(Special Scenarios/Pulmonary Physiology/Miscellaneous) Flashcards by Cooper Pulliam

At higher elevations, why is it so much more difficult to absorb oxygen?

There is not as much pressure to push oxygen into our pulmonary capillaries

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Roughly, what is the barometric pressure and PIO2 at the top of Mt. Everest?

PB: 253 mmHg
PIO2: 43.1 mmHg

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Prior to climbing Mt. Everest, what would be a beneficial tactic to lessen your chances of having issues?
Why?

You should climatize your body in a place in high altitudes.

If the body sees a lower than normal amount of oxygen, the kidney will release epoetin to expand your RBC count.

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What would happen if we were suddenly exposed to a very high altitude/low pressure environment?

The pressures in the blood could get so high that they want to move out of solution and reform as a gas = basically boiling

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Gas diffusion works by using a:

A. Concentration gradient
B. Diffusion gradient
C. Pressure gradient
D. Passive gradient

C. Pressure gradient

This is why if we were suddenly exposed to really low pressures = our blood PO2 of 100 mmHg will be much higher than the environment and the blood starts to boil to reform as a gas and move into the lower pressure area (environment of 40 mmHg)

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How many feet below sea level would we have to be at to experience an Atmospheric pressure of 4 ATM’s?

Roughly 90-100 ft

1 ATM = Sea level
2 ATM = 30-33 Feet below and every 30-ish feet after that = 1 more ATM

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What kind of gas/air is put into most scuba tanks?

Plain ole air
(79% Nitrogen, 21% O2)

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What happens if a scuba diver suddenly ascended back to sea level after being at very low altitudes?

The high concentration of N2 will want to get out of solution and reform as a gas = bubbles/emboli in the blood form.

Sudden change doesn’t allow the scuba diver to exhale the Nitrogen slowly over time.

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What are a couple of ways that we can avoid such high concentrations of N2 in scuba tanks?

Increase the O2 concentration a little bit
Swap the N2 for Helium (inert gas)

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What is the benefit of having more Nitrogen in our lungs over Nitrous per lecture?

Nitrogen will act to keep alveoli and airways open, whereas Nitrous outs you at a higher risk of airway collapse.

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In our anesthesia machines, once the nitrogen is swapped with something like a Nitrous and Oxygen mixture, what is our patient at risk of developing?
What is seen with this issue?

Absorption atelectasis

Alveoli start to collapse due to no filler gas in the lungs

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What is one reason per lecture, as to why a person may have a raspy, soft tone?
What would the cords look like?

Sectioned/damaged inferior laryngeal nerve

The affected side would stay open a little at all times

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Treatment for a diver having to suddenly ascend to sea level after a deep dive?

Hyperbaric Chamber Therapy

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Normal Hospital Hyperbaric chamber pressure setting?
What about military/oil rigs?

Hospital: 3 ATMs
Military/oil rig: >3 ATMs

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Examples of patients that may benefit from Hyperbaric Chamber therapy? (Other than divers)

DM Patients
Circulatory problems
Poor wound healing

(Basically anything where they can’t get a sufficient amount of oxygen to their extremities)

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True or False: The oxygent content is equal to the amount bound to Hemoglobin?

FALSE
The content incorporates the bound AND the dissolved

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At > ___ ATM’s we start to see a high risk of oxygen poisoning.

Roughly > 2 ATMs
(1520 mmHg)

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Per Dr. Schmidt, how long could we theoretically stay at 2 ATMs of pressure before running into oxygen poisoning?

30 minutes

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4 Dangerous oxygen molecules:

Hydrogen peroxide (H2O2)
Superoxide (O2-)
Nitric Oxide (NO)
Peroxynitrite (OONO-)

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What is the difference in normal O2 and superoxide?

Extra negative charge on superoxide = highly reactive

What is produced if Superoxide binds to Nitric Oxide?
Why might this be a bad thing?

Peroxynitrite

OONO- can destroy DNA = can cause long term problems such as cancer.

What may be affected if we give an NO donor to a very unhealthy patient?

Hemoglobin’s ability to carry O2 may be affected

What is the normal scavenging enzyme that destroys superoxide?

Superoxide Dismutase

True or False: Peroxidase enzymes can both destroy and make peroxide?

TRUE

This is an OTC medication that can help with scavenging some of the free radical oxygen molecules. Also useful for patients with ___?

N. Acetylcysteine Acute Liver Disease

In regard to the Iron lung, when would the plunger that is connected to the diaphragm be pulled out?

During inspiration (moves back in during expiration)

Why is the iron lung thought to be a better long-term treatment compared to positive pressure ventilation?

The iron lung preserves the normal mechanics of breathing

Polio destroyed ____

Motor Neurons

Main nerve affected with polio

Phrenic Nerve

Did the iron lung work by pulling the outer or inner lung tissue open?

Outer lung tissue = even pressure spread

True or False: A completely healthy 100 year old patient will still have PaO2 of 100 mmHg? Why or Why not?

FALSE: Age related discrepancy due to the A-a gas difference.

Formula to quantify the A-a gas difference caused by normal aging?

(Age + 10) / 4

2 reasons, per lecture, as to why there is a greater A-a difference with aging?

More dead space Increased shunting

What does the "R" stand for in the arterial gas equation? What does it tell us? Normal number?

Respiratory Quotient Tells us the amount of CO2 produced divided by the amount of O2 used 0.8 *(mls??)*

What is the respiratory quotient influenced by?

The compound that we are burning for energy (ATP).

Normal Respiratory quotient for: Just Carbs: Just Fats: Just Proteins:

Carbs: 1 Fats: 0.7 Proteins: 0.8

Why is the RQ lowest when just burning fats?

Less CO2 is being produced because more water is formed.

Of the 3 things we can burn for energy, which is the one we use last? Such as if we were starving?

Proteins

If you were to actually measure/physically quantify the CO2 going out or the O2 going in, it would be described as the

(RER) Respiratory Exchange Ratio (Same as RQ basically)

Variables needed to actually perform the RER formula:

Arterial Blood draw Barometric Pressure FIO2 "R" (CO2 produced and O2 used)

PACO2 can be estimated by looking at ___.

ETCO2

How does ETCO2 and PaCO2 change with increasing age?

Widens out, with the ETCO2 getting progressively lower than the PaCO2

What is the "normal" arterial and Alveolar difference for CO2?

<3 mmHg (PaCO2 higher)

Examples that would widen out the A-a gas difference?

Age V/Q Mismatches Abnormal diffusion barriers (Increased diameter)

Which 2 nerves do our irritant receptors use?

Vagus and Trigeminal (nose)

What do our J receptors look at? What are 2 disease processes that may cause these receptors to be set off?

Blood volume in the lungs HF, Pneumonia

When are our basic pulmonary stretch receptors set off?

With a very deep tidal volume (VT of about 2L's)

What are 2 ways/methods in which we could lengthen our breath holding time per lecture?

1. Supplemental oxygen 2. Hyperventilation for a few minutes prior to the breath hold

Hiccups and the sensation of getting the wind knocked out of you are caused by:

Phrenic nerve spasm or injury