title: Blood oxygenation and decarboxylation determinants during venovenous ECMO for respiratory failure in adults.
abstract: OBJECTIVE
  This study was designed to optimize the latest generation venovenous (vv)-extracorporeal membrane oxygenation (ECMO)-circuit configuration and settings based on the evaluation of blood oxygenation and CO2 removal determinants in patients with severe acute respiratory distress syndrome (ARDS) on ultraprotective mechanical ventilation.
  
  
  METHODS
  Blood gases and hemodynamic parameters were evaluated after changing one of three ECMO settings, namely, circuit blood flow, FiO(2ECMO) (fraction of inspired oxygen in circuit), or sweep gas flow ventilating the membrane, while leaving the other two parameters at their maximum setting.
  
  
  RESULTS
  Ten mechanically ventilated ARDS patients (mean age 44 ± 16 years; 6 males; mean hemoglobin 8.0 ± 1.8 g/dL) on ECMO for a mean of 9.0 ± 3.8 days) receiving femoro-jugular vv-ECMO were evaluated. vv-ECMO blood flow and FiO(2ECMO) determined arterial oxygenation. Decreasing the ECMO flow from its baseline maximum value (5.8 ± 0.8 L/min) to 40% less (2.4 ± 0.3 L/min) significantly decreased mean PaO2 (arterial oxygen tension; 88 ± 24 to 45 ± 9 mm Hg; p < 0.001) and SaO2 (oxygen saturation; 97 ± 2 to 82 ± 10%; p < 0.001). When the ECMO flow/cardiac output was >60%, SaO2 was always >90%. Alternatively, the rate of sweep gas flow through the membrane lung determined blood decarboxylation, while PaCO2 (arterial carbon dioxide tension) was unaffected when the ECMO blood flow and FiO(2ECMO) were reduced to <2.5 L/min and 40%, respectively. In three additional patients evaluated before and after red blood cell transfusion, O2 delivery increased after transfusion, allowing lower ECMO flows to reach adequate SaO2.
  
  
  CONCLUSIONS
  For severe ARDS patients receiving femoro-jugular vv-ECMO, blood flow was the main determinant of arterial oxygenation, while CO2 elimination depended on sweep gas flow through the oxygenator. An ECMO flow/cardiac output >60% was constantly associated with adequate blood oxygenation and oxygen transport and delivery.
authors.affiliation: Service de Réanimation Médicale, Groupe Hospitalier Pitié-Salpêtrière, Institute of Cardiometabolism and Nutrition, Assistance Publique-Hôpitaux de Paris-Université Pierre et Marie Curie, Paris 6, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Schmidt
authors.forename: Guillaume
authors.initials: G
authors.lastname: Tachon
authors.forename: Christine
authors.initials: C
authors.lastname: Devilliers
authors.forename: Grégoire
authors.initials: G
authors.lastname: Muller
authors.forename: Guillaume
authors.initials: G
authors.lastname: Hekimian
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bréchot
authors.forename: Sybille
authors.initials: S
authors.lastname: Merceron
authors.forename: Charles Edouard
authors.initials: CE
authors.lastname: Luyt
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Trouillet
authors.forename: Jean
authors.initials: J
authors.lastname: Chastre
authors.forename: Pascal
authors.initials: P
authors.lastname: Leprince
authors.forename: Alain
authors.initials: A
authors.lastname: Combes
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001784:Blood Gas Analysis; D016009:Chi-Square Distribution; D003653:Decarboxylation; D017707:Erythrocyte Transfusion; D015199:Extracorporeal Membrane Oxygenation / Q000379:methods*; D005260:Female; D006439:Hemodynamics; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D012128:Respiratory Distress Syndrome / Q000628:therapy*; D016896:Treatment Outcome
chemical_list: D006454:Hemoglobins; D010100:Oxygen