Battlefield medics and emergency responders have seen patients with no visible wounds suddenly go into shock from internal bleeding. At that point, no matter how fast medical personnel responds, the patient can still die, according to Lt. Col. Will Smith, an Emergency Medicine Physician in the Army Reserve.
He adds, “By the time a patient goes into shock, the body has difficulty keeping the brain and heart functioning. Early recognition and treatment of shock is paramount to saving the life of a patient with internal injuries.”
To predict shock before it happens, researchers at the Army Institute of Surgical Research www.usaisr.amedd.army.mul in collaboration with colleagues at the University of Colorado www.colorado.edu, Children’s Hospital Colorado, www.childrenscolorado.org and Flashback Technologies Inc. www.flashbacktechnologies.com have developed software that can predict when a patient will go into shock.
The device called the compensatory reserve index, tracks arterial waveforms resulting when waves of blood pressure are created as the heart pumps blood into the vessels. Within 30 seconds, the rate is determined, and then decides if the patient is using up their compensatory reserve.
A small screen on the prototype uses green, yellow, and red to denote how much of a patient’s reserve has been used. Green indicates that the patient is still strong, yellow that the patient is weakening, and red indicates that the patient is in imminent danger of crashing.
The device combines the software with a common medical device called a pulse oximeter, a small portable instrument that measures heart rate and the level of oxygen in the blood. Results of the clinical trials have been submitted to FDA along with a request for approval of the software as a medical device.
The researchers are studying the situation further to by analyzing data from old medical records on actual patients to see whether shock could have been successfully predicted just from the records alone without using the software. They found that if the software had been used in just one of the cases, a life could have been saved.
Obstetricians may have difficulty recognizing the actual amount of bleeding and predicting how well the mother will compensate during childbirth. So in another research effort, the Army Institute of Surgical Research and the San Antonio Military Medical Center www.goarmy.com/amedd/health-care/facilities/san-antonio-medical-center.html are now testing how well the compensatory reserve index could be used to track blood loss during childbirth since postpartum hemorrhage is a major cause of maternal death especially in the developing world.