Lec 2-Lung Vol/Capacity, Pulm Function Testing

Question 1

Measuring lung volumes

Answer 1

Total ventilation is vol of air that enters or leaves lungs per minute
VE= tidal vol x freq OR VE=VT x f

• Tidal vol varies with age/gender/body position/metabolic activity
• typically is around 500mL
• we measure it with spirometry

Question 2

Lung volumes and capacities

Answer 2

• add
• Expiratory reserve volume (ERV): Taking a tidal breath out and then decide we want to breathe out further
• Residual volume: We still have abt 1L of air left in our lungs after doing ERV, we can’t access this amount
• Any capacity containing RV can’t be directly measured with spirometry
• Total lung capacity (TLC): every volume/maximal ?
• Inspiratory capacity (IC): Tidal vol + IRV
• Functional residual capacity (FRC): When you breathe out and then just stay there and it feels comfortable (RV + ERV???)
• Vital capacity (VC): Max amt of air that you can voluntarily inhale or exhale

**diagram slide 4 + 5, KNOW typical volumes and which cannot be measured by spirometry, and equations

Question 3

Forced vital capacity/FEV1

Answer 3

• Measuring these can help to diagnose lung disease
• Inhale to TLC, breathe out as fast as possible. After 2.5 sec, there’s no more air they can breathe out. Anything left is RV, anything they squeezed out was FVC
• FEV1: Forced expiratory vol in 1 second, should be abt 80%

**both graphs on slide are the same

Question 4

Flow volume loop

Answer 4

• Person inhales to TLC, breathes out til they cant anymore
• Can determine FVC and PEFR (peak expiratory flow rate)
• PEFR measures when air is coming out the fastest
  Add

Question 5

Types of airway diseases

Answer 5

Obstructive and restrictive

Question 6

Obstructive airway diseases

Answer 6

• Obstruction to airflow as it enters or leaves
• More resistance to air movement (harder to do)
• Restriction is usually in the lumen (hole in airway), in airway wall, or surrounding the airway
• Eg. Asthma, chronic bronchitis, aspiration of foreign material

Question 7

Asthmatic bronchial wall—obstructive

Answer 7

• Too many submucosal glands producing extra mucous
• Too much airway smooth muscle, contracts too fast
• Excess mucosal edema
• Add symptoms on slide

Question 8

Restrictive airway diseases

Answer 8

• Can’t fully fill lungs bc theres some restriction
• Eg. Pulm fibrosis, elastic tissue is replaces with thickened fibrotic (scar) tissue
• Can be due to alterations in parenchyma, diseases of pleura, diseases of chest wall, diseases of neuromuscular apparatus

Question 9

Graphs of FVC and FEV1 in patients with lung disease

Answer 9

Slide 11 graph

• Obstructive will have a rly low FEV1 bc there is smaller space to move air thru. Will also have a low FVC bc small airways collapse prematurely so air still in lungs cant pass. Will have a smaller percentage
• Fibrosis (restrictove) will have a more normal percentage