what is the purpose of PFT
indentify and quantify pulmonary impairment and diagnose obstructive and restrictive lungs disease
-test lung function
what are the two major categories PFT can help diagnose
-obstructive
-restrictive
explain what an obstructive disease is
pt is able to get air in but not able to get air out-flow issue
-increase in airway resistance
explain what a restrictive disease is?
pt is not able to get air in but able to get air out
-reduced lung volumes
what are the indications for PFT
- identify and quantify changes in pulmonary function
- detect the presence of pulmonary diseases
3.quantify the severity of a pulmonary impairment
- help quantify the progression or reversibility of the disease
- evaluate need and quantify therapeutic effectiveness
- to perform epidemiologic surveillance for pulmonary disease
- assess pt for risk for postoperative pulmonary complications
- determine pulmonary disability
what are the contraindications of a PFT
- pt w/acute unstable cardiopulmonary problems
2.hemoptysis
- pneumothorax
4.myocardial infarction
5.pulmonary embolism
- pt with acute chest or abdominal pain
7.nausea
8.pt who have had a recent cataract removal surgery
- pt w/dementia or confusion
what is spirometer
measures volume and flow rates
what is pneumotachometer
measures pressure and flow
what are the types of spiratometers
1.water seal
2.bellows
3. dry rolling seal
how often do we calibrate? what type of syrine do we use? and what % of accuracy does calibration need to be at?
1.daily
2. 3.0L syringe
3. +/- 3.5%
what is the primary problem with obstructive diseases
increased airway resistance-Raw
define Raw and what is the equation
- Raw is the difference in pressure b/w the ends of the airways divided by flow rate of gas moving through the airways
- equation=Raw=ΔP/V˙
which pts have a reduced MVV
-pt w/mod-severe obstructive disease
-MVV may be normal or reduced in pt with mod restrictive disease
-MVV reduced in malnourished pt
what is the MVV test
test the respiratory muscles
12-15 second test with pt breathes rapidly
obstructive vs restrictive
anatomy affected:
ob-airways
re-lung parenchyma,thoracic pump
breathing phase:
ob- expiration
re-inspiration
pathophysiology:
ob:↑ Raw
re:↓ lung or thoracic compliance
measurements:
ob- flow rates
re-volume or capacities
what is the FVC maneuver
the volume that can be expired as forcefully and rapidly as possible after a maximum inspiration
-most commonly performed test
what is measures during the FVC maneuver
FEV1-forced expiratory volume in 1 sec
FEF200-1200-forced expiratory flow 200-1200 (↓ values=airway obstruction)-6.0L/sec
FEF25-75- force expiratory flow 25-75 (↓= small airway obstruction)-4.7L/sec
PEFR-peak expiratory flow rate-10Lsec (600L/min)
define what slow vital capacity is
- volume of air expired but through unforced maneuver
-spirometry test that displays the volume of gas measured on a low complete expiration after a maximal inspiration without forced or rapid effort
-used to determine level of obstruction
-FVC is smaller than SVC=obstructive
what does it mean when the FVC cant be completed in 3 second
means obstructive disease
what indicated an obstructive disease
1.↓ FEV1
2.↓ FEV1/FVC ratio <70%
3.↓ FEF 25-75., FEF 200-1200
4. curved loop
describe reversibility
-if baseline test indicate airway obstruction determining the reversibility is indicated
-pre/post bronchodilator
-FVC is done after bronchodilator therapy (wait 10mins before FVC)
-increase of 12% greater=obstructive pattern reversible
what is the formula for % improvement:
post FEV1- pre FEV1 x 100
describe what PEFR
-measures large airway function
-maximum flow obtain during FVC
-must perform 3 PEF maneuver
-largest 2 of 3 must be within .67L/sec
-portable devices
-easy for pt to monitor asthma
what are the 3 zones for PEFR
green
yellow
red
