Arterial Blood Gas Interpretations, Oxygen Therapy And Increased WOB

Question 1

What is oxygen therapy?

Answer 1

Oxygen therapy is the administration of oxygen at concentrations greater than those found in ambient air in order to treat or prevent hypoxaemia. It is a drug that must be prescribed according to a target saturation range

Question 2

What are the indications for o2 therapy?

Answer 2

Documented hypoxaemia 
Severe trauma
Acute MI
short term therapy
Decrease the symptoms associated with chronic hypoxaemia

BELOW 9kPa is a strong indicator for oxygen therapy

Question 3

What SaO2 levels are an indicator for Oxygen therapy?

Answer 3

SaO2 less than 90% (some say 92% on room air)

Question 4

What are some of the complications of oxygen therapy?

Answer 4

Oxygen toxicity 
Depression of ventilation 
Retinopathy of prematurity 
Absorption atelectasis 
Fire hazard

Question 5

What tools can be used to assess o2 levels?

Answer 5

Pulse oximetry
Non- invasive
Measures SpO2 only

Arterial blood gases
Gold standard test for assessing respiratory failure
Measures PaO2, pH, PaCO2, HCO3, SaO2
Invasive

Question 6

What is the amount of oxygen delivered dependent on?

Answer 6

Oxygen flow rate
Patients inspiratory volume
Respiratory rate

Question 7

What types of oxygen delivery methods are possible?

Answer 7

Nasal cannula- a plastic disposable device consisting of two tips or prongs 1c, long, connected to oxygen tubing
Simple face mask
Reservoir masks

Question 8

What is the normal range to PaCO2?

Answer 8

4.7-6kPa

Question 9

What is the normal values for PaO2?

Answer 9

10-14kPA

Question 10

What are the normal values for the hydrogen ion- pH?

Answer 10

pH 7.35-7.45

Question 11

What are the normal values for the bicarbonate ion- HCO3?

Answer 11

22-26mmol l-1

Question 12

What does PaO2 and PaCO2 mean?

Answer 12

Partial pressure of arterial oxygen

Partial pressure of arterial carbon dioxide

Question 13

Respiratory acidosis

Answer 13

The normal blood ph ranges is 7.35-7.45. In order for normal metabolism to take place, the body must maintain this narrow range at all times through homeostatic mechanisms. When the ph is below 7.35, the blood is said to be acidic, this can only exist when there is TOO MUCH co2 (paCo2) in the blood or TOO LITTLE bicarbonate (HCO3) in the blood.

Hypoventilaition could cause a respiratory acidosis as there is a a co2 build up
Pulmonary disorders such as atelectasis, pneumonia, pneumothorax, pulmonary oedema, or chronic obstructive pulmonary disease

Question 14

What is Respiratory alkalosis?

Answer 14

It is a pH greater than 7.45 with a paCO2 less than 4.7kPa. Any condition that causes hyperventilation can result in respiratory alkalosis. Hyperventilation removes carbon dioxide at a faster than normal rate, subsequently resulting in a decrease in hydrogen ions.
Some conditions that cause hyperventilation include psychiatric causes, hyperventilation syndrome, anxiety, stress

Question 15

What is a metabolic acidosis?

Answer 15

It is defined as a pH of less than 7.35 with a bicarbonate level of less than 22mmol l-1. Metabolic acidosis is caused by either a deficit of bicarbonate in the bloodstream or an excess of acid(other than that of an increase of carbonic acid as a result of increased co2.)
What are the causes of metabolic acidosis?
Lactic acidosis, chronic renal failure, chronic diarrhoea (bicarbonate loss)

Question 16

What is a metabolic alkalosis?

Answer 16

It is defined as a pH greater than 7.45 with a bicarbonate level greater than 26mmoll-1. Either an excess of bicarbonate or a loss of acid with ion the body can cause metabolic alkalosis.
Some potential causes include excess base from ingestion of antacids, excess use of bicarbonate, or use of lactate in dialysis.
Loss of acids can occur secondary to protracted vomiting

Question 17

How to determine whether a patient needs increased or decreased oxygen therapy

Answer 17

50%- fio2

The oxygen pa02 can be compensated with increasing oxygen therapy. 10-14 is normal