Oxygen measurements

Question 1

What is the maximum quanity of O2 that can combine with haemoglobin in a unit volume of blood?

Answer 1

1g haemoglobin can combine with 1.34 ml O2

Question 2

What are normal Hb levels?

Answer 2

male-160g/litre
female- 135g/litre

Question 3

what is the O2 saturation equation?

Answer 3

O2 saturation = O2 bound to Hb (ml/l) / O2 capaciity (ml/l)
x100

Question 4

what does spO2 stand for?

Answer 4

peripheral oxygen saturation (measured using pulse oximetry)

Question 5

What does SaO2 stand for?

Answer 5

arterial oxygen saturation

Question 6

define oxygen content/ CaO2

Answer 6

the total volume of oxygen carried in a litre of blood

Question 7

what are the units of oxygen content?

Answer 7

mls per litre of blood

Question 8

What is the equation for oxygen content?

Answer 8

oxygen content= oxygen carried by Hb + oxygen in solution

Question 9

What factors does the oxygen content of arterial blood depend on?

Answer 9

1- partial pressure of inspired oxygen
2-the adequacy of ventilation and gas exchange
3-haemoglobin level and affinity of Hb for oxygen

Question 10

what does PaO2 determine?

Answer 10

the oxygen saturation of haemoglobin (the oxygen dissociation curve)

Question 11

Does anemia affect PO2 or oxygen saturation?

Answer 11

No

Question 12

Define hypoxaemia

Answer 12

lack of oxygen in the blood (PaO2 is below normal)

Question 13

Define Hypoxia

Answer 13

reduced oxygen supply to the tissues

Question 14

Define cyanosis

Answer 14

Blue coloration of the skin and mucus membranes resulting from raised levels of deoxyhaemoglobin caused by hypoxaemia

Question 15

What causes hypoxaemia?

Answer 15

1-hypoventilation
(causes hypercapnia which raises CO2 in the blood)

2-diffusion limitaion
(more effect on O2 as CO2 is 20 times more soluble)

3-shunt

4-V/Q mismatch or inequality

Question 16

Why does a shunt cause hypoxaemia?

Answer 16

arterial blood which has not passed through ventilation areas of the lung

Question 17

what is a V/Q inequality/

Answer 17

ventilation and perfusion are not matched

Question 18

PH blood range

Answer 18

7.35-7.45

Question 19

PCO2 blood gas range

Answer 19

4.8-6.0

Question 20

PO2 blood gas range

Answer 20

10.0-13.5

Question 21

Sa02 blood gas range

Answer 21

95.0-98.0

Question 22

HCO3 blood gas range

Answer 22

22.0-26.0

Question 23

units of PCO2 and Po2

Answer 23

KPa

Question 24

SaO2 units

Answer 24

%

Question 25

HCO3 units

Answer 25

mmol/L

Question 26

When does respiratory failure occur?

Answer 26

when insufficent oxygen passes from the air in the alveoli into the blood

Question 27

What are the oxygen levels in the blood of someone with hypoxaemia?

Answer 27

10KPa

Question 28

How is respiratory failure defined?

Answer 28

PaO2 < 8KPa

Question 29

What are the two types of respiratory failure?

Answer 29

type 1- oxygenation
tyoe 2- ventilation

Question 30

What is type 1 respiratory failure?

Answer 30

-oxygenation
-low levels of oxygen in the blood (hypoxaemia) with a normal or reduced arterial partial pressure of CO2
-PaCo2<6KPa

Question 31

What is type 2 respiratory failure?

Answer 31

-ventilation
hypoxaemia with raised CO2
-PaCO2> 6KPa

Question 32

define oxygen capacity

Answer 32

is the maximum quantity of oxygen which can combine with haemoglobin in a unit volume of blood.