Detecting, managing and monitoring haemostasis: viscoelastometric point‑of‑care testing (ROTEM, TEG and Sonoclot systems)

2 Introduction

The causes of haemorrhage are very diverse in nature. Common causes include gastrointestinal bleeding, ruptured aortic aneurysm, traumatic injury and complications associated with surgery or childbirth. In all circumstances, the presence of an underlying or acquired coagulopathy will further complicate the clinical management of the patient and may delay the establishment of haemostasis.

Any surgical procedure carries an inherent risk of bleeding. If surgery is considered to be extensive or involves a particularly vascular part of the body, then the risk of unexpected or severe bleeding is increased. Although some bleeding is inevitable during surgery, the causes of any excess bleeding can be diverse and need to be identified and treated without delay.

Whilst mortality is low for most surgical procedures, ranging from less than 0.1% for most routine surgery to 1–2% for cardiac surgery and 5–8% for elective vascular cases, this may be greatly increased when severe bleeding occurs during the operative procedure.^[1]

In the UK, obstetric haemorrhage occurs in approximately 3.7 births per 1000.^[2] The diagnosis and management of obstetric haemorrhage can be challenging and due to the dilution of blood with amniotic fluid, it may be difficult to assess the extent of blood loss. Normal coagulation during pregnancy is also altered and this may complicate subsequent treatment.

Patients who suffer from trauma, such as road traffic accidents, often present with multiple injuries and require immediate medical intervention. Within this population it is recognised that major haemorrhage is the primary cause of death. Furthermore, due to the extent of the injuries sustained, it has been recognised that approximately 25% of these patients arrive in the emergency department with an established coagulopathy, further complicating subsequent treatment.^[3]

Major blood loss due to any of the above conditions leads to a reduced capacity within the body to deliver oxygen and nutrients to the tissues and organs. This in turn prolongs recovery and increases the risk of further complications. Uncontrolled bleeding can lead to complications such as hypothermia, haemodilution, acidosis and an increased use of clotting factors. This can further exacerbate the bleeding problem and cause a vicious cycle to develop.

The examples above are all potential causes of primary bleeding. However, as part of diagnosis and treatment, it is also important for the clinician to assess the patient for any acquired or underlying coagulopathy. This includes conditions such as disseminated intravascular coagulation, hyperfibrinolysis, thrombocytopenia, inherited or acquired platelet disorders and vitamin K deficiency.

The use of viscoelastometric point-of-care testing enables the clinician to establish whether a coagulopathy is present and if so, to determine the underlying cause. This information guides treatment and determines whether the primary cause of bleeding has been adequately corrected, and if specific blood components need to be administered. The type of coagulopathy identified will help to identify which blood components would be most beneficial to the patient.