Feasibility and safety of low-flow extracorporeal carbon dioxide removal to facilitate ultra-protective ventilation in patients with moderate acute respiratory distress syndrome

Abstract

BackgroundMechanical ventilation with a tidal volume (VT) of 6 mL/kg/predicted body weight (PBW), to maintain plateau pressure (Pplat) lower than 30 cmH2O, does not completely avoid the risk of ventilator induced lung injury (VILI). The aim of this study was to evaluate safety and feasibility of a ventilation strategy consisting of very low VT combined with extracorporeal carbon dioxide removal (ECCO2R).MethodsIn fifteen patients with moderate ARDS, VT was reduced from baseline to 4 mL/kg PBW while PEEP was increased to target a plateau pressure – (Pplat) between 23 and 25 cmH2O. Low-flow ECCO2R was initiated when respiratory acidosis developed (pH < 7.25, PaCO2 > 60 mmHg). Ventilation parameters (VT, respiratory rate, PEEP), respiratory compliance (CRS), driving pressure (DeltaP = VT/CRS), arterial blood gases, and ECCO2R system operational characteristics were collected during the period of ultra-protective ventilation. Patients were weaned from ECCO2R when PaO2/FiO2 was higher than 200 and could tolerate conventional ventilation settings. Complications, mortality at day 28, need for prone positioning and extracorporeal membrane oxygenation, and data on weaning from both MV and ECCO2R were also collected.ResultsDuring the 2 h run in phase, VT reduction from baseline (6.2 mL/kg PBW) to approximately 4 mL/kg PBW caused respiratory acidosis (pH < 7.25) in all fifteen patients. At steady state, ECCO2R with an average blood flow of 435 mL/min and sweep gas flow of 10 L/min was effective at correcting pH and PaCO2 to within 10 % of baseline values. PEEP values tended to increase at VT of 4 mL/kg from 12.2 to 14.5 cmH2O, but this change was not statistically significant. Driving pressure was significantly reduced during the first two days compared to baseline (from 13.9 to 11.6 cmH2O; p < 0.05) and there were no significant differences in the values of respiratory system compliance. Rescue therapies for life threatening hypoxemia such as prone position and ECMO were necessary in four and two patients, respectively. Only two study-related adverse events were observed (intravascular hemolysis and femoral catheter kinking).ConclusionsThe low-flow ECCO2R system safely facilitates a low volume, low pressure ultra-protective mechanical ventilation strategy in patients with moderate ARDS.

ARDS: challenges in patient care and frontiers in research

“…This technique should only be used in the most severe cases of ARDS [34], and only by well-trained staff [35]. Extracorporeal carbon dioxide techniques have been used to allow mechanical ventilatory support at very low tidal volumes (3-4 mL·kg −1 PBW) [36,37]. However, convincing evidence of the benefit of both techniques is absent and eagerly awaited.…”

Mechanical Ventilation during Extracorporeal Membrane Oxygenation in Patients with Acute Severe Respiratory Failure

“…The result remained unchanged even after multivariable adjustment (OR: 1.33; 95% CI: 1.14–1.59; p < 0.01). More recently, some authors also explored the use of ultra-protective ventilation (i.e., tidal volume reduced to 4 mL/kg predicted body weight while PEEP was increased to target a plateau pressure between 23 and 25 cmH 2 O) with the help of low-flow extracorporeal carbon dioxide removal (ECCO 2 R) in moderate ARDS [50]. …”

Do we need randomized clinical trials in extracorporeal respiratory support? No

“…We may wonder, however, what change in mortality we may expect on decreasing the tidal volume from 6 to 4 ml/kg PBW in a moderate ARDS population, where the chances of developing VILI are undoubtedly lower than in the severe ARDS population. Further, if PEEP is not increased in this population, lifethreatening hypoxemia may be anticipated, as a result of the reduction of mean airway pressure [12,13]. The rationale for such an RCT is weak and anyway it is hard to expect, in moderate ARDS patients (having a ca.…”