The circulatory system is a continuous network of arteries, veins and capillaries which circulate nutrients and oxygen to, and metabolic waste from, cells in the body to help fight diseases and to maintain a healthy balance.

Blood volume is the amount of blood in the circulatory system which is dependent on body weight. Larger people can tolerate slightly more blood loss than smaller people. On average, an adult male weighing 154 lbs (70 kg) has a blood volume of slightly more than 5 quarts (about 5 liters).

Blood loss from the circulatory system (bleeding or technically, hemorrhaging) can be the result of trauma, surgical procedures or medical conditions. Bleeding can occur internally, sometimes with no visible signs or symptoms or externally, either through natural body openings or through a break in the skin.

One of the most important functions of the body is maintaining blood volume and circulating blood to and from all body regions. Therefore, in a clinical setting, it is important to be able to monitor circulating blood volume in a patient. A fast, non-invasive and portable patient blood volume monitoring device has yet to be introduced.
Under controlled conditions like a blood donation, 8–10% of the donor’s blood volume is taken without serious medical difficulties. However, uncontrolled or undetected bleeding without timely medical intervention will develop into a biological cascade which can be fatal.

During a hemorrhagic event, too much blood loss will result in hemorrhagic shock (inadequate oxygenated blood delivery to the body’s tissues). This clinical state is extremely dangerous and continuation of the shock cascade may not be fatal, but, can still result in irreversible cellular and organ damage.

The treatment of hemorrhagic shock is first to detect that the patient is bleeding; this may not be obvious or easy and made more difficult by internal bleeding (a patient can bleed to death without any external blood loss). Well established techniques to control bleeding (hemostasis) are used to stabilize the patient’s condition. Additional fluid resuscitation (transfusion) may be required for desired blood volume and blood pressure.

Patient monitoring is critical to measure current parameters and track trends to assess the patient’s state of health. Zynex® Monitoring Solutions is pursuing technological advances in blood volume monitoring, to assist physicians and hospital staff in the early detection of blood loss to improve patient care and outcomes.