Question

You are dispatched to a residence for a chest pain call. As you enter the living room, you notice that the patient is seated on the couch. He is pale, diaphoretic, and having trouble staying awake. His wife said he just got into a big fight with his son and began having chest pain. H£ has a cardiac history, so he took one of his prescribed nitroglycerin pills. After placing the patient on high concentration oxygen by nonrebreather mask and performing the primary assessment, you recognize that the patient's blood pressure is low, his breathing is faster than normal, and his pulse is fast.

1. How would the patient's low blood pressure affect his preload and afterload?
2. How would these changes to preload and afterload affect the patient's cardiac out-put?
3. How is the patient's body attempting to compensate for these changes?

Answer 1

Low blood pressure affects preload and afterload, which in turn affects cardiac output. The body compensates for these changes by increasing heart rate and respiratory rate.

Step-by-step explanation:

1. The patient's low blood pressure would decrease his preload and afterload. Preload refers to the amount of blood that fills the ventricles before they contract. With low blood pressure, there is less blood available to fill the ventricles, resulting in decreased preload. Afterload refers to the resistance the ventricles must overcome to pump blood out of the heart and into the arteries. With low blood pressure, there is less resistance, leading to decreased afterload.

2. These changes to preload and afterload would affect the patient's cardiac output. Cardiac output is the amount of blood pumped by the heart per minute. Decreased preload and afterload would decrease the amount of blood pumped by the heart, resulting in decreased cardiac output.

3. The patient's body is attempting to compensate for these changes by increasing heart rate and respiratory rate. The increased heart rate helps to increase cardiac output by pumping blood more frequently, while the increased respiratory rate helps to deliver more oxygen to the tissues.