DSA Flashcards
Nitrogen Washout Technique
- Determines FCR (functional residual capacity)
- pts breath 100% O2 through one-way valve, all expired gas is collected, monitored until N2 reaches zero
- Total volume of all gas expired is determined, and multiplied by % of N2 in mixed expired air (80%)
Helium Dilution
- measures residual volume
- inhalation of a known concentration (C1) of helium (insoluble in blood) from a known volume (V1)
- Change in concentration (C2) allows for determination of V2=FCR
Body Plethysmography
-measures residual volume
-enclosed rigid box
-breath against shutter
a. Pressure in lungs changes
b. Pressure in box changes proportionally in opposite directions
(Boyle’s Law p1v1=p2v2)
Kidneys can change HCO3 levels by…
kicking HCO3 into the urine or kick H+ into the urine
Increase in CO2 always leads to ____ because of ____.
- acidosis
2. the H2CO3 and H+
Respiratory Disturbance
anything that alters how much CO2 moves from the blood to the alveoli
Metabolic Distrubance
stuff like ingesting too many Tums, increase in lactic acid…
If the pH is within normal values, do you need to even check anything else out?
YUP–> make sure that the PaCO2 and HCO3 levels are normal as well
PiO2
inspired oxygen (Patm - 47mmHg)
At body temperature, the water vapor pressure is __
47mmHg
FiO2
21%
Hypoxia hypoxia
- the PaO2 is below normal because either the alveolar PO2 is reduced or the blood is unable to equilibrate fully with the alveolar air
- can be environmental like altitude, emphysema, fibrosis
- if you see reduced O2, this is probably the right answer
Anemic hypoxia
- lungs are in perfect working condition, but the oxygen carrying capacity of the blood has been reduced.
- Carbon Monoxide produces anemic hypoxia
- The tissues do not get sufficient oxygen to maintain their metabolic needs because the blood is not carrying it.
Circulatory hypoxia
tissue is not receiving sufficient oxygen because the heart cannot pump the blood to the tissue (or the arteries leading to the tissue have been blocked by clots etc…).
-Sickle cell anemia can lead to circulatory hypoxia
Histotoxic hypoxia
no problem getting the oxygen to the tissue - the lungs, blood and circulatory system are all working just fine. However, the tissue is unable to use the oxygen.
-Cyanide leads to histotoxic hypoxia
What do the central chemoreceptors respond to/detect?
they respond to CO2 via detecting H+ in the CSF
CO2 crosses the…
the BBB, and then H+ is produced, and this is what the central chemoreceptors are activated by
The CSF has more or less protein than plasma?
much LESS
*also no cholesterol
How does the choroid plexus help out in chronic hypocapnia?
- it pumps H+ into the CSF to reset the chemoreceptors
- they also will switch it back to normal when hypercapnia is reached
What altitude do we stop seeing Nitrogen?
6000; this is the altitude at which humans need supplemental oxygen
For every 10m deeper below the water surface you go, the barometric pressure increases by..
1atm
* always add 1 atm to account for the pressure above the water
ex. 10 m below is 2 atm
How do we get Patm to Pmmhg?
Patm X 760 mmHg
Summary of Sympathetic
- Short pre, long post
- Pre in lateral horn, post in paravertebral ganglion
- White rami (t1-L2/3) and gray rami (c1-co1)
- NT: acetylcholine at pre, norepinephrine at post
* *exception: post in sweat glands are cholinergic
Summary of Parasympathetic
- Long pre, short post
- Pre in CN 3, 7, 9, 10, S2-4 , post in innervated viscera and cranial parasympathetic ganglia
- NT: pre and post is acetylcholine
Indications of Pulmonary Function Test
- evaluate sympoms/signs of lung disease
- asses progression of lung disease
- monitor effectiveness of therapy
- evaluate pre-op patients
- screen people at risk of lung disease
- monitor potentially toxic effects of drugs
Contraindications of Pulmonary Function Test
- unless you have one of the 6 indications you shouldn’t do one
- also if the disease is not lung disease, but is causing lung problems this test wouldn’t work
Spirometry
measures air in and out of lungs
Forced Vital Capacity tes
inhale as deep as you can, and measures how much they can get out
FEV1/FVC
1. Less than lower limit of normal: Yes v. No
- Yes: obstructive; No: restrictive or normal
Obstructive Pattern vs. Restrictive Pattern
- FVC
- FEV1
- FEV1/FVC
- TLC
- decrease or normal vs. decreased
- decreased vs. decreased or normal
- decreased vs. normal
- normal or increased vs. decreased
What does air trapping do?
increase RV
Vomit/diarrhea
loss of HCO3
Ingestion of too many tums
HCO3 change (i think increase)
Anion gap indicates
- indicates unmeasured chemicals present:
1. Diabetic/alcoholic ketoacidosis, starvation
2. Lactic acidosis
3. Salicylates (aspirin)
What is a normal A-a O2 gradient?
less than 20 (<20mmHg)
An increase in the A-a O2 gradient means
something is wrong with the alveoli (diffusion impairment)
