The arterial-to-end-tidal CO2 and the arterial-to-maximum ...

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The arterial-to-end-tidal CO2 and the arterial-to-maximum expiratory partial pressure of carbon dioxide (PCO2) gradients are both elevated and equal to each other. This finding is consistent with:
 
  a. chronic obstructive pulmonary disease.
  b. left-sided heart failure.
  c. esophageal intubation.
  d. pulmonary embolism.

Question 2

The ability of certain specialized cells of the heart to depolarize spontaneously is known as which of the following?
 
  a. Diastasis c. Automaticity
  b. Excitability d. Conductivity

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Answer to Question 1

ANS: D
Normally, the difference between the PCO2 measured at the end of a maximum exhalation and the PaCO2 is minimal. Patients with chronic obstructive pulmonary disease or left-sided heart failure do not show an increase in this difference. However, patients with pulmonary embolism show an increased gradient.

Answer to Question 2

ANS: C
Automaticity describes the ability of certain specialized cells of the heart to depolarize. Diastasis refers to the long period of reduced ventricular filling that follows the rapid-filling period. Excit-ability is defined as the ability of a cell to respond to an electrical stimulus. Conductivity is de-fined as the ability of cardiac tissue to propagate an action potential.

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TYSM

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