Which of the following ECG rhythm interval measures is considered abnormal?
QTc interval 0.33 to 0.47 seconds
QT interval that varies with HR
QRS interval <0.12 seconds
PR interval 0.12 to 0.24 seconds
The Correct Answer is A
The QTc (corrected QT) interval is a measure of the time it takes for the ventricles to depolarize and repolarize during a cardiac cycle. It is corrected for heart rate (HR) to account for variations in the cardiac cycle length.
The normal range for the QTc interval varies depending on the calculation method used but generally falls within 0.36 to 0.44 seconds. In the given options, the range of 0.33 to 0.47 seconds for the QTc interval is wider than the normal range, suggesting a prolonged QTc interval, which can be indicative of a potential risk for arrhythmias, including ventricular tachycardia and torsades de pointes.
B. QT interval that varies with HR in (option B) is normal because The QT interval alone can vary with heart rate, and this is considered a normal physiological adaptation.
C. QRS interval <0.12 seconds in (option C) is normal because The QRS interval represents the time it takes for ventricular depolarization and is normally less than 0.12 seconds.
D. PR interval 0.12 to 0.24 seconds in (option D) is normal because The PR interval represents the time it takes for atrial depolarization and conduction through the AV node. The normal range is typically 0.12 to 0.20 seconds.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is ["9"]
Explanation
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Doseinmcg/min=2mcg/kg/min×60kg=120mcg/min
Convert this to mg/min since the concentration is in mg:
120mcg/min=0.12mg/min120 \text{ mcg/min} = 0.12 \text{ mg/min}120mcg/min=0.12mg/min
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Determine the concentration of Dopamine:
- Total amount of Dopamine: 200 mg in 250 mL of saline
- Concentration:
Concentration=200mg250mL=0.8mg/mL\text{Concentration} = \frac{200 \text{ mg}}{250 \text{ mL}} = 0.8 \text{ mg/mL}Concentration=250mL200mg=0.8mg/mL
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Calculate the pump rate in mL/min:
To find the rate in mL/min needed to deliver 0.12 mg/min:
Pumprate=Desireddose(mg/min)Concentration(mg/mL)\text{Pump rate} = \frac{\text{Desired dose (mg/min)}}{\text{Concentration (mg/mL)}}Pumprate=Concentration(mg/mL)Desireddose(mg/min)
Pumprate=0.12mg/min0.8mg/mL=0.15mL/min\text{Pump rate} = \frac{0.12 \text{ mg/min}}{0.8 \text{ mg/mL}} = 0.15 \text{ mL/min}Pumprate=0.8mg/mL0.12mg/min=0.15mL/min
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Convert the pump rate to mL/hour:
Multiply by 60 to convert from mL/min to mL/hour:
Pumprate=0.15mL/min×60min/hour=9mL/hour\text{Pump rate} = 0.15 \text{ mL/min} \times 60 \text{ min/hour} = 9 \text{ mL/hour}Pumprate=0.15mL/min×60min/hour=9mL/hour
So, you should set the pump to deliver Dopamine at a rate of 9 mL/hour.
Correct Answer is A
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. In the context of shock, a MAP of 50 mm Hg is considered low and indicates inadequate tissue perfusion.
To improve tissue perfusion and restore blood pressure, the nurse would anticipate administering large volumes of intravenous fluids, such as Lactated Ringers (LR). Fluid resuscitation aims to increase intravascular volume and improve cardiac output, ultimately leading to improved tissue perfusion.
B. Cardiac Output (CO) is 4 L/min in (option A) is incorrect because Cardiac output represents the volume of blood pumped by the heart per minute. While a low cardiac output may require intervention, it does not specifically indicate the need for large volumes of fluid administration.
C. Stroke volume is 70 ml/beat in (option C) is incorrect because Stroke volume refers to the volume of blood ejected by the heart with each contraction. While stroke volume can be an important determinant of cardiac output, it alone does not indicate the need for large fluid volumes.
D. The heart rate is 80 bpm in (option D) is incorrect because: Heart rate is the number of heartbeats per minute. While the heart rate can impact cardiac output, it does not provide direct information about fluid resuscitation needs.
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