Schmerler - Principles 613 Apnea/hypoxia 102511

Front 1

The respiratory center in the ____ and ____ integrates sensory info about level of O2 and CO2 in blood and determines signals to send to resp muscles.

Back 1

medulla oblongata and pons

Front 2

Respiratory center detects changes that activate central and peripheral _____, sending impulses to respiratory center and triggering incr or decr. in ____.

Back 2

chemoreceptors, breathing rate

Front 3

This center antagonizes effects of pneumotaxic center, and promotes inspiration by stimulation of neurons in medulla oblongata

Back 3

apneustic center

Front 4

This respiratory center is located dorsally in medulla and controls inspiration, neurons located near termination sites of afferent fibers of cranial nerves 9 and 10 --> causes inspiration when stimulated

Back 4

dorsal respiratory group

Front 5

This respiratory area is located in the pons and controls pattern and rate of breathing, communicates w apneustic center to TURN OFF INSPIRATION

Back 5

pneumotaxic area

Front 6

This respiratory area extends full length of ventral medulla and stimulates muscles of expiration (passive)

Back 6

ventral respiratory group

Front 7

These compose the respiratory rhythmicity center in the medulla

Back 7

ventral resp group and dorsal resp group

Front 8

The apneustic and pneumotaxic centers are located in the

Back 8

pons

Front 9

This respiratory center inhibits:

Back 9

pneumotaxic center

Front 10

These respiratory centers stimulate

Back 10

apneustic center, dorsal resp group, ventral resp group

Front 11

These sensors of the resp center are located anterolaterally in medulla and are extremely sensitive to H+ ions

Back 11

central

Front 12

H+ crosses blood-brain barrier (well/poorly) and CO2 therefore indirectly controls this region through formation of _____ and dissociation to ____.

Back 12

poorly, carbonic acid, H+

Front 13

CO2 + H20 --> H2CO3 -->

Back 13

H+ + HCO3-

hydrogen ion and carbonic acid

Front 14

Central sensors in resp center respond to changes in _____ which is effective in regulating PaCO2.

Back 14

CSF H+

Front 15

Increases in PaCO2 elevate CSF H+ concentration which activates

Back 15

chemoreceptors.

Front 16

Over the course of ____, CSF HCO3- can compensate to match any change in arterial HCO3-.

Back 16

a few days

Front 17

Peripheral chemoreceptors are located in these 2 spots and are innervated by those 2 nerves

Back 17

carotid bodies (CN9)
aortic bodies (CN10)

Front 18

Peripheral chemoreceptors are sensitive to changes in these 4 things:

Back 18

O2, CO2, pH, and arterial perfusion pressure

Front 19

Peripheral chemoreceptors stimulate inspiratory center when PaO2 decreases, most seen when MAP <

Back 19

70 mmHg

Front 20

The effect of peripheral chemoreceptors in response to hypoxia is eliminated by as little as ___ MAC.

Back 20

0.1 MAC

Front 21

Changes in peripheral chemoreceptor response to hypoxia may be dicey in patients with:

Back 21

COPD - dependent on hypoxic resp drive!

Front 22

These 2 receptors in lungs can influence respiration:

Back 22

stretch and irritant

Front 23

Three components of the respiratory process:

Back 23

ventillation, diffusion, perfusion

Front 24

ventillation

Back 24

mechanical movement of air flow to and from atmosphere and alveoli, involves work of breathing and requires nervous system control

Front 25

Surfactant is produced by ____ cells and reduces ____ of fluid lining alveolar sacs, decreasing tendency to ____.

Back 25

type II cells, surface tension, collapse

Front 26

This is the movement of gases down a pressure gradient from an area of high pressure to low pressure.

Back 26

diffusion

Front 27

CO2 diffuses ____ faster than O2.

Back 27

20x

Front 28

The normally thin alveolar membrane can thicken when pulmonary pathologies exist, such as

Back 28

pulmonary edema or ARDS

Front 29

4 Factors affect diffusion through alveolar-capillary membrane

Back 29

partial pressure and gradients, surface area, thickness, and length of exposure

Front 30

Atmospheric air is composed of these molecules

Back 30

N2, O2, CO2, H2O vapor

Front 31

Atmospheric air exerts this pressure at sea level:

Back 31

760 mmHg

Front 32

Repiratory process doesnt actively involve the use of

Back 32

N2 or H20 vapor

Front 33

Pressures exerted by O2 and CO2 in the alveoli and in end capillary vessels:

Back 33

O2 100mmHg
CO2 40mmHg

Front 34

The purpose of denitrogenating prior to induction is:

Back 34

to replace N2 in lungs with O2

Front 35

What are the pressures of O2 and CO2 in mixed venous blood?

Back 35

O2 40 mmHg
CO2 45 mmHg

Front 36

This law states that when a gas is exposed to liquid, some of it will dissolve into the liquid, determined by the partial pressure of that gas on the liquid and its solubility.

Back 36

Henry's Law

Front 37

This gas is highly soluble into blood:
This gas is highly insoluble in blood:

Back 37

CO2 dissolves
O2 insoluble

Front 38

Pressure gradient

Back 38

difference between partial pressures, exists between atmosphere and alveoli and between alveoli and pulm capillaries

Front 39

The greater the pressure difference across a gradient...

