title: Evaluation of a noninvasive method for cardiac output measurement in critical care patients.
abstract: OBJECTIVE
  Thermodilution (TD) is the gold standard to monitor cardiac output (CO) in critical care. However, there is concern about the safety of right-ventricular catheterization. The CO(2) rebreathing technique allows noninvasive CO determination by means of the indirect Fick principle. Our objectives were: (a) to assess the accuracy of a new system of CO measurement using the CO(2) partial rebreathing method (PRCO); (b) to evaluate whether the PRCO itself may induce changes in CO.
  
  
  METHODS
  Prospective study in the intensive care department in a university-affiliated hospital.
  
  
  METHODS
  Twenty-two mechanically ventilated critically ill patients.
  
  
  METHODS
  CO measured simultaneously by PRCO and TDCO.
  
  
  RESULTS
  PRCO and TDCO values were compared by concordance analysis. Stability of cardiac output during PRCO was evaluated by comparing the TDCO measurements before, during, and after the partial rebreathing period using analysis of variance. From a total of 79 valid sets of measurements, bias and precision was calculated at -0.18+/-1.39 l/min. The concordance analysis of lower and intermediate CO values (<7 l/min) yielded a bias and precision calculation of -0.07+/-0.91 l/min. No changes in hemodynamics were observed during the partial rebreathing period.
  
  
  CONCLUSIONS
  The noninvasive partial CO(2) rebreathing technique may be an alternative method for CO determination in mechanically ventilated critically ill patients. The rebreathing maneuver alone does not induce changes in CO.
authors.affiliation: Critical Care Center, Hospital San Martín, La Plata, Argentina.
authors.forename: Gastón E
authors.initials: GE
authors.lastname: Murias
authors.forename: Ana
authors.initials: A
authors.lastname: Villagrá
authors.forename: Sara
authors.initials: S
authors.lastname: Vatua
authors.forename: Maria
authors.initials: M
authors.lastname: del Mar Fernandez
authors.forename: Héctor
authors.initials: H
authors.lastname: Solar
authors.forename: Ana
authors.initials: A
authors.lastname: Ochagavía
authors.forename: Rafael
authors.initials: R
authors.lastname: Fernández
authors.forename: Josefina
authors.initials: J
authors.lastname: López Aguilar
authors.forename: Pablo V
authors.initials: PV
authors.lastname: Romero
authors.forename: Lluis
authors.initials: L
authors.lastname: Blanch
mesh_terms: D001944:Breath Tests; D002245:Carbon Dioxide / Q000032:analysis; D002302:Cardiac Output; D003422:Critical Care / Q000379:methods*; D006785:Hospitals, University; D006801:Humans; D007362:Intensive Care Units; D008991:Monitoring, Physiologic / Q000379:methods*; D011446:Prospective Studies; D012121:Respiration, Artificial; D013030:Spain
chemical_list: D002245:Carbon Dioxide