Cardiac Assessment for Critically Ill

Question 1

Which of the following statements about the P Wave in an ECG is false?

1. It represents atrial depolarization
2. It is a positive wave on the graph
3. Normal duration time is 0.06 to 0.10 seconds
4. It represents ventricular repolarization

Answer 1

It represents ventricular repolarization

The P wave of the cardiac cycle is a positive wave that represents atrial depolarization or atrial contraction. The normal duration of the P wave is 0.06 to 0.10 seconds.

Question 2

1. Artifact on an ECG may be caused by which of the following?
2. Electrical interference at the bedside
3. Poor electrode contact with the skin
4. Excessive movement of the patient

Answer 2

All of the Above

Artifact shows a misrepresentation of the cardiac waveform on the cardiac monitor and may be caused by electrical interference, poor electrode contact, or excessive patient movements.

Question 3

In which of the following cardiac arrhythmias is the QRS complex abnormally shaped as well as wider than normal?

1. Sinus Tachycardia
2. Premature Ventricular contraction (PVCs)
3. Atrial Fibrillation
4. Premature atrial contractions (PACs)

Answer 3

Premature Ventricular contraction (PVCs)

PVCs are the result of ventricular irritability caused by hypoxemia, acid-base disturbances, electrolyte abnormalities, CHF, myocardial inflammation, coronary artery disease, and an excessive dosage of digitalis. PVCs are characterized by abnormally shaped QRS complexes, which are wider than normal. Lidocaine, procainamide, or propranolol is administered to treat PVCs.

Question 4

1. A patient with a blood pressure of 110/50 mm Hg and a pulse rate of 75 beats/min has which of the following pulse pressures?
   
   1. 40 mm Hg
   2. 50 mm Hg
   3. 60 mm Hg
   4. 70 mm Hg

Answer 4

60 mm Hg

Pulse pressure is the difference between the systolic and diastolic pressures. Normal is 40 mm Hg. In this question, the patient’s blood pressure was 110/50, and the difference is 60 mm Hg (110–50).

Question 5

1. A weak pulse is detected distal to the arterial catheter in a patient. This is indicative of which of the following?
   
   1. Infection
   2. Hemorrhage
   3. Thrombosis
   4. Tachycardia

Answer 5

Thrombosis

One of the complications of arterial lines is a thrombosis distal to the puncture site. If thrombosis and embolization occur, a weak pulse would be palpated distal to the puncture site. A continuous flush of saline and heparin through the system helps prevent clot formation.

Question 6

1. Which of the following conditions results in a decreased central venous pressure (CVP) reading?
2. Hypovolemia
3. Vasoconstriction
4. Air bubbles in the CVP line

Answer 6

1 and 3

CVP is the measurement of right atrial pressure. The normal value is 2 to 6 mm Hg. Decreased values are seen with leaks in the CVP measuring line and low blood volume (hypovolemia).

Question 7

1. The respiratory therapist palpates no pulse on a patient, but the ECG monitor shows QRS complexes on the tracing. The therapist should:
   
   1. Get immediate ABG studies.
   2. Recommend cardioverting the patient.
   3. Begin cardiac compressions.
   4. Recommend administering nitride.

Answer 7

Begin cardiac compressions.

A QRS pattern seen on the cardiac monitor when no pulse is present is referred to as pulseless electrical activity (PEA). The monitor is indicating an erroneous tracing. If no pulse is palpated, cardiac compressions must be initiated.

Question 8

1. After a cardiac arrest, a 48-year-old female begins receiving mechanical ventilation. A pulmonary artery catheter is in place. The following data are obtained:

BP 94/52 mm Hg Pulse 116/min PCWP 10 mm Hg PAP 40/22 mm Hg QT 3.5 L/min

Based on these data, which of the following has increased?

1. Pulmonary vascular resistance
2. Left atrial pressure
3. Stroke volume
4. Systemic vascular resistance

Answer 8

Pulmonary vascular resistance

Normal systolic PAP is 20 to 30 mm Hg. The PAP in this question is elevated indicating pressure in the pulmonary vasculature has increased. This indicates an increase in pulmonary vascular resistance caused, for instance, by pulmonary vasoconstriction or an embolus. The CVP is slightly elevated, normal <6 mm Hg, as blood backs up into the right atrium due to the resistance to blood flow through the pulmonary vessels. The left atrial pressure (PCWP) is normal in this question (5 to 10mmHg).

Question 9

You notice that your PAP and PVR has increase which of the following can be the cause

1. Pulmonary Embolus
2. Left Ventricular Failure
3. Aortic Stenosis
4. Overhydration

Answer 9

Pulmonary Embolus

The PAP and pulmonary vascular resistance has increased. This occurs as a result of pulmonary vasoconstriction, or, in this case, a pulmonary embolism. The clot in the pulmonary vessels is blocking blood flow resulting in an increased PAP. PCWP is normal. Therefore left ventricular function is normal.

Question 10

1. The following data have been recorded for a patient receiving mechanical ventilation:

CVP 5 mm Hg

PAP 28/10 mm Hg

PCWP 22 mm Hg

QT 2.8 L/min

On the basis of these data, the patient most likely has

1. Pulmonary hypertension
2. Left ventricular failure
3. Pulmonary embolism
4. Right ventricular failure

Answer 10

1. Left ventricular failure
   * PCWP is elevated indicating left ventricular failure. PCWP is an indication of left atrial pressure, with normal being 5 to 10 mm Hg. This may lead to cardiogenic pulmonary edema and decreased cardiac output, which is seen in this question. Right heart function is normal indicated by normal values for both CVP and PAP.*