spirometry Flashcards
what is FVC forced vital capacity?
The volume of air in the lungs that can be exhaled following a deep inhalation
what is FEV1 forced expiratory volume in 1 second?
A measure of how much air can be exhaled in one second following a deep inhalation
what is TCLO transfer factor for carbon monoxide?
A measure of how much oxygen diffuses from the lung alveoli to blood in the capillaries
what shows a restrictive pattern?
FEV1/FVC>70%
A restrictive ventilatory pattern is seen in conditions where lung volume is reduced - eg, pulmonary fibrosis, scoliosis. The spirometry results will show the following:
FVC and FEV1 are reduced proportionately so the FEV1/FVC is normal
FVC reduced <70%
FEV1 reduced
what shows an obstructive pattern?
FEV1/FVC<70%
An obstructive ventilatory pattern is seen in conditions in which airways are obstructed due to diffuse airways narrowing of any cause - eg, COPD, cystic fibrosis, asthma, bronchiectasis and airway obstruction due to lung tumours. Spirometry results will show the following:
The FVC and FEV1 are reduced disproportionately so the FEV1/FVC reduced (<70%)
FVC normal or reduced
FEV1 reduced <80%
when is TCLO reduced?
normally in restrictive causes
TLCO is reduced in any condition that reduces the effective surface area of the alveoli. A reduced TLCO suggests impaired gas exchange. A reduced TLCO can be seen in both restrictive and obstructive conditions (e.g. damage to the capillary bed in COPD can be a cause) but most commonly it is associated with restrictive diseases such as pulmonary fibrosis.
examples of obstructive causes?
Asthma
COPD
Bronchiectasis
Bronchiolitis obliterans
examples of restrictive causes?
Pulmonary fibrosis
Asbestosis
Sarcoidosis
Acute respiratory distress syndrome
Infant respiratory distress syndrome
Kyphoscoliosis e.g. ankylosing spondylitis
Neuromuscular disorders
Severe obesity
