measurements of ventilation

Question 1

define tidal volume

Answer 1

volume of gas moved into or out of the lungs during a normal breath

Question 2

What is the VT of a healthy adult?

Answer 2

500ms (7ml/kg)

Question 3

Define respiratory rate?

Answer 3

number of breaths taken per minute

Question 4

What is the normal adult respiratory rate?

Answer 4

-between 12-20 breaths per minuete

Question 5

What factors affect respiratory rate?

Answer 5

-excersise
-emotion
-injury

Question 6

What clinical factos increase RR?

Answer 6

-fever
-dehydration
-anxiety
-respiratory disease
-heart disease

Question 7

What clinical factors decrease RR?

Answer 7

-head injury
-narcotic overdose
-sleep apnoea

Question 8

What is minute ventilation?

Answer 8

the total volume of air which the lung exchanges with the outside

Question 9

What are the units of minute ventilation?

Answer 9

ml/min

Question 10

What is the equation for minute ventilation?

Answer 10

tidal volume x respiratory rate

Question 11

What is normal minute ventilation?

Answer 11

5-9 litres/min

Question 12

What is dead space ventilation?

Answer 12

due to the lungs structure some air inspired in each breath remains in the conducting airway and never reaches the gas exchange areas

Question 13

Define alveolar ventilation

Answer 13

the volume of air/min which reaches the gas exchange regions

Question 14

What is the relationship between minute ventilation, dead space ventilation and alveolar ventialtion?

Answer 14

minute ventilation = dead space ventilation + alveolar ventilation

Question 15

Describe dead space in the lungs

Answer 15

-divided into anatomic deadspace (air in conducting airways)
-alveolar deadspace- air within alveoli that are poorly perfused
physiological dead space-total dead space

Question 16

What is the relationship between physiological dead space, anatomic deadspace and alveolar deadspace?

Answer 16

physiological dead space= anatomic deadspace+ alveolar dead space

Question 17

What is the alveolar ventialtion equation?

Answer 17

VA= (VT-VD) x RRml/min

Question 18

what does alveolar ventialtion help determine?

Answer 18

the alveolar partial pressure of carbon dioxide PACO2 and oxygen PAO2

Question 19

What is PAO2?

Answer 19

partial pressusre of xygen in alveoli

Question 20

What is PaO2?

Answer 20

parital pressure of oxygen in arterial blood

Question 21

What is PvO2?

Answer 21

partial pressure of oxygen in venous blood

Question 22

What is PACO2, PaCO2 and PCO2

Answer 22

PACO2-partial pressure of co2 in alveoli
-PaCO2-partial pressure of co2 in arterial blood
-PCO2-partial pressure of carbon dioxide

Question 23

What is the actual equation for alveolar ventilation?

Answer 23

VA= VCO2/PaCO2 ml/min

Question 24

describe what happnes during hypoventilation

Answer 24

-a reduction in ventilation causes an increase in pp of CO2 in arterial blood
-reduction in ventilation
-hypercapnia
-acidosis would occur due to carbonic acid formation

Question 25

Describe what happens during hyperventilation

Answer 25

-if co2 stays constant yet ventilation increased then PaCO2 drops. -ventilation increases -hypocapnia -alkalosis (Blood PH increases to more than 7.45)

Question 26

What happens when alveolar ventilation increase?

Answer 26

more oxygen rich air into alveoli and increases PAO2 and remove CO2 reducing PACO2

Question 27

What happnes when alveolar ventilation decreases?

Answer 27

-CO2 levels will increase within the alveoli and PACO2 will increase and PAO2 will drop

Question 28

What is respiratory failure?

Answer 28

when insufficent oxygen passes from the air in the alveoli into the blood to meet demand

Question 29

Describe the causes of type 1 respiratory failure

Answer 29

-results in hypoxaemia -inhaling air with with reduced pp of O2 -mismatch in ventialtion and perfusion -shunt -diffusion defect -alveolar hyperventialtion

Question 30

Describe the causes of respiratory failure

Answer 30

-COPD -depressed breathing effort -neuromuscular conditions -chest wall deformity (hypoxaemia,hypercapnia,acidaemia) -alveolar hypoventilation

Question 31

What is type 2 respiratory failue?

Answer 31

decrease in PaO2 and increase in PaCO2