title: A novel continuous capnodynamic method for cardiac output assessment in a porcine model of lung lavage.
abstract: BACKGROUND
  We have evaluated a new method for continuous monitoring of effective pulmonary blood flow (COEPBF ), i.e. cardiac output (CO) minus intra-pulmonary shunt, during mechanical ventilation. The method has shown good trending ability during severe hemodynamic challenges in a porcine model with intact lungs. In this study, we further evaluate the COEPBF method in a model of lung lavage.
  
  
  METHODS
  COEPBF was compared to a reference method for CO during hemodynamic and PEEP alterations, 5 and 12 cmH2 O, before and after repeated lung lavages in 10 anaesthetised pigs. Bland-Altman, four-quadrant and polar plot methodologies were used to determine agreement and trending ability.
  
  
  RESULTS
  After lung lavage at PEEP 5 cmH2 O, the ratio of arterial oxygen partial pressure related to inspired fraction of oxygen significantly decreased. The mean difference (limits of agreement) between methods changed from 0.2 (-1.1 to 1.5) to -0.9 (-3.6 to 1.9) l/min and percentage error increased from 34% to 70%. Trending ability remained good according to the four-quadrant plot (concordance rate 94%), whereas mean angular bias increased from 4° to -16° when using the polar plot methodology.
  
  
  CONCLUSIONS
  Both agreement and precision of COEPBF were impaired in relation to CO when the shunt fraction was increased after lavage at PEEP 5 cmH2 O. However, trending ability remained good as assessed by the four-quadrant plot, whereas the mean polar angle, calculated by the polar plot, was wide.
authors.affiliation: Department of Anaesthesiology, Surgical Services and Intensive Care Medicine, Karolinska University Hospital, Solna, Sweden.|Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Hällsjö Sander
authors.affiliation: Maquet Critical Care AB, Solna, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Hallbäck
authors.affiliation: Department of Surgical Sciences, Section of Anaesthesiology and Critical Care, Hedenstierna's Laboratory, Uppsala University, Uppsala, Sweden.|CIBERES, CIBER de enfermedades respiratorias, Instituto Carlos III, Madrid, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Suarez Sipmann
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.|Maquet Critical Care AB, Solna, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Wallin
authors.affiliation: Department of Anaesthesiology, Surgical Services and Intensive Care Medicine, Karolinska University Hospital, Solna, Sweden.|Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Oldner
authors.affiliation: Department of Anaesthesiology, Surgical Services and Intensive Care Medicine, Karolinska University Hospital, Solna, Sweden.|Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Björne
mesh_terms: D000818:Animals; D018893:Bronchoalveolar Lavage; D019296:Capnography / Q000379:methods*; D002302:Cardiac Output / Q000502:physiology*; D011175:Positive-Pressure Respiration; D011651:Pulmonary Artery / Q000502:physiology*; D015203:Reproducibility of Results; D013552:Swine