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. Sodium nitroprusside is a potent vasodilator used to reduce systemic vascular resistance and afterload, thereby improving cardiac output and tissue perfusion in cardiogenic shock. In this scenario, where the patient has cool and clammy skin with high SVR, indicating peripheral vasoconstriction,
increasing the rate of sodium nitroprusside infusion can help vasodilate peripheral vessels, reduce afterload, and improve tissue perfusion
A. Dopamine is a medication commonly used in the management of cardiogenic shock to increase cardiac output and systemic blood pressure. However, in this scenario where the patient is cool and clammy with high SVR, indicating vasoconstriction and potential peripheral hypoperfusion, increasing the rate of dopamine infusion may further increase systemic vascular resistance and exacerbate peripheral vasoconstriction. This can worsen tissue perfusion and exacerbate the patient's condition.
.
C. Nitroglycerin is another vasodilator commonly used in the management of cardiogenic shock to reduce preload and afterload, thereby improving cardiac output and tissue perfusion. However, decreasing the rate of nitroglycerin infusion may further exacerbate vasoconstriction and increase SVR, worsening tissue perfusion in this scenario. Therefore, decreasing the rate of nitroglycerin infusion is not indicated.
D. Intravenous fluids such as 5% dextrose in normal saline are typically administered to maintain adequate intravascular volume and perfusion pressure in shock states. However, decreasing the rate of intravenous fluid infusion may further decrease intravascular volume and preload, potentially exacerbating hypoperfusion and worsening the patient's condition. Therefore, decreasing the rate of intravenous fluid infusion is not indicated in this scenario.
Correct Answer is B
Explanation
B. Endotracheal intubation and positive pressure ventilation are indicated in patients with respiratory failure who are unable to maintain adequate oxygenation or ventilation with non-invasive interventions. Intubation allows for the delivery of positive pressure ventilation, oxygenation, and airway protection. It also facilitates the clearance of secretions and administration of medications. Given the patient's severe hypoxemia, impending respiratory distress, and deteriorating condition, endotracheal intubation and positive pressure ventilation are the most appropriate interventions to ensure adequate oxygenation and prevent further deterioration.
A. CPAP is a non-invasive ventilation modality that provides a continuous positive pressure to the airways throughout the respiratory cycle. While CPAP may be beneficial in certain cases of respiratory failure, it may not be sufficient for a patient with severe hypoxemia (SpO2 of 80%) and impending respiratory distress. CPAP is typically indicated for patients with conditions such as obstructive sleep apnea or mild to moderate respiratory failure.
C. Mini-tracheostomy may be considered in certain cases of upper airway obstruction or inadequate airway clearance. However, in this scenario, the patient's hypoxemia is likely due to severe respiratory failure rather than upper airway obstruction. While suctioning may be necessary to clear secretions, it does not address the underlying cause of hypoxemia or provide ventilatory support.
D. While administration of supplemental oxygen is important in the management of hypoxemia, a non- rebreather mask may not be sufficient for a patient with severe hypoxemia and impending respiratory distress. Non-rebreather masks can deliver high concentrations of oxygen but may not provide adequate positive pressure support or airway protection. In this case, endotracheal intubation and positive pressure ventilation are more appropriate to ensure adequate oxygenation and ventilation.
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