Oxygen therapy

Question 1

decreased body temp
decreased 2,3-BPG
decreased pH
CO

what do these do to the oxyHb binding curve?

Answer 1

left shift

Question 2

increased body temp
increased 2,3-BPG
increased pH

what do these do to the oxyHb binding curve?

Answer 2

right shift

Question 3

what are three causes of hypoxia?

Answer 3

hypoxemia
impaired blood flow
dysoxia

Question 4

definition: hypoxemia

Answer 4

failure of respiratory system to oxygenate arterial blood

Question 5

what are causes of hypoxemia?

Answer 5

low ambient pO2 
hypoventilation 
Hb deficiencies 
impaired A-a diffusion 
V/Q mismatch 
shunts

Question 6

cyanide poisoning causes what type of hypoxia?

Answer 6

dysoxia

Question 7

what are causes for a V/Q mismatch?

Answer 7

gravity 
lung disease 
shunts 
alveolar dead space 
aging

Question 8

does an anatomic shunt respond to oxygen therapy?

Answer 8

no

Question 9

what is the effect of hypoxia in the brain?

Answer 9

cerebral vasodilation - increased cerebral blood flow

Question 10

what is the goal of oxygen therapy?

Answer 10

maintain adequate tissue oxygenation

Question 11

what are the clinical objectives / indications for oxygen therapy?

Answer 11

1. correct hypoxemia
2. relieve symptoms of hypoxia / hypoxemia
3. prevent / minimize increased cardiopulmonary workload associated with hypoxia / hypoxemia

Question 12

what are the physiologic effects of breathing 100% inspired oxygen at atmosphere pressure for 0-12 hours?

Answer 12

normal pulmonary function
tracheobronchititis
substernal chest pain

Question 13

what are the physiologic effects of breathing 100% inspired oxygen at atmosphere pressure for 12-24 hours?

Answer 13

decreasing VC

Question 14

what are the physiologic effects of breathing 100% inspired oxygen at atmosphere pressure for 24-30 hours?

Answer 14

decreasing lung compliance
increasing pO2 (A-a)
decreasing exercise pO2

Question 15

what are the physiologic effects of breathing 100% inspired oxygen at atmosphere pressure for 30-72 hours?

Answer 15

decreasing diffusion capacity

Question 16

oxygen toxicity primarily affects which organs?

Answer 16

lungs

CNS

Question 17

oxygen toxicity is primarily determined by what factors?

Answer 17

PO2 and exposure time

Question 18

the pathology of oxygen toxicity is thought to be caused by what process?

Answer 18

oxygen free radicals

Question 19

what is the pathological response of oxygen toxicity (4)?

Answer 19

1. damage to capillary endothelium
2. thickening of alveolar-capillary membrane (interstitial edema)
3. alveolar exudate and consolidation causing physiological shunting
4. end stage - pulmonary fibrosis and HTN

Question 20

what are the effects of oxygen induced hypoventilation of COPD patients with chronic hypoxemia and hypercapnia?

Answer 20

1. central response to CO2 is blunted
2. primary stimulus to breathe is oxygen deprivation (hypoxemia)
3. high blood O2 levels suppress peripheral chemoreceptors and depress ventilatory drive

Question 21

when delivering oxygen therapy to patients with COPD and high CO2, how much oxygen should be used?

Answer 21

lowest level possible to maintain saturation (mid 80s)

Question 22

what is the pathophysiology of retinopathy of prematurity?

Answer 22

1. excessive blood-oxygen levelsl produce retinal vasoconstriction causing necrosis of blood vessels
2. new vessels form
3. hemorrhage of new vessels - scarring, detachment, blindness

Question 23

what is the pathophysiology of absorption atelectasis?

Answer 23

nitrogen, the primary gas in the alveoli, is “washed out” by oxygen

1. inspired oxygen above 50% depletes both alveolar and blood nitrogen within minutes
2. removal of nitrogen from blood lowers total pressure of gases in venous system
3. large pressure gradient occurs between pulmonary capillary blood and alveoli
4. in obstructed alveoli, oxygen continues outward movement without repletion causing alveolar collapse
5. increase in physiologic shunt (alveoli are perfused but not ventilated)

Question 24

what are the clinical guidelines for oxygen therapy (3)?

Answer 24

1. give minimum dose needed to obtain desired result
2. ordered in liters/minute and/or percent FiO2
3. ongoing assessment and titration

Question 25

what is the normal oxygen range for blood gas analysis?

Answer 25

80-100 mm Hg

Question 26

what is the MOA of hyperbaric oxygen?

Answer 26

1. increased atmostphere pressure = increased partial pressures
2. decreased air bubble volume
3. increased oxygen content in blood available for use by tissues (in PLASMA)

Question 27

what are the indications for hyperbaric oxygen therapy?

Answer 27

air embolism
CO poisoning
wound therapy

Question 28

what are complications of hyperbaric oxygen therapy?

Answer 28

barotrauma caused by high pressure

CNS, lung toxicity

Question 29

venturi mask: advantages

Answer 29

delivers exact FiO2

FiO2 independent of ventilation rate

Question 30

which mask is good for COPD patients / SOB?

Answer 30

venturi