Data interpretation: Spirometry Flashcards
What is the difference between lung volume and lung capacity?
Lung volume: Volume of air in the lungs at various phases of resp cycle
Lung capacity: How much air can be inhaled after a maximum exhalation
Which 4 lung volumes add together to form the Total Lung Capacity (TLC), in spirometry?
Tidal Volume (TV)
Expiratory Reserve Volume (ERV)
Inspiratory Reserve Volume (IRV)
Residual Volume (RV)
TV+IRV+ERV+RV = TLC
Define Total Lung Capacity (TLC), in spirometry?
- Maximum volume of air the lungs can accommodate
- Sum of all volume compartments
- Volume of air in lungs after maximum inspiration
What type of lung diseases cause normal-increased TLC, and what is the mechanism?
Obstructive lung diseases
Premature airway closure increases the volume of air retained in the lungs at the end of expiration (air trapping)
Trapped air already in lung with maximum inhaled air causes pulmonary hyperinflation, which causes increased TLC
Obstructive diseases that don’t affect alveoli will not increase TLC or RV
Give 4 examples of lung conditions that cause an normal-increased TLC, in spirometry?
COPD: Increased
Emphysema: Increased
Chronic bronchitis: Normal-Increased
Asthma: Normal
Bronchiectasis
What type of lung conditions normal-decreased Total Lung Capacity, and what is the mechanism?
Restrictive lung diseases
Loss of elastic recoil and fibrosis makes lungs stiffen and unable to expand
Give 5 examples of lung conditions that cause normal-decreased TLC, in spirometry?
CTD-ILDs eg. Sarcoidosis: Normal
ILDs eg. IPF: Decreased
TB: Normal
Pleural effusion: Normal
Pneumothorax: Normal
What is kyphoscoliosis, and how does it effect the TLC value in spirometry?
Kyphoscoliosis: Abnormal curvature of the spine in the sagittal and coronal planes and can include a rotation of the spinal axis
Causes chest wall defects which produce restrictive lung function, but normal TLC
Give 6 examples of conditions that cause chest wall defects, which cause a restricted spirometry pattern but normal TLC in spirometry?
Ankylosing spondylitis
Kyphoscoliosis
Trauma
Neuromuscular conditions
Scleroderma
Morbid obesity
What is Tidal Volume (TV or VT) in spirometry?
Volume of air inspired and expired with each breath, in quiet breathing
What is Residual Volume (RV) in spirometry?
Volume of air remaining in lungs after maximum exhalation (beyond TV and ERV)
What is Inspiratory Reserve Volume (IRV) in spirometry?
The extra volume of air that can be inspired with maximal effort after reaching the end of a normal, quiet inspiration (beyond tidal volume)
What is Expiratory Reserve Volume (ERV) in spirometry?
The extra volume of air that can be exhaled forcibly after reaching the end of a normal, quiet exhalation (beyond tidal volume)
What is Vital Capacity (VC) in spirometry?
Maximum volume of air a person can expel from the lungs (TV + ERV) after a maximum inhalation (TV + IRV)
Which 3 spirometry values added together form the VC?
TV+IRV+ERV = VC
What is Inspiratory Capacity (IC) in spirometry?
The maximum volume of air that can be inspired after reaching the end of a normal, quiet expiration
TV+IRV = IC
What is Functional Residual Capacity (FRC) in spirometry?
Maximum volume of air in the lung at the end of a normal, quiet tidal exhalation
ERV+RV = FRC
When identifying the spirometry pattern, what are the 3 values you should analyse?
Patient predicted Forced Vital Capacity (FVC)
Patient predicted Forced Expiratory Volume 1 (FEV1)
Patient FEV1:FVC ratio
What is Forced Vital Capacity (FVC) in spirometry?
The maximum amount of air you can forcibly exhale from your lungs after fully inhaling
What is the normal range for FVC in spirometry?
80-120%
What are the 3 types of spirometry patterns that can be identified from FVC, FEV1 and FEV1:FVC ratios in spirometry?
Normal pattern
Restrictive pattern
Obstructive pattern
What is the Forced Expiratory Volume 1 (FEV1) in spirometry?
Volume if air that has been exhaled at the end of the first second of forced expiration
How is the FEV1:FVC ratio calculated in spirometry, and what is the normal range?
