Which of the following factors can directly affect cardiac output?
Respiratory rate
Stroke volume
Heart rate
Blood pressure
Correct Answer : B,C
B. stroke volume is the amount of blood ejected from the left ventricle with each contraction (systole) of the heart. Changes in stroke volume directly affect cardiac output. An increase in stroke volume leads to an increase in cardiac output, while a decrease in stroke volume results in a decrease in cardiac output. Factors that can affect stroke volume include preload, afterload, and contractility of the heart.
C. Heart rate refers to the number of heartbeats per minute. Heart rate directly affects cardiac output by determining how frequently the heart contracts and pumps blood. An increase in heart rate (tachycardia) leads to an increase in cardiac output, while a decrease in heart rate (bradycardia) results in a decrease in cardiac output. Factors such as sympathetic and parasympathetic nervous system activity, hormones, and medications can influence heart rate.
A. Respiratory rate does not directly affect stroke volume or heart rate but changes in respiratory rate can indirectly impact cardiac output through their effects on venous return and preload.
D. Blood pressure represents the force exerted by the blood against the walls of the arteries. While blood pressure does not directly affect cardiac output, it is influenced by cardiac output and systemic vascular resistance (SVR).
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
B This maneuver, called the Valsalva maneuver, can sometimes help to restore normal heart rhythm in cases of SVT. It involves blowing forcefully into a syringe or performing a similar action that increases intra-abdominal pressure, which can stimulate the vagus nerve and help to slow down the heart rate.
A Defibrillation is a treatment used for life-threatening cardiac arrhythmias, particularly ventricular fibrillation or pulseless ventricular tachycardia. It involves delivering a therapeutic dose of electrical energy to the heart with a device called a defibrillator.
C Drawing troponin levels may be appropriate if there is suspicion of myocardial infarction as the cause of chest palpitations or if there are other symptoms suggestive of acute coronary syndrome. However, in the context of SVT presenting with chest palpitations and a racing heart, the priority is to address the arrhythmia first
D Amiodarone is an antiarrhythmic medication used to treat various types of cardiac arrhythmias, including ventricular and supraventricular arrhythmias. While it can be effective in certain cases of SVT, it is not typically the first-line treatment or the immediate next step in managing SVT in the emergency department.
Correct Answer is B
Explanation
B. The QT interval represents ventricular depolarization and repolarization. It starts at the beginning of the QRS complex and ends at the end of the T wave. The QT interval reflects the total time it takes for both ventricular depolarization and repolarization to occur. Prolongation of the QT interval can be associated with an increased risk of arrhythmias, including torsades de pointes.
A. The QRS complex represents ventricular depolarization, which is the electrical activation of the ventricles. The duration of the QRS complex provides information about the time it takes for ventricular depolarization to occur. A prolonged QRS complex can indicate abnormalities in ventricular conduction, such as bundle branch blocks or ventricular hypertrophy.
C. The ST segment represents the early part of ventricular repolarization. It starts at the end of the QRS complex and ends at the beginning of the T wave. Changes in the ST segment, such as elevation or depression, can indicate myocardial ischemia or injury.
D. The PR interval represents the time it takes for the electrical impulse to travel from the atria to the ventricles. It includes atrial depolarization, atrial contraction, and the delay at the atrioventricular node. The PR interval does not specifically provide information about ventricular depolarization and repolarization.
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