title: Noninvasive Measurement of Carbon Dioxide during One-Lung Ventilation with Low Tidal Volume for Two Hours: End-Tidal versus Transcutaneous Techniques.
abstract: BACKGROUND
  There may be significant difference between measurement of end-tidal carbon dioxide partial pressure (PetCO2) and arterial carbon dioxide partial pressure (PaCO2) during one-lung ventilation with low tidal volume for thoracic surgeries. Transcutaneous carbon dioxide partial pressure (PtcCO2) monitoring can be used continuously to evaluate PaCO2 in a noninvasive fashion. In this study, we compared the accuracy between PetCO2 and PtcCO2 in predicting PaCO2 during prolonged one-lung ventilation with low tidal volume for thoracic surgeries.
  
  
  METHODS
  Eighteen adult patients who underwent thoracic surgeries with one-lung ventilation longer than two hours were included in this study. Their PetCO2, PtcCO2, and PaCO2 values were collected at five time points before and during one-lung ventilation. Agreement among measures was evaluated by Bland-Altman analysis.
  
  
  RESULTS
  Ninety sample sets were obtained. The bias and precision when PtcCO2 and PaCO2 were compared were 4.1 ± 6.5 mmHg during two-lung ventilation and 2.9 ± 6.1 mmHg during one-lung ventilation. Those when PetCO2 and PaCO2 were compared were -11.8 ± 6.4 mmHg during two-lung ventilation and -11.8 ± 4.9 mmHg during one-lung ventilation. The differences between PtcCO2 and PaCO2 were significantly lower than those between PetCO2 and PaCO2 at all five time-points (p < 0.05).
  
  
  CONCLUSIONS
  PtcCO2 monitoring was more accurate for predicting PaCO2 levels during prolonged one-lung ventilation with low tidal volume for patients undergoing thoracic surgeries.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Peking University First Hospital, Beijing, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Peking University First Hospital, Beijing, China.
authors.forename: Dong-Xin
authors.initials: DX
authors.lastname: Wang
mesh_terms: D000368:Aged; D001785:Blood Gas Monitoring, Transcutaneous / Q000379:methods*; D002245:Carbon Dioxide / Q000032:analysis* / Q000378:metabolism; D005260:Female; D006801:Humans; D008168:Lung / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D061810:One-Lung Ventilation; D013510:Pulmonary Surgical Procedures; D013990:Tidal Volume
chemical_list: D002245:Carbon Dioxide