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october exam > respiratory physiology > Flashcards

respiratory physiology Flashcards

1
Q

muscles used for inspiration

A

quiet breathing: external intercostals, diaphragm

forced inspiration: SCM, scalenes

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2
Q

expiration muscles

A

internal intercoastals, rectal abdominis, external/ internal oblique, transversus abdominis

i let the air out of my TIRES

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3
Q

is expiration active or passive

A

passive driven by chest wall recoil

active if increased minute ventilation (COPD)

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4
Q

what law is used in inspiration

A

boyles- contraction of inspiratory muscles reduces thoracic pressure and increases throacic volume

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5
Q

how do you prevent airway collapse

A

pressure inside airway (alveolar pressure) must be greater than pressure outside of the airway (intrapleulal pressure)

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6
Q

formula for transpulmonary pressure

A

transpulmonary pressure (TPP)= alveolar pressure- intrapleural pressure

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7
Q

during inspiration how does the pressure change

A

alveolar pressure becomes slightly neg (muscles of inspiration contract and inctrase volume, pressure decreases)

air flows in until pressure is = to atm pressure

end inspiration: alveolar pressure = atm pressure

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8
Q

how does pressure change with expiration

A

alevolar pressure becomes +

air flows out (down pressure gradient) back into atm

alevolar pressure= atm pressure at end expiration

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9
Q

what is tidal volume

A

amount of gas exhaled/ inhaled during a breath

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10
Q

normal vt

A

6-8 ml/kg

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11
Q

where does tidal volume go when you take a breath

A

only part of it goes to the respiratory zone- the remainer sits in conducting zone (dead space)

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12
Q

what is normal dead space in a healthy 70 kg pt

A

2 ml/kg

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13
Q

what does increased vd make more difficult

A

to eliminate expiratory gases from the lungs

it widens the paco2-etco2 gradient-> CO2 RETENTION

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14
Q

what is alveolar ventilation measuring

A

the minute ventilation avaliable for gas exchange (it removes dead space from the equation)

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15
Q

equations for minute ventilation and for alveolar ventilation

A

min ventilation= vt x rr

alveolar ventilation (vt- vd) x rr

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16
Q

does gas exchange occurr in dead space

A

no

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17
Q

what is anatomic dead space

A

air confined to conducting airways

(nose and mouth-> terminal bronchioles)

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18
Q

what is alveolar dead space

A

alevoli ventilated but not perfused

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19
Q

what is apparatus dead space

A

added by equipment (facemask, HME)

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20
Q

what is physiologic dead space

A

anatomic + alveolar dead space (varies)

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21
Q

some airway conditions that increase and decrease dead space (Vd)

A

increase: face mask, hme, ppv

decrease: ETT, LMA, trach

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22
Q

drugs that increase vd

A

anticholinergics (bronchodilation_)

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23
Q

age that increases vd

A

old age

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24
Q

neck position that increases or decreases vd

A

increases: extension- opens hypopharynx

decreases: flexion

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25
Q

pathophysiology that increases vd

A

increases: decreased CO, COPD, PE

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26
Q

surgical position that increases or decreases vd

A

increased: sitting
decreased: supine, t burg

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27
Q

where does dead space begin in circle system

A

begins at y piece

anything proximal to y piece does not influence dead space, nor does it increase length of circuit

exception: incompetent valve in the circle system

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28
Q

physiologic dead space can be calculated using what equation

A

bohr equation

compares partial pressure of co2 in the blood compared to partial pressure of co2 in exhaled gas

the greater the difference betwen the two, the greater amount of dead space

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29
Q

what is alveolar compliance

A

a change in alveolar volume for a given change in pressure

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30
Q

are all alveoli ventilated equal

A

no- due to gravitational force (transpulmonary pressure or TPP)

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31
Q
A
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32
Q

greater degree of volume change during a breath means what

A

better gas exchange

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32
Q

where are alveoli the largest

A

near the apex (higher TPP)

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32
Q

where are alveoli the smallest

A

near the base- lower TPP

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33
Q

where is ventilation greatest. why?

A

lung base- due to higher alveolar compliance- has greatest rate of volume change during a breath

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34
Q

where is perfusion greatest. why?

A

perfusion is greatest at lung base- due to gravity (when standing upright)

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35
Q

blood flow always follows..

ex if supine…

A

gravitational flow

ex: if supine perfusion will be greatest in posterior lungs

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36
Q

higher V/Q ratios are in what part of the lung

A

higher towards apex

lower towards base

37
Q

dependent lung=

A

down lung (same physiology as base of the lung)

higher alveoli ventilation and higher blood flow compared to non dependent lung

38
Q

what is dead space

A

ventilation but no perfusion

39
Q

what is the v/q of dead space

A

infinity

40
Q

what is shunt

A

perfusion but no ventilation

41
Q

what is the v/q of shunt

A

0

42
Q

what is the normal ratio of ventilation to perfusion

A

0.8 (ventilation is 80% of perfusion)

43
Q

what is the most common cause of hypoxemia in pacu

A

v/q mismatch (atelectasis)

