1. Pulmonary Function Testing
SPECIALIZED TEST REGIMENS

2. The diagnosis of specific pulm. disorders requires certain testing
 The subject must go through a thorough Hx
 Regimens
Clinic or MDs office
VC, FVC, FEVT, FEVT%, FEF 25-75, , MVV, VT, f, VE
Hospital lab & CP lab
lung volumes and diffusing capacity

3. PULMONARY FUNCTION TESTING IN CHILDREN
Uses many of the same basic tests as for adults
Differences exists in dimensions and two main areas of concern
newborns, infants, and very young children cannot strictly perform tests that require and depend on pt. cooperation ( VC, FVC, MVV and DLCO)
young children may perform with variability those tests that are effort dependent and require cooperation

4. A cooperative patient and good PFT technologist
Children may not meet ATS criteria but careful evaluation of partial parameters can provide important information.

5. Techniques for infants and young children
Partial Exp. Flow-Volume Curves ( PEFV) -
record of the maximal flow developed over a portion of the VC
The forced exhalation is obtained by applying either a positive pressure to the thorax and abdomen or a negative pressure to the airway

6. RAPID THORACOABDOMINAL COMPRESSION ( RTC) the “squeeze” or “hug”
Non-intubated infants
uses an inflatable jacket that surrounds the thorax and abdomen
the PEFV is obtained by rapidly applying pressure to the thorax and abdomen at the end of insp.
performed after the infant has fallen asleep or slightly sedated ( chloral hydrate)
flow is measured using an infant mask sealed with a lubricant and attached to a low Ds pneumotach

7. FRC or Vmax FRC
By Rapid Thoraco-Abd. Compression(Squeeze) expiratory flow
limitations can now also be measured in babies. The baby wears an inflatable cuff with the help of which a forced expiration is produced. From Viasys (Jaeger)
                             

8. WOW!
testing

9. RAISED VOLUME RAPID THORACOABDOMINAL COMPRESSION - RVRTC
 Standardization of spirometry is dependent on TLC
during insp., flow is augmented by a pump to increase pressure and volume
the airway is occluded at the exh. port using a cuff with variable pressure - rapid chest compression is then performed - higher flows are generated
uses a pump to increase volume before the squeeze is performed

10. METHODS  
FORCED DEFLATION TECHNIQUE - The infant needs to intubated, sedated & paralyzed
the lungs are manually inflated to TLC using approx. +40 cmH20 - performed 4 times with a 2-3 sec breath hold
the airway is then connected to a source of negative pressure ( -40 cmH20)
air is evacuated for a max. of 3 secs or until airflow ceases
exp. flow is plotted on a flow - volume graph
lungs are reinflated with 100 % O2
reserved for the critically ill

11. BRONCHODILATOR BENEFIT TEST
Is the dz is reversible? Let’s find out.
Indication
a pt. with an FEV1% of less than 70%
Technique
follow guidelines on withholding certain meds prior to test
do PFT - give tx with bronchodilator via neb or MDI - wait mins before doing post tests
monitor pt. for adverse effects

12. Significance Calculate “ percent change of each parameter”
%change = postdrug - predrug
predrug
FEV 1 or FVC are evaluated - an increase of > 12 % and > 200 ml is significant
asthma shows the best improvement
SGaw should increase % to be significant

13. BRONCHOPROVOCATION (METHACHOLINE CHALLENGE)

14. Methacholine
Used to determine whether or not a patient has a disorder of airway hypersensitivity
And to what extent
Is a parasympathomimetic
May trigger bronchospasm

15. Methacholine challenge
the test is positive when there is a 20 % decrease in the FEV 1 - the concentration at which the decrease occurs is called the provocative concentration or PC20%
Healthy subjects do not display a decrease in FEV1 greater than 20 %
SGaw can be used with FEV1 to demonstrate a reaction
Use a 16 mg/ml stock methacholine solution

16. Technique
Subjects should be tested when asymptomatic, baseline FEV 1 > 70 % of the pt. norm
Withhold meds according to chart
2 methods accepted by ATS,1st baseline spiro
5-breath dosimeter method
2-minute tidal breathing method

17. 5-Breath Dosimeter Method
Dosimeter- deliveres a consistent volume of drug
Uses 5 doses each 4 x larger than the previous
pt. inhales 5 nebulized NS breaths 1st
perform spirometry
if no positive response, start dosimeter inhalations of 5 breaths for 2 minutes
Repeat spirometry
Use largest FEV1 and the average of 2 RAW
Look for > 20% drop in FEV1 and > 35% drop in SGAW

18. 2-Minute Tidal Breathing Method
Use nebulizer, nose clips and relaxed breathing
Perform diluent inhalation first, then spirometry
10 double concentrated doses are used, each dose is breathed for exactly 2 minutes
Spirometry is performed 30 & 90 seconds after the dose
Look for > 20% in FEV1 and >35% drop in SGAW
Give a bronchodilator & repeat spirometry in 10”

19. To caluculate the percent of decrease
Con. FEV1 – Current FEV1
Control FEV1

20. Preoperative PF Testing- to…
Estimate postop lung function
Plan periop care
Estimate morbidity & mortality
Look at
Spirometry/obstruction
Bronchodilation studies
ABG’s, Ex. Testing & DLCO

21. PULMONARY FUNCTION TESTING FOR DISABILITY
Respiratory impairment - the failure of one or more functions of the lungs as determined by PFT
Disability - the inability to perform tasks required for employment and includes medically determinable physical or mental impairment - the impairment must be expected to result in death or last for at least 12 months

22. To determine impairment
should characterize the type, extent and cause of impairment
other factors need to be known - age, educational background and the subjects motivation and energy requirements
for pulm. dz impairment, you also need a hx, physical, CXR, other appropriate imaging techniques and PFT’s - (should be specific to disorder being investigated)

23. FVC and FEV1
spirometry is the most useful for determination of impairment caused by airway obstruction
the subject should be stable- use largest of the 3 tests
the 2 largest FVC and FEV1 should be within 5% or 100 cc
should be cont. for 6 secs or no volume change detected for 2 secs
- must have a volume-time tracing so hand calculations can be performed
before and after bronchodilator - all parameters reported in BTPS and ht. obtained without shoes or arm span method
must use disability limits
Calibration of equipment is specific and must be documented

24. DLCO & ABG’s
useful in determining disability for restrictive disorders
should not be corrected for Hgb or COHb abnormalities but… the values at the time of the test should be noted
if the DLCO is > 40% predicted but < 60% , get resting ABG
ABGs
may be nonspecific due to various factors
look at other parameters along with ABGs

25. Exercise Testing subjects considered should have resting ABGs
a Steady State protocol using the treadmill is preferred
specific protocols should be followed
Limits for determining disability on the bases of pulm. impairment have been set for the US by the SS administration