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

PURPOSE 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. METHODS 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. RESULTS 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). CONCLUSIONS 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.