SPIROMETRY

WHAT YOU SHOULD KNOW

What the different volumes and capacities mean

How to set up the spirometer and powerlab for:Vital capacityForced Vital CapacityAsphyxiaHypercarbiaHypoxia

How to analyse results from these

LUNG VOLUMES/ CAPACITIES

VITAL CAPACITY

SET UP SPIROMETER Make sure soda lime is under

the bell Place the bell in Don’t need to attach one

way valves Attach disposable

mouthpiece Make tap vertical and

ventilate the spirometer (VErtical to VEntilate) = push right down and fill about 75% with air

Seal the spirometer - Horizontal ( check by blowing and air should come out of the side)

VITAL CAPACITY

Set up the computer: sampling rate to 20/S Scale amplitude to 1V Time base 1:1

WEAR NOSE CLIP!

Press start

Sit comfortably, breath and turn tap to vertical

VC = max inspiration and immediately max expiration (steady and complete)

Stop = few secs normal breathing , tap horizontal and stop the powerlab software

ANALYSING RESULTS

Draw a box around the VC Windows – Zoom Move ‘M’ to base of VC ( where just

about to breath out) Move cursor to peak of VC Read off the Volume in LITRES (directly

above the expanded trace) Return ‘M’ to its place ATPS BTPS

MEASURING FVC

Same as VC

BUT...

When inspiration reaches a peak BREATH OUT AS FAST AND HARD AS POSSIBLE AND CONTINUE FOR ~ 3secs

ANALYSING FVC/ CALCULATING FEV1

Same as VC

BUT...

Place cursor on the plateau

FEV1 = this is done from the FVC recording, but only move cursor as far as 1 sec from the base. i.e t=1sec and then read off the volume

FEV1/FVC = percentage of air breathed out in first second

ASPHYXIA – O2 LACK WITH CO2 EXCESS

Same as VC

BUT... NO soda lime ADD one way

valves REMEMBER TO

SEAL THE SPIROMETER at the end

SAMPLING AND ANALYSING THE GASES

Draw 2 samples from the sampling point to discard – pinch the tubing to prevent air leaving spirometer

Third sample – close sampling tap, place thumb over syringe to seal this

Inject air into analyser – inject 2/3 and WAIT...then as value stabilises complete the injection (should be no more than 0.2% diff)

Rate of change (%/min) = final - initial/ duration of breathing

HYPERCARBIA- CO2 EXCESS

SAME as asphyxia

BUT... FILL WITH O2 (not air)

The tap near mouthpiece should be sealed Connect the o2 supply to oxygen inlet Fill to 75% TURN OFF SUPPLY FIRST Then close tap on spirometer

Analyse for CO2 only

ANALYSING RESULTS

Measuring mean TV and Resp. Freq Draw box around recording Select data pad Click on grey box above column A Set up box will appear Mean tidal volume = cycle variables

and average peak to peak (cycle height). Press ok and answer will appear at the top of column

Resp freq = cycle variables; events count. Press okay the resp freq will appear at top of column

ALWAYS GIVE UNITS

Ventilation(L/min) = TV (L) x Resp freq (breaths/min)

HYPOXIA– O2 LACK

Exact same as VC so MAKE SURE SODA LIME IS PRESENT

BUT... Don’t refill with air Remember to ADD VALVES

SUMMARY

ADD ONE WAY VALVES FOR EXPERIMENTS ONLY

NO SODA LIME FOR ASPHYXIA AND HYPERCARBIA

FILL WITH O2 FOR HYPERCARBIA NO REFILLING IF WE WANT HYPOXIA

QUESTIONS??