Toxicity from which of the following medications may cause a patient to see a green-yellow halo around lights?
Metoprolol (Lopressor).
Enalapril (Vasotec).
Digoxin (Lanoxin).
Furosemide (Lasix).
The Correct Answer is C
Choice A rationale:
Metoprolol (Lopressor) is a beta-blocker that primarily affects the heart and blood vessels. It does not have a direct effect on the visual system, and therefore, it is not associated with the green-yellow halo symptom.
Common side effects of metoprolol include:
Fatigue
Bradycardia (slow heart rate)
Hypotension (low blood pressure)
Dizziness
Cold extremities
Bronchospasm (narrowing of the airways)
Diarrhea
Tinnitus (ringing in the ears)
Decreased exercise tolerance
Glucose intolerance
Masking of hypoglycemia symptoms Choice B rationale:
Enalapril (Vasotec) is an angiotensin-converting enzyme (ACE) inhibitor that primarily affects the kidneys and blood vessels. It does not have a direct effect on the visual system, and therefore, it is not associated with the green-yellow halo symptom.
The most common side effect of enalapril is a dry cough. This cough is thought to be caused by an increase in bradykinin levels, which can lead to the constriction of bronchial smooth muscle.
Choice D rationale:
Furosemide (Lasix) is a loop diuretic that primarily affects the kidneys and fluid balance. It does not have a direct effect on the visual system, and therefore, it is not associated with the green-yellow halo symptom.
Toxicity with furosemide manifests as extensions of its diuretic activity. Signs and symptoms of overdose or toxicity include:
Dehydration
Reduced blood volume
Electrolyte imbalances, particularly hypokalemia (low potassium levels) Choice C rationale:
Digoxin (Lanoxin) is a cardiac glycoside that affects the heart's electrical activity and muscle contractions. It has a narrow therapeutic index, meaning that there is a small difference between the therapeutic dose and the toxic dose.
One of the most characteristic signs of digoxin toxicity is a visual disturbance known as the "green-yellow halo sign." This symptom is thought to be caused by the inhibition of an enzyme in the retina called Na+/K+-ATPase.
Other common signs and symptoms of digoxin toxicity include:
Nausea and vomiting
Anorexia (loss of appetite)
Fatigue
Headache
Confusion
Arrhythmias (irregular heartbeats)
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A rationale:
Systole is derived from the Greek word "sustolē," meaning "contraction." This etymology directly aligns with the physiological process it describes.
During systole, the heart muscle contracts forcefully, generating the pressure necessary to propel blood out of the heart's chambers and into the circulatory system.
This phase is crucial for ensuring adequate blood flow to all tissues and organs, delivering oxygen and nutrients and removing waste products.
It's initiated by electrical signals generated by the sinoatrial node (SA node), the heart's natural pacemaker.
The electrical impulse travels through the heart's conduction system, triggering a coordinated contraction of the atria and ventricles.
Atrial systole occurs first, contributing to ventricular filling.
Ventricular systole follows, generating the powerful force that propels blood into the pulmonary artery (from the right ventricle) and the aorta (from the left ventricle).
Systolic blood pressure, the higher number in a blood pressure reading, measures the pressure in the arteries during ventricular systole.
Choice B rationale:
This choice describes diastole, the opposite phase of the cardiac cycle.
During diastole, the heart muscle relaxes, allowing the chambers to refill with blood.
Diastole is essential for proper heart function, ensuring that the heart can adequately fill with blood before the next systolic contraction.
Choice C rationale:
This choice refers to cardiac output, which is the total volume of blood pumped by the heart per minute.
Cardiac output is influenced by both heart rate and stroke volume (the amount of blood ejected from the ventricle with each contraction). Choice D rationale:
This choice describes ejection fraction, which is the percentage of blood that fills the ventricles during diastole that is then pumped out during systole.
Ejection fraction is a measure of the heart's pumping efficiency.
Correct Answer is C
Explanation
Answer and explanation
The correct answer is C. Normal Sinus Rhythm.
Choice A rationale:
Asystole is the absence of all electrical activity in the heart, as evidenced by a flat line on the electrocardiogram (ECG). It is a medical emergency that requires immediate cardiopulmonary resuscitation (CPR) and defibrillation.
Key features of asystole on ECG:
No discernible P waves, QRS complexes, or T waves.
A completely flat or nearly flat line on the ECG tracing.
Choice B rationale:
Atrial flutter is a rapid heart rhythm that arises from abnormal electrical activity in the atria. It is characterized by a sawtooth pattern on the ECG, with atrial rates typically between 250 and 350 beats per minute.
Key features of atrial flutter on ECG:
Absence of distinct P waves, instead replaced by flutter waves (sawtooth pattern).
Regular, rapid atrial rate (typically 250-350 bpm).
QRS complexes may be normal or slightly irregular in appearance.
Choice C rationale:
Normal sinus rhythm is the natural, healthy rhythm of the heart. It originates in the sinoatrial (SA) node, the heart's natural pacemaker, and is characterized by a regular rate of 60-100 beats per minute, with consistent P waves, QRS complexes, and T waves on the ECG.
Key features of normal sinus rhythm on ECG:
Presence of distinct P waves, QRS complexes, and T waves.
Regular rhythm with a rate of 60-100 beats per minute.
PR interval (the time between the P wave and QRS complex) is 0.12-0.20 seconds.
QRS duration (the time it takes for the ventricles to depolarize) is less than 0.12 seconds.
Choice D rationale:
Sinus bradycardia is a slow heart rhythm, with a rate below 60 beats per minute. It is often a normal finding in healthy individuals, especially athletes or during sleep. However, it can also be a sign of underlying medical conditions.
Key features of sinus bradycardia on ECG:
Presence of distinct P waves, QRS complexes, and T waves.
Regular rhythm with a rate less than 60 beats per minute.
PR interval and QRS duration are typically normal.
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