An Observational Pilot Study of the Effects of Traumatic Haemorrhagic Shock and Resuscitation on the Microcirculation

Haemorrhage following major trauma is an important preventable cause of death. Those patients who survive may have a prolonged period of debility caused by failure of key body organs. We suspect that an important contributor to this organ failure may be dysfunction in the network of small blood vessels that supply the bodies organs with oxygen and nutrients. Our study will examine the link between the microcirculation and organ failure in patients who have suffered significant bleeding after traumatic injury. We will also explore the relationship between resuscitation of the global circulation (blood pressure, cardiac output etc.)an area that is monitored in clinical practice with the state of the microcirculation, which by contrast is not monitored. Patients with severe traumatic injury commonly have problems with blood clotting. Some researchers have suggested that microcirculatory failure may be an important contributor to this problem and we will explore this in more detail. Finally, we will attempt to examine some of the mechanisms by which the microcirculation may be disrupted by trauma and subsequent bleeding. These may include inappropriate activation of white blood cells, inadequate function of oxygen carrying red blood cells and changes to the cells lining the small blood vessels.

We will use a non invasive method to assess the microcirculation termed Side Stream Dark Field microscopy. This involves recorded a video image of the movement of blood within the small blood vessels under a patients tongue. In addition we will use ultrasound to assess the flow of blood from the heart. Small samples of blood will be taken to assess blood clotting and to look at possible mechanisms of microcirculatory dysfunction.

We aim to study ten patients in the first instance. The study will be carried out within the intensive care units at Kings College Hospital.