L20: Respiratory Failure

Question 1

What is type 1 respiratory failure

Answer 1

Failure of oxygenation
Pa02 less than 8kpa
Paco2 normal or low
Ph is normal

Question 2

What is type 2 respiratory failure

Answer 2

Failure of ventialtion
Pa02 less than 8kpa
Paco2 higher than 6.7kpa
Ph is less than 7.35- exception is chronic type 2 respiratory failure where kidneys can compensate

Question 3

What are the causes of type 1 respiratory failure

Answer 3

Alveolar hyperventilation
Low oxygen levels e.g high altitude
Lung damage and diffusion deficts e.g pulmonary fibrosis, pneumonia and ARDS
Shunts
V/q mismatch e.g pulmonary embolus (reduced perfusion but normal ventilation)

Question 4

What are the causes of type 2 respiratory failure

Answer 4

Failure of alveolar ventilation :
Copd
Alveolar hypoventialtion

Question 5

If there is a respiratory cause what compensates

Answer 5

Kidney (metabolic)

Question 6

If there is a metabolic cause what compensates

Answer 6

Lungs (respiratory compensation)

Question 7

What does a reduction in alveolar ventilation cause to hydrogen ion

Answer 7

Increass due to decreased co2 reacting with water

Question 8

What does a increase in alveolar hyperventilation cause to hydrogen ion

Answer 8

Decrease in hydrogen ions due to increased carbon dioxide

Question 9

How quick are kidneys at compensating

Answer 9

Not quick, compensation will occur when its chronic

Question 10

What are the steps to interpreting abg

Answer 10

1. Is the patient hypoxic
2. What is the ph- acidotic or alkalotic
3. Check pac02- is it a respiratory cause
4. Check the bicarbonate - is it a metabolic cuase

Question 11

What are the causes of alveolar hypoventilation

Answer 11

Central nerbvous system disorders: depressant intoxcants
Disorders of respiratory muscles: myasthenia gravis, gullian barre syndrome
Defects of chest wall or funtinonal disorders
Airway obstruction: tongue, foreign body aspriation, copd

Question 12

What should be the expected pao2 is someone is one oxygen

Answer 12

Less than 10 e.g 50% should be 40kpa

Question 13

What is the base excess of less than -2mmol/ suggest

Answer 13

Metabolic compensation for respiratory alkalosis

Question 14

What does a base excess of more than 2mmol/l suggest

Answer 14

Metabolic compensation for respiratory acidosis

Question 15

What is base excess a measure of

Answer 15

Excess acid or base

Question 16

What does a negative base excess indicate

Answer 16

More acid in the blood

Question 17

What causes paraesthesia in people with anxiety (respiratory alkalosis)

Answer 17

Alkalosis causes Hypocalcaemia. This occurs when alkalosis causes hydrogen ions from the albumin to dissociate and takes up free calcium in the serum that leads to Hypocalcaemia.

Question 18

What is a patient presenting with diarrhoea likely to present with on an ABG

Answer 18

Metabolic acidosis

Question 19

How does diarrhoea cause metabolic acidosis

Answer 19

Bicarbonate is lost from the git in the diarrhoea

Question 20

What is sepsis likely to present as on a ABG

Answer 20

Metabolic acidosis

Question 21

How does sepsis cause metabolic acidosis on a ABG

Answer 21

Due to increase in lactic acid

Question 22

What is dka likely to present as on a ABG

Answer 22

Metabolic acidosis

Question 23

How does dka cause metabolic acidosis

Answer 23

Production of ketone bodies can cause acidosis

Question 24

How can we further investigate dka (other test?)

Answer 24

Capillary glucose test - high

Urinalysis- ketones and glucose present

Question 25

What is vomiting likely to present as on a ABG

Answer 25

Metabolic alkalosis

Question 26

How does vomiting cause metabolic alkalosis

Answer 26

• HCl is lost from the stomach when the person vomits

- Blood volume is also depleted which activates the RAAS that causes an increased bicarbonate absorption from the kidney