19. DSA Respiratory Adaptions Flashcards
What occurs when the PaO2 is below normal becuase the PAO2 is reduced (d/t altitude) or the blood is unable to equilibriate fully with the alveolar air (d/t COPD)
Hypoxic Hypoxia
What occurs when lungs are working fine but oxygen carrying capacity of the blood is reduced? Can be produced by carbon monoxide which has a high affinity for Hb and prevents O2 from binding, reducin the oxygen carrying capacity of the blood. Also d/t anemia
Anemic Hypoxia (dt to anemia as well)
What occurs when the tissue is not receiving sufficient oxygen because the heart cannot pump the blood to the tissue? Can be caused by sickle cell anemia due to blocking of areteries leading to tissues.
Circulatory (tissue) Hypoxia
What occurs when the tissue is unable to use the oxygen.?Cyanide can lead to this by poisoning the systems that utilize oxygen to create energy and preventing them from using O2.
Histotoxic Hypoxia
Hypocapnia: decrease in O2 and CO2, meaning there is?
Less H+ and less CO2 crossing the BBB, so less activation of the central chemoreceptors, leading to peripheral chemoreceptors sending signal to central, but central being turn off by lack of CO2/H+. Hypoxia in tissues and hypocapnia in central compartment
To deal with chronic hypocapnia, choroid plexus which makes CSF will help with resetting the chemorecptors. CSF has less protein and buffering capacity. Choroid plexus has H2CO3, which then?
Takes H+ to csf, and brings the pH of CSF back to normal, to activate the central chemoreceptors
Hypercapnia=acidification of the CSF, Choroid plexes produces HCO3 and H+. SO the HCO3 is sent to CSF to?
To bind to all the extra H+ d/t acidification. and the H+ from the CSF will be sent to the kidneys to be taken care of
INcrease in altitude, barometric pressure decreases. FIO2 is 21% regardless of the barometric pressure, However….
Its based on the amount of pressure, so it will be less quantity
What is the only difference when calculating the alveolar PO2 when the barometric pressure has changed?
Change 760mmHg to whatever the changed pressure is (decreased due to increased altitude)
At higher altitudes, no longer any nitrogen in the air, at any higher…?
you would need pressurized suits to make up for the fact that the atomospheric pressure could be dangerous
Barometric pressure is increased when you go diving. For every 10 m below water how much does the barometric pressure increase by?
1 ATM
So if you decend 40M
40/10 + 1ATM (pressure due to air ontop of water) = 5ATM
What is the equation to calculate alveolar pO2?
PAO2 = (Patm (760) - 47) x (FiO2 which is usually 0.21) - (PACO2 (given) /R (R is respiratory exchange ratio, which is 1, 0.8, or 0.7) determined by CO2 produce/O2 consumed)
How do you calculate the A-a O2 gradient ?
Take calculated PAO2 and subtract from it the PaO2 (arterial) given number
Remember that the FiO2 can change based on?
If she says in a question that he is breathing 100% oxygen, then you will multiple it by 1 instead of .21
What is the normal range for A-aO2 gradient?
8+ 20%of patients age or less than 12mmHg. If the number is higher than this, it would indicated a disease process.
