title: [Veno-arterial difference of carbon dioxide as a predictor of low cardiac output in an experimental pediatric model].
abstract: BACKGROUND
  Cardiac output (CO) measurement is not a standard of care for critically ill children, but it can be estimated by indirect methods such as veno-arterial pCO2 difference (ΔVACO2).
  
  
  OBJECTIVE
  To determine the correlation between CO and ΔVACO2 and evaluate the usefulness of ΔVACO2 in the diagnosis of low CO in an experimental pediatric model.
  
  
  METHODS
  Thirty piglets weighing 4.8 ± 0.35 kg were anesthetized and monitored with transpulmonary thermodilution. Lung injury was induced with tracheal instillation of Tween 20®. Serial measurements of central venous and arterial blood gases, as well as CO, were obtained at baseline, 1, 2 and 4 h after lung injury induction. Low cardiac output (LCO) was defined as CO lower than 2.5 Llminlm².
  
  
  RESULTS
  There was an inverse correlation between CO and ΔVACO2 (r = -0.36, p < 0.01). ΔVACO2 was 14 ± 8 mmHg in LCO state and 8 ± 6 mmHg when this condition was not present (p < 0.01). Area under the receiver operating characteristic (ROC) curves of ΔVACO2 and LCO state was 0.78 (0.68-0.86). The best cut-point was 8.9 mmHg to determine LCO with a sensibility 0.78, specificity 0.7, positive predictive value 0.27 and negative predictive value 0.96.
  
  
  CONCLUSIONS
  In this model there was an inverse correlation between ΔVACO2 and CO. The best cutoff value to discard LCO was ΔVACO2 of 8.9 mmHg, indicating that under this value the presence of LCO is very unlikely.
authors.affiliation: UCI Pediátrica, Clínica Alemana, Santiago, Chile.
authors.forename: Franco
authors.initials: F
authors.lastname: Díaz
authors.forename: Alejandro
authors.initials: A
authors.lastname: Donoso
authors.forename: Cristóbal
authors.initials: C
authors.lastname: Carvajal
authors.forename: Tatiana
authors.initials: T
authors.lastname: Salomón
authors.forename: María
authors.initials: M
authors.lastname: Torres
authors.forename: Benjamín
authors.initials: B
authors.lastname: Erranz
authors.forename: Pablo
authors.initials: P
authors.lastname: Cruces
mesh_terms: D055371:Acute Lung Injury / Q000097:blood*; D000818:Animals; D019540:Area Under Curve; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood*; D002303:Cardiac Output, Low / Q000097:blood* / Q000175:diagnosis; D004195:Disease Models, Animal; D011237:Predictive Value of Tests; D013552:Swine; D013815:Thermodilution
chemical_list: D002245:Carbon Dioxide