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Validation of a novel method for continuous saline tonometry in a procine model.
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
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2001 (English)In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 22, no 3, 453-460 p.Article in journal (Refereed) Published
Abstract [en]

Only intermittent and semi-continuous tonometric measurement of gastric and intestinal pHi is possible with the equipment available today. Earlier we developed a system for continuous saline tonometry and tested it in vitro. To assess the in vivo reliability of this method for continuous gastrointestinal saline tonometry, a standard tonometer for measurement of intestinal pCO2 and corresponding pHi was modified to allow continuous perfusion of physiological saline in a closed system and tested in a porcine model. In 11 anaesthetized and haemodynamically stable pigs, two continuous tonometry balloons were inserted into the distal small bowel, and a standard tonometry balloon was used as reference. To test long-term function of the continuous tonometers the research protocol lasted for eight hours. The two continuous saline tonometers performed well, and after an equilibration time of three hours the mean pHi values were stable between 7.35 and 7.43 and between 7.32 and 7.39 respectively. The standard tonometer measured stable pHi values. These preliminary studies indicate that continuous saline tonometry performs well over eight hours with a small bias and a good precision.

Place, publisher, year, edition, pages
2001. Vol. 22, no 3, 453-460 p.
Keyword [en]
gastrointestinal tonometry, continuous, porcine model
URN: urn:nbn:se:umu:diva-4410DOI: 10.1088/0967-3334/22/3/304PubMedID: 11556666OAI: diva2:143503
Available from: 2005-02-24 Created: 2005-02-24 Last updated: 2012-03-27Bibliographically approved
In thesis
1. Exploring Intestinal Ischemia: An experimental study
Open this publication in new window or tab >>Exploring Intestinal Ischemia: An experimental study
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background and aims: Unrecognized intestinal mucosal ischemia in severely ill patients may trigger development of multiple organ failure. Such ischemia can be evaluated by intraluminal tonometry reflecting mucosal PCO2 and intramucosal pH (pHi). The aims were to develop an apparatus for continuous saline tonometry (CST), to analyse circulatory control mechanisms during intestinal hypoperfusion and to evaluate the effect of dopexamine on intestinal circulation.

Methods: A modified standard tonometry catheter was integrated in a closed system with circulating saline. By measuring saline PCO2 in a measurement unit pHi could be calculated. This novel system was tested in vitro and in vivo. In a porcine study, CST was evaluated against standard saline tonometry, tissue oxygenation (PO2 TISSUE), jejunal mucosal perfusion (laser doppler flowmetry; LDF) and mesenteric net lactate flux during graded reductions of superior mesenteric arterial pressure (PSMA). Local control mechanisms for maintenance of intestinal oxygenation were analysed. Effects of dopexamine on the intestinal vascular bed were explored. Mucosal lactate production was assessed by microdialysis.

Results: CST measured accurate PCO2 values and changes in pHi during restricted intestinal circulation and at reperfusion. Local control mechanisms were insufficient at a PSMA of 30 mmHg, pHi was reduced to 7.10 and intestinal net lactate production was demonstrated. Absence of anaerobic intestinal metabolism was verified at PSMA ≥ 50 mmHg, pHi ≥ 7.22 and a PCO2 gap ≤ 15.8 mmHg. Dopexamine induced negative regional metabolic effects at the lowest PSMA, as expressed by decreased PO2 TISSUE and pHi, increased PCO2 gap and intestinal net lactate production.

Conclusions: CST reflected changes in pHi, induced by intestinal hypoperfusion and at reperfusion. Levels of PSMA, pHi and PCO2 gap as indicators of aerobic conditions were defined. Dopexamine induced a decrease of PO2 TISSUE and pHi as well as an increase in lactate flux at the lowest PSMA level.

Place, publisher, year, edition, pages
Umeå: Kirurgisk och perioperativ vetenskap, 2005. 59 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 938
Surgery, gastrointestinal tonometry, continuous, pig, pHi, intestinal ischemia, intestinal vascular bed, lactate, tissue oxygen tension, microdialysis, dopexamine, Kirurgi
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Research subject
urn:nbn:se:umu:diva-461 (URN)91-7305-788-6 (ISBN)
Public defence
2005-03-19, B, Tandläkarhögskolan, 9tr, Norrlands Universitetssjukhus, Umeå, 10:00 (English)
Available from: 2005-02-24 Created: 2005-02-24 Last updated: 2009-11-13Bibliographically approved

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