Resp - Respiratory Mechanics Flashcards Preview

Physiology > Resp - Respiratory Mechanics > Flashcards

Flashcards in Resp - Respiratory Mechanics Deck (65):
1

muscles of inspiration

diaphragm (75%)
external intercostals (25%)

2

accessory inspiration muscles

scalenes (raise rib 1/2)
sternocleidomastoid (raise sternum)

3

muscles of expiration (active)

abdominal wall
internal intercostals

4

causes for difficulty inspiring

scar tissue
reduced surfactant
mucous
fluid

5

causes for difficulty expiring

emphysema

6

point where laminar --> turbulent

reynolds # > 2000

7

conditions where turbulence likely occurs

velocity high
radius high

8

Reynold's number

Re = 2rvd/n

9

Ohm's law (airflow)

F = delta P/R

10

Poiseuille's law

R = 8L(viscocity)/pi(radius^4)

11

Poiseulle's law take away

smaller the airway, greater the R (reduce r by 50% increase R x 16)

12

site of most airway R (+why)

medium sized bronchi
smaller than large (up R) and in series rather than parallel (smaller ones in parallel)

13

factors increasing resistance

turbulent flow
small radius
lung volume decreasing
bronchial SM contraction
gas density elevated (SCUBA)
forced expiration

14

causes of bronchoconstriction

allergy
mucous, airway collapse
PNS during relaxed state (Ach on muscarinic)
low CO2

15

causes of bronchodilation

SNS
*Epi (beta-2)
*CO2 up

16

forced exhalation

PA drives air out
PA = Pip + P elastic recoil
further from alveoli, less recoil
exhaling air hits R, loses P
EPP

17

equal pressure point

when Pairway = Pip
if Pip > Pairway --> collapse
(EPP @ cartilage for healthy people)

18

emphysema and forced expiration

alveoli have lost elastic recoil
PA is lower, EPP happens closer to alveoli, compression of airway

19

chronic obstructive pulmonary disease (diseases)

asthma
chronic bronchitis
emphysema

20

emphysema mech

1. irritation --> many macs, release trypsin
usually alveoli release antitrypsin (but too many macs to fight)
2. breakdown of alveolar walls
3. down recoil, collapse smaller airways

21

pulmonary function tests

spirometry
lung vol measurement
diffusion capacity for CO
arterial blood gases

22

tidal volume (TV)

V in or out in quiet resp
~500 ml

23

inspiratory reserve volume (IRV)

extra V can be inspired after quiet inspiration

24

expiratory reserve volume (ERV)

extra V can be expired after quiet expiration

25

inspiratory capacity (IC)

max V in after quiet expiration (TV + IRV)

26

vital capacity (VC)

max V in after max expiration (IRV + TV + ERV)
~ 4800 ml

27

residual volume (RV)

min air remaining in lungs after max expiration

28

functional residual capacity (FRC)

V in lungs after quiet expiration (ERV + RV)

29

total lung capacity (TLC)

max V lungs can hold (VC + RV) ~6000 ml

30

abnormal spirometry results (obstructive)

can't get air out
RV up
up RV, FRC, TLC
--> slow flow, hyperinflation, down recoil

31

abnormal spirometry results (restricted)

cant get air in
TLC down
down VC, RV, FRC, VT
--> up recoil, down V

32

spirogram measurements

FVC: (V forcibly blown out after full breath)
FEV1: V forced out in 1 second
FEV1/FVC: proportion

33

normal FVC

80%

34

abnormal spirogram (obstructive)

FEV1 down (a lot)
FVC down
FEV1/FVC down (42%)

35

abnormal spirogram (restrictive)

FEV1 down
FVC down
FEV1/FVC normal or higher

36

flow volume loop action

1. inhale to TLC
2. exhale to RV as forcefully and quickly as possible
3. forcefully inspire to TLC

37

flow volume loop: forced expiration

compression of airways from Pip up --> high flow then slow down
early = pt dependent
late = pt independent

38

flow volume loop: forced inspiration

muscle force down as V up
lung recoil up as V up
airway R down as V up

39

abnormal flow volume loop (obstructive)

scooped
peak is lower but quick
slow expiration flow

40

abnormal flow volume loop (restrictive)

witch's hat
TLC, FVC is lower

41

Diffusion capacity action

1. exhale to RV
2. inhale gas (w/ small CO) to TLC
3. hold breath 10 s
4. measure exhaled gas for CO

42

diffusion capacity (obstructive)

hyperinflation and DLCO down --> emphysema
hyperinflation and DLCO normal --> asthma
normal lung volume and DLCO normal -->. chronic bronchitis

43

DLCO results

DLCO down in any condition affecting alveolar surface area
(lung resection, emphysema)

44

diffusion capacity (restrictive)

low RV and low DLCO --> scarring diseases
normal (or high) RV and normal DLCO = neuromuscular diseases, kyphosis, scoliosis

45

lung compliance

delta V/delta P

46

things that affect compliance

apex vs base
inspiration vs expiration (hysteresis)
disease
amount of CT

47

compliance (regional)

compliance greatest at base
gravity pulls on alveoli in apex, makes them more expanded

48

compliance (hysteresis)

PV curve diff for inspiration and expiration (not linear)
scoop for inspire, bump for expire

49

compliance (disease)

low compliance: stiff - pulmonary fibrosis - large transmural P needed to expand
high compliance: low recoil - emphysema

50

elastic recoil relations

directly related to stiffness (low compliance)
inversely related to distensibility (high compliance)

51

things affecting elastic recoil

elastin/collagen
*alveolar surface tension (2/3)

52

surface tension actions

increases recoil
decreases compliance
responsible for diffs in inspiration/expiration curves

53

surface tension relative to size

smaller alveoli more likely to collapse than larger

54

LaPlace's Law

P = 2T/r
T = surface tension

55

DPPC

dipalmitoyl phosphatidylchloline
hydrophilic head (go in fluid)
hydrophobic tail (go in air)
attenuate cohesion (act as detergent)

56

surfactant and alveoli size

most effective when DPPC close together -->
small alveoli have lower ST

57

surfactant fxns

1. lower surface tension (increase compliance)
2. stabilize alveoli
3. keep alveoli dry (avoid edema)

58

how surfactant keeps alveoli dry

ST usually lowers interstitial hydrostatic P (pulls fluid in)
surfactant reduces this

59

neonatal resp distress syndrome mech

abnormally low production of surfactant
up ST
collapse alveoli (atelectasis)
hypoxemia

60

neonatal resp distress syndrome Sx

cyanosis
pronounced hysteresis
high inflation P to ventilate
pulmonary edema

61

alveoli stabilizing factors

elastin/collagen (against overdistension)
surfactant
interdependence (tethering effect)
transmural pressure gradient

62

forces promoting alveolar collapse

elasticity (elastin)
alveolar surface tension

63

forces keeping alveoli open

transmural P gradient
pulmonary surfactant
alveolar interdependence

64

chest volume equilibrium

equilibrium @ ~70% TLC
< 70: recoil force out
> 70: recoil force in

65

lung/chest combined equilibrium volume

chest compressed below equilibrium
lung expanded above
chest force out is equal to lung force in
occurs @ FRC