Physiological Adaptation Q 135

---

What is the first intervention for a client experiencing myocardial infarction?

  

     A. Administer morphine

     B. Administer oxygen

     C. Administer sublingual nitroglycerin

     D. Obtain an electrocardiogram

    

    

Correct Answer: B. Administer oxygen

---

Administering supplemental oxygen to the client is the first priority of care. The myocardium is deprived of oxygen during an infarction, so additional oxygen is administered to assist in oxygenation and prevent further damage.

---

Option A: Morphine may be given after administering supplemental oxygen first. As a potent opioid, morphine has seemed to be the ideal analgesic. It has innate hemodynamic effects that are beneficial during MI. It decreases heart rate, blood pressure, and venous return, and it may also stimulate local histamine-mediated processes. Theoretically, this reduces myocardial oxygen demand.

Option C: Sublingual nitroglycerin is also used to treat MI, but they’re more commonly administered after the oxygen. Nitroglycerin remains the first-line treatment for angina pectoris and acute myocardial infarction. Nitroglycerin achieves its benefit by giving rise to nitric oxide, which causes vasodilation and increases blood flow to the myocardium.

Option D: An ECG is the most common diagnostic tool used to evaluate MI. In a myocardial infarction transmural ischemia develops. In the first hours and days after the onset of myocardial infarction, several changes can be observed on the ECG. First, large peaked T waves (or hyperacute T waves), then ST elevation, then negative T waves, and finally pathologic Q waves develop.

---