4-Pulmonary Function Tests Flashcards
physiologic dead space is = to
VD = anatomic dead space + functional dead space
physiologic dead space = volume of conducting airways + alveoli that not participate in gas xchange
minute ventilation
total rate of air movement into/out of lungs
= tidal volume x respiration rate
alveolar minute ventilation
rate that new air reaches the gas exchange areas of lungs
= respiration rate x (tital vol - dead space)
effects on alveolar minute ventilation
inc respiration rate and dec tidal vol = greater proportion of alveolar ventilation contributing to dead space
inc tidal vol greater effect that respiration rate
spirometry
measure lung volumes and air flow
-shown on a graph, slope = airflow
need other tests for helium dilution, whole body plethysmograph, esophageal balloon
imaging
- ventilation perfusion lung scan for detecting embolisms
- chest x ray
forced vital capacity
total vol that can be forcibly expired after maximal inspiration
lung volume differences in obstructive vs restrictive
restricted = dec all lung vols
obstructive = inc in TLC, inc residual, inc FRC
spirometry analysis of obstructive
graph can show flat inspiratory cuve, flat expiratory, or both
-if upper airway obstruct then variable or fixed
common causes are tumors and fibrotic structures
spirometry analysis of restrictive
lung vols are lower in general
-dec vital capacity, IC, lower RV/ERV/FRC
looks like an orange slice
evaluating FEV1 and FVC
normal ratio = 0.8
obstruct = FEV1 < FVC so dec ratio <0.7
restrict = FEV1 > FVC so ratio inc