Differential diagnosis of chest pain remains problematic. It is estimated that 12 percent of patients with AMI are sent home from the emergency department.31 Traditional measures to diagnose AMI include an ECG and measurement of cardiac enzymes, particularly creatine kinase CK-MB.32 In recent years, troponin levels have been studied to determine the efficacy of this laboratory test in diagnosis of AMI. Troponin is a protein found in striated muscle. There are three specific types: troponin-C (TnC), troponin-I (TnI), and troponin-T (TnT). TnT and TnI are specific for cardiac disease, and several studies have concluded that elevated levels of these enzymes result in greater sensitivity in diagnosing AMI and determining comprehensive risk stratification of patients with unstable angina.31,33,34 TnT and TnI will be elevated within 4 hours after myocardial damage and remain elevated for 10 to 14 days.
Nursing Care Before the Procedure
Client preparation is the same as for any study involving the collection of a peripheral blood sample (see Appendix I).
A venipuncture is performed and the sample is collected in a red-topped tube. The sample should be handled gently to avoid hemolysis and sent promptly to the laboratory.