title: Can transcutaneous carbon dioxide pressure be a surrogate of blood gas samples for spontaneously breathing emergency patients? The ERNESTO experience.
abstract: BACKGROUND
  It is known that the arterial carbon dioxide pressure (PaCO2) is useful for emergency physicians to assess the severity of dyspnoeic spontaneously breathing patients. Transcutaneous carbon dioxide pressure (PtcCO2) measurements could be a non-invasive alternative to PaCO2 measurements obtained by blood gas samples, as suggested in previous studies. This study evaluates the reliability of a new device in the emergency department (ED).
  
  
  METHODS
  We prospectively included patients presenting to the ED with respiratory distress who were breathing spontaneously or under non-invasive ventilation. We simultaneously performed arterial blood gas measurements and measurement of PtcCO2 using a sensor placed either on the forearm or the side of the chest and connected to the TCM4 CombiM device. The agreement between PaCO2 and PtcCO2 was assessed using the Bland-Altman method.
  
  
  RESULTS
  Sixty-seven spontaneously breathing patients were prospectively included (mean age 70 years, 52% men) and 64 first measurements of PtcCO2 (out of 67) were analysed out of the 97 performed. Nineteen patients (28%) had pneumonia, 19 (28%) had acute heart failure and 19 (28%) had an exacerbation of chronic obstructive pulmonary disease. Mean PaCO2 was 49 mm Hg (range 22-103). The mean difference between PaCO2 and PtcCO2 was 9 mm Hg (range -47 to +54) with 95% limits of agreement of -21.8 mm Hg and 39.7 mm Hg. Only 36.3% of the measurement differences were within 5 mm Hg.
  
  
  CONCLUSIONS
  Our results show that PtcCO2 measured by the TCM4 device could not replace PaCO2 obtained by arterial blood gas analysis.
authors.affiliation: Department of Emergency Medicine and Surgery, Centre Hospitalo-Universitaire Tenon Saint Antoine, Assistance-Publique Hôpitaux de Paris (AP-HP), Paris, France Department of Emergency Medicine, Centre Hospitalo-Universitaire Rouen, Rouen, France Institut National de la Sante et de la Recherche Médicale U1096, Université de Rouen, Rouen, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Peschanski
authors.affiliation: Department of Emergency Medicine and Surgery, Centre Hospitalo-Universitaire Tenon Saint Antoine, Assistance-Publique Hôpitaux de Paris (AP-HP), Paris, France.
authors.forename: Léa
authors.initials: L
authors.lastname: Garcia
authors.affiliation: Department of Emergency Medicine, Centre Hospitalo-Universitaire Rouen, Rouen, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Delasalle
authors.affiliation: Department of Emergency Medicine and Surgery, Centre Hospitalo-Universitaire Tenon Saint Antoine, Assistance-Publique Hôpitaux de Paris (AP-HP), Paris, France.
authors.forename: Lynda
authors.initials: L
authors.lastname: Mzabi
authors.affiliation: Department of Emergency Medicine and Surgery, Centre Hospitalo-Universitaire Tenon Saint Antoine, Assistance-Publique Hôpitaux de Paris (AP-HP), Paris, France.
authors.forename: Edwin
authors.initials: E
authors.lastname: Rouff
authors.affiliation: Department of Emergency Medicine and Surgery, Centre Hospitalo-Universitaire Tenon Saint Antoine, Assistance-Publique Hôpitaux de Paris (AP-HP), Paris, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Dautheville
authors.affiliation: Department of Emergency Medicine and Surgery, Centre Hospitalo-Universitaire Tenon Saint Antoine, Assistance-Publique Hôpitaux de Paris (AP-HP), Paris, France.
authors.forename: Fayrouz
authors.initials: F
authors.lastname: Renai
authors.affiliation: Department of Emergency Medicine and Surgery, Centre Hospitalo-Universitaire Tenon Saint Antoine, Assistance-Publique Hôpitaux de Paris (AP-HP), Paris, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Kieffer
authors.affiliation: Department of Biochemistry, Centre Hospitalo-Universitaire Tenon Saint Antoine, Paris, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Lefevre
authors.affiliation: Department of Emergency Medicine and Surgery, Groupe Hospitalo-Universitaire Pitié-Salpêtrière, Paris, France DHU Fighting against Ageing and Stress (FAST), Paris Sorbonne Université, Université Paris-06, Paris, France.
authors.forename: Yonathan
authors.initials: Y
authors.lastname: Freund
authors.affiliation: Department of Emergency Medicine and Surgery, Centre Hospitalo-Universitaire Tenon Saint Antoine, Assistance-Publique Hôpitaux de Paris (AP-HP), Paris, France DHU Fighting against Ageing and Stress (FAST), Paris Sorbonne Université, Université Paris-06, Paris, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Ray
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001785:Blood Gas Monitoring, Transcutaneous / Q000379:methods*; D002245:Carbon Dioxide / Q000097:blood*; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010313:Partial Pressure; D011446:Prospective Studies; D015203:Reproducibility of Results; D012128:Respiratory Distress Syndrome / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide
keywords: COPD; non invasive; qualitative research; respiratory; ventilation