European Resuscitation Council Guidelines for Resuscitation ... - CPR

Given the high urgency for emergency revascularisation inSTEMI and other high-risk patients, specific systems of care canbe implemented to improve STEMI recognition and shorten timeto treatment.The sensitivity, specificity, and clinical impact of various diagnosticstrategies have been evaluated for ACS. Information fromclinical presentation, ECG, biomarker testing and imaging techniquesshould all be taken into account in order to establish thediagnosis and at the same time estimate the risk so that optimaldecisions for patient admission and therapy/reperfusion are made.Signs and symptoms of ACSTypically ACS appears with symptoms such as radiating chestpain, shortness of breath and sweating; however, atypical symptomsor unusual presentations may occur in the elderly, in females,and in diabetics [9,10]. None of these signs and symptoms of ACScan be used alone for the diagnosis of ACS. A reduction in chestpain after nitroglycerin administration can be misleading and isnot recommended as a diagnostic manoeuvre [11]. Symptoms maybe more intense and last longer in patients with STEMI but are notreliable for discriminating between STEMI and non-STEMI-ACS.The patient’s history should be evaluated carefully during firstcontact with healthcare providers. It may provide the first clues forthe presence of an ACS, trigger subsequent investigations and, incombination with information from other diagnostic tests, can helpin making triage and therapeutic decisions in the out-of-hospitalsetting and the emergency department (ED).12-lead ECGA 12-lead ECG is the key investigation for assessment of an ACS.In case of STEMI, it indicates the need for immediate reperfusiontherapy (i.e. primary percutaneous coronary intervention (PCI) orprehospital fibrinolysis). When an ACS is suspected, a 12-lead ECGshould be acquired and interpreted as soon as possible after firstpatient contact, to facilitate earlier diagnosis and triage. Prehospitalor ED ECG yields useful diagnostic information when interpreted bytrained health care providers [12].Recording of a 12-lead ECG out-of-hospital enables advancednotification to the receiving facility and expedites treatmentdecisions after hospital arrival: in many studies, the time fromhospital admission to initiating reperfusion therapy is reduced by10–60 min [13,14]. Trained EMS personnel (emergency physicians,paramedics and nurses) can identify STEMI, defined by ST elevationof ≥0.1 mV elevation in at least two adjacent limb leads or >0.2 mVin two adjacent precordial leads, with a high specificity and sensitivitycomparable to diagnostic accuracy in the hospital [15–17].Itis thus reasonable that paramedics and nurses be trained to diagnoseSTEMI without direct medical consultation, as long as there isstrict concurrent provision of medically directed quality assurance.If interpretation of the prehospital ECG is not available on-site,computer interpretation [18,19] or field transmission of the ECG isreasonable. Recording and transmission of diagnostic quality ECGsto the hospital usually takes less than 5 min. When used for the evaluationof patients with suspected ACS, computer interpretation ofthe ECG may increase the specificity of diagnosis of STEMI, especiallyfor clinicians inexperienced in reading ECGs. The benefit ofcomputer interpretation; however, is dependent on the accuracyof the ECG report. Incorrect reports may mislead inexperiencedECG readers. Thus computer-assisted ECG interpretation shouldnot replace, but may be used as an adjunct to, interpretation byan experienced clinician.18 de 0ctubre de 2010 www.elsuapdetodos.comH.-R. Arntz et al. / Resuscitation 81 (2010) 1353–1363 1355BiomarkersIn the absence of ST elevation on the ECG, the presence ofa suggestive history and elevated concentrations of biomarkers(troponin T and troponin I, CK, CK-MB, myoglobin) characterisenon-STEMI and distinguish it from STEMI and unstable anginarespectively. Measurement of a cardiac-specific troponin is preferable.Elevated concentrations of troponin are particularly helpful inidentifying patients at increased risk of adverse outcome [20].Cardiac biomarker testing should be part of the initial evaluationof all patients presenting to the ED with symptoms suggestive ofcardiac ischaemia [21]. However, the delay in release of biomarkersfrom damaged myocardium prevents their use in diagnosingmyocardial infarction in the first 4–6 h after the onset of symptoms[22]. For patients who present within 6 h of symptom onset, andhave an initial negative cardiac troponin, biomarkers should be remeasuredbetween 6 and 12 h after symptom onset. In order to usethe measured biomarker optimally, clinicians should be familiarwith the sensitivity, precision and institutional norms of the assay,and also the release kinetics and clearance. Highly sensitive (ultrasensitive)cardiac troponin assays have been developed. They canincrease sensitivity for the diagnosis of MI in patients with symptomssuspicious of cardiac ischaemia [23]. If the highly sensitivecardiac troponin assays are unavailable, multi-marker evaluationwith CK-MB or myoglobin in conjunction with troponin may beconsidered to improve the sensitivity of diagnosing AMI.There is no evidence to support the use of troponin point-ofcaretesting (POCT) in isolation as a primary test in the prehospitalsetting to evaluate patients with symptoms suspicious of cardiacischaemia [23]. In the ED, use of point-of-care troponin assaysmay help to shorten time to treatment and length of ED stay [24].Until further randomised control trials are performed, other serumassays should not be considered first-line steps in the diagnosis andmanagement of patients presenting with ACS symptoms [25].Decision rules for early dischargeAttempts have been made to combine evidence from history,physical examination serial ECGs and serial biomarker measurementin order to form clinical decision rules that would help triageof ED patients with suspected ACS.None of these rules is adequate and appropriate to identify EDchest pain patients with suspected ACS who can be safely dischargedfrom the ED [26].Likewise, the scoring systems for risk stratification of patientswith ACS that have been validated in the inpatient environment(e.g. Thrombolysis in Myocardial Infarction (TIMI) score, GlobalRegistry of Acute Coronary Events (GRACE) score, Fast Revascularisationin Instability in Coronary Disease (FRISC) score or GoldmanCriteria) should not be used to identify low-risk patients suitablefor discharge from the ED.A subgroup of patients younger than 40 years with non-classicalpresentations and lacking significant past medical history, whohave normal serial biomarkers and 12-lead ECGs, have a very lowshort-term event rate.www.elsuapdetodos.comChest pain observation protocolsIn patients suspected of an ACS the combination of an unremarkablepast history and physical examination with negative initialECG and biomarkers cannot be used to exclude ACS reliably. Thereforea follow up period is mandatory in order to reach a diagnosisand make therapeutic decisions.Chest pain observation protocols are rapid systems for assessmentof patients with suspected ACS. They should generally includea history and physical examination, followed by a period of obser-