REACH-DL | Heart 4: Diving Reflex

ECG Cable and Pulse Setup

Plug the red, black and green leads into the REACH color coded ports.
Snap the leads onto the stickie electrodes, then place the stickie electrodes like this:

The black lead goes under the right clavicle.
The red lead goes on the lower left abdomen.
The green (ground) lead goes on the lower right abdomen.

Make sure you snap the leads onto the stickie electrodes before putting them on yourself.

Keep the REACH-DL flat on the table and rest your pointer or middle finger of your non-dominant hand on the pulse port. This is the hand you do not use all the time. Make sure your arm is flat on the table and your finger is relaxed.
When you are ready to start recording data, just make sure the you relax and sit very still so there is no movement interference on the data.

The ECG and the Pulse in a Resting Subject

Aim

To measure ECG and heart rate in a resting subject.

Procedure

Keep the REACH-DL flat on the table and rest your pointer or middle finger of your non-dominant hand on the pulse port. This is the hand you do not use all the time. Make sure your arm is flat on the table and your finger is relaxed.
Click on the AutoScale All button.
Type "Resting ECG" in the Mark box and click the Mark button. This will make a black mark with text on your screen.
Record for 5 minutes then click Stop.
Click File ---> Save As, name the file "DivingReflex", and save your data to your LabScribe Data folder on your Desktop.

Data Analysis

Go to the beginning of your recording by clicking on the down arrow just to the right of the Mark Button and click the mark "Resting-ECG".
Make sure to have at least 10 ECG cycles on screen. Double or half the display time by clicking the mountain icons once.

Use the mouse to click on and drag the cursors to specific points on the ECG/Pulse recording to measure the following:

The R-wave amplitude. Place one cursor on the Q wave and the second cursor on the peak of the R wave. The value for V2-V1 on the ECG channel is the amplitude. Measure the amplitudes of 4 additional R waves. Calculate the mean amplitude by adding these together and then divide by 5.
The Pulse wave amplitude. Place one cursor on the baseline that precedes the pulse wave and the second cursor on the peak of the pulse wave. The value for V2-V1 on the Pulse channel is this amplitude. Measure this amplitude for 4 additional pulse waves and then calculate the mean.
The beat period, which is the time interval between two adjacent R waves. To measure the beat period, place one cursor on the peak of an R wave and the second cursor on the peak of the adjacent R wave. The value for T2-T1 is the beat period. Measure the beat period for 4 additional pairs of R waves and then calculate the mean.
The R-Pulse interval, which is the time interval between the peak of the R wave and the peak of the pulse wave. Place one cursor on the peak of an R wave and the second cursor on the peak of the pulse wave to its right. The value for T2-T1 is this interval. Measure this interval for 4 additional ECG/Pulse cycles and then calculate the mean.

Determine your average heart rate.

Click the "two-mountain" icon to double the display time to show the entire 5 minutes of data. You may have to click it a few times.
Once you can see all your data, move the cursors to either side of the recording.
Look at the right side of the Heart Rate channel and read the MEAN value of your resting Heart Rate.

Reset Your Display Time - In the display time box, type 10 and click enter. This will reset your display time to 10 seconds for Exercise 2.

Note - Write all your values on a data table so you can refer back to them when answering the questions.

You can open and close the Journal using the "Notebook" icon.

Heart Rate and Apnea

Aim

To measure the heart rate while you are holding your breath.

Procedure

Remember to sit quietly with your hands in your lap. You will be holding your breath as long as possible in this exercise.
Click on the Record button.
Click on the AutoScale All button.
When the pulse recording looks good, type “Holding Breath” in the Mark box to the right of the Mark button. Press the mark button when you start to hold your breath (apnea).
Quickly type "Breathing Again" in the Mark box. Press the mark button when you start breathing again. Continue recording for at least 2 minutes.
Click Stop and then Save.

Data Analysis

Go to the beginning of your recording by clicking on the down arrow just to the right of the Mark Button and click the mark "Holding Breath".
Double or half the display time by clicking the mountain icons just until you can see the entire time you held your breath. You should see the 2nd mark you made “Breathing Again".

Click and drag one cursor so it is on the “Holding Breath” mark and click the other cursor and place it on the “Breathing Again” mark.
Measure data ONLY between the 2 cursors while you were holding your breath. Use the mouse to click on and drag the cursors to specific points on the ECG/Pulse recording to measure the following:

The R-wave amplitude. Place one cursor on the Q wave and the second cursor on the peak of the R wave. The value for V2-V1 on the ECG channel is the amplitude. Measure the amplitudes of 4 additional R waves. Calculate the mean amplitude by adding these together and then divide by 5.
The Pulse wave amplitude. Place one cursor on the baseline that precedes the pulse wave and the second cursor on the peak of the pulse wave. The value for V2-V1 on the Pulse channel is this amplitude. Measure this amplitude for 4 additional pulse waves and then calculate the mean.
The beat period, which is the time interval between two adjacent R waves. To measure the beat period, place one cursor on the peak of an R wave and the second cursor on the peak of the adjacent R wave. The value for T2-T1 is the beat period. Measure the beat period for 4 additional pairs of R waves and then calculate the mean.
The R-Pulse interval, which is the time interval between the peak of the R wave and the peak of the pulse wave. Place one cursor on the peak of an R wave and the second cursor on the peak of the pulse wave to its right. The value for T2-T1 is this interval. Measure this interval for 4 additional ECG/Pulse cycles and then calculate the mean.

