Temporal changes in tissue cardiorespiratory function during faecal peritonitis

Abstract

This long-term septic model exhibited an early decline in tissue oxygenation, the degree of which related to predicted mortality. Clinical and biochemical deterioration, however, progressed despite cardiovascular recovery. Early circulatory dysfunction may thus be an important trigger for downstream processes that result in multi-organ failure. Furthermore, the utility of tissue PO2 monitoring to highlight the local oxygen supply-demand balance, and dynamic O2 challenge testing to assess microcirculatory function merit further investigation.

Understanding the microcirculation in sepsis: still a long way to go...

“…This hypothesis is also supported by the fact that animals with higher stroke volume, described by the authors as having ''good prognosis'' sepsis, had preserved tPO 2 in all the studied organs. Nevertheless, early microvascular alterations have been reported previously in experimental and clinical studies [2], so it is possible that the effects observed by Dyson et al [1] were indeed the result of such changes.…”

“…They observed an early decline in regional tissue oxygenation, as assessed by measurement of tissue partial pressure of oxygen (tPO 2 ), especially in animals with low stroke volume at baseline. A stepwise increase in FiO 2 (oxygen challenge test) failed to increase the tPO 2 sufficiently during the early phase of sepsis, but the response to oxygen challenge improved in all organ beds except the kidney by 24 h. The strengths of this study [1] are that it provides information about cardiovascular function at both global and regional levels and that it evaluated regional perfusion simultaneously in several tissues-muscle, bladder, renal cortex, and liver. This multilevel approach would be expected to provide insight into the pathophysiology of sepsis and organ dysfunction.…”

“…In this issue of Intensive Care Medicine, Dyson et al [1] present the results of an experimental study in which they evaluated the temporal changes in myocardial function and regional tissue oxygenation in peripheral and deep organs in a rat model of fecal peritonitis. They observed an early decline in regional tissue oxygenation, as assessed by measurement of tissue partial pressure of oxygen (tPO 2 ), especially in animals with low stroke volume at baseline.…”

“…Although changes in global hemodynamics have been reported to be discordant with microcirculatory alterations in sepsis [3], a critical decrease in global perfusion would nevertheless be expected to influence microvascular perfusion. In the study by Dyson et al [1], animals were resuscitated according to a fixed fluid regime and not according to physiological targets. In the early phase of sepsis during which changes in tPO 2 were observed, it is difficult to determine whether the alterations were because of microcirculatory failure or merely inadequate, low global oxygen delivery (DO 2 ).…”

“…Although tPO 2 may reflect the balance between oxygen supply and demand as Dyson et al [1] allude to, quantification of this relationship can be troublesome. The increase in tPO 2 during an oxygen challenge test does not necessarily mean that microvascular perfusion has improved.…”