Pulmonary function test Flashcards
what is pulmonary function test also known as
spirometry, lung function test
what is the pulmonary function test
the measurement of breathing, you may carry out the test or a technician may perform the test- have to interpret results
what does spirometry tell us
shows abnormalities in lung function, static lung volume- how much air the lungs can hold, dynamic lung volume- the flow of air through the airways, how fast that volume of air can be move
no specific normal volume- predicted with age, weight height, nationality
what abnormalities does spirometry look for
movement of air- airflow- impedances- reduction in speed, volume of air in
indications for use- diagnostic
evaluate symptoms, signs, or previous abnormal results, measure effects of disease on pulmonary function, screen at risk groups- e.g. smokers, assess proprioceptive risk
indications for use- monitoring
assess therapeutic intervention on lung function (over time or after therapy), monitor adverse reactions to drugs, assess potential environmental or occupational exposures
indications for use- disability
assess impairment or disability from lung disease, assess risks as part of insurance evaluation, assess prognosis, does not impact quality of life, perceived level of disability/ breathlessness, ADL’s
indications for use- research
clinical research, epidemiologic surveys
contraindications
pneumothorax, haemoptysis, aneurysm- could be thoracic/abdominal/ cerebral in nature, recent myocardial infarction or unstable angina, CVS instability, cerebral instability, recent surgery (chest, abdomen, and eyes), recent chest infection- may hinder results
what might some of the contraindications be a problem
changes in pressure in thorax, in abdomen, in intracranial area- don’t want to rupture
factors influencing airway resistance
type of airflow, lung volume- linked to age, gender, etc., elastic recoil, bronchial smooth muscle tone- constrictions, airway obstruction
what is measure- forced vital capacity
the volume expired forcefully (following a maximal inspiration), until residual volume is reached
80% of predc.= normal
what is measure- FEV1
forced expiratory volume in one second- the volume of air a subject can exhale in the first second of a maximal breath out, following a maximal inspiration
80% of predic.
what is measure-FEV1:FVC
looks at the amount expelled within the first second compared with the overall volume achieved
the ratio should be 75% or higher to be normal
pec flow
maximum rate of expiratory flow, highlights issue- may be referred on for more accurate results
the spirometry procedure
sit upright, wearing comfortable loose- fitting clothes, after a relaxed breath out, take a maximal breath in, seal your lip around the mouthpiece and blow out as fast and completely as possible
an acceptable spirogram demonstrates
quick and forceful exhalation, no coughing, smooth lines on graph, minimum exhalation time of 6 seconds with no change in volume in last second
in practice 3 acceptable spirograms are used which show reproductively and no variations in effort
classifications of spirometry results
normal- volume and flow normal, restrictive- a restriction in lung volume or obstructive- obstruction to flow
restrictive disease- stop patient taking maximal inhalation
obstructive disease- COPD, asthma, emphysema, bronchitis
FEV1 results
obstructive- mild=80%, moderate= 50-80%, severer= 30-50%, very severe >30%
restrictive- <80%, combined- <80%
FVC results
obstructive >80%, FVC predicted <80%,
FEV1/ VC, FEV1/FVC
Obstructive- FE1/VC/FVC <70%
restrictive- FEV1/VC/FVC >70%
volume time plot-
the volume of gas exhaled is plotted over time- want it to minimum 6 secs for good tet, the slop of the curve at ant point is equal to flow
volume time plot- obstructive
the slope or gradient of the curve is much less steep as air struggles to get out quickly because the airways are obstructed. FEV1 will be reduced but the total volume may be less affected
volume time plot-restrictive
the slope or gradient of the curve is very similar to normal as there is no obstruction to flow in the airways but the overall volume is less so the FEV1 and FVC are both reduced
