The nurse needs to estimate quickly the heart rate of a patient with a regular heart rhythm. Which method will be best to use?
Print a 1-minute electrocardiogram (ECG) strip and count the number of QRS complexes.
Calculate the number of small squares between one QRS complex and the next and divide it into 1500.
Use the 3-second markers to count the number of QRS complexes in 6 seconds and multiply by 10.
Count the number of large squares in the R-R interval and divide by 300.
The Correct Answer is C
This method, known as the 6-second method, involves counting the number of QRS complexes in a 6-second interval on the electrocardiogram (ECG) strip and then multiplying that number by 10 to calculate the heart rate per minute. The advantage of this method is that it provides a relatively quick estimate of the heart rate.
A. Printing a 1-minute ECG strip and counting the number of QRS complexes in (option A) is incorrect because it can be time-consuming and may not be practical in situations where a quick estimate is needed.
B. Calculating the number of small squares between one QRS complex and the next and dividing into 1500 in (option B) is incorrect because it is a method used to calculate heart rate, known as the "1500 method," but it is not as quick as the 6-second method and requires more time and measurement precision.
D. Counting the number of large squares in the R-R interval and dividing by 300 is another method used to calculate heart rate, known as the "300 method," but it is also less quick and less accurate for assessing heart rate in patients with regular rhythms.
It's important to note that if the heart rhythm is irregular, these methods may not provide an accurate estimate of the heart rate, and a longer monitoring period or a different approach may be necessary.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Hypovolemic shock is a life-threatening condition resulting from severe blood or fluid loss. The patient in this scenario exhibits signs of hypovolemic shock, such as low blood pressure, tachycardia, cool and clammy skin, and decreased urine output.
When assessing the prescription options, the nurse should consider the appropriateness of each intervention for hypovolemic shock. Plasmanate is a type of plasma protein fraction that is used for volume expansion in certain situations. However, in hypovolemic shock, the primary intervention is to restore intravascular volume promptly. Plasmanate alone may not be sufficient for rapid-volume resuscitation.
In hypovolemic shock, the initial management typically involves the administration of crystalloid solutions, such as Lactated Ringers or Normal Saline, to restore intravascular volume. Therefore, the prescription of Plasmanate as the primary intervention raises concerns and should be questioned by the nurse.
A. Dopamine (Intropin) 12 mcg/min in (option A) is incorrect because: Dopamine is a vasopressor medication used to increase blood pressure and cardiac output. It is a suitable option for hypovolemic shock to support blood pressure and tissue perfusion.
B. Dobutamine (Dobutrex) 5 mcg/kg/min in (option B) is incorrect because: Dobutamine is an inotropic medication that helps improve cardiac contractility and cardiac output. It can be beneficial in cases of hypovolemic shock with signs of poor cardiac function.
D. Bumetanide (Bumex) 1 mg IV in (option D) is incorrect because: Bumetanide is a loop diuretic used to promote diuresis. However, in the context of hypovolemic shock, diuretics are generally not the first-line treatment as they can further reduce intravascular volume and worsen the patient's condition.
It is essential for the nurse to consult with the healthcare provider regarding the prescription order of Plasmanate and consider alternative interventions for rapid volume resuscitation in hypovolemic shock.

Correct Answer is B
Explanation
Mean arterial pressure (MAP) is a measure of the average pressure within the arteries during one cardiac cycle. It represents the perfusion pressure that drives blood flow to organs and tissues. MAP is calculated using the formula:
MAP = Diastolic blood pressure + 1/3 (Systolic blood pressure - Diastolic blood pressure)
Blood loss, particularly in cases of significant hemorrhage, leads to a decrease in blood volume. When blood volume decreases, there is less circulating blood available to generate pressure within the arterial system. This reduction in blood volume results in decreased MAP.
Therefore, in the case of massive blood loss after trauma, the student can correlate it with a lower blood volume, which in turn leads to a lower MAP. The decrease in blood volume reduces the perfusion pressure, compromising organ and tissue perfusion
A. It causes vasoconstriction and increased MAP in (option A) is incorrect because: While vasoconstriction can occur as a compensatory mechanism to maintain blood pressure, it does not necessarily lead to an increased MAP in the context of significant blood loss.
C. It raises cardiac output and MAP in (option C) is incorrect because Blood loss typically leads to a reduction in cardiac output due to decreased blood volume. Therefore, it does not raise cardiac output and MAP.
D. There is no direct correlation to MAP in (option D) is incorrect because: There is indeed a direct correlation between blood loss and MAP. As blood volume decreases, MAP decreases as well.
Therefore, the correct correlation between blood loss and MAP is that lower blood volume lowers MAP.
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