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INTRODUCTION: Venovenous extracorporeal membrane oxygenation (V-V ECMO) is recommended for the support of patients with severe COVID-19 associated severe respiratory failure (SRF). We report the characteristics and outcome of COVID-19 patients supported with V-V ECMO in a Hungarian centre. METHODS: We retrospectively collected data on all patients admitted with proven SARS CoV-2 infection who received V-V ECMO support between March 2021 and May 2022. RESULTS: Eighteen patients were placed on ECMO during this period, (5 women, age (mean ± SD) 44 ± 10 years, APACHE II score (median (interquartile range)) 12 (10-14.5)). Before ECMO support, they had been hospitalised for 6 (4-11) days. Fifteen patients received noninvasive ventilation for 4 (2-8) days, two patients had high flow nasal oxygen therapy, for one day each. They had already been intubated for 2.5 (1-6) days. Prone position was applied in 15 cases. On the day before ECMO initiation the Lung Injury Score was 3.25 (3-3.26), the PaO2/FiO2 ratio was 71 ± 19 mmHg. The duration of V-V ECMO support was 26 ± 20 days, and the longest run lasted 70 days. Patients were mechanically ventilated for 34 ± 23 days. The intensive care unit (ICU) and the hospital length of stay were 40 ± 28 days and 45 ± 31 days, respectively. Eleven patients were successfully weaned from ECMO. The ICU survival rate was 56%, the in-hospital survival was 50%. All patients who were discharged from hospital reported a good health-related quality of life Rankin score (0-2) at the 5-16 months follow-up. CONCLUSIONS: During the last three waves of the COVID-19 pandemic, we achieved a 56% ICU and a 50% hospital survival rate at our low volume centre.
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The roles of the alveolar and systemic CO2 on the lung mechanics were investigated in dogs subjected to cardiopulmonary bypass. Low-frequency pulmonary impedance data (Z(L)) were collected in open-chest dogs with an alveolar CO2 level (FA(CO2)) of 0.2-7% and during systemic hypercapnia before and after elimination of the vagal tone. Airway resistance (R(aw)), inertance (I(aw)), parenchymal damping (G) and elastance (H) were estimated from the Z(L). The highest R(aw) observed at 0.2% FA(CO2),which decreased markedly up to a FA(CO2) of 2% (212 ± 24%), and remained unchanged under normo- and hypercapnia (FA(CO2) 2-7%). These changes were associated with smaller decreases in I(aw) (-16.6 ± 3.7%), mild elevations in G (25.7 ± 4.7%), and no change in H. Significant increases in all mechanical parameters were observed following systemic hypercapnia; atropine counteracted the R(aw) rises. We conclude that severe alveolar hypocapnia may contribute to minimization of the ventilation-perfusion mismatch by constricting the airways in poorly perfused lung regions. The constrictor potential of systemic hypercapnia is mediated by vagal reflexes.