Experiment HE-6: Breath by Breath Measurement of Respiratory Exchange Ratio (RER)

Transcription

1 Experiment HE-6: Breath by Breath Measurement of Respiratory Exchange Ratio (RER) Background The two sources of energy available for human metabolism are carbohydrates (CHO) and fats. These molecules are broken down, or catabolized, into carbon dioxide, water, and energy. However, the oxidation of fats requires more oxygen than the oxidation of carbohydrates. The oxidation of a molecule of carbohydrate is expressed by the following equation: 6 O 2 + C 6 H 12 O 6 = 6 CO H 2 O + 38 ATP As shown in this equation, 6 molecules of carbon dioxide are produced for every 6 molecules of oxygen consumed during the oxidation of carbohydrates, a ratio of 1.0. The oxidation of a molecule of fatty acid is expressed by this equation: 23 O 2 + C 16 H 32 O 2 = 16 CO H 2 O ATP As shown in this equation, 16 molecules of CO 2 are produced for every 23 molecules of O 2 consumed during the oxidation of fatty acids, a ratio of 0.7. The energy requirements of the body are met with a mixture of energy derived from carbohydrates and fats. The activity being performed determines the proportion of carbohydrates and fats being utilized. At rest, a body derives about 40% of its energy from carbohydrates and 60% from fats. As the intensity of activity increases, the demand for energy increases, and a greater proportion of this demand is met by the oxidation of carbohydrates. When maximal oxygen uptake is occurring at the most intense exercise level, carbohydrates are supplying 100% of the energy because the catabolism of fat is too slow to supply the amount of energy required. As the ratio of energy supplied by fats and carbohydrates shifts during changes in activity, the ratio of carbon dioxide produced to oxygen consumed also shifts. The ratio of carbon dioxide produced to oxygen consumed during cellular metabolism can be measured by determining the changes in the concentrations of oxygen and carbon dioxide in the air that passes into and out of the lungs. These measurements are possible because the amounts of oxygen and carbon dioxide exchanged between the alveoli and the capillaries in the lungs are directly dependent on the amounts of carbon dioxide produced and oxygen consumed during cellular respiration. The amounts of oxygen consumed and carbon dioxide produced are measured using an oxygen/carbon dioxide gas analyzer connected to a spirometer. The gas analyzer measures the concentration of oxygen and carbon dioxide in inspired and expired air, and the spirometer determines the volumes of inspired and expired air. When the concentrations and volumes are brought together in a series of equations, the volume of oxygen consumed per minute (VO 2 ) and the volume of carbon dioxide produced per minute (VCO 2 ) are determined. The ratio of VCO 2 /VO 2 is the Respiratory Exchange Ratio (RER), which can be used to determine the proportion of carbohydrates and fats utilized, and the energy expended per liter of oxygen consumed, during an activity (Table HE-6-1 on page HE-6-1). The fat and carbohydrate percentages utilized during an activity are determined using the following equations: ((1.00-RER)/( )) x 100 = %Fat utilized 100% - %Fat utilized = %CHO utilized The energy expended during an activity is calculated from the RER and the volume of oxygen consumed. For example, if the RER is 0.90, the energy expended is 4.92kcal/liter O 2. If 2.5 liters of oxygen are consumed per minute for 20 minutes, a total of 246 kcal are expended during the activity: (2.5LO 2 /minute)(20min)(4.92kcal/liter O 2 ) = 246kcal At less intense activity levels, the rates of energy expenditure and RER values are lower. To expend the same amount of energy at a less intense level of activity, the duration of activity must be longer. For example, if the RER is 0.80, the energy expended is 4.80kcal/liter O 2. If 1.7 liters of oxygen are consumed per minute, 8.16kcal are expended per minute: (1.7LO 2 /minute)(4.80kcal/liter O 2 ) = 8.16kcal/min To expend 246 kcal at a rate 8.16kcal/min would require 30 minutes, 9 seconds: 246 kcal/(8.16 kcal/min) = minutes. Table HE-6-1: Respiratory Exchange Ratio (RER) as a Function of the Proportions of Energy Sources. RER Energy kcal/liter O 2 % Energy from CHO % Energy from Fats HE-6-1

