Chapter 2 Resp Intro

Front 1

Low VA/Q units impy (VA/Q>0.8)

Back 1

poor are absent

Front 2

(VA/Q=0) ventilation with respect to blood flow

Back 2

impairing O2 uptake

Front 3

High VA/Q units imply (VA/Q>0.8)

Back 3

poor or absent

Front 4

VA/Q=~ blood flow with respect to ventilation resulting in inefficient elimination of CO2 from:

Back 4

the pulmonary arterial blood

Front 5

VA/Q=0 complete loss of ventilation with respect to blood flow is called a

Back 5

shunt

Front 6

complete loss of pulmonary blood flow with respect to ventilation (VA/Q=~ is called

Back 6

dead space

Front 7

The ratio of alveolar CO2 excretion to blood O2 uptake is called___ and has a resting value of about ____

Back 7

respiratory exchange ratio (R)
R= 0.8

Front 8

The ratio of CO2 production to O2 consumption at tissue level.

Back 8

respiratory quotient (RQ)
RQ=CO2production/ O2 comsumed

Front 9

what can cause the R value to deviate from 0.8?

Back 9

excercise or high metabolic states

Front 10

O2 is carried in blood by: dissolved O2 in____ and combined with _____?

Back 10

plasma and hemoglobing

Front 11

CaO2=
SaO2=
PaO2=

Back 11

arterial o2 content
Hb O2 saturation
arterial O2 tension

Front 12

____ equation: amount of O2 transported in blood to the peripheral tissue (O2 delivery or DO2) DO2=CaO2x10 QC

Back 12

Fick

Front 13

QC=

Back 13

cardiac output in L/min

Front 14

In adults at sea level and rest DO2 is

Back 14

1000mL/min

Front 15

Rate of O2 uptake by the body is measure by analyzing__&__ O2 in ventilator circuit; about __mL/min in adults under rest condition

Back 15

Inspired and expired O2
250

Front 16

O2 extraction fraction can increase under what conditions?

Back 16

(exercise) increase tissue demand
(congestive heart failure decrease cardiac output & O2 del.
servere anemia reduced CaO2

Front 17

Bc the brain and heart extracts the highest % of O2 they are highly susceptible to O2 deprivation caused by a lack of blood flow known as___and low CaO2 ___

Back 17

ischemia
hypoxemia

Front 18

Oxygenated blood is measure by ____ or know as ____

Back 18

spectrophotometry
oximetry

Front 19

Deoxyhemoglobin and Oxyhemoglobin is also known as being in the

Back 19

T or tense state
R or relaxed state

Front 20

The transition between states is induced by the ___ of the heme iron when O2 in bound or released

Back 20

shift

Front 21

90% of CO2 that enter the blood diffuses into RBCs under goes 3 chemical reaction:

Back 21

remains as dissolved CO2
combins with NH3 group of Hb to form carbaminohemoglobin
combins with H2O to form H2CO3

Front 22

when CO2 binds with H2O to form H2CO3 it dissociates into

Back 22

H+-->HCO-3 bicarbonate

Front 23

The remain 10% of CO2 in the plasma exists as ___ CO2 and___ compounds after reacting w/ NH3 groups of plasma

Back 23

dissolved
carbamino

Front 24

dissolved CO2 in plasma determines

Back 24

H2CO3 and pH

Front 25

The reaction rate of CO2 w/ H2O in the RBC is about 13,000 times faster than in plasma due to the influence of __ __an catalytic enzyme

Back 25

carbonic anhydrase

Front 26

as HCO-3 accumalates in RBC its intracellular concen. rises; HCO-3 then diffuses down its concen. gradient into__ it is respon. for nearly all__ in plasma

Back 26

plasma
HCO-3

Front 27

Cl- the most abundant anion in plasma, diffuses into the RBC this is called the__ __ which maintain intracellular electrical neurtality

Back 27

chloride shift

Front 28

some movement of H2O inward occurs simultaneously w/ the Cl- shift to maintain osmotic equilibrium resulting in a slight__ of the RBC venous blood relative to lose in artrial blood

