Assessment of the patient with chest pain in the accident and emergency department

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THROMBOLYTIC THERAPY ‘FAST TRACKING’

This article will review measures enabling emergency staff to identify patients with chest pain who are likely to need admission to a cardiac care unit, in particular those with manifestations of acute ischaemic heart disease - acute myocardial infarction and unstable angina. Other non-cardiac causes of chest pain will also be discussed.

The presentation of a patient with chest pain in the emergency department should always be taken seriously, since mappropriate discharge or delays in assessment and treatment for some patients may have catastrophic coiisequences. Not all patients who present to hospital with chest pain are, however, likely to require intensive cardiac care. In fact, such patients represent a minority of attenders, and there is a need to develop strategies for the appropriate stratification of patients according to their potential for complications, and likely benefit from expensive resources. It is cstimated that the cost per patient day on a cardiac care unit (CCU) is double that of a general ward (Norris 1903).

Tom Quinn RN FESC Spec~al~it Nurse Cardiology (West Midlands). Evidence Supported Medicine Union 27 Highfield Road Ebrm~ngham B I5 3DP UK

Accldenr '2nd Emeigrn‘yN"isinp

(1997,

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The introduction of intravenous thrombolytlc therapy as standard treatment for patients m,ith acute niyocnrdial infarction (GISSI
66 Accident and Emergency Nuning

Resources, including CCU beds, are limited. In 1995 there were 191 CCUs in the UK, together with 68 combined intensive care and coronary care units, providing a total of 1832 beds (CMA Medical Data Ltd 1996). There is growing interest in the development of strategies for the identification and risk stratification of chest pain patients, to ensure that those most likely to benefit from CCU admission are admitted to an appropriate facility, with those at lower risk ‘triaged’ to a lower dependency and less expensive facility (Quinn 1993). The options generally available in the UK are limited in most centres to: admit to CCU; admit to a general medical ward; or discharge home. In the USA a number of ‘intermediate care units’ have been in operation for some years. These facilities provide basic ECG monitoring, often adjacent to (or an integral part of) the emergency room (Gaspoz et al 1991; Gibler et al 1995; Tosteson et al 1996), but are generally not equipped or staffed to provide the same standard of monitoring and intervention as a conventional coronary care unit.

TO ADMIT

OR NOT?

The consequences can be catastrophic if a patient with chest pain caused by acute myocardial infarction or unstable angina is inappropriately discharged from A & E: sudden death on the way home from hospital is not unheard of, for example. In the USA, between 2% and 4% of patients with acute myocardial infarction are sent home inappropriately from the emergency department (Lee et al 1987; McCarthy et al 1993). Such incidents account for the largest number (20%) of malpractice claims against emergency physicians (Dunn 1986; Karcz et al 1994). Comparable figures for the UK are unknown since the medical defence organizations do not keep specific details of claims in this respect.

RISK STRATIFICATION A number of studies have been undertaken over the past two decades in an attempt to develop and test strategies for determining the probability of a patient with chest pain having sustained a myocardial infarction, or being at risk of suffering severe complications. Both groups of patients would be more likely to benefit from admission to a CCU or intensive care facility than, say, a patient with very low probability of either MI or of developing complications.

The largest study undertaken to date is the Multicenter Chest Pain Study (Goldman et al 1996), which investigated the risk of complications in more than 15 000 patients with chest pain presenting to seven emergency departments in Boston, Connecticut, Cincinnati and Michigan between the periods 1984-1986 and 1990-1994. In the earlier period of the study, data were obtained from some 10 682 patients in order to identify from the clinical presentation potential predictors of the development of serious complications, such as cardiac arrest, shock, serious arrhythmias or the need for emergency revascularization. These predictors were then applied to a further 4676 patients in the latter period of the study, in an attempt to validate their ability to predict complications. The main predictors of complications from the earlier (derivation) set of patients were ST segment elevation; Q waves or other features associated with acute ischaemia on the initial ECG; hypotension (systolic blood pressure < 100 mmHg); pulmonary rales; or an exacerbation of known ischaemic heart disease. When applied to the later (validation) set of patients, these criteria enabled stratification of patients according to their risk of developing both moderate (non-life threatening arrhythmia, heart failure without shock, recurrent ischaemia) and major complications (cardiac arrest, life threatening arrhythmia, requirement for pacemaker, cardiogenic shock, need for intra-aortic balloon pump or emergency revascularization) or a myocardial infarction during the first 12 hours of hospitalization. The development of complications early in the hospital course (
Chest