2 In this experiment, students will measure the VO 2, VCO 2, RER, and proportion of fat and carbohydrates utilized while the subject was resting, hyperventilating, recovering from hyperventilation, and recovering from light or moderate exercise. These measurements will be performed quickly and easily using an iworx GA-200 CO 2 /O 2 gas analyzer that is connected to a spirometry system. 5 After a short time, LabScribe will appear on the computer screen as configured by the BBB-VO2-RER-LS2 settings. 6 For your information, the settings used to configure the LabScribe software and IWX/214 units for this experiment are listed in Table HE-6-2 on page HE-6-2. These settings are programmed on the Preferences Dialog window, which can be viewed by selecting Preferences from the Edit menu on the LabScribe Main window. Equipment Required PC or Mac Computer IWX/214 data acquisition unit USB cable IWX/214 power supply SP-304 Spirometer with flow head tubing A-FH-300 Flow head GA-200 CO 2 /O 2 gas analyzer with filter Nafion gas sample tubing Breathing mask Barometer and thermometer IWX/214 Setup 1 Place the IWX/214 on the bench, close to the computer. 2 Check Figure T-1-1 in Chapter 1 for the location of the USB port and the power socket on the IWX/ Check Figure T-1-2 in Chapter 1 for a picture of the IWX/ 214 power supply. 4 Use the USB cable to connect the computer to the USB port on the rear panel of the IWX/ Plug the power supply for the IWX/214 into the electrical outlet. Insert the plug on the end of the power supply cable into the labeled socket on the rear of the IWX/214. Use the power switch to turn on the unit. Confirm that the red power light is on. Start the Software Table HE-6-2: Settings on the Channel Window of the Preferences Dialog Used to Configure the iworx Recording System for Experiment HE- 6. Parameter Units/Title Setting Acquisition Mode Start Stop Setup the Metabolic Cart Chart User User Display Time Sec 10 Speed Samples/Sec 200 Mode/ Function Channel A1 CO 2 Conc. (%) S BNC Channel A2 O 2 Conc. (%) S BNC Channel A4 Air Flow S DIN8 Channel C1 Lung Volumes STPD Channel C2 Relative VCO2 S Channel C3 Relative VO2 S 1 Locate the SP-304 spirometer, the A-FH-300 flowhead, and the airflow tubing in the iworx kit (Figure HE-6-1 on page HE-6-2). S STPD Vol. Human VCO2- Breath VO2- Breath Channel C4 RER S RER 1 Click on the LabScribe shortcut on the computer s desktop to open the program. If a shortcut is not available, click on the Windows Start menu, move the cursor to All Programs and then to the listing for iworx. Select LabScribe from the iworx submenu. The LabScribe Main window will appear as the program is opens. 2 On the Main window, pull down the Settings menu and select Load Group. 3 Locate the folder that contains the settings group, IPLMv4.iwxgrp. Select this group and click Open. 4 Pull down the Settings menu, again. Select the BBB-VO2- RER-LS2 settings file. Figure HE-6-1: The SP-304 spirometer, the A-FH-300 flowhead, and the airflow tubing. HE-6-2

3 2 Firmly push the paired airflow tubes onto the two sampling outlets of the A-FH-300 flow head, and the other ends of the two airflow tubes onto the two sampling inlets of the SP-304 spirometer unit. of the gas analyzer (Figure HE-6-4 on page HE-6-3). Attach the other end of the Nafion sampling tube to the filter. 3 Plug the DIN8 connector of the SP-304 spirometer into the Channel 4 input of the IWX/214 (Figure HE-6-2 on page HE6-3). Figure HE-6-4: The GA-200 gas analyzer, inlet filter, and Nafion sampling tubing. I F THE GA-200A IS BEING USED IN THIS EXPERIMENT : Connect the specialized cable between the output of the Figure HE-6-2: The SP-304 spirometer connected to the Channel 4 input of an IWX/214 unit. 4 Locate the breathing mask in the iworx kit. Attach the mask to the inlet of the A-FH-300 flow head (Figure HE-6-3 on page HE-6-3). carbon dioxide sensor, which is located on the terminal block on the rear panel of the GA-200A gas analyzer, and the BNC input of Channel 1 on the IWX/214: Find the color-coded wires on one end of the cable. Insert the red wire into Socket 15 on the terminal block, as counted from left to right. This socket is the current output signal of the sensor (Figure HE-6-5 on page HE-6-3). Figure HE-6-5: The rear panel of the GA-200A gas analyzer showing the cables attached to the outputs of the carbon dioxide sensor, on the left, and the oxygen sensor, on the right. Figure HE-6-3: A breathing mask attached to the inlet of an A-FH-300 flowhead. The Nafion sampling tubing is attached to the port on the mask. 5 Locate GA-200A or GA-200B gas analyzer, the gas analyzer power supply, two sensor output cables, a gas inlet filter, and a Nafion sampling tubing in the iworx kit (Figure HE-6-4 on page HE-6-3). Insert the black wire into Socket 13 on the terminal block, as counted from left to right. This socket is the is the reference ground for that signal. Connect the other end of this cable to the BNC input of Channel 1 on the IWX/214. Connect the BNC output of the oxygen sensor, labeled 6 Position the gas analyzer on the desktop, so that the analyzer can be connected to the data recording unit and the subject at the same time. Oxygen Sensor and 0-1V=0-100% (Figure HE-6-5 on page HE-6-3) to BNC input of Channel 2 on the IWX/214 using a male BNC-BNC cable. 