title: An assessment of tonometry and regional splanchnic blood flow during aortic cross-clamping in the pig.
abstract: We aimed to evaluate the tonometer in the assessment of gastrointestinal ischaemia induced by an infrarenal aortic cross-clamp. Nine anaesthetized pigs were cannulated for haemodynamic monitoring and radionuclide labelled microsphere (RLM) injection. Gastric and sigmoid tonometers were positioned. After haemodynamic stabilization an infrarenal aortic cross-clamp was applied. Animals were sacrificed at the completion of the study and tissue sampled from the stomach and sigmoid colon for regional blood flow measurements. Measurements were made pre-clamp, post-clamp, pre-release and post-release. Haemodynamic parameters, gastric intramucosal pH (pHi) and blood flow did not change throughout the experiment. Arterial pH increased during cross-clamp and returned to baseline post-release. Arterial bicarbonate fell post release. Sigmoid blood flow fell during cross-clamp. The sigmoid pHi fall, delayed until pre-release, remained low post-release. Although there was a consistent fall in sigmoid pHi, 63% of post-clamp values remained within the baseline range. We conclude that maintaining haemodynamic parameters around baseline values resulted in maintenance of gastric mucosal perfusion as indicated by a steady gastric pHi. However, below the aortic cross-clamp, delay between change in sigmoid colon blood flow and change in pHi and wide variation in sigmoid pHi limits the value of an individual pHi measurement in detecting ischaemia.
authors.affiliation: Department of Intensive Care, St George Hospital, Sydney, N.S.W.
authors.forename: T
authors.initials: T
authors.lastname: Jacques
authors.forename: R
authors.initials: R
authors.lastname: Morris
authors.forename: N
authors.initials: N
authors.lastname: Lalak
authors.forename: R
authors.initials: R
authors.lastname: Englund
authors.forename: D
authors.initials: D
authors.lastname: Gibb
mesh_terms: D000818:Animals; D001011:Aorta; D001639:Bicarbonates / Q000097:blood; D003250:Constriction; D005753:Gastric Mucosa / Q000737:chemistry*; D006439:Hemodynamics; D006863:Hydrogen-Ion Concentration; D007511:Ischemia / Q000175:diagnosis* / Q000503:physiopathology; D008863:Microspheres; D011312:Pressure; D013152:Splanchnic Circulation; D013270:Stomach / Q000098:blood supply*; D013552:Swine
chemical_list: D001639:Bicarbonates