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VALUE

OF THE INITIAL

ECG

In both the above studies, xi iniportant prcdictoi of sustaining MI or developin g d serious complication \vay infomlation gained thin the initial EC<;. These findings confirm those of earlier, \nlaIler series (Bell et al 1090; Brush et al 198.5: I~,~tzelI et at 1991 ; Fesmire et al 10X9; Stark et al 10X7; Yusufrt al 1984). Howmer, the ECC; may be particularly labile during r the e;wty l1ours t-01lo\\@ symptom onset (Adan~s et al 1’993). A de~~-tx of- caution stioutd al\0 be applied to nixagenient decisions in those patients \vho have a history compatible mith acute MI and a nornlal ECX 011 initial asst’ssnlent: a mrmal ECG does not cxludc significant heart disease (Norcll et al I’PX?: K~sufet al 1’984). While the risk of conplicatlons in those mith a norn~al ECG is repordy low, a normal EC<; does uot of itself uecessarily nieari that the patient can safely by discharged fi-oni the A 8, E department. Moreover, the abiliy ofjunior lnedical staff correctly to interpret EC<& in the A & E departrnent ha\ beers hund \\mting 111 several series (Emerson et al 1989; Jayes et al ICK; Lee et al 1987; McCalIion et at 1000; White et al 1995). The availability ofa prior E<:G (recorded ou a previous admission, for example) may influence triage decisions in patients with chest pain lvheii the current recording has features consistent \vith ischaemia or infurction. Lee et al (1990) found no difference in admission decisions between patients \vith acute infarction whether or not a previous recording \z’as available. However, in those patients mithout obvious infxction, C:C:U admission was less likely in those in whonl a prior recording \\;a~ available for comparison. When the ECG is clearly severely abnormal (e.g. acute ST segment elevation, or left bundle branch block) then clearly the patient requires rapid admission to a CCU or equivalent montored facility, together with assessment for thrombolytic treatment (Quinn & Thompson 1995). There are other patients \vho may require urgent management, hoxvever, apart from thrombolytic therapy. This group includes those with recognized colitraiIidications to

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- Differential

pain assessment

diagnosis

of chest

in A & E 67

pain

Myocardial Infarction Unstable angina Stable angina Perlcardltls Myocarditis DIssection of the aorta Pulmonary embolism Pancreatltis Oesophagltls Cholecystitls Intercostal neuralgia Subdlaphragmatic abcess Pleurisy Cervical spine disease Chostrochondrlus Pneumonia Trauma (e.g. rib #)

thrombolytic therapy, such as recent mrgery or bleeding, severe hypertension, or recent laser treatment for retinopathy, and those in whmn the evidence for benefit is uncertain or absent (those \\;ith ST depression), \vho nonetheless ha1.e a high mortality The ECG should not be \4ewed in isolation froin the patient’s hirtor) and clinical state. The technique remains a cornerstone in the early assessment of patients with che\t pain (and a range of other conditions), and it is rccoliinlended that all A Cy-E nurses at‘ competent in the recording of a 1 Z-lead ECG.

The nature, intensity and duration of chest pain are important aspects of the initial assessment. Pain intensity has been shoxvn to bear a positive (although statistically weak) correlation to suL>sequent infarct size, incidence of ventricular fibrillation and heart failure (Herlitz et at 1986). The ability of CCU nurses to assess patients’ pain has been sho\vn to correlate nelt with patients’ own assessment (Thompson et al 199-I). Hoxvever, acute MI or ischaenlia are not giving rise to chest pain the only conditions (see Table). Where the patient has had pain of such severity as to require opiates, then clearI) adnlission to hospital is warranted.

