Development of an Algorithm for Prediction of Onset of Hemodynamic Instability in Humans

Hemorrhagic shock is typically identified by the degree of hypotension that develops as a result of blood loss and remains a leading cause of death on the battlefield as well as worldwide.

Monitoring for the onset of circulatory shock in a wounded soldier on the battlefield is typically performed by measurement of arterial blood pressure (mean, systolic, diastolic), arterial oxygen saturation (oximetry), or simple auscultation of the pulse (rate and character).

Shock is typically recognized by non-specific signs and subjective symptoms such as: cold clammy skin, pallor, weak thready pulse, unstable vital signs, and diminished mentation. Unfortunately, these signs are imprecise, subjective, and inconsistent.

Therefore, a definition based on the absence or presence of hypotension can be misleading since it does not represent the underlying problem of or the solution to hemorrhagic shock.

The resulting challenge is that shock is easily diagnosed in late stages when therapy is ineffective while early diagnosis is difficult because shock is first recognized by imprecise signs and subjective symptoms.

The near-infrared diffuse optical spectroscopy (NIR-DOS) developed at the Beckman Laser Institute,UC Irvine, has ability to analyzes tissue regions deeper below the skin surface and reports on larger tissue volumes in muscle and brain.

The FDPM DOS instrument generates harmless amounts of low-level non-ionizing NIR ligh. The DOS probe will be applied to the selected sites with standard of care procedure. The measurement will be repeated several times to monitor the physiology. The monitoring will continue intermittently during the period of the experiment.

Army Medical Center, civilian and military

Inclusion Criteria:

• Healthy nonsmoking normotensive males or females.
• Age 18 to 55 years old, Military or civilian.
• Active duty military members who are 17 years old

Exclusion Criteria:

• Age <18 and >55 years, except for 17 year old active duty military members.
• History of hyperthyroidism,hypertension, cardiovascular abnormalitY, respiratory illnesses,anaphylaxis,pre-syncopal/syncopal episodes,abnormal blood clotting,
• Taking drugs to alter autonomic function
• History of alcohol or drug abuse

• Brooke Army Medical Center
• Beckman Laser Institute University of California Irvine