MECHANISMS OF HYPOXEMIA

Question 1

what are the 5 categories of hypoxemia?

Answer 1

ventilation perfusion mismatch
shunt flow
hypoventilation
Low FIO2 (always 0.21)
diffusion defect

Question 2

what are the causes of low V/Q?

what results?

Answer 2

atelectasis
pneumonia
cariogenic edema (CHF)
non-cariogenic edema (ARDS)
lung trauma

*hypoxic pulmonary vasoconstriction

Question 3

T/F, arterial oxygenation does not improve with supplemental oxygen?

Answer 3

T

Question 4

diffusion defect is due to?

Answer 4

thickened alveolar membrane
-inflammation, edema, fibrosis
thickened air blood interface

Question 5

causes of respiratory alkalosis?

Answer 5

activation of irritant nerve receptors
hypoxemia
sepsis
liver disease
neurologic disease
pregnancy
ASA intoxication
psychogenic

Question 6

hypoventilation disorders?

Answer 6

obstructive hypoventilation
central and sleep related hypoventilation
restrictive hypoventilation

Question 7

central alveolar hypoventilation can be due to?

Answer 7

drugs: narcotics

central neurologic depression: obesity-hypoventilation syndrome

neurologic trauma, closed head injury

neuromuscular disorders: ALS, muscular dystrophies, Guillain-Barre syndrome

brainstem diseases

Question 8

regional alveolar hypoventilation?

Answer 8

obstructive hypoventilation: COPD

chest wall deformities, kyphoscoliosis, fibrothorax, thoracoplasty

Question 9

three main responses to maintain acid base balance?

Answer 9

blood buffers

respiratory compensation of metabolic acidosis or alkalosis

renal response

Question 10

Accounts for more than 50% of buffering capacity in the blood

Answer 10

Carbonic acid/bicarbonate system

Question 11

Largest buffer store in the ECF

Answer 11

Albumins and globulins

Question 12

Buffer intracellular fluid

Answer 12

Hgb and protein anions

Question 13

Renal tubules and ICF

Answer 13

Phosphate buffer