Pt has respiratory acidosis (low blood pH) due to his asthma exacerbation. What will the nurse expect to see?
No change in affinity of hemoglobin with oxygen
Decrease in affinity of hemoglobin with oxygen
Increase in affinity of hemoglobin with oxygen
Decrease in blood CO2
The Correct Answer is B
Choice A reason: Respiratory acidosis does not cause no change in affinity of hemoglobin with oxygen. It causes a decrease in affinity of hemoglobin with oxygen, which means that hemoglobin releases more oxygen to the tissues. This is known as the Bohr effect, which is a physiological response to low pH and high CO2 levels.
Choice B reason: Respiratory acidosis causes a decrease in affinity of hemoglobin with oxygen, which means that hemoglobin releases more oxygen to the tissues. This is the correct statement that describes the expected finding in this patient. The decrease in affinity of hemoglobin with oxygen is a compensatory mechanism that tries to restore the oxygen balance in the body.
Choice C reason: Respiratory acidosis does not cause an increase in affinity of hemoglobin with oxygen. It causes a decrease in affinity of hemoglobin with oxygen, which means that hemoglobin releases more oxygen to the tissues. An increase in affinity of hemoglobin with oxygen would mean that hemoglobin holds on to oxygen more tightly, which would worsen the hypoxia in the patient.
Choice D reason: Respiratory acidosis does not cause a decrease in blood CO2. It causes an increase in blood CO2, which is the primary cause of the low pH. A decrease in blood CO2 would indicate respiratory alkalosis, which is a condition of high pH and low CO2 levels.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Choice A reason: This is not the definition of ejection fraction. The percentage of blood that leaves the heart in a minute is related to the cardiac output, which is the product of the heart rate and the stroke volume.
Choice B reason: This is the correct definition of ejection fraction. It is the ratio of the stroke volume (the amount of blood pumped by the left ventricle) to the end-diastolic volume (the amount of blood in the left ventricle at the end of diastole). It is a measure of the efficiency of the heart and reflects the contractility of the cardiac muscle.
Choice C reason: This is not the definition of ejection fraction. The amount of blood that leaves the heart with each beat is the stroke volume, which is one of the factors that determine the ejection fraction.
Choice D reason: This is not the definition of ejection fraction. The amount of blood that leaves the heart in a minute is the cardiac output, which is influenced by the ejection fraction, but not equivalent to it.
Correct Answer is A
Explanation
Choice A reason: This is the correct mechanism of action of propranolol. Propranolol is a beta blocker medication, which means that it blocks the beta receptors in the heart and blood vessels. This reduces the sympathetic stimulation in cardiac muscle, which lowers the heart rate, contractility, and oxygen demand. This also reduces the renin release from the kidneys, which lowers the blood pressure.
Choice B reason: This is not the mechanism of action of propranolol. Propranolol does not increase the diuretic response in the renal tubules. This is the effect of diuretic medications, such as furosemide or hydrochlorothiazide, which increase the urine output and decrease the blood volume and pressure.
Choice C reason: This is not the mechanism of action of propranolol. Propranolol does not inhibit the conversion of angiotensin I to angiotensin II. This is the effect of angiotensin-converting enzyme (ACE) inhibitors, such as lisinopril or enalapril, which block the formation of angiotensin II, a potent vasoconstrictor that raises the blood pressure.
Choice D reason: This is not the mechanism of action of propranolol. Propranolol does not block alpha receptors throughout the body. This is the effect of alpha blockers, such as doxazosin or prazosin, which block the alpha receptors in the blood vessels and cause vasodilation, which lowers the blood pressure.
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