DSA

Question 1

Nitrogen Washout Technique

Answer 1

• 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%)

Question 2

Helium Dilution

Answer 2

• 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

Question 3

Body Plethysmography

Answer 3

-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)

Question 4

Kidneys can change HCO3 levels by…

Answer 4

kicking HCO3 into the urine or kick H+ into the urine

Question 5

Increase in CO2 always leads to ____ because of ____.

Answer 5

1. acidosis

2. the H2CO3 and H+

Question 6

Respiratory Disturbance

Answer 6

anything that alters how much CO2 moves from the blood to the alveoli

Question 7

Metabolic Distrubance

Answer 7

stuff like ingesting too many Tums, increase in lactic acid…

Question 8

If the pH is within normal values, do you need to even check anything else out?

Answer 8

YUP–> make sure that the PaCO2 and HCO3 levels are normal as well

Question 9

PiO2

Answer 9

inspired oxygen (Patm - 47mmHg)

Question 10

At body temperature, the water vapor pressure is __

Answer 10

47mmHg

Question 11

FiO2

Answer 11

21%

Question 12

Hypoxia hypoxia

Answer 12

• 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

Question 13

Anemic hypoxia

Answer 13

• 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.

Question 14

Circulatory hypoxia

Answer 14

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

Question 15

Histotoxic hypoxia

Answer 15

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

Question 16

What do the central chemoreceptors respond to/detect?

Answer 16

they respond to CO2 via detecting H+ in the CSF

Question 17

CO2 crosses the…

Answer 17

the BBB, and then H+ is produced, and this is what the central chemoreceptors are activated by

Question 18

The CSF has more or less protein than plasma?

Answer 18

much LESS

*also no cholesterol

Question 19

How does the choroid plexus help out in chronic hypocapnia?

Answer 19

• it pumps H+ into the CSF to reset the chemoreceptors

- they also will switch it back to normal when hypercapnia is reached

Question 20

What altitude do we stop seeing Nitrogen?

Answer 20

6000; this is the altitude at which humans need supplemental oxygen

Question 21

For every 10m deeper below the water surface you go, the barometric pressure increases by..

Answer 21

1atm

* always add 1 atm to account for the pressure above the water
ex. 10 m below is 2 atm

Question 22

How do we get Patm to Pmmhg?

Answer 22

Patm X 760 mmHg

Question 23

Summary of Sympathetic

Answer 23

1. Short pre, long post
2. Pre in lateral horn, post in paravertebral ganglion
3. White rami (t1-L2/3) and gray rami (c1-co1)
4. NT: acetylcholine at pre, norepinephrine at post
   * *exception: post in sweat glands are cholinergic

Question 24

Summary of Parasympathetic

Answer 24

1. Long pre, short post
2. Pre in CN 3, 7, 9, 10, S2-4 , post in innervated viscera and cranial parasympathetic ganglia
3. NT: pre and post is acetylcholine

Question 25

Indications of Pulmonary Function Test

Answer 25

1. evaluate sympoms/signs of lung disease
2. asses progression of lung disease
3. monitor effectiveness of therapy
4. evaluate pre-op patients
5. screen people at risk of lung disease
6. monitor potentially toxic effects of drugs

Question 26

Contraindications of Pulmonary Function Test

Answer 26

• 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

Question 27

Spirometry

Answer 27

measures air in and out of lungs

Question 28

Forced Vital Capacity tes

Answer 28

inhale as deep as you can, and measures how much they can get out

Question 29

FEV1/FVC

1. Less than lower limit of normal: Yes v. No

Answer 29

1. Yes: obstructive; No: restrictive or normal

Question 30

Obstructive Pattern vs. Restrictive Pattern

1. FVC
2. FEV1
3. FEV1/FVC
4. TLC

Answer 30

1. decrease or normal vs. decreased
2. decreased vs. decreased or normal
3. decreased vs. normal
4. normal or increased vs. decreased

Question 31

What does air trapping do?

Answer 31

increase RV

Question 32

Vomit/diarrhea

Answer 32

loss of HCO3

Question 33

Ingestion of too many tums

Answer 33

HCO3 change (i think increase)

Question 34

Anion gap indicates

Answer 34

• indicates unmeasured chemicals present:
  1. Diabetic/alcoholic ketoacidosis, starvation
  2. Lactic acidosis
  3. Salicylates (aspirin)

Question 35

What is a normal A-a O2 gradient?

Answer 35

less than 20 (<20mmHg)

Question 36

An increase in the A-a O2 gradient means

Answer 36

something is wrong with the alveoli (diffusion impairment)