7 Place the braided end of the Nafion sampling tube on the gas sampling port of the mask (Figure HE-6-3 on page HE6-3). I F THE GA-200B IS BEING USED IN THIS EXPERIMENT : 8 Place the filter on the inlet port in the lower right front corner Connect the BNC output of the carbon dioxide sensor, labeled CO2 SENSOR, 0.8-4V=0-10% (Figure HE-6-6 on page HE-6-4) to BNC input of Channel 1 on the IWX/214 using a male BNC-BNC cable. HE-6-3

4 Connect the BNC output of the oxygen sensor, labeled Oxygen Sensor and 0-1V=0-100% to BNC input of Channel 2 on the IWX/214 using a male BNC-BNC cable. Figure HE-6-7: The current and the expected low calibration concentrations of oxygen as seen in CAL 1 mode. Figure HE-6-6: The rear panel of the GA-200B gas analyzer showing the outputs of the carbon dioxide sensor, on the left, and the oxygen sensor, on the right. 9 Have the subject try on the mask. Adjust the length of the straps so that the mask fits the subject comfortably. Check around the edge of the mask to make sure there are no leaks between the subject s skin and the rim of the mask. Remove the mask from the subject. 10 Connect the power supply of the GA-200 to the power input on the rear panel of the unit. Plug the power supply into the outlet. Turn on the analyzer and let it warm-up for at least 15 minutes before using it. Calibrating the GA-200 Gas Analyzer Both models of the GA-200 are calibrated at the factory and are ready to measure both oxygen and carbon dioxide concentrations over the ranges normally recorded from human and animal subjects. The factory calibration of each model of the GA-200 can be checked each day using a sample of room air. Before the gas analyzer is used, the following simple procedure can be performed. One-Point Calibration 1 Disconnect the braided end of the Nafion sampling tubing from the sampling port on the mixing chamber. Leave the other end of the sampling tube attached to the filter on the inlet of the gas analyzer. 2 Place the open end of the tubing away from the users to prevent the sampling of exhaled air. 3 Warm-up the GA-200 for at least 30 minutes before performing a calibration. MODEL GA-200A: After the warm-up period, press the Cal1 key one time. Values for the current O 2 reading and the calibration point (20.93%) will appear on the GA-200 display screen (Figure HE-6-7 on page HE-6-4). Wait ten seconds for the calibration gas to move into the analyzer. Wait for the display to indicate calibration cycle complete, Calibration OK. Press the Cal 1 key again to show the current CO2 concentration and the CO2 calibration point (0.04%) (Figure HE-6-8 on page HE-6-4). Press the Enter key to start the CO 2 calibration cycle. Figure HE-6-8: The current and expected low calibration concentrations of carbon dioxide as seen in CAL 1 mode. Wait for the display to indicate that the calibration cycle is complete, Calibration OK. As soon as the screen reads Calibration OK for the CO 2 calibration concentration, press the Run button and the unit is ready to use. MODEL GA-200B: After the warm-up period, press the Cal 1 key two times. This displays the current O 2 reading and the calibration point (Figure HE-6-7 on page HE-6-4). Wait ten seconds for the calibration gas to move into the analyzer. Press the Enter key. The GA-200 will read Calibration OK in a few seconds. As soon as the screen reads Calibration OK for the O 2 calibration concentration, press the Cal1 key again. Values for the current CO 2 reading and the calibration point (0.04%) will appear on the GA-200 display screen (Figure HE-6-8 on page HE-6-4). Press the Enter button. The GA-200 will read Calibration OK in a few seconds. As soon as the screen reads Calibration OK for the CO 2 calibration concentration, press the Run button and the unit is ready to use. Warning: If you are unable to calibrate, start over by using the Test key to Restore Factory Calibration. Press the Enter key to start the oxygen calibration cycle. HE-6-4

