Respiratory Control

Objective:

To explain in short essays or diagrams how breath holding, hyperventilation, and re-breathing affect ventilation, at the level of 85% proficiency for each student.

In order to achieve this objective, you will need to be able to:

Measure the influence of breath holding, hyperventilation, and re-breathing on the depth and rate of respiration.
Examine the sounds made by air moving through the respiratory airways.

Materials:

Group Supplies:

Tape measure

Nose clips

Alcohol swabs

70% ethanol solution

Disposable autoclave bag

Scotch tape

paper bag

Stethoscope

Nonin Pulse Oximeter

The following equipment is optional

[Pneumograph apparatus and pressure - displacement transducer

or Air flow sensor

pressure - displacement preamplifier (D. G Ward) (set to record activity within a range of DC to AC with variable gain)

digital to analog converter Dataq, DI-154)

computer with display software (WinDaq and WinDaq Browser)]

Use of a Pneumograph or Air Flow meter or Visual Observation to determine factors influencing Rate and Depth of Respiration

A chest pneumograph is an apparatus that measures the circumference of the chest. As the subject breathes, chest movements produce changes within the pneumograph that are transmitted to a recorder. The chest pneumograph can accurately reflect air movement during breathing in subjects where the thorax readily changes circumference. However, in some subjects, breathing is caused by changes in the length of the thorax (diaphragm breathing) and the chest pneumograph is not a suitable instrument. An air flow meter is an apparatus that measures air flow into and out of the airways and thus is not influenced by chest circumference. When neither a pneumograph nor an air flow meter is available, the rate and depth of respiration can be measured qualitatively by visual observation.

Methods and Results:

The instructor will demonstrate the method of setting up the pneumograph or air flow meter and discuss the interpretation of the results. Work in pairs so that one person can mark the record to identify the test for later interpretation. Ideally, the student being tested should face away from the recording apparatus to prevent voluntary modification of the record.

When neither a pneumograph nor an air flow meter is available, the rate and depth of respiration can be measured qualitatively by visual observation.

The amplifier for conditioning signals from the pneumograph or air flow meter is labeled pressure / displacement,

The pressure and displacement transducers are the following.

In addition to measuring respiration, measure heart rate and pO₂ with the Nonin Pulse Oximeter.

Attach the pneumograph tubing firmly, but not restrictively, around the thoracic cage at the level of the sixth rib, leaving room for chest expansion during testing. If the subject is female, position the tubing above the breasts to prevent slippage during testing. The air flow meter is positioned inside a mouth piece. Record or observe quiet breathing for 1 minute with the subject in a sitting position.

Record breaths per minute. _______________________________

This part is not relevant for visual observation. The subject must have measured their vial capacity in the spirometry lab. Record a maximal inhalation followed by a maximal exhalation. Note the direction the pneumograph or air flow recording moves during inspiration and during expiration. Use this data to calibrate the instruments.

For example, if your vital capacity reading is 4000 mL and the vital capacity tracing occupies a vertical distance of 40 mm on the pneumograph or air flow recording, then a vertical distance of 1 mm equals 100 mL of air.

Record your computed value. ____________________ mL air/mm
Have the subject breathe normally for 2 minutes, then inhale deeply and hold his or her breath for as long as he or she can.

Time of breath-holding interval. _________________________ sec

As the subject breathes, record or observe the recovery period (time to return to normal breathing — usually slightly over 1 minute):

Time of recovery period. ______________________________ sec

Did the subject have the urge to inspire or expire during breath holding?

________________________________________________________________
Have the subject exhale forcefully and completely and then hold his or her breath for as long as he or she can.

Time of breath-holding interval. _________________________ sec

As the subject breathes, record or observe the recovery period (time to return to normal breathing — usually slightly over 1 minute):

Time of recovery period. ______________________________ sec

Did the subject have the urge to inspire or expire during breath holding?

________________________________________________________________

Have the subject hyperventilate (breathe deeply and forcefully at the rate of 1 breath/4 sec) for about 30 seconds.

Caution: A sensation of dizziness may develop. (As the carbon dioxide is washed out of the blood by overventilation, the blood pH increases, leading to a decrease in blood pressure and reduced cerebral circulation.) The subject may experience a lack of desire to breathe after forced breathing is stopped. If the period of breathing cessation — apnea-is extended, cyanosis of the lips may occur.

Record or observe both during and after hyperventilation. How does the pattern obtained during hyperventilation compare with that recorded during the vital capacity measurement?

____________________________________________________________

Is the respiratory rate after hyperventilation faster or slower than during normal quiet breathing?

______________________________________________________________
Have the subject hyperventilate and then hold his or her breath for as long as he or she can.

Time of breath-holding interval. _________________________ sec

As the subject breathes, record or observe the recovery period (time to return to normal breathing — usually slightly over 1 minute):

Time of recovery period. ______________________________ sec

Did the subject have the urge to inspire or expire during breath holding?

________________________________________________________________
Have the subject breathe into a paper bag for 3 minutes, then record or observe his or her breathing movements.

Caution: During the bag-breathing exercise the subject's partner should watch the subject carefully for any problematic reactions.

Is the breathing rate faster or slower than that seen during normal quiet breathing?
__________________________________________________________________

Is the breathing rate faster or slower than that seen after hyperventilating?
_______________________________________
Run in place for 2 minutes, and then have your partner determine the length of time that you can hold your breath.

Time of breath-holding interval. _____________________ Sec
To examine the effect of respiration on the heart and circulation, conduct the following test. Have your lab partner record the rate and relative force of your radial pulse before beginning.

rate _______________ beats/min relative force __________________

Inspire forcibly. Immediately close your mouth and nose to retain the inhaled air, and then make a forceful and prolonged expiration. Your lab partner should observe and record the condition of the blood vessels of your neck and face, and again immediately palpate the radial pulse.

Observations of blood vessels in neck and face
____________________________________________________________

Radial pulse ____________________ beats/min Relative force _______________

Explain the changes observed. _________________________________________

10. Observe the subject's breathing patterns as he or she performs activities from the list below.

talking	swallowing water
yawning	coughing
laughing	lying down
standing	running in place
doing a math problem