title: Changes in p(i)CO(2) reflect splanchnic mucosal ischaemia more reliably than changes in pH(i) during haemorrhagic shock.
abstract: BACKGROUND
  Gastric tonometry is intended to reveal alterations in splanchnic perfusion and oxygenation. Based on the tonometric measurement of gastric mucosal partial pressure of carbon dioxide (pCO(2)) and the simultaneous determination of arterial blood gas parameters (bicarbonate concentration [HCO(3-)], pH and pCO(2)), several parameters can be calculated.
  
  
  OBJECTIVE
  To identify the most suitable tonometric parameter [gastric mucosal pH (pH(i)), intramucosal pCO(2) (p(i)CO(2)), the difference between tonometric and arterial pCO(2) concentrations (pCO(2) gap), [H+] gap] that reliably reflects gastric hypoperfusion and hypoxia during severe haemorrhagic shock.
  
  
  METHODS
  Randomised, controlled experimental study.
  
  
  METHODS
  An artificial stenosis of the left anterior descending coronary artery (LAD) was induced. Subsequently, the animals were haemorrhaged to a mean arterial pressure of 45 mmHg, which was maintained for 60 min.
  
  
  RESULTS
  Tonometric measurements were performed in 17 land-race pigs before and after induction of LAD stenosis and after haemorrhagic shock. P values obtained using the Wilcoxon signed-rank testing were used to compare the level of significance for the tonometric parameters and the corresponding arterial blood gas values [arterial pCO2 (p(a)CO(2)), [HCO(3-)], arterial pH (pH(a))]. While induction of critical coronary stenosis did not provoke any changes, all parameters changed significantly during haemorrhagic shock. The lowest P value was found for pH(i) (P=0.00013) followed by [H+ gap] (P=0.0005). P values higher by a factor of ten were found for pCO(2) gap (P=0.00119) and were highest for p(i)CO(2) (P=0.00562). P values of the corresponding arterial blood gas parameters were lower by a factor of ten than the P value of p(i)CO(2).
  
  
  CONCLUSIONS
  pH(i), pCO(2) gap and [H+] gap are considerably influenced by changes of systemic arterial blood gas values. This is demonstrated by lower P values of the corresponding arterial blood gas values in comparison with p(i)CO(2). Therefore pH(i), pCO(2) gap and [H+] gap seem to indicate more likely systemic changes, whereas p(i)CO(2) appears to reflect disturbances of regional gastric tissue perfusion and oxygenation more reliably than any other derived tonometric parameter.
authors.affiliation: Institute for Surgical Research, Clinic of the Ludwig-Maximilians-University Munich, Grosshadern, Marchioninistrasse 15, 81377 Munich, Germany. Franz.Meisner@medizin.uni-ulm.de
authors.forename: F G
authors.initials: FG
authors.lastname: Meisner
authors.forename: O P
authors.initials: OP
authors.lastname: Habler
authors.forename: G I
authors.initials: GI
authors.lastname: Kemming
authors.forename: M S
authors.initials: MS
authors.lastname: Kleen
authors.forename: A
authors.initials: A
authors.lastname: Pape
authors.forename: K
authors.initials: K
authors.lastname: Messmer
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000032:analysis* / Q000097:blood / Q000378:metabolism; D005753:Gastric Mucosa / Q000098:blood supply*; D007511:Ischemia / Q000175:diagnosis* / Q000209:etiology; D008365:Manometry / Q000379:methods*; D010313:Partial Pressure; D012771:Shock, Hemorrhagic / Q000503:physiopathology*; D013152:Splanchnic Circulation / Q000502:physiology*; D018709:Statistics, Nonparametric; D013552:Swine
chemical_list: D002245:Carbon Dioxide