module 6 quiz questions

Question 1

Define hypercapnia (hypercarbia)

Answer 1

Increased carbon dioxide in the arterial blood

Question 2

hypercapnia immediate cause

Answer 2

Caused by hypoventilation of the alveoli (CO2 passes very readily from the blood to the alveolar space (20x more readily than with O2, so is affected only by exchange in alveolar gases that occurs with ventilation)) `

Question 3

three occurrences that can bring the immediate cause of hypercapnia to happen.

Answer 3

Can be a result of anything decreasing drive/ability to breathe, including:

Drugs, diseases of the medulla, chest injuries

Question 4

Define hypoxemia

Answer 4

Reduced oxygenation of arterial blood

Question 5

explain the difference from hypoxia to hypoxemia.

Answer 5

Different from hypoxia, which is reduced oxygenation of tissues

It is much harder for oxygen to diffuse across the alveolocapillary membrane, so there are several factors that can affect oxygenation of the blood

Question 6

Explain the 3 mechanisms that can reduce oxygenation of the blood

Answer 6

Hypoxemia results from defects in one or more of the 3 mechanisms of oxygenation: oxygen delivery to the alveoli (decreased oxygen in air/ventilation), diffusion of oxygen from the alveoli into the blood (decreased diffusion across alveolocapillary membrane & balance between V & Q), and anatomical right to left shunting (pulmonary circulation is partially bypassed due to physical short circuit of blood flow)

Question 7

By what two means can oxygen delivery to the alveoli be decreased? Be familiar with examples of conditions/diseases that can cause this

Answer 7

Oxygen delivery to the alveoli: decreased oxygen in the air/decreased ventilation (a problem with unconscious individuals, those with disease that restricts chest expansion, COPD) & decreased diffusion across the alveolocapillary membrane (due to thickened membrane brought about through edema, or fibrosis)

Question 8

What does V/Q refer to?

Answer 8

V: alveolar ventilation & Q: perfusion (the amount of blood perfusing the alveolar capillaries)

Question 9

What is the most common cause of hypoxemia?

Answer 9

A mismatch of the V/Q ratio

Question 10

Describe the conditions of low and high V/Q, and be familiar with examples of diseases that cause each.

Answer 10

High V/Q: inadequate perfusion of well-ventilated area, producing alveolar dead space (wasted ventilation) most common cause is pulmonary embolism & low V/Q: inadequate ventilation of well-perfused area of lung (atelectasis, asthma, pulmonary edema)

Question 11

Define Acute Respiratory Failure (there are three parts to the definition).

Answer 11

Inadequate gas exchange, leading to lower PaO2, with/without higher PaCO2 accompanied by decreased pH (<7.30)

Question 12

Identify the two types of ARF

Answer 12

Hypercapnic/hypoxemic: due to failure of ventilation

Hypoxemic: due to failure of gas exchange within the lungs

Question 13

hypercapnic cause

Answer 13

Causes: an increase in arterial CO2 (reducing ventilation by half causes a doubling of the PCO2) = hypercapnia & a decrease in arterial O2 = hypoxemia

Question 14

hypoxemic cause

Answer 14

Causes: ventilation/perfusion mismatch – often seen in people with COPD, where a lung region may not be perfused or not ventilated, impaired diffusion – often seen in interstitial lung diseases, ARDS, pulmonary edema

Question 15

Describe how hypercapnic/hypoxemic respiratory failure can be brought about, and how it is usually treated.

Answer 15

Anything interfering with the ventilation mechanism can bring this about: diseases of the nervous system, disorders of the respiratory muscles, COPD

Treated with mechanical ventilation

Question 16

Describe how hypoxemic respiratory failure can be brought about, and how it is usually treated.

Answer 16

Causes: ventilation/perfusion mismatch – often seen in people with COPD, where a lung region may not be perfused or not ventilated, impaired diffusion – often seen in interstitial lung diseases, ARDS, pulmonary edema

treated usually with administrating high concentrations of oxygen (increases the diffusion gradient)