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Nurse-initiated coronary thrombolysis

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VOL: 97, ISSUE: 15, PAGE NO: 40

Charlie Bloe, BSc, RGN, NDN, ITU Cert, is a charge nurse, medical intensive care unit, Falkirk and District Royal Infirmary

Coronary heart disease (CHD) claims the lives of 180,000 people in the UK every year: one in three men and one in four women dies of CHD.

Coronary heart disease (CHD) claims the lives of 180,000 people in the UK every year: one in three men and one in four women dies of CHD.

The disease may manifest itself as acute myocardial infarction (AMI), which occurs as a result of complete occlusion of the coronary artery lumen after the formation of a thrombus (clot) at the site of a ruptured atherosclerotic plaque. Myocardial ischaemia ensues soon after, leading eventually to myocardial necrosis.

The introduction in the 1980s of coronary thrombolytic agents (clot busters) as a treatment for AMI, using drugs such as streptokinase and tissue plasminogen activator, has resulted in significant improvements in mortality and morbidity rates (GISSI, 1986; ISIS-2, 1988).

Thrombolytic agents
AMI usually occurs as a result of thrombolytic occlusion - a blood clot in the affected coronary artery. Myocardial ischaemia and subsequent myocardial necrosis begin soon after total occlusion, but the process that leads to irreversible myocardial necrosis may take a number of hours. Ischaemic tissue may be salvageable in the early stages and if thrombolytic agents are given in time they can remove the thrombus, re-establish the blood flow, limit myocardial damage and therefore improve the outcome.

It is widely accepted that early intervention with thrombolytic agents after an AMI - in conjunction with pharmacological interventions such as the use of aspirin - is crucial to the patient's outcome and the greatest improvements in post-AMI survival rates occur in patients who are treated promptly (GISSI, 1986). The results of many large cardiac trials show that the more time elapses from the moment of total coronary artery occlusion, the greater the extent of myocardial damage: time is muscle.

Delays in treatment with thrombolytic agents occur for a number of reasons, including:

- Patients failing to recognise the severity of their symptoms and delay seeking medical advice;

- Delays in transporting patients to hospital;

- Medical practitioners who assess patients are not likely to authorise the use of thrombolytic agents without a second opinion;

- Doctors may not be able to attend and assess patients quickly enough because of their workload;

- A lack of immediate general medical beds, which can result in delays in vacating coronary care unit (CCU) beds;

- Many hospitals do not routinely initiate thrombolysis in the A&E department, which is the first point of contact for most patients with chest pain.

Some of these delays are clearly beyond the control of the receiving hospital, but it is still important that hospitals explore methods to reduce delays between admission and the application of thrombolytic therapy, which is known as the door-to-needle time.

Nurse-initiated thrombolysis
Forth Valley Acute Hospitals NHS Trust covers about 1,000 square miles of rural and urban areas in central Scotland with a population of more than 275,000. Patients with AMI are managed in a five-bed medical intensive/coronary care unit. About 250 are admitted each year.

Like most hospitals, we found it difficult to meet the nationally proposed standard of 30 minutes' door-to-needle time. In fact, our times increased from a median of 35 minutes in 1995 to 50 minutes in 1999.

For this reason a nurse-initiated thrombolysis model was proposed in which a trained nurse would undertake the immediate assessment of AMI patients and initiate thrombolysis, without discussion with or authorisation by a doctor (Table 1). The perceived advantages were that the the nurse would:

- Offer greater flexibility in the treatment of patients with chest pain;

- Support the medical staff;

- Adopt a role teaching both medical and nursing staff;

- Extend the role of the CCU nurse and keep the unit informed on developments;

- Reduce door-to-needle times to below 30 minutes;

- Improve patient outcomes;

- Ensure the more appropriate use of CCU beds;

- Be able to obtain consistent diagnosis in patients who present with chest pain.

We trained four coronary care nurses to share this role on a rostered basis, initially covering day shifts only. This system offered greater flexibility than one that employed a single practitioner.

The nurses selected had to:

- Be a minimum E grade (two were G grades, one was an F grade and one was an E grade);

- Have a minimum of three years' postregistration experience in CCU;

- Have previous expanded-role training in venepuncture, peripheral intravenous cannulation, defibrillation and IV therapy.

They attended a programme of intensive theoretical and practical training and assessment, which included:

- An in-house advanced electrocardiogram (ECG) interpretation course, covering bundle branch blocks and less common ECGs such as hyperkalaemia and pericarditis;

- A review of the thrombolysis mega-trials and the agents currently in use, with written and verbal assessments of 15 case studies to demonstrate the nurse's ability to progress through agreed thrombolysis administration protocols and treat appropriately;

- A minimum of 10 mock patient assessments;

- A three-day period of 'shadowing' the consultant cardiologist, in which the clinical and history-taking skills used in the differential diagnosis of chest pain were observed.

The period of training spanned several months, with instruction and assessment by the senior CCU charge nurse and the consultant cardiologist.

The aim was to educate the nurses in the protocol-guided interpretation of symptoms and ECG readings so they would have the skills to confirm a diagnosis of AMI and be able to identify differential diagnoses, which they used a patient assessment proforma to do (Box 1 and 2).

To minimise delays patient group directions, previously known as drug group protocols, were developed so that nurses could administer specific medicines without a prescription but within the parameters of an agreed protocol. The medicines covered were aspirin, streptokinase, tissue plasminogen activator and heparin.

Before the start of the pilot, nurses based in the A&E department - which is the point of admission and the area in which thrombolysis would be undertaken - were trained in basic ECG interpretation. The intention was that all patients admitted with chest pain would have a 12-lead ECG recorded by an A&E nurse within five minutes of admission. If the nurses thought the changes suggested an AMI, the thrombolysis CCU nurse would be paged.

The pilot began last September, with the nurses covering about 75% of day shifts. The traditional doctor-initiated treatment was practised during the remaining day shifts, at weekends and overnight.

Interim results and recommendations
Door-to-needle time was considerably shorter when a nurse initiated thrombolysis - median time was reduced from 68 to 18 minutes. These are early results based on the first 20 patients treated, but a trend is already apparent. Nurses tended to initiate thrombolysis in patients with obvious ECG changes and one would expect the assessment and initiation of treatment to be quicker in such cases.

Nurses currently assess about 40% of AMI patients who receive a thrombolytic agent. Doctors assess the rest, but we hope that the number of patients managed by nurses will increase after another four nurses have been trained.

It is reasonable to suggest that patients who are treated more quickly will have more favourable outcomes and there is data to suggest that the introduction of such protocols produces a significant and clinically important reduction in mortality (NHS Executive, 1999). A&E staff are to be commended for the speed at which they record the initial 12-lead ECG - a median of five minutes - because early ECG recording and diagnosis is essential to patient survival.

In a retrospective review by the consultant cardiologist it was agreed that nurses' decisions to initiate thrombolysis were correct in all cases, suggesting that they can reliably and safely assess and treat patients with suspected AMI.

Doctors have agreed to use the proforma from the pilot to guide assessment and treatment (Box 1 and 2). There is still a tendency for them to perform certain examinations that are not essential to decide whether to initiate thrombolysis, such as chest auscultation.

A logical extension of the project would be for thrombolysis to be initiated in the home, allowing a further reduction in treatment delays. With modern modem and fax communication systems, it should be possible for paramedics to transmit ECG recordings to a local specialist site and begin treatment in the home.

The early administration of thrombolytic agents significantly reduces the death rate of AMI patients. This nurse-initiated thrombolysis model has radically reduced the time taken to administer these agents, which has the potential to increase the number of positive outcomes for AMI patients.

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