Physiological effects of ventilation and diffusion disorders

Question 1

Define hypoxemia.

Answer 1

decreased oxygen saturation in the BLOOD

Question 2

Define hypoxia.

Answer 2

decreased oxygen saturation in the TISSUE

Question 3

What causes hypoxemia?

Answer 3

decreased oxygen in the air, hypoventilation, diffusion abnormalities (fibrosis), abnormal ventilation-perfusion ratios, shunting (alveolar collapse), CO poisoning

Question 4

What does hypoxemia lead to?

Answer 4

leads to hypoxia while tissues adapt to lower levels of oxygen (severe cases metabolic acidosis, due to anaerobic metabolism)

Question 5

What is mild hypoxemia?

Answer 5

• hemoglobin saturation is still 90%
• increase HR, peripheral vasoconstriction, diaphoresis
• slight impairment of mental function and visual acuity

Question 6

What are the main concerns of hypoxemia?

Answer 6

leads to acidosis and enzymes lose their efficiency (neurons are also sensitive to acidosis)

Question 7

What is moderate hypoxemia?

Answer 7

restless agitation, altered cognition, uncoordinated movement, euphoria, impaired judgement, delirium loss of consciousness leading to coma

Question 8

What is chronic hypoxemia?

Answer 8

• pulmonary vasoconstriction in response to alveolar hypoxia
• polycythemia (increased RBCs
• cyanosis often a late sign

Question 9

What is hypercapnia?

Answer 9

increased CO2

Question 10

What are the causes o hypercapnia?

Answer 10

- hypoventilation
pulmonary disease (edema)
- restriction of thoracic movement
- airway obstruction

Question 11

What does hypercapnia lead to?

Answer 11

• respiratory acidosis (low pH affects all tissues including heart and nervous system)
• kidneys try to buffer by excreting hydrogen and producing bicarbonate

Question 12

Define pneumothorax.

Answer 12

accumulation of air in the pleural layers

Question 13

Define hemothorax.

Answer 13

accumulation of BLOOD in the pleural layers

Question 14

Define transudate.

Answer 14

watery pleural effusion

Question 15

Define exudate.

Answer 15

contains WBC, pleural effusion

Question 16

Define empyema.

Answer 16

pus accumulation in pleura

Question 17

What is the significance of accumulations in pleura?

Answer 17

can cause atelectasis

Question 18

Define atelectasis.

Answer 18

collapse of the lung or incomplete expansion of alveoli

Question 19

What can cause pneumothorax?

Answer 19

DIRECT INJURY (atmospheric air enters through disruption of chest wall (parietal))

Question 20

What are the usual causes of hemothorax?

Answer 20

trauma or bleeding from pneumonia, TB or tumors

Question 21

Define pleural effusion.

Answer 21

accumulation of fluid in the pleural space

Question 22

What are the causes of pleura effusion

Answer 22

pulmonary infarction
trauma
tumor
infection
MI

Question 23

What causes empyema?

Answer 23

bacterial infection/absess

Question 24

What are the manifestations of empyema ?

Answer 24

cyanosis
fever
tachycardia
cough
pleural pain

Question 25

What is the treatment of empyema?

Answer 25

antibiotics and thoracenteses

Question 26

Define thoracentesis.

Answer 26

draining of the pleural space

Question 27

What are the 2 main causes of atelectasis?

Answer 27

COMPRESSION (external pressure by tumour, fluid or air)

ABSORPTION (remove air within lung; usually obstruction from mucus plug or tumour)

Question 28

Slide 17

Answer 28

slide 17