Acute Respiratory Failure

Question 1

Acute respiratory failure

Answer 1

the respiratory system fails to oxygenate or remove carbon dioxide

Question 2

Type 1 ARF: hypoxemic

Answer 2

PaO2 < 60 mmHg
CO2 ≤ 50 mmHg

Question 3

Type 2 ARF: hypercapnic

Answer 3

PaCO2 > 50 mmHg

Question 4

How does oxygenation failure occur?

Answer 4

the PaO2 cannot be maintained through the body’s compensatory mechanisms

Question 5

What are the five mechanisms which can lead to hypoxemia?

Answer 5

hypoventilation
intrapulmonary shunting
ventilation-perfusion mismatch
diffusion defects
decreased barometric pressure

Question 6

Hypoventilation in failure to oxygenate

Answer 6

PAO2 (alveolar) and PaO2 are both reduced
alveolar CO2 can increase as it collects in the lungs but cannot be released

Question 7

Intrapulmonary shunting

Answer 7

large amounts of blood returns to the left side of the heart without having gone through alveolar gas exchange
PaO2 decreases as the condition worsens

Question 8

Ventilation-perfusion mismatch in failure to oxygenate

Answer 8

normal V/Q of 1.0
can occur in pneumonia, pulmonary edema, or pulmonary embolisms

Question 9

Diffusion defects

Answer 9

normal rate of 0.25 seconds across the alveolar-capillary membrane
the accumulation of fluid in respiratory failure increases the time it takes O2 and CO2 to travel across the membrane

Question 10

Low cardiac output, low hemoglobin levels, and tissue hypoxia

Answer 10

less oxygen is sent to tissues whether through time or decreased levels

Question 11

How does hypercapnia affect cerebral function?

Answer 11

increases cerebral blood flow which can cause restlessness and anxiety
intracranial pressure increases

Question 12

Hypoventilation in failure to ventilate

Answer 12

CO2 accumulates in the alveoli
respiratory acidosis may occur
mechanical ventilation may be required