Station 1- CXR or ABG

Question 1

Normal value of pH

Answer 1

7.35-7.45

Question 2

Normal value of PaO2

Answer 2

10.7-13.3 KPa

Question 3

Normal value of PaCO2

Answer 3

4.7-6.0 KPa

Question 4

Normal value of HCO3- (bicarbonate)

Answer 4

22-26mmol/l

Question 5

Normal value of base excess

Answer 5

-2 —> +2

Question 6

What is type 1 respiratory failure? And how do you recognize it?

Answer 6

• Occurs when the respiratory system cannot adequately provide oxygen to the body
• Caused by pneumonia, pneumothorax, COPD, pulmonary embolism
• PaO2 is less than 8 KPa
• 1 THING WRONG= low O2

Question 7

What is type 2 respiratory failure? And how do you recognise it?

Answer 7

• When the respiratory system cannot adequately remove carbon dioxide from the body
• Caused by COPD, neuromusclar disorders (reduced strength of expiratory muscles), fatigue, reduced compliance of lung wall/ tissue (rib fracture, pneumonia)
• 2 THINGS WRONG: PaO2 is less than 8 KPa AND increased PaCO2

Question 8

What are the 5 outcomes from an ABG?

Answer 8

Metabolic acidosis
Metabolic alkalosis
Respiratory acidosis
Respiratory alkalosis
Respiratory failure (1 or 2)

Question 9

Steps for analysing ABGs

Answer 9

1. Check PO2 - hypoxemia (low) or hyperoxia (high)
2. pH - Acidosis or alkalosis
3. PCO2- hypercapnia (high) or hypocapnia (low)
4. HCO3- helps mop up acids. Raised = high pH, Low = low pH.
5. Base excess- how much buffering is needed to normalise the blood. Raised = higher than normal HCO3 (alkalosis), Low = lower than normal HCO3 (acidosis)

Question 10

What is hypercapnia?

Answer 10

Increase in CO2 in the blood.
Caused by hypoventilation leading to respiratory acidosis or compensated metabolic alkalosis

Question 11

What is hypoxemia?

Answer 11

Low level of O2 in the blood
- Due to a V/Q mismatch

Question 12

Tips for exam

Answer 12

• Give some examples of pathophysiology which may be causing this issue and what treatment would help
• Put into clinical context of patients condition
• Use arrows and labels

Question 13

What is a posterior-anterior (PA) CXR? And how can you tell?

Answer 13

• Patient standing and holding the X-ray detector on their chest
• X-ray source behind to take an x-ray from their back so no major organs are in the way
• You can tell by= scapula position (retraction), larger air space, clear spinous processes

Question 14

What is an anterior-posterior CXR? How can you tell?

Answer 14

• When the patient is too poorly to go to the x-ray department so done in bed
• x-ray detector board is placed behind the patient and a portable x-ray machine is wheeled to the end of the bed
• You can tell by = smaller air space, position of scapulas, heart might look larger

Question 15

How does bone appear on CXR?

Answer 15

White = high absorption

Question 16

How does tissues appear on CXR?

Answer 16

Grey = moderate absorption

Question 17

How does air appear on CXR?

Answer 17

Black = low absorption

Question 18

Checking for a normal CXR. Which features are we looking to identify?

Answer 18

• Clavicle
• Ribs
• Heart boarder
• Aortic arch
• Vertebral bodies
• Diaphragm
• Trachea
• Costo cardiac angles and costo phrenic angles

Question 19

A-H for identifying an abnormal x-ray

Answer 19

Airway
Bones
Cardiac silhouette
Diaphragm
Effusions
Fields (lung fields)
Gadgets
Hidden areas

Question 20

Airway in A-H

Answer 20

Is the trachea central?
Does it deviate?
Does it narrow?
Does it contain any foreign objects?

Question 21

Bones in A-H

Answer 21

Can you see any rib fractures?
Can you see the abnormalities?

Question 22

Cardiac silhouette in A-H

Answer 22

Have they got an enlarged heart (cardiomegaly)?
Can you see the heart outline?
Is there any mediastinal shift

Question 23

Diaphragm in A-H

Answer 23

Is the diaphragm domed?
Is it flat?
Look at the position

Question 24

Effusions in A-H

Answer 24

Can you see a water line?
Can you see the costophrenic angle?

Question 25

Fields (lung fields) in A-H

Answer 25

Lung volumes- do lungs expand to the pleura (pneumothorax?) Visible costophrenic and costocardiac angles? Are they obscured and why?

Question 26

Gadgets in A-H

Answer 26

Are there any attachments?

Question 27

Hidden areas in A-H

Answer 27

- Lung apex - Below diaphragm - Hilum - Retrocardinal zone

Question 28

What does a chest with consolidation look like?

Answer 28

Whiteness in alveoli due to fluid Very opaque white patches 'Fluffy' - Could be caused by pneumonia

Question 29

What does a COPD chest look like?

Answer 29

Flat diaphragm (can be blurry), horizontal ribs, larger lung volume 'barrel chest'

Question 30

What does a chest with pneumothorax look like?

Answer 30

- Air in the pleural space 'pleural edge' - Deflated lung - Black space - No lung markings - Deviated trachea away from the pneumothorax - Caused by trauma (rib fracture?

Question 31

What does a chest with pleural effusion look like?

Answer 31

Build up of fluid 'Water line' Obscured lung fields and a 'meniscus sign' - Deviated trachea away from the effusion - Caused by pneumonia, cancer, heart failure, pulmonary embolism

Question 32

What does a chest with pulmonary oedema look like?

Answer 32

Fluid in the lung Patchy white in lung fields 'bat wings' Enlarged hila - Can be caused by heart failure

Question 33

Acronym for quality of x-ray

Answer 33

R- rotation: is trachea and spine central or rotated? Clavicals level and symmetrical? I- inspiration: can you see 6 anterior ribs and 9-10 posterior? P- projection: AP or PA? E- exposure: is it over or under exposed? Can you see vertebrae behind the heart?

Question 34

Potential causes for a metabolic alkalosis? Physio and MDT intervention strategies?

Answer 34

Loss of acid due to vomiting, NG tube aspiration and diuretics Interventions: referral to MDT to identify what is causing this loss of acid. Physios to monitor lung volumes, mobility and chest. Might decrease RR to reduce loss of CO2

Question 35

Metabolic acidosis - causes and interventions

Answer 35

Diarrhoea , renal problems/failure, diabetic ketoacidosis (DKA) Interventions: referral to MDT to check cause. Physio might increase RR to increase amount of CO2 leaving the blood if not already compensated

Question 36

Respiratory alkalosis: causes and interventions

Answer 36

Hyperventilation due to panic attacks, stress, pain, breathlessness, breathing pattern disorder Interventions: Referral to psychologist is caused by anxiety Physio to do ACBT, box breathing, deep breathing exercises

Question 37

Respiratory acidosis: causes and interventions

Answer 37

Alveolar hyperventilation caused by COPD, neuromuscular disorders (GB or MND) opoids. Interventions: control oxygen levels for hypoxemia If related to sputum retention then ACBT, MT. Breathlessness management Respiratory acidosis could be type 2 resp failure.