5 Two-Point Calibration The experimental protocol being used in a lab may require the gas analyzer to be calibrated periodically. Consult the operation manual for your model of the GA- 200 gas analyzer to perform a two-point calibration of the unit. Convert the Units on the O 2 and CO 2 Channels The outputs of the oxygen and carbon dioxide sensors of the GA-200 are voltages that are proportional to the concentrations of the gases being measured by the analyzer. To determine the volumes of oxygen consumed and carbon dioxide produced during metabolic testing, the voltage outputs of the sensors need to be converted, by the recording software, to the percentages of these gases in the inhaled and exhaled air. Place the braided end of the Nafion tubing away from the users to prevent the sampling of exhaled air. Allow room air to be pumped through the gas analyzer for 10 seconds before recording the outputs of the sensors. Type Output Voltage-Room Air in the Mark box to the right of the Mark button. Click on the Record button, located on the upper right side of the LabScribe Main window. The recording should scroll across the screen. While recording, press the Enter key on the keyboard to mark the recording with information about the room air gas sample. Record the outputs of the two gas sensors for about ten seconds. The recording which should be like the first segment of data in Figure HE-6-9 on page HE-6-5. Click the Stop button. To make this conversion, samples of two different concentrations of oxygen, and two different concentrations of carbon dioxide, will need to put into the GA-200 gas analyzer as the voltage outputs of each sensor are recorded. One set of samples can be taken from room air, which contains 20.93% O 2 and 0.04% CO 2. The other set of samples can be taken from gas cylinders containing a combination of these two gases at different concentrations. Cylinders containing both oxygen and carbon dioxide are readily available from suppliers. Some of the most commonly used combinations contain: 95% O 2 and 5% CO 2, or; 12% O 2 and 5% CO 2, with the balance being N 2. Record the Voltage Outputs of the Gas Sensors 1 Turn on the GA-200 for at least 15 minutes before performing any measurements, or at least 30 minutes before performing a calibration. 2 Prepare the equipment that will deliver any gas samples, other than room air, to the GA-200: Clamp and secure any gas cylinders that will used to provide gas samples near the GA-200 gas analyzer. Attach the regulator to the gas cylinder safely. Attach a Luer-Lock connector to the outlet of the regulator that will allow the Nafion sampling tube of the GA-200 to be connected to the regulator of the gas cylinder. Open the primary and secondary valves of the regulator for a few seconds to purge the air from the regulator. Close the secondary valve on the regulator to stop the flow of gas from the regulator. 3 Attach a filter to the sample inlet of the GA-200 analyzer. Attach the smooth end of the Nafion sampling tubing to the inlet of the filter. 4 Measure the voltage outputs of the oxygen and carbon dioxide sensors when measuring a sample of room air. Figure HE-4-9: The voltage outputs of the two sensors in the GA-200 gas analyzer, carbon dioxide on the top and oxygen on the bottom. 5 Measure the voltage outputs of the oxygen and carbon dioxide sensors when measuring a second sample of a gas mixture containing known concentrations of oxygen and carbon dioxide. Open the secondary valve on the regulator of the cylinder providing the second gas sample. Adjust the flow rate to about 100 ml/min. While the gas sample is flowing from the regulator, connect the braided end of the Nafion sample tubing to the Luer-Lock connector on the output of the regulator. Type Output Voltage-Second Sample in the Mark box. Click on the Record button, located on the upper right side of the LabScribe Main window. The recording should scroll across the screen. While recording, press the Enter key on the keyboard to mark the recording with information about the second gas sample. Once the recordings of the gas concentrations reach a steady level, record for another ten seconds. Click the Stop button. HE-6-5

