Report from the meeting: Gastrointestinal Tonometry: State of the Art

Abstract

Gastrointestinal (GI) tonometry, the only clinically available method for the accurate diagnosis of compromised GI blood flow, has been shown to be a sensitive predictor of increased morbidity, mortality and prolonged hospitalization. The recent introduction of the Tonocap, as a means of performing automated air tonometry, has simplified the application of GI tonometry in the clinical setting. Despite this the utility of GI tonometry remains controversial. The GI Tonometry: State of the Art meeting brought together a group of clinicians with a proven track record of research, clinical interest and expertise in this field. The aim of the meeting was to come to a consensus regarding certain issues such as the past and future roles of GI tonometry and standards for its correct usage and interpretation. Finally suggestions as to further research and clinical evaluation were made within a broader discussion regarding the complexities of applying the principles of evidence-based medicine to the introduction of a new piece of medical technology.

Randomized clinical trial to evaluate the effects of perioperative supplemental oxygen administration on the colorectal anastomosis

“…Carbon dioxide within the gastric mucosa diffuses easily across cell membranes and is in equilibrium with the gastric lumen and the tonometric balloon. Its measurement therefore gives an indirect measure of the adequacy of the splanchnic circulation 11,31 . Shortly after injury, oxygen tension starts to fall in the injured area, and at the same time carbon dioxide tension rises and pH falls 32 .…”

“…Calculation of pHi is based on the assumption that gastrointestinal bicarbonate is equal to arterial bicarbonate. However, this is not necessarily true in poorly perfused tissue 10 , so the mucosal-arterial carbon dioxide difference or gap is now used as a more specific marker of gastrointestinal perfusion 11 . Gastric tonometry has gained wide acceptance among intensive care personnel for use as a predictor of risk of complications 12,13 , to guide therapy 14 , and to predict the development of ischaemic sigmoiditis after aortic surgery 15 .…”

Fluid Management in Gastrointestinal Surgery

“…In unanesthetised healthy volunteers, 20-25% of the intravascular volume can be removed without significant disturbance of arterial blood pressure or heart rate [31]. Similarly in patients undergoing major surgery it has been demonstrated repeatedly that maintenance of commonly measured cardio-respiratory variables (heart rate, arterial blood pressure) is commonly associated with reduced organ blood flow and a poor outcome [4][5][6]32]. Static central venous pressure monitoring is all too commonly used as a brake to prevent "fluid overload" rather than a dynamic guide to fluid optimization.…”

Gas tonometry for evaluation of gastrointestinal mucosal perfusion: experimental and clinical sepsis¹. part 2

“…Recently, Chapman et al 27 published the state of the art on gastrointestinal tonometry. The authors emphasized that, while it may be possible to apply the principles of evidence-based medicine to the evaluation of a single intervention affecting outcome, applying them to the introduction of a new piece of monitoring is even more complex.…”