuscitation, and the consequence for patients is fluid overload. Patients with fluid overload have worse oxygenation, prolonged stays in the ICU, prolonged duration of mechanical ventilation and increased mortality.
In addition to fluid resuscitation, critically ill patients in the ICU can develop acquired volume overload from medications, nutrition and/or body metabolism. In COVID-19, where lung tissue is already disturbed by the rapidly expanding inflammatory process, volume overload (pulmonary edema) can worsen hypoxia in patients with acute respiratory distress syndrome (ARDS). Also, imbalance in fluid metabolism, protein-rich fluid entrance and pulmonary fluid clearance play a role in pulmonary edema.
ECMO
Extracorporeal membrane oxygenation (ECMO) is a lifesaving technique for critically ill patients. In addition to oxygenation via ECMO, these patients need fluid removal by either administering diuretics or renal replacement therapy (RRT). The American Society of Nephrology has recommended continuous renal replacement therapy (CRRT) as one of the recommended RRT modalities for patients with COVID-19 given the critical illness and hemodynamic instability.
While CRRT is effective for achieving metabolic clearance and treating AKI, slow continuous ultrafiltration (SCUF), a form of CRRT, is an efficient therapy for volume management for some of these patients who have intact kidney function.
Putting patients on diuretics, like furosemide or bumetanide, gives an unpredictable response which can cause problems in the ECMO machine, including increased negative pressure with high urine volume in a short span; interruption in ECMO blood flow and a positive fluid balance/volume overload with decreased urine output.
The advantages of SCUF in COVID-19, in addition to fluid extraction and optimization of volume status, include the ability to do pre-dialysis preparation and troubleshooting outside the patient’s room, thus minimizing exposure and limiting the use of personnel protective equipment. Multiple studies have shown that for ECMO survivors who received CRRT, the overall fluid balance was less than that of non-CRRT patients.
Study
Initially, we conducted a retrospective case series of six patients with COVID-19 on ECMO requiring SCUF for volume removal. Based on the case series, three of six patients who were on ECMO-SCUF survived with a shorter duration on the SCUF and shorter ICU stay. The other three had complications, like AKI, recurrent clotting, anemia and thrombocytopenia.
Given the large data collection we achieved during a period of 2 years (August 2020 to August 2022), we have obtained institutional review board approval for conducting a retrospective observational study in patients with COVID-19 on ECMO with volume overload. Our goal is to analyze the usefulness of SCUF in patients without any metabolic derangements, as it enables controlled fluid removal, lesser complications and better prognosis requiring ECMO and SCUF. Analysis included 58 patients with a mean age of 62 years. Data show that a shorter ECMO to SCUF interval is associated with early fluid overload reversal and improved hemodynamics.
Major drawbacks of using SCUF in critically ill patients are that it is not useful in patients with metabolic abnormalities, as solute removal is minimal, increases risk of intracranial hemorrhage and gastrointestinal bleeding and enhanced hemolysis from shear stress, positive pressure, wall impact forces and properties of non-endothelialized surfaces during combined ECMO and CRRT. Acute prerenal insufficiency with excessive ultrafiltration is a complication as well.
We are hopeful that our study will provide the information we need to determine the best approach for treating fluid overload in these patients with COVID-19.
- References:
- Adapa S, et al. J Clin Med Res. 2020;doi:10.14740/jocmr4160.
- Chen H, et al. Crit Care. 2014;doi:10.1186/s13054-014-0675-x.
- Cui X, et al. Front in Pharma.2021;doi:10.3389/fphar.2021.664349.
- For more information:
- Lakshmi Kannan, MBBS, MD, FASN, is on the adjunct clinical faculty in the department of internal medicine, division of nephrology, Pikeville Medical Center/University of Pikeville Kentucky College of Osteopathic Medicine, Pikeville, Kentucky. She can be reached at lakshmi.kannan@pikevillehospital.org.
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