title: Thermodilution measurement of cardiac output in patients with low output: room-temperature versus iced injectate.
abstract: BACKGROUND
  Measurements of cardiac output with the thermodilution technique add to data for clinical decision making and therefore must be valid and reliable. However, the results of studies on the accuracy of values obtained with room-temperature and iced injectates, especially in patients with high or low cardiac output, have been conflicting.
  
  
  OBJECTIVE
  To determine the effect of the temperature of the injectate (iced or room temperature) on cardiac output values obtained with the thermodilution technique in critically ill adults with known low cardiac output.
  
  
  METHODS
  A convenience sample of 50 subjects (41 men and 9 women) who had a cardiac index of less than 2.5 (calculated as cardiac output in liters per minute divided by body surface area in square meters) before the study had cardiac output measured by using a closed system and manual injections of room-temperature and iced injectates.
  
  
  RESULTS
  A paired t test indicated no significant difference between iced and room-temperature injectates for cardiac output (iced, 3.62 L/min; room temperature, 3.71 L/min; t = 0.99; P = .327) and cardiac index (iced, 1.95; room temperature, 1.99; t = 0.71; P = .482).
  
  
  CONCLUSIONS
  The findings support the practice of using room-temperature injectate to measure cardiac output in patients with low cardiac output.
authors.affiliation: Department of Nursing, Massachusetts General Hospital, Boston, USA.
authors.forename: M
authors.initials: M
authors.lastname: Kiely
authors.forename: L A
authors.initials: LA
authors.lastname: Byers
authors.forename: R
authors.initials: R
authors.lastname: Greenwood
authors.forename: E
authors.initials: E
authors.lastname: Carroll
authors.forename: D
authors.initials: D
authors.lastname: Carroll
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015982:Bias; D002302:Cardiac Output; D002303:Cardiac Output, Low / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D003080:Cold Temperature; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013696:Temperature; D013815:Thermodilution / Q000295:instrumentation / Q000379:methods*