Back 28

swelling

Front 29

carbonic anhydrase can be inhibited by acetazolamide, a drug used to tx __&__

Back 29

glaucoma and acute montain sickness

Front 30

PaCO2 increase as blood flows throw the systemic arteries bc the__ reaction slowly continues

Back 30

unloading

Front 31

the over all result would be the a rise in arterial PaCO2 were it not for the effect CO2 has on the brain's____

Back 31

Medullary chemoreceptors

Front 32

The inhibition of HCO-3 reabsorption from the glomerular filtrate and causes HCO-3 loss in the__

Back 32

urine

Front 33

The adequacy of function of each terminal respiratory unit is determine by local matching between

Back 33

VA/Q

Front 34

Inadequate vent. relative to perfusion (low VA/Q+shunt) has the greatest eff. on the O2 uptake by the lungs and this results in ____

Back 34

hypoxemia

Front 35

excessive ventilation relative to perfusion (high VA/Q+dead space)hinders the lungs ability to eliminate CO2& may cause_esp in indiv. w/ limited ability to increase ventilation

Back 35

Hypercapnia

Front 36

In a normal lung a slight degree of VA/Q mismatch occurs primarly bc of greater effects of ___ on the distribution of perfusion than on vent.

Back 36

gravity

Front 37

is based on the physical principles governing inert gas elimination by the lungs. allow a more complete description of distributions of the VA/Q ratio

Back 37

MIGET

Front 38

When inert gas in solution is infused into systemic veins, the proportion of gas eliminated by vent. from a lung unit depends on the___ of gas and VA/Q ration

Back 38

solubility

Front 39

solution containg low concent. of 6 inert gases of diff. solubility (sulfur,hexafluoride{SF6}, ethane,cyclopropane, isoflurane, diethl ether, and aceton)is infused slowlyinto periph. vein until a steady state is reached to...

Back 39

to obtain the VA/Q distribution of the lungs

Front 40

The inert gas concentration in the arterial mixed ____ and___ samples are collected and analyed.

Back 40

venous and expired gas

Front 41

retention and excretion value for the inert gases are graped agaist there ___ in blood.

Back 41

solubility

Front 42

A lung containing __ unit shows increase retention ofthe least solube gas sulfur hexafluride (SF6)

Back 42

shunt

Front 43

A lung having large amounts of ventilation-to-lung units w/ very high-solubility gases __and ___

Back 43

ether and acetone

Front 44

with age the disperion of ventilation and perfusion does it
increares or decreases

Back 44

increases

Front 45

The causes of age related VA/Q mismatch often is attributed to degenerative processes in the small___ with aging.

Back 45

airways

Front 46

Various abnormal patterns of VA/Q distributions measured by the ___ method adequately explain gas exchange abnormalities in diseased lungs.

Back 46

MIGET

Front 47

VA/Q Distributions in lung diseases:

Back 47

emphysema, low VA/Q units in COPD, pts w/ predominanly choronic bronchitis likely reflect airway obstruction caused by retained secretions & mucous gland HYPERPLASIA

Front 48

Even though low VA/Q interferes w/ the effic. of CO2 elmination, it is often associated w/ normal or even low ___ bc reg. chemoreceptors in the medulla increase vent. drive in respones to a rising ___; this increase total min. ventilation.

Back 48

PaCO2
PaCO2

Front 49

__ lowers the PCO2 of units, balancing out the high PCO2 of low VA/Q units

Back 49

hyperventilation

Front 50

VA/Q mismatch is the primary mechanism for ___ seen in sever COPD pt. These pt req. an increase min ventilation to achieve a given PaCO2 or PaO2 and this incur an increase ____

Back 50

Hyercapia and work of breathing

Front 51

the ___ PO2 appears to be the most important factor involved iin regulating the distribution of VA/Q within the lung

Back 51

alveolar

Front 52

high altitude residents have a better VA/Q matching than sea-level residents, as reflected by smaller __ differences

