Author Question: A patient in the intensive care unit is receiving mechanical ventilation, has a pulmonary artery ... (Read 184 times)

daltonest1984 · **on:** Jul 16, 2018

A patient in the intensive care unit is receiving mechanical ventilation, has a pulmonary artery catheter in place, and is being monitored continuously with a capnometer.

The patient's arterial partial pressure of carbon dioxide (PaCO2) is 41 mm Hg and the partial pressure of end-tidal carbon dioxide (PetCO2) is 36 mm Hg. There is a sudden decrease in the PetCO2 to 18 mm Hg causing an alarm to sound. The most likely cause of this development is which of the following?
a. Hypovolemia
b. Apneic episode
c. Pulmonary embolism
d. Increased cardiac output

Question 2

While trying to use a finger probe to assess a patient's oxygenation status,

the respiratory therapist finds that the pulse rate and the ECG monitor heart rate are not con-sistent and the oxygen saturation measured by pulse oximeter (SpO2) reading is blank. The patient is awake, alert, and in no obvious respiratory distress. The respiratory therapist should first take which of the following actions?
1. Change the probe site.
2. Draw an arterial blood gas.
3. Adjust the probe position on the finger.
4. Remove the probe, and perform a capillary refill test.
a. 1 and 2 only
b. 2 and 3 only
c. 3 and 4 only
d. 1 and 4 only

stano32 · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: C
Pulmonary embolism will cause a decrease in blood flow to the lungs. This increases alveolar dead space and leads to a decrease in the partial pressure of end-tidal carbon dioxide (PetCO2). Hypovolemia would also cause a decrease in the PetCO2, but it would not occur as suddenly as it did in this situation. The fact that the patient has an indwelling pulmonary artery catheter in-creases the risk of developing a pulmonary embolism, which often will have a quick onset. An apneic episode would have increased the PetCO2. An increased cardiac output would increase the PetCO2 because increases in cardiac output result in better perfusion of the alveoli and a rise in PetCO2.

Answer to Question 2

ANS: C
The fact that the patient is awake, alert, and in no respiratory distress decreases the likelihood that the problem is with the patient. Therefore, the first action in this case should not be to draw an arterial blood gas (ABG). In cases where the pulse oximeter cannot identify a pulsatile signal, the oxygen saturation measured by pulse oximeter (SpO2) reading may not be present. This could be alleviated by adjusting the probe position on the finger. Absent SpO2 readings could also be due to low perfusion states. Performing a capillary refill test on the finger being used for the probe would show whether or not the finger has adequate blood flow. If this is true, the next step would be to change the site.