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 A
Explanation
The ABG results show a pH of 7.50, PaCO2 of 29 mmHg, and HCO3 of 23 mEq/L, indicating respiratory alkalosis. In respiratory alkalosis, there is a decrease in PaCO2 (hypocapnia), which can be caused by excessive ventilation.
To address the respiratory alkalosis, the nurse should decrease the respiratory rate. This would help reduce the amount of ventilation provided and allow the patient to retain more carbon dioxide (CO2), thereby increasing the PaCO2 levels and restoring acid-base balance.
B. Leaving the ventilator at the current settings in (option B) is incorrect because it may exacerbate respiratory alkalosis as it would maintain the same level of ventilation.
C. Increasing the tidal volume (VT) in (option C) is incorrect because it would not address the respiratory alkalosis. Tidal volume refers to the volume of air delivered with each breath, while the issue in this case is excessive ventilation leading to hypocapnia.
D. Increasing the FiO2 (fraction of inspired oxygen) in (option D) is incorrect because it is not indicated based on the given ABG results. The oxygenation (PaO2) level is within normal limits (80 mmHg), suggesting adequate oxygenation.
It is important to consult with the healthcare provider or respiratory therapist for further guidance on adjusting the ventilator settings based on the patient's condition and response to therapy.
Correct Answer is A
Explanation
Premature ventricular contractions (PVCs) are abnormal heart rhythms originating from the ventricles. They can be triggered by various factors, including irritation or stimulation of the airway during suctioning.
In this situation, the priority is to ensure adequate oxygenation and ventilation for the patient. Stopping the suctioning procedure and providing ventilatory support with 100% oxygen helps maintain oxygen levels and minimizes further cardiac dysrhythmias.
B. Check the patient's potassium level in (option B) is incorrect because While electrolyte imbalances, including low potassium levels (hypokalemia), can contribute to cardiac dysrhythmias, checking the potassium level is not the immediate priority when PVCs occur during suctioning.
C. Give prescribed PRN antidysrhythmic medications in (option C) is incorrect because: Administering antidysrhythmic medications without further assessment or evaluation may not be appropriate in this situation.
D. Decrease the suction pressure to 80 mm Hg in (option D) is incorrect because: While adjusting suction pressure may help prevent further irritation, it is not the initial priority when PVCs are present during suctioning.
E. Documenting the dysrhythmia in the patient's chart in (option E) is incorrect because: Documentation is important but should not be the initial action when a patient experiences PVCs during suctioning. Patient safety and immediate intervention take precedence.
Therefore, when PVCs occur during suctioning, the nurse should stop the procedure, provide ventilatory support with 100% oxygen, and assess the patient's response to intervention.
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