Lung Volumes
Objectives
History
68 year old female with dyspnea at rest for 2 years.
Smoked 2 packs a day for the past 40 years.
Criteria for restriction:
Our patients TLC is 62% of prdiced, hence has restrictive defect.
Caution: Do not make definitive comment about restriction from Vital capacity. If a patient has marked hyperinflation, Vital capacity can be reduced. If the flow rates are increased along with reduced Vital capacity one can surmise there may be restriction. It is always a good idea not to commit yourself about restriction untill TLC is available.
Severity of restriction: When the predicted % of TLC is
Our patient's predicted TLC is 62%, hence mild restrictive defect.
Criteria for a significant change:
Lung volumes should increase at least by 10% of predicted value to consider it as a significant change. The 2 standard deviation of repetetive performance of lung volumes is 10%. Hence one cannot consider a change as significant unless it is over 10% of predicted value.
Our patient has changed TLC by %.
Restrictive pattern:
Caution: When the Vital capacity is small computer changes the dimentions of graphic display and you may not appreciate the charecteristics.
Restrictive defect: is a PFT interpretation term. Anytime the TLC is less than 80% of predicted we interpret the patien as having a restrictive defect. There are many conditions with normal lungs and reduced TLC eg Pregnancy.
Restrictive disease: refers to diseased lungs with reduced TLC eg Diffuse interstitial fibrosis.
Restrictive defect:
Lung diseases
Lung resection
Abdominal distension
Chest wall problems
Pleural disease
The list is incomplete.