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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
pathophysiology that increases vd
increases: decreased CO, COPD, PE
26
surgical position that increases or decreases vd
increased: sitting decreased: supine, t burg
27
where does dead space begin in circle system
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
28
physiologic dead space can be calculated using what equation
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
29
what is alveolar compliance
a change in alveolar volume for a given change in pressure
30
are all alveoli ventilated equal
no- due to gravitational force (transpulmonary pressure or TPP)
31
32
greater degree of volume change during a breath means what
better gas exchange
32
where are alveoli the largest
near the apex (higher TPP)
32
where are alveoli the smallest
near the base- lower TPP
33
where is ventilation greatest. why?
lung base- due to higher alveolar compliance- has greatest rate of volume change during a breath
34
where is perfusion greatest. why?
perfusion is greatest at lung base- due to gravity (when standing upright)
35
blood flow always follows.. ex if supine...
gravitational flow ex: if supine perfusion will be greatest in posterior lungs
36
higher V/Q ratios are in what part of the lung
higher towards apex lower towards base
37
dependent lung=
down lung (same physiology as base of the lung) higher alveoli ventilation and higher blood flow compared to non dependent lung
38
what is dead space
ventilation but no perfusion
39
what is the v/q of dead space
infinity
40
what is shunt
perfusion but no ventilation
41
what is the v/q of shunt
0
42
what is the normal ratio of ventilation to perfusion
0.8 (ventilation is 80% of perfusion)
43
what is the most common cause of hypoxemia in pacu
v/q mismatch (atelectasis)
44
to combat dead space what does the body do
bronchioles constrict to minimize ventilation to poorly perfused alveoli
45
to combat shunt what does the body do
HPV reduces pulmonary blood flow to poorly ventilated alveoli
46
what is the law of laplace
describes the relationship between pressure, radius and wall tension
47
what is the formula for law of laplace
P= 2T/R
48
increased tension= __
increased likelihood of alveoli to collapse
49
decreased radius=
increased likelihood of alveoli to collapse
50
what does surfactant do
equalizes surface tension- keeps alveolar pressures constant- prevents smaller alveoli from collapsing
51
do smaller alveoli have more surfactant
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
when do T2 pneumocytes start producing surfactant
between 22-26 weeks- peak production at 35-36 weeks
53
the time of pneumocyte production of surfactant is why ____ is given to premature infants to hasten fetal lung maturity
betamethasone
54
v/q ratio of each alveolar unit is determined from the relative pressures between:
alveolus (PA), arterial capillary (Pa), venous capillary (Pv) and intersitial space (Pist)
55
rules for zones of west
PA is always in slot of number of zone Pa is always > pv
56
zone 1 west zone
dead space PA >Pa>Pv ventilation, no perfusion
57
what makes zone 1 worse
Hotn, PE, excessive airway pressure bronchioles of underperfused alveoli constrict and reduce vD
58
zone 2 zone west
v/q= 1 Pa >pA> pV
59
zone 3 zone of west
Pa>pV> pA blood flow in absence of ventilation hpv restricts blood flow to underventilated alveoli
60
alveolar gas equation
look at study guide
61
hypoxemia
low concentrationn of o2 in the blood (pao2 <80 mmhg)
62
hypoxia
a state of insufficient o2 to support the tissues
63
the a-a gradient is the difference between
alveolar o2 (pao2) and arterial oxygen (pao2)
64
what is a-a gradient used for
dx hypoxemia
65
what is normal a-a gradient
<15 mmhg (always will have small shunting due to thesbian, bronchial and pleural veins delivering deoxygenated blood to L heart)
66
a large difference between PAo2 and pao2 implies
significant shunting, v/q mismatch or diffusion defect (alveolar-capillary thickening) across alveolar capillary membrane
67
what are some things that increase A-a gradient
-aging -vasodilators (dec HPV) -R to L shunt- atelectasis, PNA, bronchial intubation, intracardiac defect -diffusion limitation (alveolocapillary thickening hinders o2 diffusion)
68
hypoxemia with normal a- gradient
low fio2 and hypoventilation
69
hypoxemia with increased A-a gradient
diffusion limitation, V/Q mismatch and shunt
70
volume of gas that can be forcibly inhaled after a tidal inhalation
inspiratory reserve volume
71
volume of gas that enters and exits the lungs during tidal breathing
tidal volume
72
volume of gas that can be forcibly exhaled after a tidal exhalation
expiratory reserve volume
73
volume of gas that remains in the lungs after complete exhalation- cannot be exhaled from the lungs; oxygen reserve during apnea
residual volume
74
volume above residual volume where the small airways begin
closing volume
75
IRV + TV + ERV + RV
total lung capacity
76
IRV + TV+ ERV
vital capacity
77
IRV + TV
inspiratory capaccity
78
RV + ERV (frc is the lung volume at end expiration)
functional residual capacity
79
RV + CV absolute volume of gas contained in the lungs when small airways close
closing capacity
80
volume capacity in ml/kg
65-75
81
frc in ml/kg
35
82
how is vital capaicty and frc calculated
based on IBW
83
what can obstructive lung disease cause? examples?
air trapping. asthma, bronchitis, emphysema have increased FRC, closing capacity and TLC
84
spirometry cannot measure ____, therefore it cannot measure ___ or ___
residual volume; TLC or FRC
85
__ and __ are dynamic measurements that assess small airway closure. can or cannot be measured with spirometry?
closing volume and capacity. cannot
86
FRC= __ + ___
erv + rv
87
can frc be measured by spirometry
no bc RV cannot be exhaled
88
frc can be used to estimate
how long a pt can be apneic before desaturating if you know frc and oxygen consumption (vo2) desat time= frc/ vo2
89
things that decrease frc
general anesthesia obesitypregnancy neonates supine lithotomy trend nmb agents light anesthesia excessive iv fluids high fio2 reduced pulm compliance
90
things that increase frc
old age prone sitting lateral obstructive lung disease peep sigh breaths
91
factors increasing closing volume
CLOSE-P copd, LV failure, obesity, surgery, age extremes, pregnancy
92

october exam (12 decks)

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