Extra-Corporeal Carbon Dioxide Removal in Exacerbations of Chronic Obstructive Pulmonary Disease

Around 20% of the patients requiring hospitalization for Acute Exacerbation of Chronic Obstructive Pulmonary Disease (AECOPD) develop hypercapnia, which is associated with an increased risk of death. Once Non Invasive Ventilation (NIV) has been initiated, a reduction in Respiratory Rate (RR) and improvement in pH within 4 h predicts NIV success. If pH \<7.25 and RR \>35 breath per minutes persist, NIV failure is likely. Worsening acidosis, after initial improvement with NIV, is also associated with a worse prognosis. In addition, it has been shown that delaying intubation in patients at high risk for NIV failure has a negative impact on patient survival. Hence, assessing the risk of NIV failure is extremely important. NIV has some limitations: a) intolerance, discomfort and claustrophobia requiring frequent interruptions; b) poor patient-ventilator synchrony, especially in presence of air leaks or high ventilatory requirements. Since removing carbon dioxide by means of an artificial lung reduces the minute ventilation required to maintain an acceptable arterial partial pressure of carbon dioxide (PaCO2), the investigators hypothesize that applying Extra-Corporeal CO2 Removal (ECCO2R) in high-risk AECOPD patients may reduce the incidence of NIV failure and improve patient-ventilator interaction. After the beginning of ECCO2R, NIV could be gradually replaced by High Flow Nasal Cannula Oxygen Therapy (HFNCOT), potentially reducing the risk of ventilator induced lung injury, improving patient's comfort and probably allowing the adoption of a more physiologically "noisy" pattern of spontaneous breathing.


Eligibility Criteria:
Inclusion Criteria:

Patients admitted to Emergency or Pulmonology Department, with history of COPD (pulmonary function test available, any Global Obstructive Lung Disease -GOLD- stage), treated with NIV for acute hypercapnic respiratory failure due to AECOPD defined by:

* pH \<7.35 + PaCO2 \>45 mmHg (acute hypercapnic respiratory failure) or pH \<7.35 + PaCO2 \> 20% of baseline value (acute on chronic hypercapnic respiratory failure)
* Acute worsening of respiratory symptoms that results in additional therapy
* Respiratory failure not fully explainable with cardiac failure and at high risk for NIV failure, defined by:
* No improvement or worsening of respiratory acidosis (pH \<7.35 and PaCO2 \>45 mmHg) after 2 hours of NIV + one of the following: RR ≥30 bpm; use of accessory respiratory muscle or paradoxical breathing (Combination criteria for NIV failure) or
* Glasgow Coma Scale ≤ 11 after 2 hours of NIV (Single criteria for NIV failure) or
* Inability to fit mask (facial deformity/intervention/burns) or marked intolerance to interface because of patient's agitation (Single Criteria for NIV failure)

Exclusion Criteria:

* Age \>80 years old
* Contraindications to anticoagulation (any of the following: platelet count \<30.000/mm3; activated partial thromboplastin time (aPTT) \>1,5; stroke or severe head trauma or intracranial arteriovenous malformation or cerebral aneurysm in the previous 3 months; central nervous system mass lesion; history of congenital bleeding diatheses; gastro-intestinal bleeding in the previous 6 weeks; gastro-esophageal varices)
* Cirrhosis
* PaO2/FiO2 ≤ 150 mmHg
* Hemodynamic instability (80-90 mmHg increase or 30-40 mmHg decrease systolic arterial pressure compared to baseline value or need of vasopressors to maintain systolic blood pressure higher than 85 mmHg or electrocardiogram evidence of ischemia/arrhythmias)
* Body Mass Index ≥37
* Impending respiratory arrest
* Catheter access to femoral vein or jugular vein impossible
* Patient moribund, decision to limit therapeutic interventions
* Opposition to participate obtained from the patient or their legally acceptable representative