Ventilation and respiration part 1

Question 1

gases always flow from

Answer 1

area of high pressure to low pression region

Question 2

Boyle’s law

Answer 2

The pressure of a gas in an enclosed container is inversely proportional to the volume of the container

Question 3

ATM vs Intrapulmonary pressure at rest

Answer 3

alv 760 mmHg and pleural is 756 mmHg

Question 4

ATM vs intrapulmonary pressure during inhalation

Answer 4

alv 758mmHg and pleural 754 mmHg

Question 5

ATM vs intrapulmonary pressure during exhalation

Answer 5

alv 762 mmHg and pleural 756 mmHg

Question 6

pleural pressure (intrapleural)

Answer 6

pleural space (potential space) exists in a constant negative pressure that varies relative to inspiration/expiration, effort, and gravity
The average intrapleural pressure (at rest) is 
     -4 to -5 cmH2O. This is highly variable:
during force exhalation can be +70 mmHg 
and inhalation against an obstruction is -50 mmHg

Question 7

Compliance (stretchiness)

Hooke’s law

Answer 7

think of the old sock analogy- compliance can be measured by volume/pressure.The lungs are distended some volume for each unit of pressure applied=Normal Adult Compliance is 0.1 to 0.4 L/cm H20.

Question 8

resistance

Answer 8

Normal adult airway resistance is ~ 1.0 - 2.0 cmH2O/L/sec
R in an intubated pt ~ 6 cmH2O/L/sec
gas flow=change in pressure/resistance
resistance is inversely proportionate to gas flow
and change in pressure in directly proportionate to gas flow

Question 9

flow types

Answer 9

Flow in a tube may be described as:
laminar; stream lined, parallel molecular movement, generally low flow rates
turbulent; random flow, resistance from sides of tube and molecular collision, generally occurs at high flow rates and pressure gradients

Question 10

alveolar filling

Answer 10

not all alveolar fill equally at the same time

it all depends on compliance and resistance

Question 11

dynamic compliance vs static compliance

Answer 11

dynamic compliance is the stretchiness during flow movement. Vt ( delivered) / PIP - PEEP
static is no flow at all (during plateau)
Vt(delivered)/Plateau - PEEP

Question 12

formula for resistance

Answer 12

𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒=𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒/𝐹𝑙𝑜𝑤
flow is inversely proportionate to resistance
and pressure is directly proportionate

Question 13

flow resistance-spontaneous respiration/inspiration

Answer 13

varies depending tidal volume

• high inspiratory volume=flow resistance goes down
• high expiratory volume= high resistance flow goes up

Question 14

flow and equal pressure

Answer 14

Flow is proportional to muscular effort but only to a point. Beyond this point, airways collapse.
This point is referred to as the “equal pressure point”
Beyond this point, “dynamic compression” of the airways occur. like pinching a straw/collapsing
poseuille’s law- explains the effect of inspiration and expiration on airway diameter. Emphysema can be an example

Question 15

hyperpnea

Answer 15

Large volumes with or without increase in RR

Question 16

hyperventilation

Answer 16

Increased Rate and/or depth

CO2 should decrease resulting in respiratory alkolosis

Question 17

hypoventilation

Answer 17

Rate and or depth are decreased
CO2 should rise
Respiratory Acidosis

Question 18

Kussmaul’s breathing

Answer 18

Rapid and deep breathing pattern
Usually in response to metabolic acidosis
CO2 drops to balance pH

Question 19

Cheyne-strokes breathing

Answer 19

Gradual increase in volume and rate followed by gradual decline in both with apneas in between
Indicates low cerebral perfusion secondary to heart failure
CO2 will vary throughout cycle

Question 20

Biot’s breathing

Answer 20

Rapid deep breathing followed by apnea
Seen in patients with high cerebral pressures
CO2 will vary. trigger by a strong stimulus which is CO2 retention due to apnea

Question 21

internal vs external respiration

Answer 21

internal- movement of gas btw the blood and the tissue

external - movement of gas btw alveoli and blood

Question 22

factors affecting diffusion

Answer 22

molar mass- how big or small a molecule is
concentration
surface area
thickness of the membrane

Question 23

concentration (Dalton’s Law)

Answer 23

Each gas in a mixture of gases exerts it own pressure as if all the other gases were not present”
The pressure of that gas in a mixture is called its “partial” pressure.

Question 24

Henry’s Law

Answer 24

The quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility coefficient
> parital pressure the more dissolved gas
>solubility coefficent the more dissolved gas

Question 25

Graham’s Law- molar mass

Answer 25

States that the relative rate of diffusion is inversely proportional to the square root of the molecular mass
In simple terms the smaller the molecular weight of a molecule the easier it will diffuse