The body starts to compensate for the loss of blood with peripheral vasoconstriction. Skin may start to become pale and cool to the touch. A class three hemorrhage involves the loss of 30-40% or 1500-2000mL of blood. At this stage the patient will begin to go into hemorrhagic shock. Blood pressure drops, heart rate increases along with respiratory rate, neurological signs such as confusion and anxiety arise; ischemia (deficiency of blood) begins to affect the extremities, allowing the body to conserve blood supply for important vital organs. A class four hemorrhage is the most severe. Blood loss is greater than 40%. Cardiac arrest occurs. Immediate action is required; bleeding must be contained within minutes or else the patient will die (Garrioch, 2004).
Surgeons would administer EPR when the patient goes into cardiac arrest. EPR would allow surgeons the necessary time to repair the body before vital organs are affected and the body can no longer sustain life. Dr. Tisherman states that "the ultimate goal of this study is to rapidly cool trauma victims who have suffered cardiac arrest from bleeding with a flush of ice-cold sodium chloride to preserve the patient to enable surgical control of bleeding, followed by delayed resuscitation with cardiopulmonary bypass (Clinical trials, 2011).".
The study has specific qualifications in order to perform this operation on a patient. Most likely the patient will be suffering from a gunshot or stab wound and will be hanging onto life by a thread. In order to perform the surgery, the patient must be between the ages of 18-65 and have one sign of life at the scene, exsanguinating hemorrhage, if the patient has a loss of pulse it must be less than five minutes prior to arrival at the emergency department, and finally if a thoracotomy is performed without immediate return of a pulse in the carotid arteries after clamping the descending thoracic aorta (Clinical Trials, 2011).