Back 52

P(A-a)O2

Front 53

O2 from the ambient air is carried into the terminal alveolar units of the lungs by 2 physical processes:

Back 53

-bulk gas flow in the conducting airways
-molecular diffusion in the distal alveolar units

Front 54

The diffusion gradient between gas and blood for O2 is the PO2 diff. between ___and___ . In normal indiv. gradent is about__mm Hg(PaO2 of 100mm Hg)

Back 54

alveolar gas/mixed venous blood
60

Front 55

At rest the diffusion process is virtually complete within the first third__ sec of the mean capillary transit time of 0.75

Back 55

0.25

Front 56

Diffusion of gases across the ac membrane is descibed by ___ Law of diffusion

Back 56

Fick's

Front 57

Fick's law states for a given gas, the amount of ___ transferred across a membrane's surface area a diffusion constant(derived form the gas solubility and molecular weight) the diffusion pressure gradient

Back 57

gas

Front 58

increase gas solubility and decrease gas density would increase it's

Back 58

diffusibility

Front 59

Gas diffusion rate is inversely proportional to the thickness of the

Back 59

membrane

Front 60

is the gas of choice to measure the diffus. capacity of the lung

Back 60

carbon monoxide

Front 61

unlike O2 the part. pressure of CO in capillary blood is neglegible and equilibraton between___ and __ gas CO never occurs

Back 61

blood and alveolar

Front 62

Bc CO equilibration between cap blood cap blood and alveolar gas never occurs the CO diffusion rate is strictly determined by the characterist of the

Back 62

ac membrane

Front 63

The reason blood CO pressure is negligible is that Hb has an extremely high___ for CO (more than 200 times great than O2) and it instantly removes CO form solution.

Back 63

affinity

Front 64

The effectiveness of gas exchange can be measure by:
However no measurement technique allows an exact descrip. of the complex behavior of gas exchange in the lungs.

Back 64

-simple approach is to measure gas tension in arterial blood.
-complicated approach rely on tracer gases and modeling of gas exchange such as MIGET

Front 65

The___ PO2 provides some info about the degree of VA/Q matching. the advantage of the measurement is its simplicity

Back 65

arterial

Front 66

Normal PaO2 decrease with___

Back 66

age

Front 67

Regression equations have been developed to predict the age-specific PaO2 in __ and __positions

Back 67

supine and sitting

Front 68

Supine PaO2 is normally ___ than upright or seated PaO2

Back 68

lower

Front 69

The supine and sitting position equations have large errors of estimation. The def of hypoxemia in adults depends on the ___ of the indiv. and the ___

Back 69

age and altitude

Front 70

A low PaO2 while breathing room air indicates the presence of VA/Q __,___or alveolar ___ but normal PaO2 does not necess. imply a normal VA/Q distrib. of the lung

Back 70

VA/Q mismatch, shunt, hyperventilation

Front 71

The alveolar-arterial PO2 diff.
(P[A-a]O2) is calculated as the diff between the PAO2 and the PaO2.

Back 71

PAO2 is computed from the alverolar gas equation

Front 72

The P(A-a)O2 in healthy adults breathing room air increases with__

Back 72

age

Front 73

The rule is P(A-a)O2 for indiv. should be no more than half the chrono logic age and no more than__mm Hg while breathing room air

Back 73

25

Front 74

the upper normal limit of P(A-a)O2 for a 30 yr old is __mm Hg and for a 60 yr old is __mm Hg

Back 74

15/25

Front 75

Diffusion disequilibrium may contribute to increased P(A-a)O2 during __ and __and also increase w/ high____

Back 75

excercise and high altitudes
alveolar PO2

Front 76

The presence of right-to-left shunt can be differentiated from low-VA/Q causes of hypoxemia by ___

Back 76

breath 100% O2

Front 77

Healthy indiv. have a small shunt that amounts to __% to %__ of the cardiac out put.

