Extracorporeal CO2 removal and renal replacement therapy in acute severe respiratory failure in COVID-19 pneumonia: Case report

Extracorporeal Carbon Dioxide Removal: From Pathophysiology to Clinical Applications; Focus on Combined Continuous Renal Replacement Therapy

Lung-protective ventilation (LPV) with low tidal volumes can significantly increase the survival of patients with acute respiratory distress syndrome (ARDS) by limiting ventilator-induced lung injuries. However, one of the main concerns regarding the use of LPV is the risk of developing hypercapnia and respiratory acidosis, which may limit the clinical application of this strategy. This is the reason why different extracorporeal CO₂ removal (ECCO₂R) techniques and devices have been developed. They include low-flow or high-flow systems that may be performed with dedicated platforms or, alternatively, combined with continuous renal replacement therapy (CRRT). ECCO₂R has demonstrated effectiveness in controlling PaCO₂ levels, thus allowing LPV in patients with ARDS from different causes, including those affected by Coronavirus disease 2019 (COVID-19). Similarly, the suitability and safety of combined ECCO₂R and CRRT (ECCO₂R-CRRT), which provides CO₂ removal and kidney support simultaneously, have been reported in both retrospective and prospective studies. However, due to the complexity of ARDS patients and the limitations of current evidence, the actual impact of ECCO₂R on patient outcome still remains to be defined. In this review, we discuss the main principles of ECCO₂R and its clinical application in ARDS patients, in particular looking at clinical experiences of combined ECCO₂R-CRRT treatments.

Effect of extracorporeal carbon dioxide removal on respiratory quotient measured by indirect calorimetry: Unraveling the mystery

NEW FINDINGS

Several studies report progressive hypoxemia once extracorporeal carbon dioxide removal is started in patients with hypercapnic respiratory failure, possibly due to an altered respiratory quotient. In this quality control report we show that the respiratory quotient is only altered minimally when extracorporeal carbon dioxide removal is started, and that the progressive hypoxemia is rather due to an increase of shunt.

ABSTRACT

The use of extracorporeal carbon dioxide removal (ECCO₂ R) has been proposed in patients with Acute Respiratory Distress Syndrome to achieve lung-protective ventilation and in patients with selective hypercapnic respiratory failure. However, several studies report progressive hypoxemia as expressed by a need to increase the inspired oxygen fraction to maintain adequate oxygenation or by a decrease in PaO₂ /FiO₂ ratio once ECCO₂ R is started. We present a case of a patient who was admitted to the intensive care unit for a COVID-19 pneumonia and was intubated for hypercapnic respiratory insufficiency. ECCO₂ R was started and the patient subsequently developed progressive hypoxemia. To test whether the hypoxemia was due to the ECCO₂ R blood samples were taken in different settings: A) "no ECCO₂ R": blood flow 150 ml/min with a ECCO₂ R gas flow of 0 l/min, and B) "with ECCO₂ R": blood flow 400 ml/min with gasflow 12 l/min. We measured PaO₂ , P_A O₂ , PaO₂ /FiO₂ ratio, DA-aO_2, PaCO₂ and the respiratory quotient by indirect calorimetry in each setting. Respiratory quotient was 0,60 without ECCO₂ R and 0,57 with ECCO₂ R. The P_A O₂ was 220,4 mmHg without ECCO₂ R and raised to 240,3 mmHg with ECCO₂ R and the PaO₂ /FiO₂ ratio decreased from 177 to 171. Our study showed only a minimal change in respiratory quotient when ECCO₂ R was started. We were the first to directly measure the respiratory quotient before and after the initiation of ECCO₂ R in a patient with hypercapnic respiratory failure. This article is protected by copyright. All rights reserved.

Antibiotics and ECMO in the Adult Population-Persistent Challenges and Practical Guides

Extracorporeal membrane oxygenation (ECMO) is an emerging treatment modality associated with a high frequency of antibiotic use. However, several covariables emerge during ECMO implementation, potentially jeopardizing the success of antimicrobial therapy. These variables include but are not limited to: the increased volume of distribution, altered clearance, and adsorption into circuit components, in addition to complex interactions of antibiotics in critical care illness. Furthermore, ECMO complicates the assessment of antibiotic effectiveness as fever, or other signs may not be easily detected, the immunogenicity of the circuit affects procalcitonin levels and other inflammatory markers while disrupting the immune system. We provided a review of pharmacokinetics and pharmacodynamics during ECMO, emphasizing practical application and review of patient-, illness-, and ECMO hardware-related factors.