pulmonary function testing Flashcards
Upper airway:
Mouth/nose –> trachea
Lower airway:
Larynx –> alveoli
- oxygenation problems
Airways have multiple layers
– Smooth muscle tissue surrounding the airway
– Epithelial lining made up of
pseudostratified ciliated columnar cells
■ Mucociliary escalator
– Mucus layer that is produced by goblet cells
Actions of the pulmonary system
– Oxygenation
– Ventilation
Muscles of inspiration
– Diaphragm !
– Intercostals
– Accessory muscles
■ Sternocleidomastoids, Scalene, Trapezius
Basic physiology of a breath
– Brain sends signals for muscles to contact –> thoracic volume increases,
thus decreasing alveolar pressure –> air flows into the lungs
– Exhalation is passive, occurs due to elastic recoil of the lung
– How easily the lungs return to their normal shape
elasticity
– How “stiff” the lungs are
– Change in volume / change in pressure
compliance
– change in pressure / change in volume
■ Volume indirectly assessed by measuring flow
resistance
Measurement of volume & flow
spirometry
maximum inspiration followed by maximum exhalation
forced vital capacity (FVC)
The amount of air exhaled within the 1st second of an FVC
maneuver
Forced Expiratory Volume in 1 Second (FEV1)
Exactly what it sounds like - Math. FEV1 / FVC x 100 = %
%FEV1/FVC
Maximum expiratory effort
Peak Expiratory Flow
– Measures the ability of the lungs to transfer gases across the alveolar-capillary membrane
- difference between the volume of CO inhaled and the volume of CO exhaled
Diffusing Capacity of Carbon Monoxide (DLCO)
Decreased DLCO
Anemia, carboxyhemoglobin, PE, pulmonary fibrosis, emphysema
Increased DLCO:
Polycythemia, exercise, CHF
– Uses measurements of volume
and pressure to determine lung
volumes
– Expensive, not as convenient but
most accurate
– Better if patient is unable to
participate in typical spirometry
Plethysmography
low FEV1/FVC
obstructive (give bronchodilator like albuterol)
normal FEV1/FVC
restrictive
– Also referred to as negative inspiratory force (NIF)
– Maximum inspiratory pressure pulled against a closed airway
– Normal -80 to -100
– > - 20 (less negative) suggestive of weakness & need for ventilatory
support
– Helpful in neuromuscular disorders (Guillain-barre, Myasthenia gravis)
Assessing Muscle Strength:
Maximum Inspiratory Pressure (MIP)
- restrictive from some kind of neuromuscular issue and it might affect the diaphragm
Tid bits for pulmonary function testing
■ Always get 3 attempts
■ Nose plug helps
■ Take breaks