6 6 Select Save As in the File menu, type a name for the file. Choose a destination on the computer in which to save the file, like your lab group folder). Designate the file type as *.iwxdata. Click on the Save button to save the data file. Convert the Units on Gas Concentration Channels 1 Use the Display Time icons to adjust the Display Time of the Main window to show the complete calibration data on the Main window at the same time. The required data can also be selected by: Placing the cursors on either side of data required Clicking the Zoom between Cursors button on the LabScribe toolbar to expand the segment with the four selected pulse cycles to the width of the Main window. 2 Click the 2-Cursor icon (Figure HE-6-10 on page HE-6-6) so that two blue cursors appear on the Main window. Place one cursor on the section of data recorded when gas analyzer was collecting a sample of room air and the second cursor on the section of data recorded when the second sample was collected. Make sure 2 point calibration is selected in the pull-down menu in the upper-left corner of the window. Put a check mark in the box next to Apply units to all blocks. Notice that the voltages from the positions of the cursors are automatically entered into the value equations. Enter the two concentrations of carbon dioxide measured from the two samples in the corresponding boxes on the right side of the conversion equations. Enter the name of the units, %, in box below the concentrations. Click on the OK button in the lower right corner of the window to activate the units conversion. Before Starting 1 Read the procedures for each exercise completely before beginning the experiment. Have a good understanding of how to perform these exercises before making recordings. Note: Do not hold the spirometer amplifier in your hand; the heat of your hand will alter the volumes recorded. 2 It is important that the subject is healthy and has no history of respiratory or cardiovascular problems. Figure HE-4-10: The LabScribe2 toolbar. 3 Convert the voltages at the positions of the cursors to concentrations using the Simple Units Conversion dialogue window (Figure HE-6-11 on page HE-6-6). 3 The settings file, BBB-VO2-RER-LS2, used in this experiment programs the computed function used on the Lung Volume STPD channel to convert the data recorded on the Air Flow channel to breath volumes at standard temperature and pressure, dry (STPD). 4 Enter the calibration voltage of the SP-304 spirometer, barometric pressure, inhaled and exhaled air temperatures, and water vapor pressure into the Spirometer Calibration Dialog window used on the Lung Volume STPD channel. Note: 1. If a barometer is not available, find the atmospheric pressure for your area from an on-line weather service or a local weather station. 2. Use Table HE-6-4 on page HE-6-11 in the Appendix to determine the water vapor pressure that corresponds to the room temperature. Click on the words STPD Vol. Human (Air Flow), which are next to the title of the Lung Volume STPD channel, to open the computed function pull-down menu. Figure HE-4-11: The Simple Units Conversion dialogue window with the voltages at the cursors set to equal the concentrations used in calibration. 4 To convert the voltages on the Expired CO2 Concentration (%) channel, click on the arrow to the left of the channel title to open the channel menu. Select Units from the channel menu, and select Simple from the Units submenu. Select Setup Function from this pull-down menu to open the Spirometer Calibration Dialog window. Set the flow head type to 300, for the 300L/min model. Enter the calibration voltage that is listed on the label of the SP-304 spirometer unit, into the equation that sets the calibration voltage equal to one liter of lung volume. Make sure the No Reset time is selected, and the first 5 seconds of the recording are used to zero the baseline of the Lung Volume STPD channel. 5 On the Units Conversion window: HE-6-6

7 Enter the values for the Atmospheric Pressure in mmhg, Temperature of Inhaled Air (Room Temperature) in o C, and Water Vapor Pressure in mmhg. At this point, set the Temperature of Exhaled Air to 34 o C. Click OK. 5 Allow the SP-304 to warm up for 10 minutes before recording for the first time. 6 Determine if the airflow tubes between the flowhead to the spirometer amplifier are attached to the proper inlets on each device. Since this test does not need to be recorded, click on the Save to Disk button in the lower left corner of the Main window. If LabScribe is in Preview mode, there will be a red X across the Save to Disk button. Click on the Preview button. Have the subject inhale through the mask while the flowhead is connected to the mask. Click on the AutoScale button at the upper margin of the Air Flow and Lung Volume STPD channels. Note: