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. 1996 Jun;51(6):606–610. doi: 10.1136/thx.51.6.606

Gastric intramural pH in mechanically ventilated patients.

Z Mohsenifar 1, J Collier 1, S K Koerner 1
PMCID: PMC1090491  PMID: 8693442

Abstract

BACKGROUND: The hypothesis that gastric intramural pH (pHi) is predictive of outcome in haemodynamically stable, mechanically ventilated patients was tested in 25 patients on assisted mechanical ventilation for respiratory failure. METHODS: Simultaneous samples of arterial blood and gastric juice were obtained from patients on assist control, synchronised intermittent and pressure control ventilation during the first 48 hours of mechanical ventilation. Gastric pHi was calculated from the equation: pHi= 6.1 + log HCO3/(gastric PCO2 X 0.03). The outcome was survival or death due to respiratory or circulatory failure within 45 days of admission. RESULTS: Gastric pHi proved to be a better predictor of outcome than all presently utilised parameters. Although all patients included in this study were haemodynamically stable and were similar for all laboratory indices, the only variable capable of accurately predicting outcome was gastric pHi. Patients with a normal arterial pH but a gastric intramural pH of less than 7.25 had an observed mortality of 66%. Standard severity of illness scores grossly underestimated mortality rates. The sensitivity and specificity of a gastric pHi value of less than 7.25 in predicting death were 86% and 83%, respectively. A receiver operator curve for all variables exaggerates the superiority of gastric pHi as a predictor of outcome. CONCLUSION: Low gastric pHi, a marker of gastrointestinal ischaemia, may occur in the presence of normal haemodynamics and may be used to predict severity of illness and mortality accurately.

