Resp: FEV, Respiratory failure, Asthma Flashcards
What is FEV 1
Forced expiratory volume in 1 second
Where a person takes maximal inspiration and then exhales maximally as fast as possible
Procedure to measure FEV 1
Breathe in to total lung capacity
Exhale as fast as possible in one second
Volume produced is FVC for one second
What is FEV 6
Forced expiratory volume 6 seconds
When is flow of air in res cycle greatest
Expiration, and declines in rate as volume decreases
What does FEF25 mean
Flow at point when 25% of total volume is exhaled has been exhaled
Define FVC
Forced Vital capacity
Name 4 obstructive lung diseases
- COPD
- Asthma
- Bronchiectasis
- Bronchitis
When is the value of FEV1 normal
When it is 80% of the normal predicted value for that patient
What indicates airways restriction
- Ratio of FEV1/FVC greater than 0.7 AND FVC is lower than 80% of predicted value
- Just a low FVC (less than 80% of predicted value
What indicates airways obstruction
- FEV1/FVC less than 0.7 (in other words they can breathe fast in the first second but obstruction stops them from fully expelling their total capacity volume)
Define type I respiratory failure
- Hypoxia but not hypercapnia
What causes type I respiratory failure
- High altitude
- VQ mismatch
- Shunting
- Diffusion problem (oxygen can’t enter capillaries due to parenchymal disease)
What defines type II respiratory failure
- Hypoxia
- Hypercapnia
- pH DECREASED
What causes type II respiratory failure
- Increased respiratory resistance (COPD, asthma)
- Reduced breathing effort (brain stem lesions! Obeisty)
- Guillain-Barré Syndrome
- MND
- Ankylosing Spondylitis
- Decrease in area of the lung available for gas exchange
ANYTHINg that causes inadequate alveolar ventilation
CO2 CAN’T BE ELIMINATED
Where in the lungs is V/Q ration higher
Apex
Lower in base of lungs
Why iS V/Q lower at the base of the lung
Because Perfusion increases as we go down the lungs faster than ventilation due to gravity
What is a V/Q of 0
Area with perfusion and no ventilation = shunt
What is dead space
Area with ventilation and no perfusion (V/Q of infinity)
Effect of pulmonary embolism on V/Q
High V/Q
Because there is a decrease in Q, making value bigger
What most commonly causes type I res failure
Pulmonary embolism
What most commonly causes type II resp failure
Hypoventilation
What neurological conditions can result in reduced ventilation
- MG
- Guillain-Barre syndrome
- Encephalitis
- MND
- Space-occupying lesions (increased ICP which can compress brainstem)
What conditions can decrease Q in V/Q
- Pulmonary embolism
- Cardiac failure
- Shunt (VSD)
- Pulmonary hypertension
What conditions can decrease V in V/Q
- COPD
- Neurological weakness
- Obesity
- Reduced drive from narcotics