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ARTICLES: Andrej Pernat, Max Harry Weil, Wanchun Tang, Hitoshi Yamaguchi, Andreja Marn Pernat, Shijie Sun, and Joe Bisera Effects of hyper- and hypoventilation on gastric and sublingual PCO2 J Appl Physiol 1999; 87: 933-937 [Abstract] [Full text] [PDF]

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Perfusion and haemodynamics vs tissue energetics

Richard G Fiddian-Green   (2 February 2009)

Perfusion and haemodynamics vs tissue energetics 2 February 2009
Richard G Fiddian-Green, FRCS, FACS None Send letter to journal: Re: Perfusion and haemodynamics vs tissue energetics richardfg{at}hotmail.com Richard G Fiddian-Green	This study addressed the relationship between PCO2, perfusion and haemodynamics to the exclusion to tissue energetics other than lactate which is an unreliable measure of tissue energetics. If a rise in PCO2 inhibits oxidative phosphorylation in a dose-related manner due to mass action and a fall in PCO2 enhances oxidative phosporylation by similar means, as previously suggested, then the absolute values of PCO2 should give a measure of tissue energetics. In figure 1 the PgCO2 was the same as the PslCO2 and both were higher than the PaCO2 [circa 65 mmHg vs 85 mmHg]. In figure 2 PgCO2 during haemorrhage was again the same as the PslCO2 and higher than the PaCO2 [circa 20 mmHg vs 50 mmHg]. In figure 3 PgCO2 during haemorrhage was greater than the PslCO2 and both greater than the PaCO2 [circa 100mmHg, 85 mmHg, and 50 mmHg]. No statistics are provided and even if they were the number of animals studied might not be large enough to show significant differences. These findings suggest that the tissue measurements of PCO2 might be far more important than the PaCO2, and indeed the PetCO2, in so far as assessing the adequacy of tissue energetics is concerned and that the PgCO2 might give a better measure of the severity of any disturbance present than the mouth. This is vitally important if, as previously suggested, the PgCO2 reflects changes in the liver better than the PslCO2 and hepatic function is an important determinant of the ability to withstand tissue anaerobiosis. The pH, or [H+], is also of importance in this respect because it is reflective of the magnitude of the protonmotive force driving ATP resynthesis. Knowing both the PgCO2 and pHi should give the best opportunity of assessing the adequacy of tissue enrgetics in the acutely ill.