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Selected References

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  1. Antonsson J. B., Boyle C. C., 3rd, Kruithoff K. L., Wang H. L., Sacristan E., Rothschild H. R., Fink M. P. Validation of tonometric measurement of gut intramural pH during endotoxemia and mesenteric occlusion in pigs. Am J Physiol. 1990 Oct;259(4 Pt 1):G519–G523. doi: 10.1152/ajpgi.1990.259.4.G519. [DOI] [PubMed] [Google Scholar]
  2. Bass B. L., Schweitzer E. J., Harmon J. W., Kraimer J. Intraluminal pCO2: a reliable indicator of intestinal ischemia. J Surg Res. 1985 Oct;39(4):351–360. doi: 10.1016/0022-4804(85)90114-3. [DOI] [PubMed] [Google Scholar]
  3. Beydon L., Chasse M., Harf A., Lemaire F. Inspiratory work of breathing during spontaneous ventilation using demand valves and continuous flow systems. Am Rev Respir Dis. 1988 Aug;138(2):300–304. doi: 10.1164/ajrccm/138.2.300. [DOI] [PubMed] [Google Scholar]
  4. Cunningham J. A., Cousar C. D., Jaffin J. H., Harmon J. W. Extraluminal and intraluminal PCO2 levels in the ischemic intestines of rabbits [correction of rats]. Curr Surg. 1987 May-Jun;44(3):229–232. [PubMed] [Google Scholar]
  5. Danek S. J., Lynch J. P., Weg J. G., Dantzker D. R. The dependence of oxygen uptake on oxygen delivery in the adult respiratory distress syndrome. Am Rev Respir Dis. 1980 Sep;122(3):387–395. doi: 10.1164/arrd.1980.122.3.387. [DOI] [PubMed] [Google Scholar]
  6. Doglio G. R., Pusajo J. F., Egurrola M. A., Bonfigli G. C., Parra C., Vetere L., Hernandez M. S., Fernandez S., Palizas F., Gutierrez G. Gastric mucosal pH as a prognostic index of mortality in critically ill patients. Crit Care Med. 1991 Aug;19(8):1037–1040. doi: 10.1097/00003246-199108000-00011. [DOI] [PubMed] [Google Scholar]
  7. Fiddian-Green R. G., Amelin P. M., Herrmann J. B., Arous E., Cutler B. S., Schiedler M., Wheeler H. B., Baker S. Prediction of the development of sigmoid ischemia on the day of aortic operations. Indirect measurements of intramural pH in the colon. Arch Surg. 1986 Jun;121(6):654–660. doi: 10.1001/archsurg.1986.01400060048005. [DOI] [PubMed] [Google Scholar]
  8. Fiddian-Green R. G. Associations between intramucosal acidosis in the gut and organ failure. Crit Care Med. 1993 Feb;21(2 Suppl):S103–S107. doi: 10.1097/00003246-199302001-00017. [DOI] [PubMed] [Google Scholar]
  9. Fiddian-Green R. G., McGough E., Pittenger G., Rothman E. Predictive value of intramural pH and other risk factors for massive bleeding from stress ulceration. Gastroenterology. 1983 Sep;85(3):613–620. [PubMed] [Google Scholar]
  10. Gutierrez G., Clark C., Brown S. D., Price K., Ortiz L., Nelson C. Effect of dobutamine on oxygen consumption and gastric mucosal pH in septic patients. Am J Respir Crit Care Med. 1994 Aug;150(2):324–329. doi: 10.1164/ajrccm.150.2.8049810. [DOI] [PubMed] [Google Scholar]
  11. Gutierrez G., Palizas F., Doglio G., Wainsztein N., Gallesio A., Pacin J., Dubin A., Schiavi E., Jorge M., Pusajo J. Gastric intramucosal pH as a therapeutic index of tissue oxygenation in critically ill patients. Lancet. 1992 Jan 25;339(8787):195–199. doi: 10.1016/0140-6736(92)90002-k. [DOI] [PubMed] [Google Scholar]
  12. Hartmann M., Montgomery A., Jönsson K., Haglund U. Tissue oxygenation in hemorrhagic shock measured as transcutaneous oxygen tension, subcutaneous oxygen tension, and gastrointestinal intramucosal pH in pigs. Crit Care Med. 1991 Feb;19(2):205–210. doi: 10.1097/00003246-199102000-00016. [DOI] [PubMed] [Google Scholar]
  13. Hussain S. N., Roussos C. Distribution of respiratory muscle and organ blood flow during endotoxic shock in dogs. J Appl Physiol (1985) 1985 Dec;59(6):1802–1808. doi: 10.1152/jappl.1985.59.6.1802. [DOI] [PubMed] [Google Scholar]
  14. Khuri S. F., Kloner R. A., Hillis L. D., Tow D. E., Barsamian E. M., Maroko P. R., Braunwald E. Intramural PCO2: a reliable index of the severity of myocardial ischemic injury. Am J Physiol. 1979 Aug;237(2):H253–H259. doi: 10.1152/ajpheart.1979.237.2.H253. [DOI] [PubMed] [Google Scholar]
  15. Knaus W. A., Draper E. A., Wagner D. P., Zimmerman J. E. APACHE II: a severity of disease classification system. Crit Care Med. 1985 Oct;13(10):818–829. [PubMed] [Google Scholar]
  16. Magder S., Erian R., Roussos C. Respiratory muscle blood flow in oleic acid-induced pulmonary edema. J Appl Physiol (1985) 1986 Jun;60(6):1849–1856. doi: 10.1152/jappl.1986.60.6.1849. [DOI] [PubMed] [Google Scholar]
  17. Marini J. J., Rodriguez R. M., Lamb V. The inspiratory workload of patient-initiated mechanical ventilation. Am Rev Respir Dis. 1986 Nov;134(5):902–909. doi: 10.1164/arrd.1986.134.5.902. [DOI] [PubMed] [Google Scholar]
  18. Maynard N., Bihari D., Beale R., Smithies M., Baldock G., Mason R., McColl I. Assessment of splanchnic oxygenation by gastric tonometry in patients with acute circulatory failure. JAMA. 1993 Sep 8;270(10):1203–1210. [PubMed] [Google Scholar]
  19. Mohsenifar Z., Hay A., Hay J., Lewis M. I., Koerner S. K. Gastric intramural pH as a predictor of success or failure in weaning patients from mechanical ventilation. Ann Intern Med. 1993 Oct 15;119(8):794–798. doi: 10.7326/0003-4819-119-8-199310150-00004. [DOI] [PubMed] [Google Scholar]
  20. Mohsenifar Z., Jasper A. C., Koerner S. K. Relationship between oxygen uptake and oxygen delivery in patients with pulmonary hypertension. Am Rev Respir Dis. 1988 Jul;138(1):69–73. doi: 10.1164/ajrccm/138.1.69. [DOI] [PubMed] [Google Scholar]

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