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

Golden Jubilee National Hospital

Golden Jubilee National Hospital is located in Clydebank, Scotland. It is described as a national resource for NHS Scotland and is managed by the National Waiting Times Centre Board.

The hospital has over 200 beds and 1400 staff, and specialises in orthopaedics, heart conditions and lung disease. It has 4 cardiac catheterisation labs, 16 theatres, and is home to regional and national heart and lung services.

Clinicians have used viscoelastometric testing within cardiothoracic surgery since 2002, initially at the Western Infirmary and latterly at the Golden Jubilee. They currently use the TEG system across all their clinical sites, and have a total of 32 TEG channels allowing them to run 32 individual tests at any time. They also have 3 ROTEM systems (12 channels) used alongside the TEG systems. All viscoelastometric testing at the Golden Jubilee is carried out at point of care in theatres or intensive therapy unit, with the support of the local point-of-care testing committee.

Anaesthetists carry out all tests, maintenance activities and quality control procedures at the Golden Jubilee. All educational requirements are done in-house by anaesthetic consultants who pass on their knowledge and skills to junior doctors during their rotation through the hospital.

Dr Lynne Anderson carried out an audit published in 2006 to assess the impact of using viscoelastometric testing within cardiothoracic surgery. The audit looked at the demographic data and transfusion requirements of 990 patients covering 6 months prior to the introduction of the ROTEM systems (488 patients) and 6 months after (502 patients). The table below summarises the changes in blood use observed.

This audit confirmed the clinical impression that both the number of patients requiring blood components and the number of units transfused were significantly reduced following the introduction of the ROTEM system. During the audit, tests were performed post-operatively in almost all bleeding patients and did not influence intra-operative management of the patients. Results of the audit therefore reflect post-operative transfusion requirements. Admission and discharge haemoglobin levels were not significantly different during the 2 time periods.

Although the NHS in Scotland does not currently pay the Scottish National Blood Transfusion Service for blood and blood components, the estimated costs and six-month savings available at the time of the audit are represented in the table below.

Although the cost benefits noted within this audit are important, from a clinical perspective the reduced short- and long-term clinical risks associated with blood transfusion were also considered to be of major benefit to patients.

Subsequent analysis following the audit has demonstrated that reductions in blood and blood component use have been maintained.

Further detailed information regarding this audit can be found in:

Anderson L et al. (2006) An audit of red cell and blood component use after the institution of thromboelastometry in a cardiac intensive care unit. Transfusion Medicine 16, 31–9.

John Radcliffe Hospital, Oxford

The John Radcliffe Hospital is part of the Oxford University Hospitals NHS Trust and is Oxfordshire's main accident and emergency site. The John Radcliffe is the largest of the trust's hospitals, covering around 66 acres. It provides acute medical and surgical services including trauma, intensive care and cardiothoracic services. It is situated in Headington, about 3 miles east of Oxford city centre.

Clinicians at the John Radcliffe have used viscoelastometric testing since 2001.There are currently 18 point-of-care TEG systems in use (36 channels). There are 4 within cardiac surgery, 2 in cardio-thoracic critical care, 4 in general surgery and 4 in general intensive care. There are a further 2 TEG systems used in vascular services and 2 in the transplant laboratories.

Tests are carried out by dedicated clinical haemostasis practitioners, who are also responsible for the operation of cell salvage devices, and operating department practitioners and nurses within critical care. These staff are also responsible for maintenance and quality control of the equipment. Results from tests are considered essential for the assessment of blood component requirements, especially prior to the administration of fresh frozen plasma, cryoprecipitate or platelets.

The initial procurement of the TEG system at the John Radcliffe was supported by the Trust blood bank and the point-of-care service. Since the introduction into cardiac surgery, cardiothoracic critical care and adult intensive care units, benefits have been observed in 3 different areas of blood management.

Firstly, exposure of patients to transfusion of blood and blood components has been reduced. For example, within adult intensive care, red cell transfusions have been reduced by 31%, fresh frozen plasma transfusions by 43% and platelet transfusions by 35%.This benefits patients due to the inherent risks associated with blood transfusion.

Secondly, the use of the TEG has enabled the trust to reduce the number of blood transfusions administered outside of agreed guidelines. This puts the trust in a better position at times of national blood shortage and minimises disruption to clinical activity.

