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
In the early stage of septic shock, the body initiates compensatory mechanisms to combat the infection and restore adequate tissue perfusion. Tachypnoea (rapid breathing) and tachycardia (elevated heart rate) are common early signs of septic shock.
Tachypnoea occurs as a response to increased metabolic demand and to compensate for impaired oxygenation and tissue perfusion. Tachycardia is the body's attempt to maintain cardiac output and compensate for decreased blood pressure.
B. Pallor and cool skin in (option B) is incorrect because Pallor and cool skin can occur in later stages of septic shock when perfusion to the peripheral tissues is compromised. However, they are not specific to the early stage.
C. Blood pressure 84/50 mm Hg in (option C) is incorrect because A blood pressure reading of 84/50 mm Hg indicates hypotension, which is typically seen in later stages of septic shock. In the early stage, blood pressure may still be within normal or slightly decreased range.
D. Respiratory acidosis in (optionD) is incorrect because: Respiratory acidosis refers to an imbalance in acid-base status and is not specific to the early stage of septic shock. Acid-base disturbances may occur at any stage of shock but are not indicative of the early stage.
Correct Answer is B
Explanation
Systemic vascular resistance represents the resistance to blood flow in the systemic circulation. It is an important indicator of afterload, which is the force against which the left ventricle must pump to eject blood into the systemic circulation. By monitoring the changes in SVR, the nurse can assess the impact of medications aimed at reducing left ventricular afterload.
A. Pulmonary artery wedge pressure (PAWP) in (option A) is incorrect because: PAWP is a measure of left ventricular preload and reflects the pressure within the left atrium and left ventricle at end-diastole. It is not specifically related to afterload reduction.
C. Pulmonary vascular resistance (PVR) in (option C) is incorrect because: PVR represents the resistance to blood flow in the pulmonary circulation. It is not directly related to left ventricular afterload.
D. Central venous pressure (CVP) in (option D) is incorrect because: CVP reflects the pressure in the right atrium and is an indicator of right-sided cardiac function. It is not specifically related to left ventricular afterload reduction.
Therefore, to assess the effectiveness of medications in reducing left ventricular afterload, the nurse should monitor the systemic vascular resistance (SVR).
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