Breathlessness accompanying an episode of chest pain may indicate the presence of associated heart failure, which carries a high ulortality and requires treatment with oxygen, diuretics and opiates, together with vasodilators such as nitrogtvcerine in particularly severe cases. Urgent medical attention is mandated in these patients.

68 Accident and Emergency Nursing

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5 3 4 Time after onset of acute myocardial 1

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8 1996 Curr Opin

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Fig. Relative release of cardiac markers in patients with acute myocardial infarction, CK - creatine kinase; LDH lactate dehydrogenase. Source: Morris S, Wu A H B, Heller G V I996 The role of cardiac imaging and biochemical markers in patients with chest pain. Current Opinion in Cardiology I I : 386-393

HYPOTENSION All studies into the initial presentation of patients with suspected MI have demonstrated a clear relationship between hypotension on admission, and subsequent mortality (Norris et al 1969; FTT Collaborative Group 1993). A systolic pressure of 100 mmHg or less on admission indicates a patient at high risk. However, with many cardiac patients now taking medications which tend to lower the blood pressure (beta blockers, nitrates, calcium channel blockers and angiotensin-converting enzyme inhibitors), it may be prudent to determine where possible a patient’s ‘usual’ blood pressure, if there is hypotension in the absence of associated features, such as cool peripheries, mental dulling or restlessness.

PRE-HOSPITAL

EVENTS

The occurrence of an adverse event in the prehospital phase of a chest pain patient’s presentation must be taken into account during the initial assessment. Valuable information may be obtained from the patient, accompanying relatives or ambulance staff. In particular, a period of unconsciousness or syncope, serious arrhythmia (for example, a broad complex tachycardia, a rapid narrow complex tachycardia or profound bradycardia), or cardiac arrest may herald the onset of further complications. The Multicenter Chest Pain Study demonstrated the importance of early complications (albeit during the initial

hospitalization) in predicting an adverse hospital course (Goldman et al 1996). As discussed above, the requirement for opiates in the prehospital phase will usually mandate admission to hospital for further assessment and monitoring.

OTHER ASSESSMENT STRATEGIES Chest

radiograph

While not essential (indeed, not recommended because it may delay urgent treatment) as an initial assessment tool in patients with chest pain thought to be cardiac in origin, the chest radiograph may be very useful in excluding non-cardiac causes of pain. In particular, the identification of a widened mediastinum resulting from acute dissection of the ascending aorta may be lifesaving. Other causes of chest pain (pulmonary embolism, pneumonia, pneumothorax, rib fractures) may be identified. It is important, however, to be aware of the limitations of the radiograph and its interpretation in patients with chest pain should be by a suitably experienced individual.

Cardiac enzymes and ‘markers’ myocardial damage

of

The usefulness of biochemical tests in the initial assessment of patient with chest pain is limited principally by the time after presentation in which such tests may reliably indicate or exclude myocardial damage. The rate of release of socalled ‘cardiac markers’ in patients with acute

Chest pain assessment in A & E 69

Non-invasive

imaging

techniques

A variety of nocinvncivr tt’sts arc available to ,1ssessnlt’nt of in~ocardial fLinction. pcrniit These include transthorc~cic ecllocardiogr‘lph) (Salk ct ~1 1001 ; Fleischmann ct ,11 1001) ni)ocnrdial perfusion imaging using 31ld cinglc photon emission coniputcd tonqraph~~ (Sl’E
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SUMMARY The cwxssnlent ofpnticnts Lvith chest pain is an importut qcxt of cnlrrgcncy cart’. The growing pressure on bed availability necessitates the need for ‘I ‘new mind sc‘t’ (Iloberts end Kleiman l’Y#) on the part of all professionals of inappropriate involved. The co~neque~~es discharge of patients from the A & E deparnxnt may be catastrophic. Those in need of cniergcncy intervention should be r,lpidl) identified rind appropriate rcferrdls niadc, or trcatlllent conunenced in A & E itself. Not ,111 ,ittenders with chest pdin will. lio\vevrr, require the high level of monitoring ,uld cur provided on ,I <:CU. dthough dnlission to J louver dependency fkility to dllow for cdreful cdiological follou~up may be necessary for a COIIsidernblc proportion of patients.

REFERENCES

70 Accident and Emergency Nursing

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