title: Accuracy of transcutaneous carbon dioxide monitoring in hypotensive patients.
abstract: OBJECTIVE
  Continuous blood gas monitoring is frequently necessary in critically ill patients. Our aim was to assess the accuracy of transcutaneous CO₂ tension (PtcCO₂) monitoring in the emergency department (ED) assessment of hypotensive patients by comparing it with the gold standard of arterial blood gas analysis (ABGA).
  
  
  METHODS
  All patients receiving PtcCO₂ monitoring in the ED were included. We excluded paediatric patients, patients with no ABGA results during a hypotensive event, patients whose ABGA was not performed simultaneously with PtcCO₂ monitoring, and patients who received sodium bicarbonate for resuscitation. The included patients were classified into hypotensive patients and normotensive patients. A hypotensive patient was defined as a patient showing a mean arterial pressure under 60 mm Hg. The agreement in measurement between PaCO₂ tension (PaCO₂) and PtcCO₂ were investigated in both groups.
  
  
  RESULTS
  The mean difference between PaCO₂ and PtcCO₂ was 2.1 mm Hg, and the Bland-Altman limits of agreement (bias ± 1.96 SD) ranged from -15.6 to 19.7 mm Hg in the 28 normotensive patients. The mean difference between PaCO₂ and PtcCO₂ was 1.1 mm Hg, and the Bland-Altman limits of agreement (bias ± 1.96 SD) ranged from -19.5 to 21.7 mm Hg in the 26 hypotensive patients. The weighted κ values were 0.64 in the normotensive patients and 0.60 in the hypotensive patients.
  
  
  CONCLUSIONS
  PtcCO₂ monitoring showed wider limits of agreement with PaCO₂ in urgent situations in the ED environment. However, acutely developed hypotension does not affect the accuracy of PtcCO₂ monitoring.
authors: Department of Emergency Medicine, Korea University College of Medicine, , Seoul, South Korea.
authors: Jung-Youn
authors: JY
authors: Kim
authors: Young-Hoon
authors: YH
authors: Yoon
authors: Sung-Woo
authors: SW
authors: Lee
authors: Sung-Hyuk
authors: SH
authors: Choi
authors: Young-Duck
authors: YD
authors: Cho
authors: Sang-Min
authors: SM
authors: Park
mesh_terms: D000368:Aged; D062186:Arterial Pressure / Q000502:physiology; D001785:Blood Gas Monitoring, Transcutaneous; D002245:Carbon Dioxide / Q000097:blood*; D016022:Case-Control Studies; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D007022:Hypotension / Q000097:blood* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
chemical_list: D002245:Carbon Dioxide
keywords: resuscitation, clinical care