Muscle oxygenation as an indicator of shock severity in patients with suspected severe sepsis or septic shock.

The aim of this pilot study was to evaluate the potential of a new noninvasive optical measurement of muscle oxygenation (MOx) to identify shock severity in patients with suspected sepsis.We enrolled 51 adult patients in the emergency department (ED) who presented with possible sepsis using traditional Systematic Inflammatory Response Syndrome criteria or who triggered a "Code Sepsis." Noninvasive MOx measurements were made from the first dorsal interosseous muscles of the hand once potential sepsis/septic shock was identified, as soon as possible after admission to the ED. Shock severity was defined by concurrent systolic blood pressure, heart rate, and serum lactate levels. MOx was also measured in a control group of 17 healthy adults.Mean (± SD) MOx in the healthy control group was 91.0 ± 5.5% (n = 17). Patients with mild, moderate, and severe shock had mean MOx values of 79.4 ± 21.2%, 48.6 ± 28.6%, and 42.2 ± 4.7%, respectively. Mean MOx for the mild and moderate shock severity categories were statistically different from healthy controls and from each other based on two-sample t-tests (p < 0.05).We demonstrate that noninvasive measurement of MOx was associated with clinical assessment of shock severity in suspected severe sepsis or septic shock. The ability of MOx to detect even mild septic shock has meaningful implications for emergency care, where decisions about triage and therapy must be made quickly and accurately. Future longitudinal studies may validate these findings and the value of MOx in monitoring patient status as treatment is administered

Geologic, geomorphic, and edaphic underpinnings of dryland ecosystems: Colorado Plateau landscapes in a changing world

Abstract Drylands represent more than 41% of the global land surface and are at degradation risk due to land use and climate change. Developing strategies to mitigate degradation and restore drylands in the face of these threats requires an understanding of how drylands are shaped by not only soils and climate, but also geology and geomorphology. However, few studies have completed such a comprehensive analysis that relates spatial variation in plant communities to all aspects of the geologic–geomorphic–edaphic–plant–climate system. The focus of this study is the Colorado Plateau, a high‐elevation dryland in the southwestern United States, which is particularly sensitive to future change due to climate vulnerability and increasing land‐use pressure. Here, we examined 135 long‐term vegetation‐monitoring sites in three national parks and characterized connections between geology, geomorphology, soils, climate, and dryland plant communities. To first understand the geologic and geomorphic influences on soil formation and characteristics, we explore associations between soil pedons, bedrock geology, and geomorphology. Then, we characterize principal axes of variation in plant communities and ascertain controls and linkages between components of the edaphic–geomorphic system and plant community ordinations. Geologic and geomorphic substrate exerted controls on important properties of the soil profile, particularly depth, water‐holding capacity, rockiness, salinity, and fine sands. Ordination identified five distinct plant communities and three primary axes of variation, representing gradients of woody‐ to herbaceous‐dominated communities (Axis 1), saline scrublands to C3 grasslands (Axis 2), and annual to perennial communities (Axis 3). Geology, geomorphology, and soil explained a large proportion of variation in Axis 1 (74%), while climate variables largely explained Axis 2 (68%), and Axis 3 was not well explained by the random forest models. The variables identified as most influential to each axis were, respectively: (1) soil depth; (2) aridity, lithology, and soil salinity; and (3) temperature and precipitation. We posit that Axis 3 represents a land degradation gradient due to historic grazing, likely exacerbated by dry conditions. Results provide a novel framework that links the geologic and geomorphic evolution of landscapes, with the distribution of soils and plant communities that can guide ecosystem management, exemplifying an approach applicable to drylands globally

Patient enrollment.

<p>Muscle oxygenation (MOx) was measured from spectra acquired from patients. Q-residuals measure the similarity between patient spectra and the spectra that were used to train the algorithm that measures MOx. High Q-residuals (> 95% confidence interval) indicate a level of dissimilarity that renders MOx measurements invalid. MOx from 51 subjects was included in the final data set analyzed.</p

Photograph of the optical probe placed on a subject’s hand.

<p>The spectrometer and associated equipment is on a mobile cart at the bedside.</p

Reflectance spectra of oxygenated and deoxygenated first dorsal interosseous muscles (back of the hand) from a healthy adult.

<p>Only the highlighted regions in the visible and near infrared (NIR) are used in the analyses to determine muscle oxygenation.</p

Clinical shock severity stratification scoring system.

<p>Clinical shock severity stratification scoring system.</p

Schematic diagram of the optical spectral acquisition system configuration.

<p>A fiber-optic probe brings the incident light to the subject and returns reflected light to a spectrometer for computer processing.</p

Muscle oxygenation (MOx) (mean ± SD) as a function of shock severity based on clinical scoring.

<p>Patients in mild and moderate shock categories were statistically significantly lower than healthy controls (*), and the mean MOx decrease between mild and moderate groups was also significant, p < 0.05. Statistical hypothesis testing was not performed on the severe group due to the small number of patients in that group.</p