44
Q

to combat dead space what does the body do

A

bronchioles constrict to minimize ventilation to poorly perfused alveoli

45
Q

to combat shunt what does the body do

A

HPV reduces pulmonary blood flow to poorly ventilated alveoli

46
Q

what is the law of laplace

A

describes the relationship between pressure, radius and wall tension

47
Q

what is the formula for law of laplace

A

P= 2T/R

48
Q

increased tension= __

A

increased likelihood of alveoli to collapse

49
Q

decreased radius=

A

increased likelihood of alveoli to collapse

50
Q

what does surfactant do

A

equalizes surface tension- keeps alveolar pressures constant- prevents smaller alveoli from collapsing

51
Q

do smaller alveoli have more surfactant

A

all alveoli have the same amount of surfactant.

larger alveoli have a relatively smaller concentration of surfactant compared to smaller alveoli - which have a relatively larger concentration of surfactant

52
Q

when do T2 pneumocytes start producing surfactant

A

between 22-26 weeks- peak production at 35-36 weeks

53
Q

the time of pneumocyte production of surfactant is why ____ is given to premature infants to hasten fetal lung maturity

A

betamethasone

54
Q

v/q ratio of each alveolar unit is determined from the relative pressures between:

A

alveolus (PA), arterial capillary (Pa), venous capillary (Pv) and intersitial space (Pist)

55
Q

rules for zones of west

A

PA is always in slot of number of zone

Pa is always > pv

56
Q

zone 1 west zone

A

dead space

PA >Pa>Pv

ventilation, no perfusion

57
Q

what makes zone 1 worse

A

Hotn, PE, excessive airway pressure

bronchioles of underperfused alveoli constrict and reduce vD

58
Q

zone 2 zone west

A

v/q= 1

Pa >pA> pV

59
Q

zone 3 zone of west

A

Pa>pV> pA

blood flow in absence of ventilation

hpv restricts blood flow to underventilated alveoli

60
Q

alveolar gas equation

A

look at study guide

61
Q

hypoxemia

A

low concentrationn of o2 in the blood (pao2 <80 mmhg)

62
Q

hypoxia

A

a state of insufficient o2 to support the tissues

63
Q

the a-a gradient is the difference between

A

alveolar o2 (pao2) and arterial oxygen (pao2)

64
Q

what is a-a gradient used for

A

dx hypoxemia

65
Q

what is normal a-a gradient

A

<15 mmhg (always will have small shunting due to thesbian, bronchial and pleural veins delivering deoxygenated blood to L heart)

66
Q

a large difference between PAo2 and pao2 implies

A

significant shunting, v/q mismatch or diffusion defect (alveolar-capillary thickening) across alveolar capillary membrane

67
Q

what are some things that increase A-a gradient

A

-aging
-vasodilators (dec HPV)
-R to L shunt- atelectasis, PNA, bronchial intubation, intracardiac defect
-diffusion limitation (alveolocapillary thickening hinders o2 diffusion)

68
Q

hypoxemia with normal a- gradient

A

low fio2 and hypoventilation

69
Q

hypoxemia with increased A-a gradient

A

diffusion limitation, V/Q mismatch and shunt

70
Q

volume of gas that can be forcibly inhaled after a tidal inhalation

A

inspiratory reserve volume

71
Q

volume of gas that enters and exits the lungs during tidal breathing

A

tidal volume

72
Q

volume of gas that can be forcibly exhaled after a tidal exhalation

A

expiratory reserve volume

73
Q

volume of gas that remains in the lungs after complete exhalation- cannot be exhaled from the lungs; oxygen reserve during apnea

A

residual volume

74
Q

volume above residual volume where the small airways begin

A

closing volume

75
Q

IRV + TV + ERV + RV

A

total lung capacity

76
Q

IRV + TV+ ERV

A

vital capacity

77
Q

IRV + TV

A

inspiratory capaccity

78
Q

RV + ERV (frc is the lung volume at end expiration)

A

functional residual capacity

79
Q

RV + CV absolute volume of gas contained in the lungs when small airways close

A

closing capacity

80
Q

volume capacity in ml/kg

A

65-75

81
Q

frc in ml/kg

A

35

82
Q

how is vital capaicty and frc calculated

A

based on IBW

83
Q

what can obstructive lung disease cause?

examples?

A

air trapping.

asthma, bronchitis, emphysema have increased FRC, closing capacity and TLC

84
Q

spirometry cannot measure ____, therefore it cannot measure ___ or ___

A

residual volume; TLC or FRC

85
Q

__ and __ are dynamic measurements that assess small airway closure. can or cannot be measured with spirometry?

A

closing volume and capacity. cannot

86
Q

FRC= __ + ___

A

erv + rv

87
Q

can frc be measured by spirometry

A

no bc RV cannot be exhaled

88
Q

frc can be used to estimate

A

how long a pt can be apneic before desaturating if you know frc and oxygen consumption (vo2)

desat time= frc/ vo2

89
Q

things that decrease frc

A

general anesthesia
obesitypregnancy
neonates
supine
lithotomy
trend
nmb agents
light anesthesia
excessive iv fluids
high fio2
reduced pulm compliance

90
Q

things that increase frc

A

old age
prone
sitting
lateral
obstructive lung disease
peep
sigh breaths

91
Q

factors increasing closing volume

A

CLOSE-P

copd, LV failure, obesity, surgery, age extremes, pregnancy

92
Q
A

october exam (12 decks)

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