Lung Physio Question

[joshua_msu]

---

Members don't see this ad.

How would a person with restricitve lung disease breathe? Is it at low lung volumes with hyperventilation? Also, how would someone with COPD breathe? High Lung volumes and hypoventilation?

This was from NBME Form A, and I cant seem to find it in my notes for the life of me.

Thanks.

 

[idq1i]

How would a person with restricitve lung disease breathe? Is it at low lung volumes with hyperventilation? Also, how would someone with COPD breathe? High Lung volumes and hypoventilation?

This was from NBME Form A, and I cant seem to find it in my notes for the life of me.

Thanks.

Restrictive: tachypnea, low Vt
Obstructive: higher lung volumes, rate dependent on disease progression

 

[ucbdancn00]

How would a person with restricitve lung disease breathe? Is it at low lung volumes with hyperventilation? Also, how would someone with COPD breathe? High Lung volumes and hypoventilation?

This was from NBME Form A, and I cant seem to find it in my notes for the life of me.

Thanks.

two quick impt points to remember

1) Restrictive (fibrosis, etc)--HALLMARK: decreased TLC; so they are breathing at lower lung volumes. you will probably see difficulties with inspiration as well as hyperventilation depending on the level of fibrosis.

Restricted lung becomes like "lower part of lung" which normally has increased ventilation, increased perfusion and smaller alveoli. With restriction--> smaller alveoli--> you can theoretically ventilate better at a higher inspiratory pressure. Hence you will have inspiration problems. Depending on the severity of the fibrosis, you will see a decrease in PO2. This will stimulate peripheral chemoR and increased breathing. Since the expiratory flow rate may increase with restrictive dz, you will be able to get rid of CO2 (hence no stimulation of central chemoR).

2) COPD--HALLMARK: Decreased FEV1/FVC ratio; larger volumes (air gets in but can't get out), increasing CO2--> increased H+ in CSF (trigger central chemoR). CO2 will trigger peripheral chemoR as well. hence you get hyperventilation (initially)....hyperventilation (over time) will lead to decreased CO2 and hypoventilation...

the main problem is a V/Q mismatch--You have a lung that is more like top of the lung (dilated air spaces (less ventilated), but way too little blood for it to make a difference). So as you accumulate air in your lungs....the perfusion isn't enough to allow for efficient gas exchange and you start accumulating CO2 and wastes. This will increase the acid in the CSF and allow stimulation of central chemo R and increased breathing. Over time, as the hyperventilation gets rid of C02...decreased cerebral CO2 levels will decrease stimulation of central chemoR and give you hypoventilation.

hope this is correct and understandable....and i hope it helps. g'luck

ucb

 

[Arnold Chiari]

How would a person with restricitve lung disease breathe? Is it at low lung volumes with hyperventilation? Also, how would someone with COPD breathe? High Lung volumes and hypoventilation?

This was from NBME Form A, and I cant seem to find it in my notes for the life of me.

Thanks.

the question was:

Person with pulmonary fibrosis is most likely to minimize the work of breathing by using which of the following breathing patterns?

Respiratory frequency (high or low)
Tidal volume (high or low)

so the solution is: high frequency low volume

 

[HiddenTruth]

two quick impt points to remember

1) Restrictive (fibrosis, etc)--HALLMARK: decreased TLC; so they are breathing at lower lung volumes. you will probably see difficulties with inspiration as well as hyperventilation depending on the level of fibrosis.

Restricted lung becomes like "lower part of lung" which normally has increased ventilation, increased perfusion and smaller alveoli. With restriction--> smaller alveoli--> you can theoretically ventilate better at a higher inspiratory pressure. Hence you will have inspiration problems. Depending on the severity of the fibrosis, you will see a decrease in PO2. This will stimulate peripheral chemoR and increased breathing. Since the expiratory flow rate may increase with restrictive dz, you will be able to get rid of CO2 (hence no stimulation of central chemoR).

2) COPD--HALLMARK: Decreased FEV1/FVC ratio; larger volumes (air gets in but can't get out), increasing CO2--> increased H+ in CSF (trigger central chemoR). CO2 will trigger peripheral chemoR as well. hence you get hyperventilation (initially)....hyperventilation (over time) will lead to decreased CO2 and hypoventilation...

the main problem is a V/Q mismatch--You have a lung that is more like top of the lung (dilated air spaces (less ventilated), but way too little blood for it to make a difference). So as you accumulate air in your lungs....the perfusion isn't enough to allow for efficient gas exchange and you start accumulating CO2 and wastes. This will increase the acid in the CSF and allow stimulation of central chemo R and increased breathing. Over time, as the hyperventilation gets rid of C02...decreased cerebral CO2 levels will decrease stimulation of central chemoR and give you hypoventilation.

hope this is correct and understandable....and i hope it helps. g'luck

ucb

Solid explanation. Just to mention as a side note, I think your peripheral O2 receptors get stimulated when P02 decrs below 60mm. They're on O2 by then.

 

[ucbdancn00]

Solid explanation. Just to mention as a side note, I think your peripheral O2 receptors get stimulated when P02 decrs below 60mm. They're on O2 by then.

thanks man....you and your semantics 🙂.......i'll remember the 60 now though.

appreciate the love

ucb