title: Determinants of Transcutaneous Ear Lobe CO2 Tension (PtCO2) at 37°C During On-Pump Cardiac Surgery.
abstract: OBJECTIVE
  There are no available criteria for determining the optimal flow rate and mean arterial pressure level in patients undergoing cardiopulmonary bypass (CPB). Transcutaneous carbon dioxide tension (PtCO2) has been proposed for microcirculation monitoring and it could be useful for guiding hemodynamic optimization under CPB. The goal of this exploratory study was to determine the factors that influence PtCO2 variations during CPB.
  
  
  METHODS
  Cutaneous ear lobe CO2 tension was monitored along with hemodynamic parameters every 10 minutes during CPB, until aortic unclamping.
  
  
  METHODS
  French university teaching hospital.
  
  
  METHODS
  Patients scheduled for cardiac surgery requiring CPB were prospectively included.
  
  
  METHODS
  None.
  
  
  RESULTS
  A total of 41 patients were included (520 observations). There was a statistically significant association between PaCO2 and PtCO2 (beta = 0.493 [0.154-0.832], p = 0.043), mostly when PaCO2 was outside the normal range. When PaCO2 was normal, PtCO2 was inversely correlated with mean arterial pressure (after adjustment for PaCO2 and body temperature: Beta -0.245, SE = 0.037, p<0.001) but not with CPB flow rate (p = 0.11).
  
  
  CONCLUSIONS
  The factors that influence PtCO2 during CPB cardiac surgery are PaCO2, body temperature, and mean arterial pressure. When PaCO2 is normal, a PtCO2 elevation might be explained by insufficient mean arterial pressure. Whether low PtCO2 values during CPB should trigger the administration of vasoconstrictors remains to be evaluated.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, and Université Paris Descartes-Sorbonne Paris Cité, Paris, France.
authors.forename: Arthur
authors.initials: A
authors.lastname: Neuschwander
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, and Université Paris Descartes-Sorbonne Paris Cité, Paris, France.
authors.forename: Severine
authors.initials: S
authors.lastname: Couffin
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, and Université Paris Descartes-Sorbonne Paris Cité, Paris, France.
authors.forename: Thi Mum
authors.initials: TM
authors.lastname: Huynh
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, and Université Paris Descartes-Sorbonne Paris Cité, Paris, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Cholley
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, and Université Paris Descartes-Sorbonne Paris Cité, Paris, France.
authors.forename: Gabrielle Pinot
authors.initials: GP
authors.lastname: de Villechenon
authors.affiliation: Division of Cardiovascular Surgery, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, and Université Paris Descartes-Sorbonne Paris Cité, Paris, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Achouh
authors.affiliation: Division of Cardiovascular Surgery, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, and Université Paris Descartes-Sorbonne Paris Cité, Paris, France.
authors.forename: Jean Noel
authors.initials: JN
authors.lastname: Fabiani
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, and Université Paris Descartes-Sorbonne Paris Cité, Paris, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Safran
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, and Université Paris Descartes-Sorbonne Paris Cité, Paris, France; ECSTRA Team, Epidemiology and Biostatistics Sorbonne Paris Cité Research Centre UMR 1153, Inserm, Sorbonne Paris Cité, Paris, France. Electronic address: romainpirracchio@yahoo.fr.
authors.forename: Romain
authors.initials: R
authors.lastname: Pirracchio
mesh_terms: D000368:Aged; D001785:Blood Gas Monitoring, Transcutaneous / Q000379:methods; D001831:Body Temperature / Q000502:physiology*; D002245:Carbon Dioxide; D013504:Cardiovascular Surgical Procedures / Q000379:methods / Q000639:trends; D001026:Coronary Artery Bypass / Q000379:methods* / Q000639:trends; D054644:Ear Auricle / Q000098:blood supply*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods* / Q000639:trends; D011446:Prospective Studies
chemical_list: D002245:Carbon Dioxide
keywords: carbon dioxide; cardiopulmonary bypass; microcirculation; monitoring