Back 77

2/5

Front 78

Bc PaO2 shows little response to variations in FIO2 at shunt fraction that exceed 25% the clinician may be encouraged to reduce toxic and marginally effective concen. of ___

Back 78

O2

Front 79

The shunt calculation freq. overestimates the true shunt bc alveoli w/ very low VA/Q ratios (<0.1) may__ completely during O2 breathing

Back 79

collapse

Front 80

hypoventilation ___ the PaO2 and ___ the arterial

Back 80

decrease/ increases

Front 81

VA/Q mismatch (low-VA/Q units) is most common cause of ___ associated with lung diseases

Back 81

hypoxemia

Front 82

High VA/Q units do not cause Hypoxemia directly because the blood perusing these units is well___

Back 82

oxygenated

Front 83

bc the absence of ___ in the shunt pathway, Hypoxemia resulting from rt-to-lt shunt can not be corrected via brathing of 100% O2.

Back 83

ventilation

Front 84

Ex: of right-to-left shunt include:

Back 84

atelectasis, arterivenous malformation (osler-Weber-rendu disease, liver cirrhosis, & congenital heart disease

Front 85

Low mixed venous O2 content may also contribute to__

Back 85

hypoxemia

Front 86

for a given VA/Q mismatch, the lower the mixed venous O2 content the lower the ___

Back 86

arterial PO2

Front 87

The response to supplemental O2 depends on the relative contributions of VA/Q mismatch and rt-to-lt shunt to hypoxemia if mixed venous O2 content remain the same

Back 87

VA/Q mismatch and rt-to-lt shunt to hypoxemia

Front 88

Complex disturbances of cellular function can be produce by___, bc of inadequate production of high energy phospate compounds such as ATP.

Back 88

hypoxia

Front 89

when blood PaO2 is reduced acutely, symptoms and signs of cerebral hypoxia such___ cardiac hypoxia such as myocardial ischemia or arrhythmias tend to manifest first

Back 89

impaired judgment, motor incoordination, or altered mental status

Front 90

Mechanisms tissue hypoxia

Back 90

-hypoxemic -Anemic
-Stagnant -Histotoxic

Front 91

___results from an inadequate amount of O2 in the blood (reduced PaO2) caused by either lung diseases or decrease O2 in the inspired air (at high altitude)

Back 91

Hypoxemic hypoxia

Front 92

___results from a reduction in blood O2 content, which may be caused by severe __ or the presence of dyshemoglobin states (such as carboxyhemoglobin or methemoglobin)

Back 92

anemic hypoxia/ anemia

Front 93

O2 is useful in CO poisoning bc it displaces CO from Hb and decreases the half-life of ___ and CO in the tissue.

Back 93

carboxhemoglobin

Front 94

___is a result of poor tissue perfusion as may be seen in cases of severe cardiac failure, hypovolemic shock, cardiac arrest and peripheral vascular diseases.

Back 94

Stagnant hypoxia

Front 95

stagnant hypoxia
the amount of O2 dilivered to the tissues each min is reduced in these condition due to__or__

Back 95

low cardiac output or poor tissue perfusion (tissue edema

Front 96

__is an inability to use O2 at the cellular level, as with cyanide or sulfide poisoning. Poisons inhibit elecrton-transfer function by cytochrome oxidaxe so that O2 cannot be reduced to ___

Back 96

Histotoxic/H2O

Front 97

O2 has little effect for Histotoxic unless the toxic process is __

Back 97

reversed

Front 98

Stagnant Hypoxia O2 is not helpful unless tissue perfussion can be___

Back 98

restored

Front 99

___ is the PO2 in blood of the pulmonary artery. It is a measurment that reflects the O2 concent. of the pooled venous blood returning form the body to the heart.

Back 99

mixed venous PO2

Front 100

in the absence of impaired O2 utilization(cyanide poisning and sepsis) mixed venous O2 content is directly related to ___

Back 100

cradiac output

Front 101

When cardiac output and thus O2 delivery decrease, the tissues respond by extracting more O2 from the blood to maintain tissue oxygenation, causing venous O2 content to ___

Back 101

fall