Abnormalities of Gastric Mucosal Oxygenation in Septic Shock

Abstract

Splanchnic mucosal perfusion abnormalities have been implicated in the development of sepsis and multiorgan failure. We employed reflectance spectrophotometry for direct assessment of the microvascular hemoglobin oxygen saturation (HbiO2) and hemoglobin concentration (rel Hb(conc)) in the mucosa of the upper gastrointestinal tract. Owing to the high recording frequency together with a small catchment volume, assessment of spatial heterogeneity is enabled. Results were as follows: In healthy controls (n = 7), mean HbiO2 was 70.3 +/- 2.1%, with narrow dispersion and near-Gaussian distribution of the histogram. In patients presenting with hyperdynamic septic shock (n = 15) mean HbiO2 was reduced to 51.0 +/- 1.6% in spite of high normal whole-body oxygen delivery, with tailing of the histogram to severely hypoxic values (18.4 % of data < 40%). In parallel, markedly reduced rel Hb(conc) values were recorded and the standardized intramucosal pH (pHi) was lowered to 7.25 +/- 0.01. Short-term infusion of dopexamine (2 microg/kg/min) caused a significant rise in HbiO2 and rel Hb(conc), whereas whole-body oxygen uptake and standardized pHi values were not altered. In conclusion, decreased oxygenation and tissue hemoglobin concentration, with the appearance of severely hypoxic microdomains, were noted in patients with hyperdynamic sepsis, strongly suggesting pronounced microcirculatory disturbances in this compartment. The partial responsiveness of these abnormalities to dopexamine warrants further elucidation.

Jejunal tissue oxygenation and microvascular flow motion during hemorrhage and resuscitation

“…By injecting black ink into different layers of the intestinal wall, they demonstrated that the catchment volume of spectrophotometric data was limited to mucosal and, to a lesser degree, to submucosal vessels. In previous studies, we and others have hypothesized that measurements of HBjO 2 are limited to the mucosal and probably submucosal layer of the intestinal wall (8,13,27). However, in a recent investigation, we were able to demonstrate that the light emitted by the eluminating microlightguide penetrates the whole intestinal wall and is reflected by a mirror intermittently placed under the preparation resulting in an increase in light intensity detected by the photomultiplier tube (25).…”

The role of vasoactive agents in the resuscitation of microvascular perfusion and tissue oxygenation in critically ill patients

“…However, though dopexamine infusion was associated with a partial correction of spectrophotometric gastric Hbi O2 , pCO 2 g-a remained unaltered [76]. This might be compatible with persistence of microcirculatory weak units Increase of urine output and creatinine clearance, rise in bilirubin, no significant change in pCO 2 g-a AVP Argenine vasopressin, OPS orthogonal polarization spectral, pCO 2 g-a arterial-to-gastric pCO 2 gradient, MAP mean arterial pressure, EDTA ethylenediaminetetraacetic acid in combination with shunting, not sensed by spectrophotometry due to incorporation of arteriolar and venular hemoglobin.…”

Vasopressin V1A receptors mediate the increase in gastric mucosal oxygenation during hypercapnia

“…The flexible light-guide probe introduced into the stomach is positioned facing the greater curvature (Scheeren et al 2002), a site demonstrated to represent the microvascular oxygenation of other gastric and upper intestinal mucosa regions (Temmesfeld-Wollbruck et al 1998). Online evaluation of the signal quality throughout the experiments allows verification of the correct position of the probe tip.…”