Thirdly, reducing blood transfusions has reduced costs. The adult intensive care unit spent £198,756 on blood and blood components in the financial year April 2003 to March 2004. Based on audit results, it is estimated that £98,053 of this was spent on unnecessary transfusions. By using the TEG system to enable clinicians to make more informed decisions regarding transfusion, the estimated financial saving in blood use in the adult intensive care unit is £65,488 per year.

In summary, the trust found that the TEG system has had a positive impact on blood management. The technology has helped clinicians to make informed decisions regarding individualised treatment of bleeding at the time of need and at point of care.

The Royal Brompton

The Royal Brompton Hospital is part of the Royal Brompton and Harefield NHS Foundation Trust and is situated in Chelsea, London. The hospital is a specialist centre for the treatment of heart conditions and lung disease. It has 295 beds, more than 1600 staff, 6 operating theatres and 4 catheter laboratories.

The Royal Brompton has 5 TEG systems (10 channels) within its theatre complex which specialises in cardio-thoracic surgery. These are routinely used for the assessment of clotting for all patients. The devices are located centrally within the theatre where they are operated and maintained by clinical perfusion scientists. There are plans at the Royal Brompton to build a new point-of-care testing room, centrally within the main theatre suite. This will enable all testing equipment to have a central location for more convenient maintenance and quality control.

Clinical perfusionists have been trained to carry out the tests, maintain the equipment on a daily basis and perform the required quality controls. Any problems with the equipment that cannot be addressed locally can be escalated to the trust 'point-of-care' committee as required. All education is carried out by the 'point-of-care' manager in conjunction with the manufacturer.

Anaesthetists, perfusionists and haematologists have also assessed the utility of the ROTEM and Sonoclot systems. They have preliminary data that suggests the Sonoclot system is helpful in the assessment of platelet function and the ROTEM system for the assessment of fibrinogen. TEG is also a useful adjunct when exploring the haemostasis defects incurred via extra corporeal membrane oxygenation, a technique used to provide cardiac and respiratory support for patients whose heart and lungs are not working sufficiently. Patients having this procedure are particularly susceptible to coagulopathies and often require the transfusion of blood components to stabilise and maintain haemostasis.

Intensivists and anaesthetists at the Royal Brompton have developed a treatment algorithm using laboratory parameters and TEG to guide the management of bleeding after cardiac surgery. This provides a step-by-step approach to the identification and management of bleeding and demonstrates how this technology can help clinicians to identify the most appropriate blood components to administer for a given scenario. The algorithm is available for download here.

Clinicians at the Royal Brompton have specifically found the technology useful for establishing a pre-operative clotting baseline, for the monitoring of haemostasis during surgery and in the post-operative period, and to guide transfusion decisions.

British Army

The British Army currently uses viscoelastometric point-of-care testing as part of the emergency trauma services provided for the armed services at Camp Bastion in Afghanistan and at the Queen Elizabeth Hospital in Birmingham where injured troops are cared for when repatriated to the UK.

Camp Bastion Field Hospital is the major military trauma centre for Helmand Province, Afghanistan. The multidisciplinary medical team is British-led and commanded and staffed by both the regular and Territorial Army, as well as international staff from allied nations.

In order for this technology to be effectively adopted into routine use, it was recognised that staff need to have a good level of knowledge and understanding of the system and to be familiar with its use. For this reason, prior to being deployed to Afghanistan, military medical staff carry out an intensive pre-deployment training course which includes education on the theory, practice and interpretation of viscoelastometric results. This is provided by a cohort of consultant doctors who are experts in the field. The course includes theoretical understanding of the technology, practical experience, maintenance, quality control and troubleshooting. This is followed by a 1 week series of practical exercises.

It was also recognised that viscoelastometric testing should always be available as required. There are 3 ROTEM systems at Camp Bastion, 2 located in theatre and 1 which is used for research purposes. This allows for increased capacity and helps to maintain availability of the test during maintenance activities or repairs. A further 2 ROTEM systems are used in the Queen Elizabeth Hospital, in theatre and in the Trauma Critical Care unit.

Soldiers who sustain traumatic injuries often require massive blood transfusions and their management can be further complicated due to their location and access to blood and blood components.