If the user clicks the Preview button and an error window appears the Main window indicating the iworx hardware cannot be found, make sure the iworx unit is turned on and connected to the USB port of the computer. Then, click on the OK button in the error window. Pull down the LabScribe Tools menu, select the Find Hardware function, and follow the directions on the Find Hardware dialogue window If the proper end of the flowhead is attached to the mask, the traces on the Air Flow and Lung Volume STPD channels will go up during inhalation. If the traces on these channels go down during inhalation, reverse the positions of the airflow tubing at the inlets of the spirometer amplifier. Click on the Stop button. 7 The settings file, which was selected earlier, programs LabScribe to record the concentrations of oxygen and carbon dioxide in the inhaled and exhaled air. The computed functions used on the Relative VCO2 and Relative VO2 channels convert the data recorded on the O2 and CO2 Concentration channels, and the Lung Volumes STPD channel, to the VCO2 and VO2 in each breath. 8 Enter the channels used to calculate VCO2 and VO2, the weight of the subject, and the concentrations of oxygen and carbon dioxide in room air into the Metabolic Output Calculation Dialog window used on the Relative VCO2 and VO2 channels. Click on the words VCO2 (LungVolumes STPD) that are next to the title of the Relative VCO2 channel, to open the computed function pull-down menu. Select Setup Function from this pull-down menu to open the Metabolic Output Calculation Dialog window. Select the CO2 Concentration (%) as the carbon dioxide channel and Lung Volumes STPD as the volume channel. Enter the weight (in kg) of the subject and the concentration of carbon dioxide (%) in inhaled air on the window. Click on the words VO2 (LungVolumes STPD) that are next to the title of the Relative VO2 channel, to open the computed function pull-down menu. Select Setup Function from this pull-down menu to open the Metabolic Output Calculation Dialog window. Select the O2 Concentration (%) as the oxygen channel and Lung Volumes STPD as the volume channel. Enter the weight (in kg) of the subject and the concentration of oxygen (%) in inhaled air on the window. Click OK. Enter the channels used to calculate RER into the RER Calculation Dialog window used on the RER channel. Click on the words RER (VCO2) that are next to the title of the RER channel, to open the computed function pull-down menu. Select Setup Function from this pull-down menu to open the RER Calculation Dialog window. Select Relative VO2 as the VO2 channel and Relative VCO2 as the VCO2 channel. Select 60 as the Time (in seconds) over which the data on the RER channel will be averaged when the RER value is determined. When a single cursor is placed in the center of the range of RER data to be averaged, the RER function will automatically average the data that is on either side of the cursor. For example, if the time to average is set at 60 secs, the RER function will average the 30 seconds before and the 30 seconds after the position of the cursor. Click OK. 9 Click on the Save to Disk button, in the lower left corner of the Main window, to change LabScribe from Preview mode to Record mode. If LabScribe is in Record mode, there will be a green arrow on the Save to Disk button. Exercise 1: VCO 2, VO 2, and RER at Rest Aim: To determine the effect of breathing at rest on VCO 2, VO 2, and RER. Procedure 1 Instruct the subject to sit quietly, become accustomed to breathing through the mask and the flowhead, and breathe normally before any recordings are made. 2 Have the subject remove the mask from his or her face before the volume channels are zeroed. 3 Type <Subject s Name> Inhalation at Rest in the Mark box that is to the right of the Mark button. Note: The LabScribe software will zero the Lung Volume STPD channel during the first five seconds of recording. No air should be moving through the flowhead during this time. HE-6-7

