O2 toxicity

Question 1

def of o2 toxicity

Answer 1

• series of reversible, pathological, inflammatory changes of lung tissue
• that can produces a progressive and lethal form of lung injury that is acute respiratory distress syndrome (ARDS).”

Question 2

what are the hazards of supplemental o2

Answer 2

1. o2 toxicity
2. retinopathy of prematurity
3. Absorption atelectasis

Question 3

what are the Physiological responses to O2 based on duration of exposure

Answer 3

0-12
- tracheobronchitis, cough, sub-sternal chest pain but normal pulmonary function

12-24
- decreased vital capacity due likely to absorption atelectasis

25-30
- decreasing PaO2 (↑ A-a gradient), decreasing lung compliance

30-72
- decreasing diffusing capacity

Question 4

What are the moa of o2 toxcity

Answer 4

cellular production of O2 free radicals
damage to cell (membranes)
immune response (inflammation) –> more damage

Question 5

What are the criteria for risk of O2 toxcity

Answer 5

• adult: 100% for 24hrs
  –50% or more for 2-3 days will cause damage
• newborns:more susceptible because less ability to get rid of free radicals and left shifted (better sats at lower FiO2)

Question 6

what is the deal with free radical theory

Answer 6

states that organisms age because cells accumulate free radical damage over time

Question 7

what are some free radiicals

Answer 7

superoxides
anions
peroxides
hydroxyl radicals

they can overwhelm anti-oxidant enzymes

Question 8

what are 2 antioxidant enzymes

Answer 8

superoxide dismutase

glutathione

Question 9

what is HOT

Answer 9

a method of treating certain diseases/disorders by delivering oxygen at pressures above those that can be achieved at one atmosphere, or sea level (normobaric pressure: 760 mmHg).

Question 10

what is the method of adminstration of HOT

Answer 10

• adminsttering 100% FIo2 at 2.5 - 3 ATM to superoxygenate plasma
• either a multiplace or a monoplace chamber.
• multiplace chamber can hold 12 or more people.
• monoplace chamber can hold only 1 patient.

Question 11

what are the physiological effects of HOT

Answer 11

• bubble reduction
• hyperoxygenation of blood and tissue
• vasoconstriction
• enhanced host immune function
• neovascularization

Question 12

What are 2 indication of HOT that RT will involve in

Answer 12

1. air embolism
   - ->reduce volume of bubble
2. carbon monoxide poisoning

Question 13

What other condition is HBO therapy associated with

Answer 13

Wound healing
1) emergency : surgical infection, traumatic ischemia, failed flaps and grafts

2)scheduled treatment, healing of compromised wounds

Question 14

what are the criteria for hypercarbia o2 therapy for acute CO poisoning

Answer 14

1. history of unconsciouesness
2. presence of neuropsychiatric abnormality
3. presence of cardiac instability or cardiac sichemia
4. carboxyhemoglobin level 25%

Question 15

what does 2 - 3 atm hyperbaric therapy equals to in pao2

Answer 15

1500-2200 mmhg Pao2 in plasma

Question 16

what is the results of hyperbaric therapy

Answer 16

• decreases late neurological sequalae (as compared to just o2 therapy)
• minimizes dmg to the brain tissue

Question 17

what is a better predicitor of neurological outcomes of HOB therapy?

Answer 17

presenting sign and symptoms over Hb-co

Question 18

how does HBO help with wound healing?

Answer 18

1. tissue hypoxia triggers a signal for wound healing
2. a big player in wound healing is marcophages
3. marcophages is sensitive to the tissue o2 level, especially the Po2 gradient between area of perfusion
4. the gradient(A-ao2) has a direct relationship with the rate of healing
5. HBO augments the signals, as it stimulates more macrophages to help in wound healing

Question 19

What are the complications of HOB therapy

Answer 19

Barotrauma

• ->ear or sinus trauma
• ->tympanic membrane rupture
• ->gas embolism
• ->alveolar overdistention or pneumothroax

o2 toxicity

• ->pulmonary toxic reaction
• ->CNS toxic reaction

other

• ->fire
• ->claustrophobia
• ->decrease cardiac output
• ->sudden decompression