Although invasive mechanical ventilation is a keystone in the management of acute respiratory distress syndrome, it has been shown to cause pulmonary damage (ventilator-induced lung injury).1

Therefore, extracorporeal ventilation techniques have gained reputation, with venovenous extracorporeal membrane oxygenation (VV-ECMO) and extracorporeal CO2 removal (ECCO2R) being the most notable ones.2,3

Despite their popularity there is no evidence supporting their combined use. Here, we present a case in which ECCO2R was employed as a bridge technique to enable complete liberation of VV-ECMO in a challenging weaning situation.

We report the case of a 24-year-old patient admitted with acute respiratory failure. The patient had a history of tuberculous lymphangitis ten years prior. On arrival, she was in poor clinical condition, with a baseline oxygen saturation of 55%, fever, and tachypnea. Orotracheal intubation and initiation of invasive mechanical ventilation were performed. Nasopharyngeal cultures obtained at arrival were positive for influenza B virus. A chest X-ray revealed extensive bilateral lung consolidations (additional supplemental files, Fig. 1).

Despite treatment, patient's respiratory status continued to deteriorate, and she was considered a candidate for VV-ECMO. Cannulation was performed through the right femoral vein (21-Fr cannula) and right jugular vein (17-Fr cannula).

Lung stiffness with static lung compliance below 20ml/cmH2O was observed. After seven days of VV-ECMO therapy, successive trials of temporary disconnection were performed, showing a marked increase in respiratory effort and pCO2 levels, preventing ECMO withdrawal (Table 1). Additionally, the patient experienced tracheal bleeding, requiring the discontinuation of systemic anticoagulation. Around day 12, a clot emerged in the oxygenation membrane, accompanied by a progressive loss of its effectiveness.

Due to ECMO weaning failure and a lack of improvement in pulmonary compliance, at day 16 we decided to initiate ECCO2R therapy using the PrismaLung+® system (Baxter International Inc.). This veno-venous extracorporeal CO2 removal system consists of a polymethylpentene membrane coated with phospholipid, with a surface area of 0.8m2, coupled with a renal replacement therapy (RRT) system (PrisMax2®, Baxter International Inc.). A 13Fr double-lumen catheter was inserted into the left femoral vein and PrismaLung+® system was started with a gradually increasing blood flow of up to 400ml/min and a gas sweep flow of 10lpm. Instead of systemic anticoagulation, we employed anticoagulation of the extra-corporeal circuit with a fixed dose of 500IU/h of unfractionated heparin.

Within the next 24h, a decrease in pCO2 was observed, and ECMO was successfully removed. ECCO2R was removed three days later without complications derived from its use.

The patient was transferred to a regular hospital ward after 26 days and 4 days later, she was discharged home.

Despite current recommendations there is a reported ECMO weaning failure rate of 40%. Main predictors for weaning failure were an increased pCO2 level and increased respiratory rate.4

Advances in technology to deliver ECCO2R therapy have simplified this approach, making feasible the allocation of a membrane lung within a conventional RRT circuit to allow simultaneous removal of fluids, metabolites and CO2. Therefore, this low-flow technique, based on the use of less invasive catheters with lower anticoagulation requirements could potentially decrease the number of adverse events compared to ECMO.5

In our case, ECCO2R therapy allowed us to reduce the risk of bleeding and improved active mobility of the patient enabling the shift from controlled ventilation to pressure support.

We propose the use of ECCO2R as a bridge therapy for ECMO-VV liberation in patients with lung stiffness (defined as static lung compliance <20ml/cmH2O) who failed weaning trials due to increased work of breathing and/or hypercapnia rather than hypoxemia. To achieve this, we propose the following management algorithm (additional supplemental files, Fig. 2).