title: Gastric mucosal-to-end-tidal PCO2 difference during major abdominal surgery: influence of the arterial-to-end-tidal PCO2 difference?
abstract: OBJECTIVE
  Because gastric mucosal PCO2 must be referenced to arterial values via a gastric-to-arterial PCO2 gap (Pg-aCO2), the gastric-to-end-tidal PCO2 difference (Pg-ETCO2) may be proposed as a surrogate method to monitor Pg-aCO2. However, the influence of arterial-to-end-tidal PCO2 (Pa-ETCO2) on its value remains unknown. Pa-ETCO2 may be enhanced by a low cardiac output and subsequent reduced perfusion of the lungs. This study was designed to compare such gaps observed during abdominal surgery in patients with or without preoperative cardiac dysfunction.
  
  
  METHODS
  Haemodynamic, metabolic and tonometric variables were measured in seven patients with Crohn's disease and in five patients with chronic heart failure scheduled for abdominal surgery. Data were collected before skin incision (T0); at extractor placement (T1), 30 (T2) and 60 (T3) min later; at organ extraction (T4), 30 (T5) and 60 (T6) min later, and at the end of surgery (T7).
  
  
  RESULTS
  Gradients appeared larger in the cardiac group. The difference was significant for Pg-ETCO2 during the whole study period, while it was only reached at T1-T2 for Pa-ETCO2 and at T5-T6 for Pg-aCO2. Gaps did not change significantly over the peroperative time points in either group. No major haemodynamic variations were registered in either group.
  
  
  CONCLUSIONS
  In patients with preoperative chronic heart failure, Pg-ETCO2 remained constant throughout a major general surgical procedure and was only moderately influenced by the Pa-ETCO2 gap. In these patients, Pg-ETCO2 may be used as a reliable index of gastrointestinal perfusion after control of PaCO2.
authors.affiliation: Hôpital Claude Huriez, Département d'anesthésie-réanimation II, Centre Hospitalier Universitaire, Lille, France.
authors.forename: G
authors.initials: G
authors.lastname: Lebuffe
authors.forename: T
authors.initials: T
authors.lastname: Onimus
authors.forename: B
authors.initials: B
authors.lastname: Vallet
mesh_terms: D000005:Abdomen / Q000601:surgery*; D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D001158:Arteries; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D005753:Gastric Mucosa / Q000098:blood supply*; D006333:Heart Failure / Q000097:blood; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D016343:Monitoring, Intraoperative; D018709:Statistics, Nonparametric; D013990:Tidal Volume / Q000502:physiology*; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide