SPIROMETRY, LUNG FUNCTION TESTS, and the CONTROL OF RESPIRATION

Wet Spirometer

Figure from: www.gen.umn.edu/.../ spirometerlab.htm

A wet spirometer is a plastic bell floating in water, so no air can enter or leave -- except the air you send in or out through a tube that empties into the bell from below. When you put air in, the bell floats higher and the amount of air that you put in can be measured by the difference in the level of the bell.

To measure a normal breath:

1. Put the noseclip on

2. Put a clean mouthpiece on the valve assembly

3. Put the mouthpiece in your mouth and take a few breaths, so you will get used to breathing with it.

4. Which end of the valve assembly is air coming out of when you exhale? Connect that end of the valve assembly to the spirometer hose, so that the air you exhale goes into the spirometer.

5. Read the volume indicator scale after each breath, to see how much you exhaled.

Use the wet spirometer to measure your subject’s Tidal Volume, Expiratory Reserve Volume, and Vital Capacity.

TIDAL VOLUME - breath in and out normally. Record the change in volume in the bell with each breath.

Subject

Trial 1 Tidal Volume (L)

Trial 2 Tidal Volume (L)

Trial 3 Tidal Volume (L)

Average Tidal Volume (L)

EXPIRATORY RESERVE - breath in and out normally. On the next breath exhale, record the bell volume, and then exhale as much more as you can. This is the expiratory reserve volume.

Subject

Trial 1 Expiratory Reserve (L)

Trial 2 Expiratory Reserve (L)

Trial 3 Expiratory Reserve (L)

Average Expiratory Reserve (L)

VITAL CAPACITY - Inhale as much as you possibly can and exhale as much and as fast as you can (like blowing out the candles on a birthday cake).

Subject

Trial 1 Vital Capacity (L)

Trial 2 Vital Capacity (L)

Trial 3 Vital Capacity (L)

Average Vital Capacity (L)

Minute Ventilation is the amount of air you move into and out of your lungs in one minute. There are basically two ways of measuring this; you can calculate it from tidal volume and respiration rate, or you can collect air and measure its volume.

***Note: your subject’s average tidal volume is in Liters, you will need to convert the tidal volume to mL before you calculate minute ventilation.***

Using the tidal volume you measured (mL/breath) and the subject’s respiratory rate (breaths/min), calculate your subject's minute ventilation (mL/min). You will need to measure your subject’s respiratory rate by counting her breaths.

Subject

Average Tidal Volume (mL/breath)

Respiratory Rate (Breaths/min)

Minute Ventilation (mL/min)

Control of Ventilation

How does your subject know she should breathe?

What factor(s) control breathing? Create a list of things you think may be the triggers for inhaling and do a literature search to decide which of them is best supported by evidence. Find actual data from credible sources! Turn in a brief (2 page) summary of what you found out. Remember to use proper citation style.