Back 39

the more rapid the flow of gases

Front 40

These increase pressure gradient:

Back 40

exercise, PP mech vent, intermittent PP breathing

Front 41

Causes of hypoxemia

Back 41

hypoventillation, low FiO2, V/Q mismatch, diffusion impairment, right to left shunt

Front 42

These causes of hypoxemia do not alter A-a gradient

Back 42

hypoventillation, low FiO2

Front 43

These causes of hypoxemia increase A-a gradient:

Back 43

VQ mismatch, diffusion impairment, right to left shunt

Front 44

The greater the available alveolar-capillary membrane surface area....

Back 44

the greater the amt of O2 and CO2 that can diffuse across it

Front 45

This pulm disorder destroys alveolar-capillary membrane and reduces surface area, impairing gas exchange

Back 45

emphysema

Front 46

These pulmonary disorders can reduce functioning surface area for gas exchange:

Back 46

severe pneumonia, lung tumors, pneumothorax, pneumonectomy

Front 47

The thinner the mebrane for gas exchange...

Back 47

the more rapid the rate of diffusion of gases

Front 48

Conditions that increase membrane thickness and decrease gas exchange:

Back 48

fluid in alveoli or interstitium or both (pulm edema, pneumonia)
inflammation/fibrosis of alveoli (ARDS, pneumoconiosis - dust in lungs from mines)

Front 49

Diffusion of O2 requires about ___ seconds to reach equilibrium (balance between alveolar and capillary gas levels).

Back 49

0.25

Front 50

During high CO (exercise/stress) blood flows ____ through alveolar-capillary system, which can create hypoxia if pt has diffusion problems (pulm edema, pneumonia)

Back 50

faster

Front 51

O2 binds loosely and reversibly to hemoglobin to form ______ for transport to the tissues where it can be released.

Back 51

oxyhemoglobin

Front 52

SPO2

Back 52

percent of O2 bound to Hgb

Front 53

Oxyhemoglobin dissociation curve

Back 53

represents relationship of partial pressure of arterial PaO2 and hemoglobin saturation SaO2

Front 54

Left shift of curve indicates:

Back 54

increased affinity for O2 to Hgb -- less released into tissues

Front 55

Right shift of curve indicates:

Back 55

decreased affinity for O2 to Hgb -- more freely released into tissues

Front 56

A low PaO2 in the tissues stimulates

Back 56

O2 release from Hgb into tissues

Front 57

High PaO2 in pulm capillaries stimulates

Back 57

Hgb to bind more with O2 in lungs

Front 58

Perfusion

Back 58

pumping or flow of blood into tissues and organs
systemic and pulmonary

Front 59

systemic perfusion

Back 59

from aorta through right atrium of heart

Front 60

Pulmonary perfusion

Back 60

from pulmonary artery through left atrium

Front 61

Pulmonary perfusion depends on these 3 factors

Back 61

CO, gravity, and pulm vascular resistance

Front 62

VQ ratio

Back 62

relationship expressed as ratio of alveolar ventilation to pulmonary capilary perfusion

Front 63

VQ ratio balance depends on:

Back 63

adequate diffusion of O2 and CO2 across alveolar-capillary membrane, and mvmt of O2 into and CO2 out of alveoli

Front 64

Ideal VQ ratio

Back 64

alveolar ventilation 4 L/min and capillary perfusion 5 L/min
4/5 = 0.8

Front 65

Partial pressure of O2 and CO2 varies throughout lungs because:

Back 65

ventilation is not distributed evenly because of gravity-dependent factors

Front 66

In spontaneous breathing, airflow naturally moves toward _____ and ____ during inspiration.

Back 66

diaphragm and peripheral lung

Front 67

Pulmonary capillary perfusion is _____ dependent, making perfusion greatest in the ______ areas of the lungs.

Back 67

gravity dependent, dependent areas

Front 68

Best VQ match is located at:

Back 68

base of lungs

greatest amt of gas exchange occurs here

Front 69

______ has best ventilation and ______ has best perfusion.

Back 69

Apex, Base

Front 70

If ventilation is higher and perfusion is lower...

Back 70

high vq ratio

Front 71

If perfusion is higher and ventilation is lower...

Back 71

lower VQ ratio

Front 72

High VQ ratio means:

Back 72

normal to increased alveolar ventilation associated with decreased perfusion

Front 73

In high VQ ratio, the alveolar gas effect ...

Back 73

incr. cardiac output, decr. alveolar CO2, normally exists in upper lung fields

Front 74

High VQ ratio is abnormally present in these conditions

Back 74

decr. CO, PE, pneumothorax, destruction of pulm capillaries

Front 75

In high VQ ratio, the arterial blood gas effects...

Back 75

incr. PaO2, decr. Pa CO2, incr. pH

Front 76

The apex of lungs have _____ ventilation and ___ perfusion, causing an excess of ventilation to available perfusion.

Back 76

increased ventilation, reduced perfusion

HIGH VQ RATIO

Front 77

Middle section of lungs has ____ ventilation and ____ perfusion, causing a _____ VQ ratio.

