title: Changes in end-tidal carbon dioxide and volumetric carbon dioxide as predictors of volume responsiveness in hemodynamically unstable patients.
abstract: OBJECTIVE
  The purpose of this study was to determine whether changes in PETCO2 and exhaled CO2 (VCO2) can predict fluid responsiveness after a preload challenge.
  
  
  METHODS
  A retrospective review of prospectively recorded data.
  
  
  METHODS
  A medical intensive care unit of a university-affiliated tertiary care hospital.
  
  
  METHODS
  Mechanically ventilated patients undergoing a preload challenge.
  
  
  METHODS
  In the authors' intensive care unit, fluid responsiveness is determined by a passive leg raising (PLR) maneuver and/or a 500-mL crystalloid challenge. An increase in the stroke volume index >10% as measured by a NICOM bioreactance cardiac output monitor (Cheetah Medical, Inc, Vancouver, WA) is used to determine fluid responsiveness. PETCO2 and volumetric capnography (VCO2) were monitored via a combined CO2 and flow sensor capnostat (Respironics NM3 Monitor; Philips Healthcare, Eindhoven, Netherlands). Patients were mechanically ventilated with tidal volumes controlled at 8 mL/kg, allowing for consistent minute ventilation.
  
  
  RESULTS
  During the study period, 44 challenges (10 PLR and 34 fluid boluses) were performed on 34 patients. There were 24 (54%) positive "fluid" responses. PETCO2 increased by 5.9% ± 7.6% in the responders compared with 1.4% ± 4.4% in the nonresponders (p = 0.02). Similarly, VCO2 increased by 11.0% ± 8.6% in the responders compared with 0.8% ± 5.6% in the nonresponders (p = 0.001). The area under the receiver operating characteristic curve was 0.67 (95% confidence interval, 0.48-0.80) for PETCO2 and 0.79 (95% confidence interval, 0.63-0.89) for VCO2. PETCO2 and VCO2 were predictive of fluid responsiveness only in those patients without underlying lung disease. The stroke volume variation was 15.8 ± 3.7 in the responders compared with 13.6 ± 4.8 in the nonresponders (p = 0.15).
  
  
  CONCLUSIONS
  Dynamic changes in PETCO2 and VCO2 may be used as adjunctive indicators of fluid responsiveness in patients without underlying lung disease.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Eastern Virginia Medical School, Norfolk, VA 23507, USA.
authors.forename: Alisha
authors.initials: A
authors.lastname: Young
authors.forename: Paul E
authors.initials: PE
authors.lastname: Marik
authors.forename: Steven
authors.initials: S
authors.lastname: Sibole
authors.forename: David
authors.initials: D
authors.lastname: Grooms
authors.forename: Alex
authors.initials: A
authors.lastname: Levitov
mesh_terms: D000328:Adult; D019540:Area Under Curve; D001810:Blood Volume / Q000187:drug effects / Q000502:physiology*; D019296:Capnography; D002245:Carbon Dioxide / Q000378:metabolism*; D002302:Cardiac Output / Q000502:physiology; D000077324:Crystalloid Solutions; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007552:Isotonic Solutions / Q000627:therapeutic use; D007866:Leg / Q000098:blood supply; D010952:Plasma Substitutes / Q000627:therapeutic use*; D011446:Prospective Studies; D012372:ROC Curve; D012039:Regional Blood Flow / Q000502:physiology; D012121:Respiration, Artificial; D012189:Retrospective Studies; D013318:Stroke Volume / Q000502:physiology; D013990:Tidal Volume / Q000502:physiology
chemical_list: D000077324:Crystalloid Solutions; D007552:Isotonic Solutions; D010952:Plasma Substitutes; D002245:Carbon Dioxide