Station 1- CXR or ABG Flashcards
Normal value of pH
7.35-7.45
Normal value of PaO2
10.7-13.3 KPa
Normal value of PaCO2
4.7-6.0 KPa
Normal value of HCO3- (bicarbonate)
22-26mmol/l
Normal value of base excess
-2 —> +2
What is type 1 respiratory failure? And how do you recognize it?
- 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
What is type 2 respiratory failure? And how do you recognise it?
- 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
What are the 5 outcomes from an ABG?
Metabolic acidosis
Metabolic alkalosis
Respiratory acidosis
Respiratory alkalosis
Respiratory failure (1 or 2)
Steps for analysing ABGs
- Check PO2 - hypoxemia (low) or hyperoxia (high)
- pH - Acidosis or alkalosis
- PCO2- hypercapnia (high) or hypocapnia (low)
- HCO3- helps mop up acids. Raised = high pH, Low = low pH.
- Base excess- how much buffering is needed to normalise the blood. Raised = higher than normal HCO3 (alkalosis), Low = lower than normal HCO3 (acidosis)
What is hypercapnia?
Increase in CO2 in the blood.
Caused by hypoventilation leading to respiratory acidosis or compensated metabolic alkalosis
What is hypoxemia?
Low level of O2 in the blood
- Due to a V/Q mismatch
Tips for exam
- 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
What is a posterior-anterior (PA) CXR? And how can you tell?
- 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
What is an anterior-posterior CXR? How can you tell?
- 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
How does bone appear on CXR?
White = high absorption
How does tissues appear on CXR?
Grey = moderate absorption
How does air appear on CXR?
Black = low absorption
Checking for a normal CXR. Which features are we looking to identify?
- Clavicle
- Ribs
- Heart boarder
- Aortic arch
- Vertebral bodies
- Diaphragm
- Trachea
- Costo cardiac angles and costo phrenic angles
A-H for identifying an abnormal x-ray
Airway
Bones
Cardiac silhouette
Diaphragm
Effusions
Fields (lung fields)
Gadgets
Hidden areas
Airway in A-H
Is the trachea central?
Does it deviate?
Does it narrow?
Does it contain any foreign objects?
Bones in A-H
Can you see any rib fractures?
Can you see the abnormalities?
Cardiac silhouette in A-H
Have they got an enlarged heart (cardiomegaly)?
Can you see the heart outline?
Is there any mediastinal shift
Diaphragm in A-H
Is the diaphragm domed?
Is it flat?
Look at the position
Effusions in A-H
Can you see a water line?
Can you see the costophrenic angle?
Fields (lung fields) in A-H
Lung volumes- do lungs expand to the pleura (pneumothorax?)
Visible costophrenic and costocardiac angles?
Are they obscured and why?
Gadgets in A-H
Are there any attachments?
Hidden areas in A-H
- Lung apex
- Below diaphragm
- Hilum
- Retrocardinal zone
What does a chest with consolidation look like?
Whiteness in alveoli due to fluid
Very opaque white patches
‘Fluffy’
- Could be caused by pneumonia
What does a COPD chest look like?
Flat diaphragm (can be blurry), horizontal ribs, larger lung volume ‘barrel chest’
What does a chest with pneumothorax look like?
- 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?
What does a chest with pleural effusion look like?
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
What does a chest with pulmonary oedema look like?
Fluid in the lung
Patchy white in lung fields ‘bat wings’
Enlarged hila
- Can be caused by heart failure
Acronym for quality of x-ray
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?
Potential causes for a metabolic alkalosis? Physio and MDT intervention strategies?
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
Metabolic acidosis - causes and interventions
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
Respiratory alkalosis: causes and interventions
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
Respiratory acidosis: causes and interventions
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.
