Question

Consider this case and answer the following questions;

Martin Smith is a 57 year old sales manager who is significantly overweight. Despite his physician’s urging, Mr. Smith continued to eat a rich diet that included red meat and high-calorie desserts. He also enjoyed unwinding with a few beers each evening. He had occasional angina that was relieved by nitroglycerin (1 tablet, 0.4 mg, sublingual).On the night of February 3, 2017, Mr. Smith went to bed early because he wasn’t feeling well. He woke up at 2 am with crushing pressure in his chest and pain radiating down his left arm. He took 1 tablet of nitroglycerin, which did not relieve the pain. Mr. Smith’s wife called 911 and two EMTs promptly arrived. They found Mr. Smith alert and oriented. His skin was pale, cool, and diaphoretic. His pulse was 118, irregular, weak and thready. His respiration was 28, regular rhythm, shallow, labored, with rales upon inspiration. His blood pressure was 156/92. Mr. Smith complained of nausea, and dyspnea when supine. The EMTs placed him on oxygen, and assisted him in taking another nitroglycerin. Paramedics arrived on the scene, performed an ECG and recognized an ST elevation myocardial infarction (STEMI)The EMTs promptly transported Mr. Smith to the nearest STEMI receiving center. Mr. Smith’s serum levels of creatine phosphokinase and lactate dehydrogenase were high. Pulmonary capillary wedge pressure was 30 mmHg (normal 5 mmHg), and his ejection fraction was 0.35 (normal 0.55). Mr. Smith was treated with a thrombolytic agent, digitalis, and furosemide. After 7 days in the hospital, he was sent home on a strict low Na+ diet. Questions:

1. Discuss the physiological reason for each of the signs that the EMTs assessed (skin, pulse, respiration, blood pressure).

2. Discuss the pulmonary edema in this case using Starlings forces. Why did it develop? Why is it so dangerous? Why did Mr. Smith have dyspnea, particularly when supine?3.Discuss the physiological reason for the test results performed at the STEMI center (creatine phosphokinase, lactate dehydrogenase, pulmonary capillary wedge pressure, ejection fraction).

4. Discuss the rationale for each treatment (thrombolytic agent, digitalis, furosemide, low Na+ diet).

Answer 1

1) Pale cool and diaphoretic skin due to circulatory crisis and adrenaline release in STEMI which causes decreased blood supply to peripheral organ so as to compensate blood supply to vital organs.

fast, weak irregular, thready pulse due to decreased blood circulation

tachypneic, shallow laboured breathing with rales: When the left ventricular end-diastolic pressure (LVEDP) increases during myocardial ischemia, that pressure can be transmitted backward to the pulmonary veins and into the pulmonary vasculature causing transient pulmonary edema

high bp due to increased sympathetic tone

2) Cardiogenic pulmonary edema (CPE) Develops because of Imbalance of Starling forces - Ie, increased pulmonary capillary pressure, decreased plasma oncotic pressure, increased negative interstitial pressure. It developed because of increased capillary hydrostatic pressure secondary to elevated pulmonaryvenous pressure. It is dangerous because it can lead to respiratory distress or cardiac arrest due to hypoxia.

3) cardiac enzymes are released on myocardial ischemia therefore level increases in blood

pulmonary capillary wedge presure increases as left ventricle dysfunction leads to increase in pulmonary wedge pressure . Ejection fraction reduces because of decreased cardiac function secondary to myocardial ischemia.

4) thrombolytic agent to dissolve thrombus that resulted in reduced blood supply to myocardium.

digitalis improves heart’s ability to pump as there is low ejection fraction

furosemide to promote excretion of intracellular water so as to provide relief in pulmonary edema.

low sodium diet as sodium promotes water retention and in order to get relief of pulmonary edema, intacellular water needs to be excreted.