Oxygen therapy Flashcards
decreased body temp
decreased 2,3-BPG
decreased pH
CO
what do these do to the oxyHb binding curve?
left shift
increased body temp
increased 2,3-BPG
increased pH
what do these do to the oxyHb binding curve?
right shift
what are three causes of hypoxia?
hypoxemia
impaired blood flow
dysoxia
definition: hypoxemia
failure of respiratory system to oxygenate arterial blood
what are causes of hypoxemia?
low ambient pO2 hypoventilation Hb deficiencies impaired A-a diffusion V/Q mismatch shunts
cyanide poisoning causes what type of hypoxia?
dysoxia
what are causes for a V/Q mismatch?
gravity lung disease shunts alveolar dead space aging
does an anatomic shunt respond to oxygen therapy?
no
what is the effect of hypoxia in the brain?
cerebral vasodilation - increased cerebral blood flow
what is the goal of oxygen therapy?
maintain adequate tissue oxygenation
what are the clinical objectives / indications for oxygen therapy?
- correct hypoxemia
- relieve symptoms of hypoxia / hypoxemia
- prevent / minimize increased cardiopulmonary workload associated with hypoxia / hypoxemia
what are the physiologic effects of breathing 100% inspired oxygen at atmosphere pressure for 0-12 hours?
normal pulmonary function
tracheobronchititis
substernal chest pain
what are the physiologic effects of breathing 100% inspired oxygen at atmosphere pressure for 12-24 hours?
decreasing VC
what are the physiologic effects of breathing 100% inspired oxygen at atmosphere pressure for 24-30 hours?
decreasing lung compliance
increasing pO2 (A-a)
decreasing exercise pO2
what are the physiologic effects of breathing 100% inspired oxygen at atmosphere pressure for 30-72 hours?
decreasing diffusion capacity
oxygen toxicity primarily affects which organs?
lungs
CNS
oxygen toxicity is primarily determined by what factors?
PO2 and exposure time
the pathology of oxygen toxicity is thought to be caused by what process?
oxygen free radicals
what is the pathological response of oxygen toxicity (4)?
- damage to capillary endothelium
- thickening of alveolar-capillary membrane (interstitial edema)
- alveolar exudate and consolidation causing physiological shunting
- end stage - pulmonary fibrosis and HTN
what are the effects of oxygen induced hypoventilation of COPD patients with chronic hypoxemia and hypercapnia?
- central response to CO2 is blunted
- primary stimulus to breathe is oxygen deprivation (hypoxemia)
- high blood O2 levels suppress peripheral chemoreceptors and depress ventilatory drive
when delivering oxygen therapy to patients with COPD and high CO2, how much oxygen should be used?
lowest level possible to maintain saturation (mid 80s)
what is the pathophysiology of retinopathy of prematurity?
- excessive blood-oxygen levelsl produce retinal vasoconstriction causing necrosis of blood vessels
- new vessels form
- hemorrhage of new vessels - scarring, detachment, blindness
what is the pathophysiology of absorption atelectasis?
nitrogen, the primary gas in the alveoli, is “washed out” by oxygen
- inspired oxygen above 50% depletes both alveolar and blood nitrogen within minutes
- removal of nitrogen from blood lowers total pressure of gases in venous system
- large pressure gradient occurs between pulmonary capillary blood and alveoli
- in obstructed alveoli, oxygen continues outward movement without repletion causing alveolar collapse
- increase in physiologic shunt (alveoli are perfused but not ventilated)
what are the clinical guidelines for oxygen therapy (3)?
- give minimum dose needed to obtain desired result
- ordered in liters/minute and/or percent FiO2
- ongoing assessment and titration
what is the normal oxygen range for blood gas analysis?
80-100 mm Hg
what is the MOA of hyperbaric oxygen?
- increased atmostphere pressure = increased partial pressures
- decreased air bubble volume
- increased oxygen content in blood available for use by tissues (in PLASMA)
what are the indications for hyperbaric oxygen therapy?
air embolism
CO poisoning
wound therapy
what are complications of hyperbaric oxygen therapy?
barotrauma caused by high pressure
CNS, lung toxicity
venturi mask: advantages
delivers exact FiO2
FiO2 independent of ventilation rate
which mask is good for COPD patients / SOB?
venturi