Critical care case study - ST elevation myocardial infarction (STEMI): Nursing

Nurse Heidi works in the emergency department, or ED, and is caring for Fritz, a 65-year-old male with a history of hyperlipidemia, who was diagnosed with an ST-segment elevation myocardial infarction, or STEMI. Nurse Heidi goes through the steps of the Clinical Judgment Measurement Model to make clinical decisions about Fritz’s care by recognizing and analyzing cues, prioritizing hypotheses, generating solutions, taking action, and evaluating outcomes.

First, Heidi recognizes important cues, including Fritz’s vital signs which are temperature 98.9 º F, or 37.1 º C, heart rate 116 beats per minute, respirations 26 breaths per minute, blood pressure 104/64 mmHg, and oxygen saturation 88% on 2 liters per nasal cannula.

Upon assessment, Nurse Heidi notes Fritz has cool, clammy, and pale skin; weak peripheral pulses; and appears restless. He reports a squeezing pain in his chest that radiates to his left arm and rates his pain as a 9 on a 0 to 10 numeric pain scale.

Next, Nurse Heidi analyzes these cues. She reviews the electronic health record, or EHR, and notes Fritz’s ECG shows ST-segment elevation in two contiguous leads, and his serum troponin and creatine kinase-MB, or CK-MB, levels are elevated. She also notes aspirin and nitroglycerin were administered by emergency medical services, or EMS, while transporting Fritz to the ED.

Nurse Heidi knows that a myocardial infarction, or MI, occurs when a coronary artery is blocked, reducing blood flow to the myocardium, or heart muscle. She also knows that hyperlipidemia is a major risk factor for an MI because it contributes to atherosclerosis, where plaque builds up in the arteries causing a blockage.

Nurse Heidi recognizes that a STEMI is a type of MI, where one of the coronary arteries is completely blocked, and the ECG shows there’s an elevation of the ST-segment in at least two contiguous leads.

Nurse Heidi understands that as blood flow to the myocardium is reduced, the myocardial cells are deprived of oxygen and become hypoxic, resulting in chest pain and an inability of the heart to pump enough blood to supply the body’s needs.

In response, the heart rate increases in an attempt to improve blood flow to the tissues, which further increases oxygen demand. Then, as oxygen-deprived cells are damaged, they release proteins like troponin, and enzymes like CK-MB, resulting in increased levels in the bloodstream. As oxygen deprivation continues, myocardial cells become ischemic and begin to die, or infarct, and irreversible cardiac damage occurs. This results in decreased contractility, which decreases cardiac output and further reduces tissue perfusion and oxygen delivery to the body.

Decreased perfusion manifests as cool, clammy skin and restlessness; and if perfusion isn’t restored, tissue damage can include more layers of the heart, contributing further to cardiac damage and dysfunction. Nurse Heidi realizes Fritz needs prompt restoration of coronary perfusion to prevent further cardiac damage.

Now, using the information she’s gathered, Nurse Heidi chooses a priority hypothesis of ineffective tissue perfusion. Then, she generates solutions to address Fritz’s ineffective tissue perfusion, including pharmacologic and non-pharmacologic interventions; and she establishes the expected outcome that after intervening, Fritz will show signs of improved tissue perfusion within 15 minutes.

Then, Nurse Heidi takes action to implement these solutions. First, she reviews orders placed by the emergency provider that include preparing Fritz for percutaneous coronary intervention, or PCI, and to titrate oxygen to achieve an oxygen saturation above 90%. There are also orders to administer IV nitroglycerin, morphine sulfate, and heparin, as well as oral clopidogrel, carvedilol, and enalapril.