A patient is taking a beta 1-adrenergic drug to improve the stroke volume of the heart. The nurse caring for this patient knows that this drug acts by increasing:
Myocardial contractility
Cardiac afterload
Venous return
Cardiac preload
The Correct Answer is A
Choice A reason: Beta 1-adrenergic drugs, like dobutamine, stimulate beta-1 receptors in the heart, increasing cyclic AMP and calcium influx, enhancing myocardial contractility. This increases stroke volume by strengthening heart contractions, directly improving cardiac output, making this the correct choice for the drug’s mechanism of action.
Choice B reason: Cardiac afterload is the resistance the heart pumps against. Beta 1-adrenergic drugs don’t directly reduce afterload; they increase contractility. Increasing afterload would decrease stroke volume, opposing the drug’s purpose, making this choice incorrect for the drug’s effect on stroke volume.
Choice C reason: Venous return affects preload, not directly influenced by beta 1-adrenergic drugs. These drugs enhance contractility, increasing stroke volume independently of venous return. While preload impacts output, it’s not the primary mechanism of beta-1 stimulation, making this choice incorrect.
Choice D reason: Cardiac preload is the initial stretch of the heart, influenced by venous return. Beta 1-adrenergic drugs increase contractility, not preload, to boost stroke volume. Preload changes are secondary and not the primary action of these drugs, making this choice incorrect.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A reason: ACE inhibitors are teratogenic, risking fetal harm, so monitoring while continuing is unsafe. Stopping the drug is critical, making this incorrect for safe pregnancy management.
Choice B reason: ARBs are also contraindicated in pregnancy due to similar teratogenic risks. Switching to an ARB is not safe, so this is incorrect compared to stopping the medication.
Choice C reason: ACE inhibitors can cause fetal abnormalities, so the patient must stop the medication and contact her provider immediately for safer alternatives. This is the correct action.
Choice D reason: Continuing ACE inhibitors, even adjusted, is dangerous in pregnancy due to teratogenicity. Immediate cessation and provider consultation are required, making this incorrect.
Correct Answer is C
Explanation
Choice A reason: Respiratory acidosis involves low pH and high PaCO2. Normal PaCO2 (44) and low HCO3- (12) point to metabolic acidosis, not respiratory, so this incorrect.
Choice B reason: Metabolic alkalosis has high pH and HCO3-. Low pH (7.31) and low HCO3- (12) rule this out, indicating metabolic acidosis, so this is incorrect.
Choice C reason: Low pH (7.31) and low HCO3- (12) with normal PaCO2 confirm metabolic acidosis, where acid accumulation lowers pH. This matches, making it the correct choice.
Choice D reason: Respiratory alkalosis has high pH and low PaCO2. Low pH and normal PaCO2 exclude this, pointing to metabolic acidosis, so this is incorrect.
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