#lung capacities

[medicineisnotmerchandise]

Obstructive vs Restrictive Lung Disorders

In obstructive lung disorders:

Residual volume (RV), functional residual capacity (FRC), and residual volume/total lung capacity (RV/TLC) ratio are increased.

Vital capacity (VC), inspiratory capacity (IC), inspiratory reserve volume (IRV), and expiratory reserve volume (ERV) are decreased.

Obstructive lung disorders include asthma and other COPDs, such as emphysema and chronic bronchitis.

In restrictive lung disorders:

Vital capacity (VC), inspiratory capacity (IC), residual volume (RV), functional residual capacity (FRC), tidal volume (VT), and total lung capacity (TLC) are all decreased.

Restrictive lung disorders include pulmonary fibrosis, adult respiratory distress syndrome, and pulmonary edema.

[mynotes4usmle]

Total Lung Capacity: TLC = VC + RV (amount of air in lungs after a max inspiration) 6700ml

Vital Capacity:  VC = IC + ERV (max air that can be expired after a max inspiration) 5500ml

Inspiratory Capacity: IC (max air inspired) 4000ml

Tidal volume: Vt (what you are doing right now) 500ml

Inspiratory Reserve Volume: IRV (ammount of air that can be inspired after a normal inspiration) 3500ml

Expiratory Reserve Volume: ERV (ammount of air that can be expired after a normal expiration) 1500ml

Residual Volume: RV (air left in the lungs after max expiration) 1200ml

Functional Residual Capacity: FRC = ERV + RV (air left in the lungs after passive expiration) 2700ml

REMEMBER

Every volume or capacity that "contains" Residual Volume (RV) CAN NOT BE MEASSURED BY SPIROMETRY!!!! because RV stays in the lungs (duh!). Those volumes & capacities are:

FRC => For this capacity you use: Helium Dilution, Nitrogen Washout, Body Plethysmography. 

RV

TLC

[malagkitnagalapong]

Gaano kalalim ang buntong hininga?

VC = IRV + ERV + TV

Where:

VC = Vital capacity (Ang sukat ng dami ng hanging nilabas pagkatapos ng isang malalim na paghinga)

IRV = Inspiratory Reserve Volume (Ang sukat ng karagdagang hangin na maari pang ilanghap pagkatapos ng isang normal na paglanghap ng hangin)

ERV = Expiratory Reserve Volume (Ang sukat ng karagdagang hangin pagkatapos ng isang pwersadong pagbuga pagktapos ng normal na pagbuga ng hangin)

TV = Tidal Volume (Ang sukat ng hangin sa normal na paghinga)

Kung desperado ka talagang masukat kung gaano kalalim ang buntong hininga mo sa hindi malamang kadahilanan, maari kang gumamit ng spirometer.