Back 77

increased ventilation, increased perfusion,
LOW VQ RATIO

Front 78

In Low VQ ratio, there will be ______ ventilation with ___ perfusion.

Back 78

decr. ventilation,
incr. perfusion

Front 79

In Low VQ ratio, the alveolar gas effects are...

Back 79

decr. O2 in alveoli
incr. CO2 in alveoli
occurs in lower lung fields

Front 80

Low VQ ratio is abnormally present in these conditions:

Back 80

hypoventilation, obstructive lung disease, restrictive lung disease

Front 81

Low VQ Ratio has these ABG effects

Back 81

decr. PaO2,
incr. PaCO2,
decr, pH

Front 82

The west zone 1

Back 82

PA>Pa>Pv

Front 83

The west zone 2

Back 83

Pa>PA>Pv

Front 84

The west zone 3

Back 84

Pa>Pv>PA

Front 85

This is the percentage of CO that flows from R heart back into L heart without undergoing pulm gas exchange ( can be true or physiologic) or not achieving normal levels of PaO2 because of abnormal alveolar function

Back 85

Pulmonary shunt

Front 86

Shunts can be _____ in the alveolar level or ______ as in PFO or ventricular septal defect.

Back 86

respiratory, cardiac

Front 87

A-a gradient is useful for

Back 87

estimating degree of physiologic shunt and hypoxemia

Front 88

Normal shunt values

Back 88

A 104 mmHg
a 95 mmHg
normal shunt is 5-10 mmHg

Front 89

Increased A-a gradient is associated with:

Back 89

aging, shunting, VQ mismatch

Front 90

Total lung capacity

Back 90

volume in lungs at max inflation

Front 91

Residual volume

Back 91

volume of air remaining in lungs after max exhalation

Front 92

Expiratory reserve volume

Back 92

max volume of air that can be exhaled from end-expiratory position

Front 93

Inspiratory reserve volume

Back 93

max volume that can be inhaled from end-inspiratory level

Front 94

Inspiratory Capacity

Back 94

sum of inspiratory reserve volume and tidal volume

Front 95

Inspiratory vital capacity

Back 95

max volume of air inhaled from point of max expiration

Front 96

Vital capacity

Back 96

Total lung capacity - residual volume

Front 97

tidal volume

Back 97

volume of air moved into or out of lungs during quiet breathing

Front 98

functional residual capacity

Back 98

volume in lungs at end-expiratory position

residual volume + expiratory reserve volume

Front 99

Functional reserve capacity is decreased by PANGOS

Back 99

pregnancy
ascites
neonates
general anesthesia
obesity
supine position

Front 100

Closing volume

Back 100

volume needed in lungs at end expiration to keep alveoli open

Front 101

Closing capacity

Back 101

closing volume + residual volume

Front 102

Closing capacity is increased by CLASSO

Back 102

chronic bronchitis
liver failure
age
surgery
smoking
obesity

Front 103

How does intra op supination affect ventilatory changes?

Back 103

cephalad shift of diaphragm, decreased FRC, VQ incr. in dependent portions of lungs

Front 104

How does anesthesia affect ventilatory changes? (there's a bunch)

Back 104

incr. RR, decr. TV, irregular breathing in lighter stages, airway resistance incr., change in thoracic muscle tone (to favor collapse), paralysis (favors collapse), positive pressure ventilation, excessive IVF (promotes shunting), absorption atelectasis with high inspired O2 conc., decr. removal of secretions and mucociliary flow, inhibition of hypoxic pulmonary vasoconstriction (HPV)

Front 105

How does positive pressure ventilation affect ventilatory changes during anesthesia?

Back 105

incr. VQ mismatch,
as ventilation incr. in nondependent areas and perfusion remains in dependent areas

Front 106

What is HPV in anesthesia ventilation changes?

Back 106

Hypoxic pulmonary vasoconstriction
positive effect
physiologic protective mechanism which prevents right to left shunting of blood

Front 107

What is the Rate of PaCO2 rise during apnea, and when is it clinically significant?

Back 107

6 mmHg first minute,
3-4 mmHg each subsequent minute

clincally significant during emergence, COPD, and brain death criteria(apneic test)

Front 108

Hypoxia leads to anaerobic ventilation, with the buildup of hydrogen ion and lactate. This causes ____

Back 108

acidosis

Front 109

Early cardiovascular symptoms of hypoxia

Back 109

excitatory and vasoconstrictive

incr. HR, Stroke volume, contractility

Front 110

Late cardiovascular symptoms of hypoxia:

Back 110

depressed and vasodilatory

decr. BP, HR --> shock --> fibrillation --> ASYSTOLE

Front 111

Anesthesia may mask this physiologic response to hypoxia:

Back 111

sympathetic response

Front 112

Hypoxia symptoms mimic the symptoms of:

Back 112

hypercapnia

Front 113

This is a common cardiac sign of hypoxia:

Back 113

arrhythmias

Front 114

Neuromuscular blockers (NMBs) affect the cephalad movement of the diaphragm, leading to:

Back 114

alteration in VQ matching