8 4 Click on the Record button. After waiting five seconds for the Lung Volume STPD channel to zero, the subject should put on the mask and check for leaks. Press the Enter key on the keyboard to mark the recording as the subject begins breathing through the mask and the flowhead. 3 Click on the Analysis window icon in the toolbar (Figure HE-6-12 on page HE-6-8) or select Analysis from the Windows menu to transfer the data displayed in the Main window to the Analysis window (Figure HE-6-14 on page HE-6-10). 5 Click the AutoScale buttons on all channels. 6 Notice that the CO 2 concentration increases with each exhalation and decreases with each inhalation as the O 2 concentration does the opposite. 7 On the Lung Volume STPD channel, the STPD Vol. Human function converts the data from the Air Flow channel to the tidal volumes at the standard temperature and pressure, dry (STPD). Note: In this experiment, the weight of the subject is incorporated into the determination of VCO 2 and VO 2. These parameters are expressed as ml/min/kg body weight, and are often referred to as Relative VCO 2 and Relative VO 2 8 On the Relative VCO2 channel, the VCO2-Breath function is programmed to determine the volume of carbon dioxide produced during the exercise. The volume of carbon dioxide produced in a minute is the parameter known as VCO 2. 9 On the Relative VO2 channel, the VO2-Breath function is programmed to determine the volume of oxygen consumed during the exercise. The volume of oxygen consumed in a minute is the parameter known as VO On the RER channel, the RER function is programmed to determine the VCO2/VO2 ratio at each point on the recording. 11 Record one to two minutes of data while the subject s respiration rate and volume are steady. Once the data is recorded, click Stop to halt the recording. Your data should be similar to Figure HE-6-13 on page HE Select Save As in the File menu, type a name for the file. Choose a destination on the computer in which to save the file, like your lab group folder). Designate the file type as *.iwxdata. Click on the Save button to save the data file. Data Analysis 1 Scroll to a section of the data where the subject s respiration rate and depth were consistent. 2 Use the Display Time icons to adjust the Display Time of the Main window to show at least a one-minute section of the recording on the Main window. The required data can also be selected by: Clicking the 2-Cursor icon (Figure HE-6-12 on page HE-6-8) on the LabScribe toolbar so that two blue cursors appear on the Main window. Placing the cursors on either side of data required. Clicking the Zoom between Cursors button on the LabScribe toolbar to expand the calibration data to the width of the Main window. Figure HE-6-12: The LabScribe toolbar. 4 Look at the Function Table that is above the uppermost channel displayed in the Analysis window. The mathematical functions, Mean, T2-T1, and Value1 should appear in this table. Values for each parameter on each channel are seen in the table across the top margin of each channel. 5 Once the cursors are placed in the correct positions for determining the mean VCO 2 and VO 2 values for a oneminute section of data as indicated by the value for T2-T1, the mean VCO 2 and VO 2 values can be recorded in the online notebook of LabScribe by typing the name and values directly into the Journal. 6 The functions in the channel pull-down menus of the Analysis window can also be used to enter the name and values of the parameter from the recording to the Journal. To use these function: Place the cursors at the locations used to measure the mean VCO2 and VO2 over one minute. Transfer the name of the mathematical function used to determine these mean values to the Journal using the Add Title to Journal function in the VCO2 Channel pull-down menu. Transfer the values for the mean VCO 2 and VO 2 to the Journal using the Add All Data to Journal function in the Relative VCO2 Channel pull-down menu. 7 Use the mouse to click on and drag the cursors to positions on the Relative VCO2 channel that are one minute apart (Figure HE-6-14 on page HE-6-10). The values for the following parameters are determined when the cursors are positioned as directed: The value for Mean on the Relative VCO2 channel is the average volume of carbon dioxide produced in one minute per kg body weight. The value for Mean on the Relative VO2 channel is the average volume of oxygen consumed in one minute per kg body weight. The value for Mean on the RER channel is the average respiratory exchange ratio (RER) over the time between the cursors on the Analysis window. 8 Record the values for the Means in the Journal using one of the techniques described in Steps 5 or 6, and on Table HE-6-3 on page HE-6-9. HE-6-8

