title: Persistently high venous-to-arterial carbon dioxide differences during early resuscitation are associated with poor outcomes in septic shock.
abstract: BACKGROUND
  Venous-to-arterial carbon dioxide difference (Pv-aCO2) may reflect the adequacy of blood flow during shock states. We sought to test whether the development of Pv-aCO2 during the very early phases of resuscitation is related to multi-organ dysfunction and outcomes in a population of septic shock patients resuscitated targeting the usual oxygen-derived and hemodynamic parameters.
  
  
  METHODS
  We conducted a prospective observational study in a 60-bed mixed ICU in a University affiliated Hospital. 85 patients with a new septic shock episode were included. A Pv-aCO2 value ≥ 6 mmHg was considered to be high. Patients were classified in four predefined groups according to the Pv-aCO2 evolution during the first 6 hours of resuscitation: (1) persistently high Pv-aCO2 (high at T0 and T6); (2) increasing Pv-aCO2 (normal at T0, high at T6); (3) decreasing Pv-aCO2 (high at T0, normal at T6); and (4) persistently normal Pv-aCO2 (normal at T0 and T6). Multiorgan dysfunction at day-3 was compared for predefined groups and a Kaplan Meier curve was constructed to show the survival probabilities at day-28 using a log-rank test to evaluate differences between groups. A Spearman-Rho was used to test the agreement between cardiac output and Pv-aCO2. Finally, we calculated the mortality risk ratios at day-28 among patients attaining normal oxygen parameters but with a concomitantly increased Pv-aCO2.
  
  
  RESULTS
  Patients with persistently high and increasing Pv-aCO2 at T6 had significant higher SOFA scores at day-3 (p < 0.001) and higher mortality rates at day-28 (log rank test: 19.21, p < 0.001) compared with patients who evolved with normal Pv-aCO2 at T6. Interestingly, a poor agreement between cardiac output and Pv-aCO2 was observed (r2 = 0.025, p < 0.01) at different points of resuscitation. Patients who reached a central venous saturation (ScvO)2 ≥ 70% or mixed venous oxygen saturation (SvO2) ≥ 65% but with concomitantly high Pv-aCO2 at different developmental points (i.e., T0, T6 and T12) had a significant mortality risk ratio at day-28.
  
  
  CONCLUSIONS
  The persistence of high Pv-aCO2 during the early resuscitation of septic shock was associated with more severe multi-organ dysfunction and worse outcomes at day-28. Although mechanisms conducting to increase Pv-aCO2 during septic shock are insufficiently understood, Pv-aCO2 could identify a high risk of death in apparently resuscitated patients.
authors: Gustavo A
authors: GA
authors: Ospina-Tascón
authors: Diego F
authors: DF
authors: Bautista-Rincón
authors: Mauricio
authors: M
authors: Umaña
authors: José D
authors: JD
authors: Tafur
authors: Alejandro
authors: A
authors: Gutiérrez
authors: Alberto F
authors: AF
authors: García
authors: William
authors: W
authors: Bermúdez
authors: Marcela
authors: M
authors: Granados
authors: César
authors: C
authors: Arango-Dávila
authors: Glenn
authors: G
authors: Hernández
mesh_terms: D000368:Aged; D002245:Carbon Dioxide / Q000097:blood*; D002302:Cardiac Output; D005260:Female; D006439:Hemodynamics; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008875:Middle Aged; D009102:Multiple Organ Failure / Q000209:etiology; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D011379:Prognosis; D011446:Prospective Studies; D012772:Shock, Septic / Q000097:blood* / Q000150:complications / Q000401:mortality / Q000628:therapy; D016019:Survival Analysis
chemical_list: D002245:Carbon Dioxide; D019344:Lactic Acid; D010100:Oxygen