A Real-Time, Portable Non-Invasive Monitoring System of Muscle Oxygen and pH in Trauma Patients

Trauma and severe hemorrhage remain the most frequent causes of death in the 1-44 year age group in both the civilian and military settings. Early recognition of shock and prompt institution of appropriate resuscitative measures are widely believed to improve outcome and decrease the progression to multi-system organ failure by virtue of maintaining end-organ perfusion. The physiological response to hemorrhage includes significant vasoconstriction to help maintain adequate perfusion to vital organs. Based on this known physiological response, noninvasive assessment of muscle oxygen and pH can provide a significantly earlier indication of blood loss than the standard vital sign measurements. Near infrared spectroscopy (NIRS) can be used to noninvasively and continuously determine muscle oxygen and pH and has been demonstrated to successfully recognize physiologic changes in a laboratory model of pre-shock (LBNP). Current NIRS systems employing fiber optic light cables are too large and fragile for portable use near the battlefield. This proposal describes novel technology for a portable, spectroscopic monitor to determine muscle oxygen and pH without fiber optic cables. The components of this system will be demonstrated on tissue-like phantom materials, as well as on human subjects. An initial design for a handheld, portable monitor will be completed as part of this Phase I project.