9 Figure HE-6-13: Gas concentrations, breath volumes, relative VCO2, relative VO2, and RER of a resting subject displayed on the Main window. Table HE-6-3: Mean VCO 2, VO 2, and the Respiratory Exchange Ratio (RER) of a Subject at Rest, Hyperventilating, and Recovering from Exercise. Environmental Conditions Experimental Periods Mean VCO2 ](ml/min/kg) Mean VO2 (ml/min/kg) Mean RER Temperature ( o C) Resting [Gas] Steady Hyperventilation [Gas] Steady Barometric Pressure (mmhg) 1st Minute After Hyperventilation First Minute After Exercise Relative Humidity (%) Second Minute After Exercise Third Minute After Exercise HE-6-9

10 Figure HE-6-14: Gas concentration, breath volumes, relative VCO2, relative VO2, and RER displayed in the Analysis window. Exercise 2: Effect of Hyperventilation on VCO 2, VO 2, and RER Aim: To measure the effect of deep breathing on VCO 2, VO 2, and RER during and after the period of hyperventilation. Procedure 1 Use the same procedures used in Exercise 1 to record the VCO 2 and VO 2 of the subject while the subject is breathing normally, hyperventilating for a minute, and then recovering from hyperventilation. 2 Mark the recording with comments that indicate the name of the subject and the beginning of each period being recorded. 3 The subject should breathe normally until his or her breathing rate and tidal volumes are consistent. Once these parameters are steady, the subject should begin hyperventilating so that his or her inhalation volume is at least 3 times the resting tidal volume. Mark the recording with a comment to indicate the beginning of the period of hyperventilation. 4 The subject should hyperventilate for at least one minute. If the subject cannot hyperventilate for one minute because he or she is feeling dizzy, the subject should return to breathing normally. The subject does not need to complete a full minute of hyperventilation. The volumes recorded during hyperventilation can be prorated to provide minute volumes. 5 After the period of hyperventilation, record the subject s breathing until it returns to normal. Mark the recording with a comment to indicate the beginning of the recovery period. Data Analysis 1 Use the same procedures used in Exercise 1 to determine the minute volumes of oxygen consumed and carbon dioxide produced per kg body weight, and the respiratory exchange ratio (RER) during the hyperventilation and recovery from hyperventilation. 2 Record the values for the mean volume of carbon dioxide produced in one minute per kg body weight, the mean volume of oxygen consumed in one minute per kg body weight, and the average RER during hyperventilation and recovery from hyperventilation on Table HE-6-3 on page HE-6-9. HE-6-10

11 Exercise 3: Effect of Moderate Exercise on VCO 2, VO 2, and RER Aim: To measure the effects of moderate exercise on VCO 2, VO 2, and RER during the recovery period after exercise. Procedure 1 Instruct the subject to exercise moderately for 3 minutes before recording the subject s carbon dioxide production and oxygen consumption. 2 Use the same procedures used in Exercise 1 to record the lung volumes from the subject during the first, second, and third minutes of recovery from exercise. 3 Mark the recording with comments that indicate the name of the subject and the beginning of each minute being recorded. Data Analysis 1 Use the same procedures used in Exercise 1 to determine the minute volumes of oxygen consumed and carbon dioxide produced per kg body weight, and the respiratory exchange ratio (RER) during the recovery from exercise. 2 Record the values for the mean volume of carbon dioxide produced in one minute per kg body weight, the mean volume of oxygen consumed in one minute per kg body weight, and the average RER during recovery from exercise on Table HE-6-3 on page HE-6-9. Questions 1 During which experimental period was the subject s VCO 2 the highest? In which period was it the lowest? 4 Evaluate the physical fitness of your subject. How does the level of your subject s physical fitness correlate to his or her RER at rest? While hyperventilating? While recovering from exercise? 5 Evaluate the diet of your subject. How does your subject s diet correlate to his or her RER at rest? While hyperventilating? While recovering from exercise? 6 How does your subject s level of physical fitness, diet, and RER correlate to those parameters from other members of the class? Appendix: Water Vapor Pressures Table HE-6-4: Table of Water Vapor Pressures for Corresponding Temperatures ( o C) Temperature( o C) Water Vapor Pressure (mmhg) Temperature( o C) Water Vapor Pressure (mmhg) During which period was the subject s VO 2 the highest? In which period was it the lowest? 3 During which period did the subject have the highest RER? In which period was the RER the lowest? HE-6-11