Respiratory practical lab report neurophysiology

Respiratory practical lab report neurophysiology

Respiratory practical
To measure a range of cardiovascular and ventilatory parameters and to investigate the ways in which they change in response to lowered oxygen level of the inhaled gas.

Learning outcomes
At the end of this practical students will be able to:
1.    reinforce the measurement of a range of physiological parameters using human subjects
2.    design an experiment as a team to study the effect of lowered oxygen level of the inhaled gas on the CV and respiratory parameters
3.    present and interpret physiological data

•    Normal air – 21% oxygen
•    Lowered oxygen level:
?    O2 level: 12%
?    O2 level: 8%
•    Calculate O2 partial pressure
•    Hypoxia vs hypoxemia
Duration: 3 min
Design of experiment:
•    What parameters to measure?
•    When and how long to measure for?
•    How to use control (normal air)?
•    Clearly write out experimental protocol

For your reference:

Each group will need:
1.    Two pre-filled Douglas bags (12% and 8% O2)
2.    Three empty Douglas bags
3.    Connections for the Douglas bags including a mouth piece and a nose clip
4.    A stop watch
5.    A blood pressure monitor
6.    Concentration and active thinking!


1.    Preparation
Volunteered subject signs the consent form, and the rest of the group members write down their names in the consent form.
Get three empty Douglas bags for collection of expired air. Make them vacuum. Fully assemble the first one (see below)

2.    Level one 12% oxygen
a.    Get a pre-filled Douglas bag with 12% oxygen for your inspired air, and connect it to the white end of the 2-way NRBV with a short tube.
b.    Let the subject sit in a comfortable position, and connect the first empty Douglas bag for them. Let them breath out to the atmosphere until they are ready for collection
c.    Measure blood pressure and heart rate
d.    Collect 3 min for control (breath in from atmosphere, and out to the first empty Douglas bag)
e.    Collect 3 min for 12% O2 (breath in from the pre-filled Douglas bag, and out to the second empty Douglas bag); measure blood pressure and heart rate
f.    Collect 3 min for recovery (breath in from atmosphere, and out to the third empty Douglas bag)
g.    Measure all three Douglas bag content (remember composition then volume); make them reusable for the next level.

3.    Level two 8% oxygen
Repeat the above steps using a pre-filled Douglas bag with 8% oxygen

4.    Put the results in your logbook and write up your lab report

5.    Tidy up all the equipment you have used

6.    Show your logbook to lecturer; sign the practical register and leave the lab quietly

7.    Calculation of partial pressure:

Enjoy the practical

Fang Lou
(Nov 2014)

Conversion to kPa:

1mbar = 1 hPa = 0.1 kPa

1 mm Hg  =  0.133 kPa

Partial Pressure (kPa):

expired air O2%
PAO2  =  ??????? x  (PA – PH2O x humidity%/100)

expired air CO2%
PACO2 =  ??????? x  (PA – PH2O x humidity%/100)

Saturation vapour pressure of water (PH2O) =  5.6 kPa

Atmosphere pressure (PA) and Humidity (%) can be read from the Barometer

Oxygen Consumption and CO2 Production (dm3.min-1):

(Baseline O2% – expired air O2%)
O2 consumption  =  ???????????????   x  minute volume

(expired air CO2% – Baseline CO2%)
CO2 production =  ?????????????????  x  minute volume

Respiratory Quotient:

CO2 produced
RQ  =  ???????
O2 consumed

Pulse Pressure (PP) =    Systolic Pressure (SP) – Diastolic Pressure (DP)

Mean Arterial Pressure (MAP) = DP + PP/3, or MAP = (SP+2DP)/3


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