In lung function tests  spirometry provides data for the following
parameters:-

FEV1,  FVC,  VC MAX,  FEV1%M,  PEF,  PIF,  MEF 25,  MEF 50,  MEF 75, 
FET

TLC,  RV,  RV%TLV,  ITGV,  IVC,  Raw IN,  sGawIN,  Raw EX,  sGawEX, 
Rawtot,  sG-tot

TLCOSB,  TLCOc,  VA,  KCO,  KCOc,  Hb,  BdFEV1,  BdFVC

H+,  PaCO2,  PaCO2,  PaCO2,  HCO3,  BE,  SAo2

1. What do these initials stand for? (for example FEV1 stands for
‘forced expiratory volume in 1 second’)

2. Changes in which parameters (over several years) are most
significant for a patient with
brochiectasis?

---

Clarification of Question by perplexed-ga on 05 Oct 2003 07:29 PDT

I meant Bronchiectasis

Hello 

These numbers have to do with the flow rates for air in and out of the
lungs.  In obstructive diseases, the rates will be lower, but the
total volume will be the same (or sometimes higher).  In restrictive
diseases, the rates and volumes will be lower.
FEV1 - forced expiratory volume, 1 second - the volume exhaled in one
second
FVC - forced vital capacity - maximum total volume that can be exhaled
VC MAX - the highest measured FVC for the patient
FEV1%M - the ratio of FEV1 to max VC
PEF - "passive" expiratory flow - non forced
PIF - "passive" inspiratory flow - non-forced
MEF 25 - max expiratory flow at 25% FVC
MEF 50 -                        50% 
MEF 75 -                        75%
FET - this is probably forced expiratory time - the time taken for
full forced expiration
TLC - total lung capacity - the maximum amount of air in the lungs
RV - reserve volume - TLC minus FVC - airspace present, but not
directly useable
RV%TLV - the percentage of the TLC that is reserve volume
ITGV - intrathoracic gas volume - total air in the thorax post
expiration - usually the same as RV, unless there is air in
non-airways segments of the chest
IVC - inspiratory vital capacity - total amount of air which can be
inhaled
Raw IN - "  these numbers are simply the unmodified data collected
during a test
sGawIN - "  and are used to compute the above values
Raw EX - "
sGawEX - "
Rawtot - "
sG-tot - "
 
These values are used to measure the gas diffusion ability of the
lungs - if there is a disorder of the lung structure, the diffusion
capacity will be lower - similarly, in emphysema where there is a loss
of lung structure, gas exchange will be similarly impacted.
TLCOSB - "transfer factor" - related to the ease of transfer of carbon
monoxide from within the airspace to the hemoglobin in the red blood
cells from a single breath

TLCOc - "transfer factor" as above, but continous, rather than based
on a single breath

VA - alveolar volume - the total lung surface available for gas
exchange
KCO - rate of carbon monoxide uptake
KCOc - continous rate of above
Hb - hemoglobin quantity - measured in a separate blood test, but
needed for these calculations

BdFEV1 - FEV1 calculated by diffusion
BdFVC - FVC calculated by diffusion
 
These numbers are from a blood gas measurement - can be either
arterial or venous - these reveal if the tissues of the body are
receiving enough oxygen - inadequate oxygenation will show low PaO2,
low pH (high acidity), and a negative base excess.  If due to
decreased breathing or gas exchange, PaCO2 may be up.
H+ - more commonly expressed as the pH this reveals acidosis vs
alkalosis
PaO2 - the partial pressure of oxygen in the blood sample
PaCO2 - the partial pressure of carbon dioxide (CO2) in the blood
sample
HCO3 - the amount of bicarbonate dissolved in the sample
BE - the "base excess" - when negative, reveals the amount of acid
present
SAo2 - the percentage "saturation" of the hemoglobin in a blood gas
sample (the percentage of total oxygen carrying capacity currently
used)


Bronchiectasis, like other obstructive lung disorders produces
decreases in the FEV1, without as large of an effect upon the the FVC
of the lung - thus, it reduces the rate at which the lungs can be
emptied, but not the total capacity of the lungs.  Thus, other indices
of expiratory flow would also be expected to be diminished (MEF 25,
50, 75), FET, etc.  The diffusion cabability of the lungs should not
be greatly diminished and the blood gas of the patient should only be
affected if the patient is in respiratory distress.

So, the most commonly affected parameters in bronchiectasis are the
flow characteristics - alterations in these values would be expected
in such patients, and may worsen over time.  Alterations in gas
diffusion, or in the blood gas values may suggest another coexisting
problem (such as pneumonia) that would warrant further investigation.


A nice site explaining pulmonary function tests:
http://www.emedicine.com/med/topic2972.htm

A short description of pulmonary function testing and the
interpretation of the values:
http://aamm.unm.edu/show_sheet.php?s_id=116

Another short and simple:
http://www.slowhand.net/drpr/pfts.htm

A very nice site from Virtual Hospital
spirometry:
http://www.vh.org/adult/provider/internalmedicine/Spirometry/SpirometryHome.html
spirometry in obstructive lung disorders:
http://www.vh.org/adult/provider/internalmedicine/Spirometry/ObstrLungDis.html

A site for nurses:
http://www.continuingeducation.com/nursing/pft/pft.pdf

A slide show on the gas exchange properties of the lungs;
http://hsc.virginia.edu/med-ed/phys/pdf/2003/section2.pdf

Please let me know if you have further questions.

synarchy


Search terms
Pulmonary function test
bronchiectasis

thanks synarchy, -a great answer, all I was looking for