The word perfusion in medicine relates to the delivery of arterial blood full of oxygen and nutrients to the tissues via the blood vessels. Peripheral perfusion looks specifically at the delivery of blood to peripheral tissues, that is, in the extremities of the body, such as feet and hands. Monitoring peripheral perfusion in critically ill patients allows medical staff and care givers to judge the effects of treatments and to allow for early intervention in case peripheral perfusion is measured as being too low.
Sometimes during cardiac failure and shock blood is redistributed to the vital organs and away from the peripheral tissues, resulting in decreased peripheral perfusion. Therefore, low peripheral perfusion can be an early indicator of cardiac failure or shock and can allow for early and life saving intervention.
Clinical signs include pale, mottled and clammy skin, at the extremities.
Peripheral perfusion is usually measured every two to four hours during a patient's stay in hospital. It can be measured as the amount of oxygen in the blood calculated as a percentage and is referred to as oxygen saturation. This can be done using a technique called pulse oxiometry. Pulse oxiometry measures the oxygen saturation of the blood using infrared light. The pulse oxiometer is usually a small device placed over a finger attached to a medical monitor so that staff can monitor oxygen saturation. It is a technique used for most critically ill patients and those with trauma and is even a compulsory requirement during surgery in some countries.
When blood supply decreases, so does the temperature of the skin. Therefore, peripheral warmth is also an important indicator of peripheral perfusion in children and newborns. The care giver would typically check the temperature of the foot at regular intervals by touch.
Studies in adults looking at toe temperature as a measure of peripheral perfusion have demonstrated a direct correlation between the two. According to the journal of Continuing Nurse Education, a study of 50 adults showed that a direct correlation between toe temperature and peripheral perfusion was proven to exist and they were even able to predict death rates based on early measurement of toe temperature.
The same article goes on to talk about evidence for peripheral warmth as a measure of peripheral perfusion in children and states that while the literature is limited, similar results to the adult studies were found.