The British Army has found the use of viscoelastometric testing in this situation very helpful. The benefits noted are:

Within Camp Bastion, trauma patients are resuscitated and transfused as part of a seamless approach from arrival, through the emergency department and into theatre. Viscoelastometric testing is carried out as soon as possible upon arrival at Camp Bastion, as coagulopathies are common in this patient population. Although results may not be available prior to initial treatment (which may include blood transfusion), as soon as early results become available, treatment options and transfusion protocols can be adjusted as required.

Casualties are often repatriated within 36 hours of their initial trauma and are flown direct from Camp Bastion to the UK. During this time, the patient's clinical condition continues to evolve and change. For this reason, on arrival at the Queen Elizabeth Hospital in Birmingham, ROTEM analysis is performed as part of the admission protocol and is used to guide ongoing haemostatic resuscitation. Further surgery usually occurs within 2–4 hours of admission and during this time, clinicians use ROTEM results to help target transfusion therapy and manage any coagulopathy.

Liverpool Women's NHS Foundation Trust

Liverpool Women's NHS Foundation Trust is 1 of only 2 specialist Foundation Trusts in the UK dedicated to the healthcare of women, babies and their families. It has a staff of 1410 and provides clinical and patient services in maternity, gynaecology, neonatal care, fertility and clinical genetics. Each year the trust delivers approximately 8000 babies.

Liverpool Women's Hospital uses the ROTEM system for all obstetric bleeding scenarios. Currently, 1 ROTEM system is used clinically and 1 is on loan and used for research purposes. The trust mainly uses the fib-tem and ex-tem assays to guide decision-making. In order to be most responsive to the needs of the patient, the system is located centrally within the obstetric operating theatre complex.

During adoption of this technology, it was recognised that in order for results to be reliable, the quality and consistency of testing would need to be maintained. For this reason, the 11 consultant anaesthetists who carry out the tests provide education to the junior doctors who rotate within the region on a 3-monthly basis. All staff are assessed for competency prior to being able to run a test or interpret results. The trust training and competency assessment form is available for download as an example.

Liverpool Women's Hospital has been using the ROTEM system since April 2011. From April 2011 to March 2012 it used the technology in conjunction with conventional transfusion of blood and blood components. A second phase then ran from July 2012 to June 2013 when a dose of 3 g fibrinogen concentrate was included in the algorithm, with further doses titrated according to the patient's response to treatment. When comparing the 2 periods, clinicians discovered that there were statistically significant reductions in the volume of fresh frozen plasma, cryoprecipitate, fibrinogen and platelets transfused for those patients who had received fibrinogen concentrate. There were also significantly fewer patients who needed 6 or more units of red cells in the latter group.

They also noted that since incorporating use of the ROTEM system to guide the use of fibrinogen concentrate in the treatment algorithm, no patients have suffered the negative effects of receiving too much fluid. This in turn has reduced the number of admissions to intensive care. This is their current algorithm and analysis of a further year's data is due to begin soon as part of their ongoing audit. For additional information please contact: Dr Shuba Mallaiah at shuba.mallaiah@nhs.net

As the normal clotting values for people who are pregnant are not clearly defined, Liverpool Women's Hospital is also currently carrying out a research study designed to establish normal values within each of the trimesters of pregnancy. The findings of this study are expected to be published in late 2014.

North Manchester General Hospital

North Manchester General Hospital is the largest hospital within the Pennine Acute Hospitals NHS Trust and is located in Crumpsall, 3.5 miles north of Manchester City Centre.

The hospital has 580 beds and offers hepatobiliary, orthopaedic, gynaecology and general surgery services. It is also the base for the regional specialist infectious diseases unit.

Consultant anaesthetist Dr Patrick Waits carried out a trial using the TEG system, with the aim of determining whether it would reduce blood component usage and expenditure, and if it would be a useful tool as part of a patient blood management approach.

The TEG 5000 system was trialled from July 2012 to March 2013. During the adoption of this technology, it was recognised that in order to maintain quality during the trial period, use would be limited to a core group of anaesthetists, theatre staff and staff within critical care. Training in the use and operation of the equipment, interpretation of results and quality assurance was provided. However, ensuring staff were available for training was difficult and caused a number of operational problems.

