Experience with a veno-venous extra corporeal CO2 removal device: Easy and safe, but only modest improvement in gas exchange.
Introduction: Protective lung ventilation strategy in patients with Adult Respiratory Distress Syndrome (ARDS) has been shown to reduce mortality and long term lung injury.However, this may at times be associated with rising CO2 levels with systemic effects. A new generation of veno-venous Extra Corporeal CO2 Removal (ECCO2R) devices have recently been introduced to support gas exchange.
Aim: We describe the use, effectiveness, safety and outcomes of patients with hypercapnic respiratory failure treated with the Hemolung (ALung) veno-venous device following its introduction in a general ICU at level 1 trauma center.
Methods: Mechanically ventilated adult patients with CO2 >10kPa and/or significant respiratory acidosis (pH<7.25) and/or persistently high peak and plateau pressures (>30cmH2O) treated with protective lung ventilation, with no contraindication to heparinisation were considered for ECCO2R assist using the Hemolung (Alung) device. This was part of our standard of care and was replacing the AV Novalung. Following cannulation (15.5F dual lumen catheter) and connection, blood flow was increased to maximum and sweep gas flow gradually increased over 2 hours to achieve maximal CO2 removal. Primary end points were pCO2, pH and ventilator parameters after starting the device, with secondary end points featuring safety and ease of use.
Results: The device was used in 6 patients with a mean age of 45. Two with severe chest injuries, one inhalational lung injury, one severe acute asthma, and two with pneumonia and lung fibrosis. Tt was commenced within 3 days of mechanical ventilation in 4 patients, at day 6 and day 16 in two. The therapy supplemented with prone position in one patient and nitric oxide in another. Four of the six patients had multi-organ failure at the time of commencement of therapy or soon after. All of these died while still on the device. Of the other two, one was successfully weaned and the other was referred for ECMO. Both were discharged home. Table 1 shows ventilator parameters and blood gas data. There were median reductions in CO2 of 10%, minute volume 28% and driving pressure 19%. Average blood flow with jugular and femoral catheters were 580 ml/min and 440 ml/min respectively, and CO2 removal 104 ml/min and 83 ml/min respectively.
Conclusion: The Alung veno-venous ECCO2R device is easy and safe to use with no complications. It provided modest improvements in gas exchange. To maximize its potential, permissive hypercapnia should still be used. Careful selection of patients is also advised.
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