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Can transcutaneous carbon dioxide pressure be a surrogate of blood gas samples for spontaneously breathing emergency patients? The ERNESTO experience
  1. Nicolas Peschanski1,2,3,
  2. Léa Garcia1,
  3. Emilie Delasalle2,
  4. Lynda Mzabi1,
  5. Edwin Rouff1,
  6. Sandrine Dautheville1,
  7. Fayrouz Renai1,
  8. Yann Kieffer1,
  9. Guillaume Lefevre4,
  10. Yonathan Freund5,6,
  11. Patrick Ray1,6
  1. 1Department of Emergency Medicine and Surgery, Centre Hospitalo-Universitaire Tenon Saint Antoine, Assistance-Publique Hôpitaux de Paris (AP-HP), Paris, France
  2. 2Department of Emergency Medicine, Centre Hospitalo-Universitaire Rouen, Rouen, France
  3. 3Institut National de la Sante et de la Recherche Médicale U1096, Université de Rouen, Rouen, France
  4. 4Department of Biochemistry, Centre Hospitalo-Universitaire Tenon Saint Antoine, Paris, France
  5. 5Department of Emergency Medicine and Surgery, Groupe Hospitalo-Universitaire Pitié-Salpêtrière, Paris, France
  6. 6DHU Fighting against Ageing and Stress (FAST), Paris Sorbonne Université, Université Paris-06, Paris, France
  1. Correspondence to Dr Nicolas Peschanski, CHU de Rouen, Service des Urgences Adultes, Pavillon Dévé 2, Hôpital Charles Nicolle, 1 rue de Germont 76031, Rouen, Cedex 76000, France; n.peschanski{at}


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.

  • respiratory
  • ventilation
  • COPD
  • non invasive
  • qualitative research

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