During the trial period, it was also agreed that due to clinician's limited experience of using the technology and interpreting results, they would be free to combine clinical parameters and other laboratory results with TEG results in order to guide decision-making.

In order to ensure the adoption of this technology was systematic and well planned, a small group supported the project including anaesthetists, the trust point-of-care team, the blood bank manager, the manufacturer and the directorate manager. The trust point of care committee was particularly helpful in providing guidance with quality assurance and writing a standard operating procedure and training competency checklist for the technology.

During the trial period, 24 surgical patients were enrolled. In 46% of cases (11/24), use of the TEG system led to a reduction in blood component administration, with an associated saving of 30 units of fresh frozen plasma and 4 therapeutic doses of platelets.

In a further 29% of cases (7/24), the TEG results indicated that fewer blood components were required but the clinicians decided, based upon clinical judgement, to administer the components. If these blood components had not been administered, this would have accounted for a further saving of 10 units of fresh frozen plasma.

In all cases, clinical opinion was that the technology improved management of bleeding.

The following table summarises the savings of blood components and the associated cost savings achieved during the trial.

The results of the trial demonstrated that the use of this technology helped clinicians to manage patients who are bleeding as part of an overall patient blood management approach.

It is anticipated that with further experience and training, greater savings would be achieved. Following the trial, Dr Waits carried out an audit over 3 months, which found 150 surgical patients who required 4 units of blood with or without blood components. It is estimated that use of the technology within this larger group of patients would save approximately £48,000 per year in blood components (£13,774 net savings in year 1). The following table provides an estimation of costs and potential savings if all capital costs paid in year 1.

If the capital cost was spread over the expected 5 year lifespan of the equipment, the saving could be calculated as follows:

Addenbrooke's Hospital

Addenbrooke's Hospital is a university teaching hospital and part of the Cambridge University Hospitals NHS Foundation Trust. It provides emergency, surgical and medical services for people living in the Cambridge area. It also provides regional specialist services including organ transplantation, cancer, neurosciences, paediatrics and genetics.

TEG systems are used within the liver theatre. A ROTEM and a Sonoclot system are also used within the Haemophilia & Thrombophilia Centre, which uses these technologies for its own patients as well as offering an 'office hours' service to patients accessing A&E and general theatre.

Dr Roger Luddington, principal clinical scientist at the Cambridge Haemophilia & Thrombophilia Centre, wrote the following description of the use of the technologies within this setting: "Despite seeing the majority of patients within the centre we choose to use citrate anticoagulated blood samples rather than native blood. This gives a longer window for sample analysis (increasing from 30mins to 2 hours) which is crucial during busy periods in clinic when there is limited machine availability.

We carry out pre-operative screening of patients where hyper-coagulation is a concern, such as pre-pancreas transplantation, but the main application of the technology in our centre is in the investigation of hypo-coagulation.

Viscoelastic measurement is used for a number of applications within the Haemophilia Centre. Initially it is used in the laboratory investigation of an unexplained bleeding diathesis. This is 1 of the only whole blood measurements of haemostatic potential at our disposal.

Each of the technologies has its own unique features to add to the diagnostic picture. The ROTEM system gives measures of clot formation and breakdown (fibrinolysis) and the Sonoclot dissects out a measure of fibrin formation kinetics and platelet involvement. Neither test is used in isolation. They are used as part of a comprehensive panel of analysis. This panel includes assessment of thrombin generation using principally platelet poor plasma, but where indicated platelet rich plasma, whole blood aggregometry, platelet nucleotide measurement and coagulation factor assessment.

The ROTEM system is also used in the assessment of the efficacy of coagulation factor treatment. This is particularly useful in the treatment of haemophiliacs with specific factor inhibitors treated with some form of bypassing agent such as recombinant VIIa or FEIBA. In the absence of specific assays for the effects of these products, the improvement in the viscoelastometric trace gives reassurance to clinicians following therapy. In the laboratory we can add these bypassing agents to patient sample ahead of treatment and perform viscoelastometry as a guide to the likely response.

The assessment of fibrinolysis is a challenging area of haemostasis. The use of both the ROTEM and Sonoclot systems allows some measure of both hypo- and hyper- fibrinolysis.

In gross abnormalities these changes can be seen in the unmodified tests. However the addition of tissue plasminogen activator to the reaction mixture is used to increase the sensitivity."