The Use of Tissue Oxygen Monitoring in Critically Injured Patients
Project Director: Mitchell Cohen, MD; Co-Investigator: Natasha Bir, MD
Project Summary
Current methods of assessing the adequacy of resuscitation of trauma patients have inherent limitations in that they do not give specific information about perfusion of critical organ beds. This project is a prospective study of seriously injured patients with multiple system trauma. It is designed to investigate the monitoring of tissue oxygen and microcirculatory flow of the deltoid muscle as an endpoint of resuscitation in an attempt to reduce both morbidity and mortality following injury. The study design and methodology are based in part on findings from our previous laboratory work measuring brain and muscle tissue oxygen during hemorrhagic shock and resuscitation. Active protocols associated with this project are solely observational, however, data collected from these observations will be used to design interventional studies to improve outcome from severe multi-system trauma.
Specific Aims:
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To establish critically abnormal levels of tissue oxygen partial pressure (PmO2) and microcirculatory flow (Qmc) in the deltoid muscle of severely injured patients as a surrogate for the adequacy of global tissue oxygenation in critically-injured patients.
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To determine the effects of blood transfusion on peripheral muscle Qmc and PmO2 after severe injury.
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To determine the effects of global hypoperfusion on peripheral muscle Qmc and PmO2 after severe injury.
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To determine the effects of central and peripheral muscle temperature changes on and PmO2 after severe injury.
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To determine the effects of fluid resuscitation on QMC and PmO2 after severe injury.
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To determine the effects of vasoactive pharmacologic agents on Qmc and PmO2 after severe injury.
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To correlate PmO2 and Qmc with standard clinical measurements of resuscitation such as base deficit, mean arterial pressure, along with the incidence of sequelae from hypoperfusion (infections, organ failure/dysfunction) and outcomes (duration of mechanical ventilation, intensive care unit stay, hospital length-of-stay) in critically injured patients.
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To apply statistical and bioinformatics techniques to visualize and quantify response of key physiological measurements such as MAP, base deficit, Qmc and PmO2 to administration of vasoactive drugs, fluid boluses and hyperoxia.
Inferior Vena Cava Diameter (IVCD) and Near-Infrared Spectroscopy (NIRS) Predict Resuscitation Status and Outcome
Project Director: Mitchell Cohen, MD; Co-Investigator: Natasha Bir, MD
Project Summary
The ideal guide to resuscitation remains elusive. Studies in non-trauma settings have indicated that inferior vena cava diameter (IVCD) as measured by ultrasound can be used reliably to assess volume status. In addition, near infrared spectroscopy (NIRS) provides a continuous non-invasive measurement of tissue hemoglobin oxygen saturation (StO2) in muscle that corresponds with systemic oxygen 
delivery. The primary interest of this study is the ability of non-invasive monitoring by ultrasound or NIRS to detect occult hypoperfusion. IVCD and NIRS measurements during and after the initial resuscitation of severely injured patients will be compared against traditional measurements such as blood pressure, base deficit, and lactate. We will also examine the ability of non-invasive monitoring to predict need for transfusion, operative intervention, and later complications such as infection, organ dysfunction, and death. Our ultimate goal is to establish criteria for goal-directed resuscitation in trauma patients using non-invasive monitoring such as IVCD and NIRS.
Specific Aims:
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To establish a reference range of IVCD measurements during normal and decreased volume status.
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To compare initial IVCD measurements and their eminence near infrared spectroscopy (NIRS) changes over time with standard resuscitation measurements: base deficit, lactate, and vital signs
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To determine if NIRS measurements and IVCD predict need for transfusions, need for operation, and/or need for fluids.
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To determine if early NIRS measurements correlate with late outcome.