Determine your average heart rate while holding your breath.

Look at the right side of the Heart Rate channel and read the MEAN value of your resting Heart Rate.
Also look at T2-T1 to find out how long you held you breath.

Write all your values on a data table so you can refer back to them when answering the questions. Use the "Notebook" icon to open and close the Journal.

Heart Rate While Testing the Diving Reflex

Aim

To measure the effects of “diving” into cold water on heart rate.

READ ALL THESE DIRECTIONS BEFORE STARTING THIS SECTION

Make sure you have a towel handy. You will also need a dishpan or plastic container to put your face into.

Do this slightly away from your computer. You DO NOT want to get your computer wet.
Sit in front of the dishpan or plastic container of room temperature water (~25^oC). If you wear glasses, take them off. If you have long hair, put it up in a ponytail.
Click Record and click AutoScale All.
When the pulse looks good, type “25C Water “in the Mark box. Do not press the Mark button until right before you submerge your face.
Hold your breath and submerge your face (up to the hairline and in front of the ears) in the water for about 20 seconds (if you can go longer, stay for 30 seconds – but NO longer). Press the mark button just before you put your face into the water.
Immediately click the F1 key on your keyboard when you take yourself out of the water.
Click Stop and then Save.
Repeat the diving exercise into the pan of 25^oC water two additional times. Allow enough time between trials for your heart rate to return to normal. Rest for at least 2 minutes between trials.
After the 3rd trial, empty the water and refill with 15^oC water, you will need a thermometer to test the temperature. It does not have to be exact (but should be close). This should be about the temperature of the cold water coming out of your sink.
Repeat this exercise using the 15^oC water. Remember to test 3 times and Save your file when you are done.
After the 3rd trial, empty the water and refill with 5^oC water, you will need a thermometer to test the temperature. It does not have to be exact (but should be close). Use the cold water from your sink and add a couple of ice cubes to cool it down a bit more.
Repeat this exercise using the 5^oC water. Remember to test 3 times and Save your file when you are done.
Dry your face and your hair, empty the water, then come back and do the data analysis.

Data Analysis

Repeat the data analysis using the same information from Exercise 1 and 2.
Measure the values during the first 5 and last 5 seconds when your face was in the water for each section.

The R-wave amplitude. Place one cursor on the Q wave and the second cursor on the peak of the R wave. The value for V2-V1 on the ECG channel is the amplitude. Measure the amplitudes of 4 additional R waves. Calculate the mean amplitude by adding these together and then divide by 5.
The Pulse wave amplitude. Place one cursor on the baseline that precedes the pulse wave and the second cursor on the peak of the pulse wave. The value for V2-V1 on the Pulse channel is this amplitude. Measure this amplitude for 4 additional pulse waves and then calculate the mean.
The beat period, which is the time interval between two adjacent R waves. To measure the beat period, place one cursor on the peak of an R wave and the second cursor on the peak of the adjacent R wave. The value for T2-T1 is the beat period. Measure the beat period for 4 additional pairs of R waves and then calculate the mean.
The R-Pulse interval, which is the time interval between the peak of the R wave and the peak of the pulse wave. Place one cursor on the peak of an R wave and the second cursor on the peak of the pulse wave to its right. The value for T2-T1 is this interval. Measure this interval for 4 additional ECG/Pulse cycles and then calculate the mean.

Determine your average heart rate while holding your breath.

Look at the right side of the Heart Rate channel and read the MEAN value of your resting Heart Rate.

You will have data for water at 25^oC, 15^oC, and 5^oC.
Put your Heart Rate data into a table or in the Journal. You can open and close the Journal by clicking the "Notebook" icon. This will help you stay organized.

Answer the following:

Exercise 2

How does your average heart rate while resting compare to your heart rate while holding breath?
How do your maximum and minimum heart rates while resting compare to the same heart rates while holding breath?
How does the average R-Pulse interval change when you are not breathing (apnea)?
How does the average pulse wave amplitude from rest and during apnea compare? Do you see any variation or trend?
Is there any effect on the blood flow through your finger when you are not breathing?

Exercise 3

What happens to your heart rate when your face is submerged in water at 25^oC?
What happens to your heart rate when your face is submerged in water at 15^oC? In water at 5^oC?
What causes your heart rate to change when your face is submerged in cold water?
How does the mammalian diving reflex help a person who falls into cold water? Think in terms of the organs that need oxygen. You may need to look up some information for this.