title: Safety of the CO-Rebreathing Method in Patients with Coronary Artery Disease.
abstract: OBJECTIVE
  To address and study the safety concerns with the improved carbon monoxide (CO) rebreathing method for measuring total blood volume in patients with coronary artery disease to implement the use of the methodology in this patient group.
  
  
  METHODS
  Eighteen patients with stable coronary artery disease (age 62 ± 7 yr, 24 ± 5 months since diagnosis) were investigated using the improved CO-rebreathing test. Before, during, and up to 2 h after the test, ECG, blood pressure, arterial oxygen saturation, carbon monoxide bound to hemoglobin (HbCO%), and cardiac function were measured. At 24 h, HbCO% and troponin-T were measured.
  
  
  METHODS
  Cross-over.
  
  
  RESULTS
  Six minutes after the CO-rebreathing test, HbCO increased from 1.5% ± 0.4% to 6.0% ± 0.6%, with a subsequent decrease to 4.5% ± 0.4% and 1.4% ± 0.4% at 2 h and 24 h after the test, respectively. Resting heart rate, stroke volume, cardiac output, and ejection fraction were 64 ± 11 bpm, 93.9 ± 16.5 mL per beat, 5.84 ± 0.99 L, and 48.5% ± 5.7% and remained unchanged during and 10 min after the rebreathing. All patients were in sinus rhythm during the 2-h observation period, without ST- or T-wave changes, with low numbers of premature beats and normal rate variability. Systolic and diastolic blood pressure gradually decreased during the observation period. Troponin-T was below the 99th percentile for all the participants 24 h after the test.
  
  
  CONCLUSIONS
  Cardiovascular function and safety indices remained unchanged after exposure to approximately 6% HbCO, indicating that the method is safe to perform in patients with stable coronary artery disease.
authors.affiliation: 1K.G. Jebsen Center of Exercise in Medicine, Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, NORWAY; 2Department of Cardiology, St. Olav's University Hospital, NORWAY; 3Clinical Services, St. Olav's University Hospital, NORWAY; 4Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Norway; and 5Levanger Hospital, Nord-Trøndelag Health Trust, Levanger, NORWAY.
authors.forename: Trine
authors.initials: T
authors.lastname: Karlsen
authors.forename: Ingeborg Megård
authors.initials: IM
authors.lastname: Leinan
authors.forename: Inger-Lise
authors.initials: IL
authors.lastname: Aamot
authors.forename: Håvard
authors.initials: H
authors.lastname: Dalen
authors.forename: Asbjørn
authors.initials: A
authors.lastname: Støylen
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis / Q000009:adverse effects; D001794:Blood Pressure; D001810:Blood Volume / Q000502:physiology*; D002248:Carbon Monoxide / Q000097:blood*; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000503:physiopathology*; D018592:Cross-Over Studies; D004562:Electrocardiography; D005260:Female; D006439:Hemodynamics; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D020107:Troponin T / Q000097:blood
chemical_list: D006454:Hemoglobins; D020107:Troponin T; D002248:Carbon Monoxide; D010100:Oxygen