Actual FEV1 divided by actual FVC, multiply by 100
Normal FEV1:FVC ratio: 80-120%
How is the patient predicted FEV1 value calculated in spirometry, and what is the normal range?
Actual FEV1 divided by reference FEV1
Normal predicted FEV1: 80-120%
How is the patient predicted FVC value calculated in spirometry, and what is the normal range?
Actual FVC divided by reference FVC
Normal predicted FVC: 80-120%
Describe the FEV1, FVC and FEV1:FVC ratio in obstructive spirometry patterns?
Reduced FEV1
Normal FVC
Reduced FEV1:FVC ratio
Describe the FEV1, FVC and FEV1:FVC ratio in restrictive spirometry patterns?
Reduced FEV1
Reduced FVC
Normal FEV1:FVC ratio
If a patient has an obstructive spirometry pattern, what test should they do next and why?
Spirometry with bronchodilator reversibility test
Confirms if patient has asthma or COPD
How is the spirometry with bronchodilator reversibility test completed?
- Patient does first spirometry readings
- Patient takes 4 puffs (each is 100 micrograms) of salbutamol inhaler
- Patient waits 20 minutes then completes post-bronchodilator spirometry
How many spirometry tests should a patient do, and which results are used to identify the spirometry pattern?
Take 3 spirometry readings (8 is the absolute maximum in one sitting)
Use best readings for interpretation
If a patient has asthma or COPD, what will the results of their BDR test and spirometry be?
Asthma: Actual post-bronchodilator FEV1 is 12 or more % greater than actual baseline FEV1
COPD: Actual post-bronchodilator FEV1 is less than 12% greater than actual baseline FEV1 (no significant improvement)
If a patient has an obstructive spirometry pattern, which 2 scoring tools should be used to assess severity?
NICE 2010 severity score
GOLD severity score
Before a patient has a spirometry test, what 5 things should you ask if they have done?
Have you smoked within the last 24 hours?
Have you drank alcohol today?
Have you had caffeine/drank tea or coffee within the last 4 hours?
Have you eaten a large meal within the last few hours?
Have you done vigorous exercise within the last few hours?
Before a patient has a spirometry test, what should they be wearing?
Loose clothing
What should you ask a patient to bring to their spirometry appointment?
Existing inhalers
Medications for breathing
Give 5 contraindications to having spirometry?
Active infection
Current/recent pneumothorax
Recent surgery
Communication problems in understanding directions
Conditions/patient unwellness that has serious consequences with aggravation by forced expiration
In spirometry, how should you instruct the patient to blow into the mouthpiece?
- Ask patient to sit upright in chair with legs uncrossed and feet flat on floor
- Ask patient to breathe normally into mouthpiece then take deep breath in
- When lungs are full, ask patient to blow air out like a sigh until lungs are empty
How can COPD and asthma be distinguished in 2 ways, despite both having obstructive spirometry patterns?
COPD: Air trapping causes high RV, high TLC and low TLCO
Asthma: No air trapping which causes normal RV, normal TLC and normal TLCO
What is the gas transfer test and carbon monoxide transfer factor (TLCO)?
Gas transfer test: How good lungs are at taking in oxygen from air and transferring it into bloodstream
TLCO: Amount of carbon monoxide (CO) transferred per minute from alveolar gas to red blood cells (RBCs)
How do you instruct a patient to complete the gas transfer test?
- Breathe normally into mouthpiece with lips tightly sealed around it and nose pegged close. Mouthpiece has tiny amounts of helium and carbon monoxide (CO) gases
- Blow all air out of lungs until they are completely empty
- Take in deep breath until lungs are as full as possible, hold for 10 seconds
- Blow out all air until lungs are empty
How can obstructive lung diseases be distinguished using TLCO?
COPD eg. emphysema: Low TLCO
Chronic bronchitis, asthma: Normal TLCO
How can restrictive lung diseases be distinguished using TLCO?
Low DLCO: Parenchymal diseases eg. ILDs, sarcoidosis
Normal DLCO: Chest wall defect causes eg. neuromuscular diseases, scleroderma, morbid obesity
How do restrictive lung diseases generally affect the residual volume?
Decreased RV
If a patient is breathless upon exertion but all lung function tests are normal, what test should they complete next?
Cardiopulmonary Exercise test (CPEX)
