1 - restrictive diseases Flashcards
how are restrictive respiratory diseases defined?
reduction in lung volume: <80% TLC = restriction. > 120 = hyperinflation (obstruction)
anatomical approach to restrictive diseases: 4 causes?
neuromuscular weakness. chest wall disorders. pleural disease. lung parenchymal disease aka interstitial lung disease.
what does restriction look like on a pulmonary function test?
no airway obstruction so FEV1/FVC > 0.75 though FEV1 and FVC are both low. TLC, RV, VC, FRC are all also low
DLCO means? correlates with? what values mean what?
diffusion capacity, correlates with oxygenation. >120 % means increased diffusion, < 80% means decreased
what does DLCO tell you about the type of lung disease?
DLCO can be normal or decreased in restriction. but normal lung parenchyma means DLCO 100%. if less than 80% there is abnormal lung parenchyma
how is diffusion capacity measured?
pt exhales to residual volume, take a big breath of CO up to TLC, hold breath 10s (CO diffusion from alveoli to blood), then exhale down to RV. measure CO concentration to see how much was taken up by pt.
4 things that affect diffusion capacity
alveolar surface area. capillary surface area. Hb concentration. alveolar-capillary membrane
things that could increase diffusion capacity?
polycythemia (more Hb to bind). pulmonary hemorrhage: Hb not in blood vessel, but still takes up gas
interpretation of diffusion capacity: in obstruction
obstruction (FEV1/FVC > 0.75): DLCO of 100% means asthma or chronic bronchitis b/c lung tissue is normal. DLCO <80% means emphysema: something is wrong with the lung tissue
interpretation of diffusion capacity: in restriction
restriction when TLC <80%: DLCO of 100% means obesity, chest wall deformity or neuromusc. weakness. DLCO <80% means interstitial lung disease aka lung parenchymal disease
causes of neuromuscular weakness (resulting in decreased ventilation)?
spinal cord injury or disease. anterior horn cell diseases like ALS, polio, rabies. guillain barre syndrome. diaphragmatic paralysis. myathenia gravis. botulism. myopathies
causes of chest wall abormalities
trauma, fractures, pain. morbid obesity. severe kyphoscoliosis. subdiaphragmatic pathology like a recent abd. surgery
diseases of the pleura: 4 examples?
large pleural effusions. pleural plaques. fibrothorax. mesothelioma. (note this is all still normal DLCO)
interstitial lung disease: aka? examples of causes?
disorders of the lung parenchyma: congenital/acquired, infections, tobacco, medications, occupational or environmental exposures, connective tissue diseases, idiopathic pulmonary fibrosis
physical signs of ILD
clubbing, velcro crackles, inspiratory squeaks, cyanosis, cor pulmonale
