Work of Breathing Graphs

[Focused1]

There is a question in UW on work of breathing.
It talks about elastic and airflow resistances..
Do we just have to memorize the graphs and the data given or is there anything else to it ?
I mean I cant really understand the concept very well... is there a source y'all are using to supplement this ?

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[IndiaInk567]

I used Boards and Beyond. It has some good videos that helped me really understand that stuff.

 

[walakin25]

i cant seem to wrap my head around work of breathing concept. Would anyone be able to explain?

 

[EmetyreUSMLEStep1Tutor1]

There is a question in UW on work of breathing.
It talks about elastic and airflow resistances..
Do we just have to memorize the graphs and the data given or is there anything else to it ?
I mean I cant really understand the concept very well... is there a source y'all are using to supplement this ?

You mean this graph?

 

[walakin25]

@Khorreed not that graph. work of breathing related to obstructive and restrictive lung diseases, its a q on uworld, qid 8260

 

[ATypicalLymphocyte]

I think they're referring to this graph:

What I did for these types of physiology concepts was simply Google them and for some reason chapters of this book always seemed to show up:
Berne & Levy Physiology: 21 Mechanical Properties of the Lung and Chest Wall: Static and Dynamic (which is the relevant chapter for the concept being discussed)

Another website that showed up frequently when looking for physiology concepts was New Human Physiology (this is a free online physiology book which might also prove useful).

 

[tasar1898]

I think I remember the graph...the concept behind it is that in restrictive you have too much recoil , so you ventilate with lots of little breaths(makes sense) while in COPD the prob is lots of airflow resistance and the patient ventilates with less breaths and more volumes ( hard to put little air in) hope that makes sense , hard to explain since English is not my native language

Edit: that sounds like gibberish..
I'll try once more --> COPD: hard to move air in/out of lungs --> ventilate with minimum amount of "breath tries" .. Remember Ventilation = Tidal volume x RR

Restrictive : no problem with moving air per se, but your lungs won't let you take maximum breath without max effort , so you ventilate with lots of little breaths

It has to do with keeping your ventilation quota with minimum amount of effort..like the capitation system of physician payment , physician gets paid same for each patient so he has to keep em all healthy to make max money with minimum amount of work

 

[walakin25]

@ATypicalLymphocyte

thanks for the links. checkin them out live! pulmonary phys = my weakness atm

@tasar1898

your english is solid chief thanks for the explanation i understood the gist of it.

 

[ATypicalLymphocyte]

I'll give it a shot as well.

Minute ventilation = Tidal volume x RR
Your body will try to keep minute ventilation constant at all times (in other words, if the tidal volume decreases, the respiratory rate will have to be increased, whereas if the respiratory rate decreases, the tidal volume will have to be increased).

Under normal (i.e., non-pathologic) conditions, your respiratory rate will be ~15 rpm (the arrow on the graph) since it ensures an adequate minute ventilation where total work is minimal.

In cases of restrictive lung disease, compliance is decreased and elasticity is increased, which makes it 1) harder for the lungs to expand/fill and 2) easier for them to empty (in cases of fibrosis, where fibrotic tissue keeps the airways open because of increased radial traction). Making it harder for the lungs to expand means more work is spent when trying to inspire higher volumes (the lung is not being compliant!) so the body will adapt by increasing the respiratory rate (fast, shallow respiration).

In cases of obstructive lung disease, compliance is increased and elasticity is decreased, which makes it 1) easier for the lungs to expand/fill (in comparison to restrictive lung disease) and 2) much harder for them to empty (no elasticity to kick air out!) so the body will adapt by increasing tidal volume (slow, deep respiration).

 

[walakin25]

I'll give it a shot as well.

Minute ventilation = Tidal volume x RR
Your body will try to keep minute ventilation constant at all times (in other words, if the tidal volume decreases, the respiratory rate will have to be increased, whereas if the respiratory rate decreases, the tidal volume will have to be increased).

Under normal (i.e., non-pathologic) conditions, your respiratory rate will be ~15 rpm (the arrow on the graph) since it ensures an adequate minute ventilation where total work is minimal.

In cases of restrictive lung disease, compliance is decreased and elasticity is increased, which makes it 1) harder for the lungs to expand/fill and 2) easier for them to empty (in cases of fibrosis, where fibrotic tissue keeps the airways open because of increased radial traction). Making it harder for the lungs to expand means more work is spent when trying to inspire higher volumes (the lung is not being compliant!) so the body will adapt by increasing the respiratory rate (fast, shallow respiration).

In cases of obstructive lung disease, compliance is increased and elasticity is decreased, which makes it 1) easier for the lungs to expand/fill (in comparison to restrictive lung disease) and 2) much harder for them to empty (no elasticity to kick air out!) so the body will adapt by increasing tidal volume (slow, deep respiration).

awesome explanation! much appreciated