Extracorporeal membrane oxygenation versus invasive ventilation in patients with COVID-19 acute respiratory distress syndrome and pneumomediastinum: A cohort trial.

BACKGROUND: Patients with severe respiratory failure due to COVID-19 who are not under mechanical ventilation may develop severe hypoxemia when complicated with spontaneous pneumomediastinum (PM). These patients may be harmed by invasive ventilation. Alternatively, veno-venous (V-V) extracorporeal membrane oxygenation (ECMO) may be applied. We report on the efficacy of V-V ECMO and invasive ventilation as initial advanced respiratory support in patients with COVID-19 and acute respiratory failure due to spontaneous PM. METHODS: This was a retrospective cohort study performed between March 2020 and January 2022. Enrolled patients had COVID-19 and acute respiratory failure due to spontaneous PM and were not invasively ventilated. Patients were treated in the intensive care unit (ICU) with invasive ventilation (invasive ventilation group) or V-V ECMO support (V-V ECMO group) as the main therapeutic option. The primary outcomes were mortality and ICU discharge at 90 days after ICU admission. RESULTS: Twenty-two patients were included in this study (invasive ventilation group: 13 [59%]; V-V ECMO group: 9 [41%]). The V-V ECMO strategy was significantly associated with lower mortality (hazard ratio [HR] 0.33 [95% CI 0.12-0.97], p = 0.04). Five (38%) patients in the V-V ECMO group were intubated and eight (89%) patients in the invasive ventilation group required V-V ECMO support within 30 days from ICU admission. Three (33%) patients in the V-V ECMO group were discharged from ICU within 90 days compared to one (8%) patient in the invasive ventilation group (HR 4.71 [95% CI 0.48-45.3], p = 0.18). CONCLUSIONS: Preliminary data suggest that V-V ECMO without invasive ventilation may improve survival in COVID-19-related acute respiratory failure due to spontaneous PM. The study's retrospective design and limited sample size underscore the necessity for additional investigation and warrant caution.

Ratio of carbon dioxide veno-arterial difference to oxygen arterial-venous difference is not associated with lactate decrease after fluid bolus in critically ill patients with hyperlactatemia: results from a prospective observational study.

BACKGROUND: High ratio of the carbon dioxide veno-arterial difference to the oxygen arterial-venous difference (PvaCO2/CavO2) is associated with fluid bolus (FB) induced increase in oxygen consumption (VO2). This study investigated whether PvaCO2/CavO2 was associated with decreases in blood-lactate levels FB in critically ill patients with hyperlactatemia. METHODS: This prospective observational study examined adult patients in the intensive care unit (ICU) with lactate levels > 1.5 mmol/L who received FBs. Blood-lactate levels were measured before and after FB under unchanged metabolic, respiratory, and hemodynamic conditions. The primary outcome was blood-lactate levels after FB. Significant decreases in blood-lactate levels were considered as blood-lactate levels < 1.5 mmol/L or a decrease of more than 10% compared to baseline. RESULTS: The study enrolled 40 critically ill patients, and their median concentration of blood lactate was 2.6 [IQR:1.9 - 3.8] mmol/L. There were 27 (68%) patients with PvaCO2/CavO2 ≥ 1.4 mmHg/ml, and 10 of them had an increase in oxygen consumption (dVO2) ≥ 15% after FB, while 13 (32%) patients had PvaCO2/CavO2 < 1.4 mmHg/ml before FB, and none of them had dVO2 ≥ 15% after FB. FB increased the cardiac index in patients with high and low preinfusion PvaCO2/CavO2 (13.4% [IQR: 8.3 - 20.2] vs. 8.8% [IQR: 2.9 - 17.4], p = 0.34). Baseline PvaCO2/CavO2 was not found to be associated with a decrease in blood lactate after FB (OR: 0.88 [95% CI: 0.39 - 1.98], p = 0.76). A positive correlation was observed between changes in blood lactate and baseline PvaCO2/CavO2 (r = 0.35, p = 0.02). CONCLUSIONS: In critically ill patients with hyperlactatemia, PvaCO2/CavO2 before FB cannot be used to predict decreases in blood-lactate levels after FB. Increased PvaCO2/CavO2 is associated with less decrease in blood-lactate levels.

Hyperammonemia, the Last Indication of High-Volume Hemodiafiltration in Adult and Children: A Structured Review.

Ammonia is a neurotoxic molecule that causes cerebral edema and encephalopathy. Ammonia is either produced in excess or poorly purified during severe hepatic insufficiency, poisoning, infection, and inborn errors of metabolism. During continuous renal replacement therapy, ammonia clearance is determined by the dialysate flow rate and the dialyzer surface area. Extra-renal blood purification for ammonia clearance has been studied in neonates with urea cycle disorders. Prognostic factors affecting patient outcome are thought to be the duration of coma, the patient's clinical status prior to dialysis, and the ammonia removal rate. In this review, we discuss the various dialytic modalities used for ammonia clearance as well as the thresholds for initiating dialysis and the better strategy ensures rapid patient protection from cerebral edema and herniation induced by hyperammonemia.