The ACLS certified nurse recognizes the following 6-second strip on a patient. CPR is in progress. What is the nurse's first step in the ACLS Algorithm?
Defibrillate.
Administer Amiodarone 300 mg IVP.
Perform synchronized cardioversion.
Administer Epinephrine 1 mg IVP.
The Correct Answer is D
Choice D rationale
In the ACLS algorithm for a non-shockable rhythm such as asystole or pulseless electrical activity, the priority after starting CPR and establishing airway/access is the administration of vasopressors. Epinephrine 1 mg is administered every 3 to 5 minutes to induce vasoconstriction via alpha-1 receptors, which increases coronary and cerebral perfusion pressure. This helps maximize the effectiveness of chest compressions and improves the likelihood of achieving a return of spontaneous circulation during a cardiac arrest.
Choice A rationale
Defibrillation is the treatment of choice for shockable rhythms, specifically ventricular fibrillation and pulseless ventricular tachycardia. These rhythms involve disorganized or rapid electrical activity that can be terminated by an unsynchronized electric shock. However, if the patient is in a non-shockable rhythm like asystole or pulseless electrical activity, providing a shock is ineffective and detrimental, as it interrupts chest compressions without any physiological benefit to the heart's underlying electrical state or myocardial cells.
Choice B rationale
Amiodarone is a class III antiarrhythmic medication used in the ACLS algorithm specifically for shockable rhythms that are refractory to defibrillation and vasopressors. It works by blocking potassium channels and slowing conduction. In the context of a non-shockable rhythm, amiodarone is not indicated and provides no benefit. The primary focus for non-shockable rhythms is identifying reversible causes and maintaining perfusion through high-quality chest compressions and epinephrine, rather than attempting to suppress nonexistent or disorganized arrhythmias.
Choice C rationale
Synchronized cardioversion is a medical procedure where a low-energy shock is timed to be delivered during the R wave of the QRS complex. This is used for hemodynamically unstable patients who still have a pulse but are experiencing supraventricular tachycardia, atrial fibrillation, or ventricular tachycardia with a pulse. It is never used in a pulseless cardiac arrest situation or for non-shockable rhythms, as there is no organized electrical activity or R wave for the machine to track.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A rationale
The dicrotic notch is a specific landmark on the arterial pressure waveform that signifies the closure of the aortic valve. This event marks the end of systole and the beginning of diastole. As the left ventricle stops ejecting blood and begins to relax, the pressure in the aorta exceeds the pressure in the ventricle, causing the aortic valve to snap shut. This closure creates a brief retrograde flow and a subsequent pressure spike.
Choice B rationale
The opening of the aortic valve occurs at the beginning of systole, which corresponds to the sharp upstroke of the arterial waveform. This is when the left ventricle contracts and pushes blood into the systemic circulation, creating the peak systolic pressure. The dicrotic notch occurs much later in the cycle, specifically on the descending limb. Therefore, the notch cannot represent the opening of the valve, as that event happens during the initial phase of pressure rise.
Choice C rationale
The closure of the mitral valve occurs at the very start of ventricular contraction, marking the beginning of isovolumetric contraction. This event happens before the aortic valve opens and before blood is even ejected into the aorta. Since the arterial waveform measures pressure in the peripheral arteries or the aorta, it does not directly reflect the closing of the mitral valve. Mitral valve events are better visualized on an atrial or pulmonary capillary wedge pressure tracing.
Choice D rationale
The opening of the mitral valve happens at the start of ventricular filling, after the aortic valve has closed and the ventricle has relaxed. This occurs during diastole. While this is an important part of the cardiac cycle, it does not produce a visible notch on the arterial pressure waveform. The dicrotic notch is strictly an arterial phenomenon related to the sudden cessation of flow from the heart and the recoil of the elastic aortic walls.
Correct Answer is D
Explanation
Choice A rationale
Systemic vascular resistance (SVR) specifically measures the resistance the left ventricle must overcome to eject blood into the systemic circulation. It does not directly cause an increase in pulmonary vascular resistance (PVR), which is the resistance in the lung's blood vessels. While severe left sided heart failure can eventually lead to pulmonary backup, an increase in SVR itself is a systemic afterload issue. Respiratory rate changes are usually secondary to compensatory mechanisms or distress rather than a direct hemodynamic effect.
Choice B rationale
An increase in systemic vascular resistance usually results in an increase in arterial blood pressure, as pressure is the product of flow and resistance. If resistance increases and the heart maintains its output, the pressure will rise. Mean arterial pressure (MAP) typically increases with higher SVR unless the heart's pumping ability fails significantly. Therefore, decreasing blood pressure is generally the opposite of what is expected when SVR increases, provided the cardiac compensatory mechanisms are still functioning effectively.
Choice C rationale
Increasing systemic vascular resistance represents increased afterload. According to the Frank Starling law and basic hemodynamics, as afterload increases, it becomes harder for the heart to pump blood out, which typically leads to a decrease in stroke volume and subsequently a decrease in cardiac output. It would be highly unusual for cardiac output to increase in response to higher resistance unless there was a massive increase in contractility or heart rate to compensate for the added pressure work.
Choice D rationale
Increased systemic vascular resistance raises the afterload on the left ventricle, forcing the myocardium to work harder to eject blood. This increased workload directly leads to higher myocardial oxygen demands. Simultaneously, the higher resistance often leads to a reduction in stroke volume and cardiac output because the ventricle cannot empty as efficiently against the high pressure. Normal SVR ranges from 800 to 1200 dynes/sec/cm-5. High SVR can lead to heart strain and decreased systemic perfusion.
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