Question

1.Apatient is having cardiac enzymes drawn to rule out a Myocardial Infarction.

a) What are the clinical indication and nursing implications for the following enzymes and their importance as a marker for Myocardial Infarction?

  CK

CK-MB

Myoglobin and Troponin

Answer 1

The cardiac enzymes are testing to rule out myocardial infarction. increased creatine kinase (CK) level and the healthcare practitioner wants to determine whether it is due to skeletal or heart muscle damage; when it is suspected that had a second heart attack or have ongoing heart damage.

The nursing implication before collecting the sample is

define and explain the test,state the specific purpose of the test, explain the procedure

Draw the sample before giving or one hour after giving I.M. injections. I.M. injections will increase the total CK level. However, in most clinical situations today, this is not a problem. Most persons admitted with a possible MI will almost always have an intravenous line started and all medications will be given intravenously, not I.M.
Be sure to obtain the blood samples on schedule. Always note on the laboratory slip, the time the sample was drawn and the hours elapsed since onset of chest pain. Be sure to draw blood samples in a 7-ml red top tube.
Be sure to handle the sample gently to prevent hemolysis. Always have the sample transported to the lab promptly because CK activity diminishes significantly after 2 hours at room temperature.

Do not collect the blood specimen from a patient who recently had an angina attack or undergone cardioversion. Cardioversion or angina attacks may increase myoglobin levels. Performing this test immediately after an MI produces misleading results, since myoglobin levels do not peak for 4 to 8 hours.

To rule out myocardial infarction Creatine kinase-MB (CK-MB) is a form of an enzyme found primarily in heart muscle cells. This test measures CK-MB in the blood.

Myoglobin is a small oxygen binding protein found in heart and skeletal muscle. Increased amount of myoglobin indicates injury of heart or skeletal muscles. Increased amount in blood may cause kidney to unable to filter and it cause kidney failure. It can be identified by urine test also.

Troponin T or I are superior markers of myocardial injury for the diagnosis of acute myocardial infarction. Troponin T or I testing can be used to diagnose reinfarction, replacing CKMB as the marker of choice for the diagnosis of reinfarction. CKMB thus should be removed from routine order sets.

Cardiac markers are used in the diagnosis of risk stratification of patients with chedt pain or acute coronary syndrome. Cardiac troponin is the first choice of cardiac enzyme to rule out ACS. Patient with elevated troponin level but negative creatinine kinase MB values who were formerly diagnosed with unstable anginaor minor myocardial injury re classified as no st elevated Mi.