Test 3: Wk11: 2.2 Mechanisms of Ventilation - Dasgupta Flashcards
Specific Compliance =
Compliance / FRC
FRC adult
FRC Child
- 5 L
0. 7 L
Specific Compliance Adult
Specific Compliance Child
Adult 0.125 / 2.5 = 0.05
Child 0.035 / 0.7 = 0.05
Compliance adult
Compliance child
adult .125
child .035
compliance =
delta V / delta P
Compliance is measure by a
spirometer
spirometer measures
lung and chest wall Compliance
lung and chest wall are in
series
total Compliance equation
1 / total Compliance = 1 / lung Compliance + 1 / Chest Wall Compliance
Compliance is the inverse of
resistance
safe to assume that chest wall compliance is
normal
the lung is made of connective proteins like
collagen and elastin
— is prominent polymeric protein in lung tissue
elastin
— degrades elastin
elastase
elastase is regulated by
alpha-1-antitrypsin
deficiency in alpha-1 antitrypsin or a mutation in alpha-1 antitrypsin synthesis results in
widespread lung tissue destruction
smoking is a major risk in emphysema because
it inhibits alpha-1 antitrypsin
Alveolar simplification
tissue destruction seen in
emphysema
Increased breakdown of structural proteins means that elements of the
alveoli, and ultimately whole alveoli, are lost
emphysema makes the FRC
much larger than normal
emphysema also causes
destruction of vasculature
most common morphological subtype of emphysema
Centrilobular emphysema
Centrilobular emphysema affects
the central portion of secondary pulmonary lobules, around the central respiratory bronchioles
— involves the superior part of the lung
Centrilobular emphysema
Centrilobular emphysema begins in the
respiratory bronchioles and spreads peripherally
Centrilobular emphysema caused by
long-standing cigarette smoking, occupational exposure to chemicals, dust etc.
Panacinar emphysema
destroys the entire alveolus uniformly
Panacinar emphysema is primarily in
the lower half of the lungs
— emphysema observed in patients with homozygous alpha1-antitrypsin (AAT) deficiency or Ritalin-induced lung emphysema
Panacinar emphysema
how does Ritalin abuse cause emphysema
Ritalin pills contain fillers which are insoluble. These fillers block fine blood vessels in the lung and cause pulmonary hypertension and damage lung tissue
In people who smoke, — at the lung bases may accompany centrilobular emphysema.
focal panacinar emphysema
reasons for decrease in compliance
interstitial lung dz
loss of surfactant
PV curve shifts — in decrease compliance
to the right
Total lung capacity in decreased compliance
lowered
reasons for increase in compliance
emphysema, loss of elastic fibers
old age
PV curve shifts — in increase compliance
to the left
Total lung capacity in increased compliance
increased
increased compliance means the lung is
softer
decreased compliance means the lung is
stiffer
slope of PV curve =
compliance
PV curve shift — with decreased pulmonary surfactant
right, decreased compliance
lungs have more surface tension and are stiffer
PV curve shift — with removal of one lobe
right, decreased compliance
lobes of the lung are in parallel and compliance is in parallel
PV curve shift — with obesity
right, decreased compliance
fat layers compress thoracic cage
PV curve shift — with pulmonary vascular congestion
right, decreased compliance
vascular congestion causes edema which floods alveoli washing away surfactant and increasing surface tension
laminar flow
all molecules of air are flowing parallel to each other
airway resistance is inversely proportional to
airway radius
airway resistance is inversely proportional to the
airway radius
laminar flow follows the — equation
Poisueille
airways are arranged in
parallel
the greatest resistance is in
largest airways
the region of the lung containing small airways is often referred to as the — because
silent zone
low airway flow velocity and resistance
the greatest airway resistance AND flow velocity is in the
largest airways
is turbulent flow or laminar flow faster
turbulent is always faster
forced exhalation makes the interpleural pressure
positve
forced exhalation is primarily mediated by
internal intercostal muscles and abdominal muscles
why is forced exhalation not a problem in normal lungs
airways are reinforced with rings of cartilage
why is forced exhalation bad in emphysema
lung elastic recoil is decreased. this causes the airway to collapse
the more effort put into a forced exhalation
the more airways collapse and resistance is higher
the faster the airflow, the smaller
the force holding open the airway - greater tendency to collapse
what happens to the airway in emphysema
loss of radial traction
loss of tissue
what happens to airways in asthma
edema of wall during flare
mucus further narrows the airway
Radial traction
the action of lung tissue on airway walls, tending to hold
them open.
“Tethering” of airways or alveoli refers
to them being attached to their neighbors
Tidal Volume
volume of inspired or expired air with each breath
Normal tidal vol mL
500mL
Dead Space Vol
air not used for gas exchange
Dead Space Vol mL
150 mL
Residual volume
amount of air remaining in lungs
Residual Vol amount
1-2 L
Total Lung Capacity
Volume of air in the lungs after a maximal inspiratory effort
Total Lung Capacity amount TLC
6000 mL
Forced Vital Capacity (FVC)
amount of air that can be exhaled as quickly during forced exhalation
Forced Vital Capacity (FVC) amount
4600 mL
Forced expiratory volume in 1 second (FEV1)
amount exhaled in the first second
Forced expiratory volume in 1 second (FEV1) amount
3800 mL
FEV1 should be
80% FVC
Functional Residual Capacity (FRC)
volume of air in the lung when the lung and chest wall have recoil force
Functional Residual Capacity (FRC) amount
2300 mL
Lung capacity is the sum of
2 or more lung volumes
Spirometer direct measurement (4)
TV
FVC
FEV1
FEF
Cannot be measured with Spirometer
RV
FRC
TLC
limitation of Helium dilution technique
cannot be used in emphysema and COPD
what does Helium dilution measure
FRC
How does body position effect FRC - Supine position
lower
What happens to FRC with age
increases - lung becomes softer
Pregnancy does what to FRC
decreases
Lung resection does what to FRC
reduce vol of lung to reduce FRC
chest wall deformity affect on FRC
decrease FRC
