title: Continuous cardiac output monitoring after cardiopulmonary bypass: a comparison with bolus thermodilution measurement.
abstract: OBJECTIVE
  The interchangeability of continuous measurement of cardiac output (CO) with the traditional bolus method in patients after cardiopulmonary bypass (CPB) is uncertain.
  
  
  METHODS
  Prospective observational clinical study.
  
  
  METHODS
  A 20-bed surgical ICU at a university hospital.
  
  
  METHODS
  Fourteen deeply sedated, ventilated, post-cardiac surgery patients, all equipped with a pulmonary artery catheter.
  
  
  METHODS
  Six hours after the end of the CPB, 56 simultaneous bolus and continuous measurements were compared by a linear regression analysis and Bland-Altman analysis. Bolus CO was estimated by averaging triplicate injections of 10 ml room-temperature NaCl 0.9%, delivered randomly during the respiratory cycle. A stringent maximum difference of 0.55 l min(-1) (about 10% of the mean bolus measured) was considered as a clinically acceptable agreement between the two types of measurements. To be interchangeable the limits of agreement (+/-2 SD of the mean difference between the two methods) should not exceed the chosen acceptable difference.
  
  
  RESULTS
  Continuous was correlated with bolus CO, with a correlation coefficient of r(2)=0.68. (p<0.01). The Bland-Altman analysis demonstrated an objective mean bias of 0.33+/-0.6 l min(-1) (confidence interval of -0.87-1.58) with 34% of measured values falling outside of the clinically acceptable limits.
  
  
  CONCLUSIONS
  Our results suggest that, in the first 6 h after CPB, continuous and bolus CO determinations are not interchangeable; one third of the values obtained by continuous CO fell outside the strict limits of clinically useful precision.
authors.affiliation: Geneva University Hospitals, Surgical Intensive Care Unit, Department of Anaesthesiology, Pharmacology and Surgical Intensive Care, 1211, Geneva 14, Switzerland. Karim.Bendjelid@hcuge.ch
authors.forename: Karim
authors.initials: K
authors.lastname: Bendjelid
authors.forename: Nicolas
authors.initials: N
authors.lastname: Schütz
authors.forename: Peter M
authors.initials: PM
authors.lastname: Suter
authors.forename: Jacques-Andre
authors.initials: JA
authors.lastname: Romand
mesh_terms: D000368:Aged; D002302:Cardiac Output / Q000502:physiology*; D002315:Cardiopulmonary Bypass; D002407:Catheterization, Swan-Ganz; D005260:Female; D006801:Humans; D007035:Hypothermia; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D011446:Prospective Studies; D013815:Thermodilution; D013903:Thoracic Surgery