Respiratory

Question 1

Normal ABG pH

Answer 1

7.35-7.45

Question 2

Normal ABG PCO2 and PO2

Answer 2

PCO2 4.6-5.6 kPa
PO2 12-14.6 kpa

Question 3

Normal ABG HCO3 and base excess

Answer 3

HCO3 22-26mmol/L
BE - 0

Question 4

Causes of hypoxia

Answer 4

Hypoxic environment
Anaemia
Stagnant
Hystotoxins
Decr circ blood volume
Lung pathology
Circ failure

Question 5

Axis on oxygen dissociation curve

Answer 5

Y o2 sat of Hb %
X o2 partial pressure mmHG

Question 6

Does increased affinity for o2 cause left or right shift in ox Hb dissociation curve

Answer 6

Left

Question 7

Causes of left shift in ox Hb dissociation curve

Answer 7

Decr pCO2
Decr H+ (alkali pH)
Decr 2,3 DPG
Decr temp
HbF

Question 8

Causes of right shift in ox Hb dissociation curve

Answer 8

Incr pCO2
Incr H+ (acidosis)
Incr 2,3 DPG
incr temp

Question 9

What is vital capacity made up of

Answer 9

Insp reserve vol + tidal vol + exp reserve vol

Question 10

What is functional residual capacity made of

Answer 10

Exp reserve vol + residual vol

Question 11

How does ventilation and perfusion vary across west zones

Answer 11

Upper zone - incr vent decr perf
Middle zone - vent = perf
Lower zone - decr vent incr perf

Question 12

What is a shunt

Answer 12

Capillary that can not take part in gas exchange ( shunts blood past alceoli)

Question 13

Why does perfusion vary across west zones

Answer 13

Less perfusion at top of lung due to gravity (when pt upright)

Question 14

West zones

Answer 14

Zone 1, where alveolar pressure is higher than arterial or venous pressure;
Zone 2, where the alveolar pressure is lower than the arterial but higher than the venous pressure
Zone 3, where both arterial and venous pressure is higher than alveolar
Zone 4, where the interstitial pressure is higher than alveolar and pulmonary venous pressure (but not pulmonary arterial pressure)

Question 15

Which west zone only exists in haemorrhage or positive pressure ventilation

Answer 15

Zone 1

Question 16

Lung compliance

Answer 16

Change in lung volume per unit pressure
‘Stretchiness’

Question 17

What happens when PEEP is too low

Answer 17

Alveoli collapse (atelectasis) decreasing o2 diffusion area
More pressure needed to re expand alveoli causing atelectotrauma

Question 18

Factors affecting lung compliance

Answer 18

Lung volume
Age
Posture
Pulmonary blood volume
Bronchial smooth muscle tone
Disease states

Question 19

Factors effecting thoracic compliance

Answer 19

Age
Posture
Skin lesions (burns)
Obesity
Abdo distension
Kyphoscoliosis

Question 20

3 aspects of breathing controls

Answer 20

Central
Chemical receptors
Stretch receptor

Question 21

Medullary control of breathing

Answer 21

Inspiratory pool - source of rhythm, incr output of muscles of resp, inhibits exp pool
Expiratory pool - gradually starts activity during inspiration, inhibits insp pool

Question 22

Pontine control of resp

Answer 22

Pneumotactic centre - fine tunes vent rate and vol, inhibits insp pool during inspiration
Apneustic centre - prolonged inspiration, acts on insp pool

Question 23

Where are peripheral and central chemoreceptors found

Answer 23

Peripheral carotid bodies
Central medulla

Question 24

What are peripheral and central chemoreceptors sensitive to

Answer 24

Peripheral - o2 conc
Central - H+ ion conc

Question 25

Do peripheral or central chemoreceptors have a greater response to CO2

Answer 25

Central

Question 26

Where are irritant receptors found and what effects do they cause

Answer 26

Upper airway and trachea mucosa
Cause Bronchoconstriction and apnoea

Question 27

Pressure receptors involved in breathing regulation and their locations

Answer 27

Pulmonary stretch receptors - airway smooth muscle
J receptors - alveolar walls
Golgi tendon organs - intercostal muscles
Muscle spindles - insp muscles and diapragm

Question 28

Pressure receptor effects to regulate breathing

Answer 28

Pulmonary stretch receptors - inhibit inspiration on distension
J receptors - vause rapid shallow breathing
Golgi tendon organs - inhibit inspiration when chest wall distended
Muscle spindles - activate when intense resp effort required