The brachial artery is the main blood vessel supplying the upper extremity, running deep along the inner side of the upper arm from the shoulder to the elbow. This artery is a direct continuation of the axillary artery and functions as the main conduit for oxygenated blood destined for the muscles of the arm, forearm, and hand. At the elbow, the brachial artery splits into the radial and ulnar arteries, which continue to supply the lower arm. A severing injury to this vessel constitutes an immediate, life-threatening emergency because of its large diameter and proximity to the body’s core circulation.
Immediate Threat: Massive Hemorrhage and Hypovolemic Shock
An injury to the brachial artery results in immediate, massive external bleeding, known as hemorrhage. As a high-pressure artery, the blood loss is rapid and often presents as a pulsatile, bright red stream. This rapid depletion of circulating blood volume leads to shock, which is the failure of the circulatory system to provide adequate oxygen to the body’s tissues.
This rapid volume loss leads directly to hypovolemic shock, where the heart can no longer pump enough blood to maintain pressure. Losing as little as 20 percent of total blood volume increases the heart and respiratory rates as the body attempts to compensate for the fluid deficit. The heart often exceeds 100 beats per minute, moving the remaining blood more quickly.
If volume loss progresses beyond 40 percent, the patient experiences a sharp drop in blood pressure. Signs of systemic failure include cool, clammy skin, paleness, and a weakened pulse as the body diverts blood away from the limbs and to the vital organs. The drop in brain perfusion can cause confusion and anxiety, indicating the body is failing to sustain its basic functions.
The Impact of Lost Circulation (Ischemia)
Beyond the life-threatening blood loss, a severed brachial artery instantly halts the flow of oxygenated blood to tissues downstream from the injury. This lack of blood supply, known as ischemia, immediately begins to starve the muscles and nerves of the forearm and hand of oxygen and nutrients. The severity of the damage is directly related to the duration of this deprivation.
Peripheral nerves, which often run alongside the brachial artery, are sensitive to oxygen deprivation and fail quickly. Sensory nerves may cease to function, causing numbness and tingling, followed by motor nerve paralysis, resulting in an inability to move the hand or fingers. Forearm muscles, responsible for grip and dexterity, are also susceptible to ischemic injury.
There is a time window, typically cited as six to eight hours, before irreversible tissue death, or necrosis, begins. Once this period is exceeded, the likelihood of permanent functional loss in the limb increases, potentially necessitating amputation. Even if blood flow is restored later, accumulated cellular damage can lead to severe swelling, a condition known as compartment syndrome, further complicating the injury.
Essential First Response Steps
The immediate response to a suspected severed brachial artery must focus on controlling the hemorrhage. The first action is to call emergency medical services immediately. While waiting for assistance, the focus must shift to applying continuous, direct pressure onto the wound site.
Use the cleanest material available, such as gauze, a clean cloth, or an article of clothing, and press down with maximum, unrelenting force. If blood soaks through the material, do not remove the original dressing; simply place additional material on top and continue to press firmly. This direct pressure compresses the injured artery against the underlying bone, slowing the flow of blood.
If bleeding is profuse and direct pressure is ineffective, the next step is to apply a tourniquet high on the upper arm, between the shoulder and the elbow. The tourniquet should be placed two to three inches above the wound but never on the joint itself. It must be tightened until the bright red, pulsatile bleeding completely stops, indicating that arterial flow has been restricted.
Once the tourniquet is in place and bleeding is controlled, record the time of application clearly on the device or near the patient. This time is important information for the medical professionals who arrive. The tourniquet should remain in place, and the patient should be kept warm and calm until transport for definitive surgical care.