Impatto della rimozione extracorporea di CO2 a bassi flussi sulla funzionalità ventricolare destra e sull’emodinamica polmonare nella sindrome da distress respiratorio acuto

INGLESE

INTRODUCTION: Acute respiratory distress syndrome (ARDS) is responsible for injuries to the alveolar epithelium and microvascular endothelium, which result in severe hypoxemia, decreased pulmonary compliance, increased pulmonary vascular resistance and right ventricle afterload. Positive-pressure ventilation is required to correct ARDS-induced hypoxemia. However, mechanical ventilation induces additional lung injuries due to overdistention, repeated stretch to the alveoli, and increased inflammatory mediator levels. Right ventricular dysfunction is a common complication of ARDS, contributing to mortality. Despite in patients with acute lung injury mechanical ventilation with a lower tidal volume results in decreased mortality, a reduction in tidal volume can lead to hypercapnia, which may consequently result in respiratory acidosis, increasing right ventricular afterload and reducing ventricular function. Extracorporeal support separating carbon dioxide removal from oxygen uptake (ECCO2R) has been proposed as therapy for severe case of ARDS. With this technique, carbon dioxide is partially removed by a pump-driven veno-venous bypass, and oxygenation is accomplished by high levels of positive end-expiratory pressure (PEEP). AIM OF THE STUDY: Purpose of this prospective study is to evaluate effectiveness of low flow ECCO2R in facilitating protective ventilation and role of CO2 removal on right ventricle function and on pulmonary hypertension predicted by right ventricular overload indices. MATERIALS AND METHODS: Extracorporeal circulation was performed by an 13-14 cm hemodialysis venous catheter. ECCO2R was provided by a low flow CO2 removal device with polymethylpentene, hollow fiber, gas-exchanger membrane. CO2 removal could be combined to renal replacement therapy, where indicated. Hemodynamic, arterial blood-gas and ultrasonography data were collected at baseline, at 2 hrs after CO2 removal start and at 2 hrs after CO2 removal stop. RISULTS AND DISCUSSION: We performed 10 treatments for a total of 546 hours between October 2021 and April 2024 on a group of patients suffering from moderate-severe ARDS and hypercapnic refractory acidosis. In this case series, veno-venous CO2 low flow removal during ARDS was very effective to achieve normocarbia and to normalize acidosis, while maintaining protective ventilation under a safe tidal volume. Furthermore, increase of RSV (p<0,0001), despite extracorporeal circulation, demonstrates a circulation improvement, probably due to right afterload reduction, as suggested to PAsP (p<0,0001) and left ventricle ESEI (p=0,03) variation, associated with a constant TAPSE value. Moreover, we observed an important relationship between hypercapnia and pH correction with right systolic overload improvement (r=0,628;p<0,0001) as with tidal volume reduction and RSV optimization (r=-0,40;p=0,029). CONCLUSIONS: Low flow ECCO2R technique is very effective to normalize acidosis and to facilitate ultraprotective ventilation in ARDS, despite its minimal invasivity. Hypercapnia and acidosis correction, induced by low flow ECCO2R, is associated with afterload reduction, ameliorating right ventricular dysfunction.