Mass General Home

Power Lab Physiological Data Collection Setup in Mock Scanner

Introduction General Setup ECG EtCO2 GSR Printer-friendly Files

1.1 - Power Lab introduction          top

1.1.1 - Data acquisition system

  • Allows for real-time display of experimental data, online and offline computations and, reversible data manipulation
  • The Chart software controls the PowerLab hardware and displays on the computer screen those electrical signals measured by the PowerLab

1.1.2 - Chart Features

  • Virtual chart recorder with up to 16 channels
  • Quick, easy set up of recording parameters
  • Recording directly to disk
  • Online calculation of heart rate, mean, systolic and diastolic pressure and more
  • Easy unit conversion (2 point signal calibration)
  • Flexible triggering and stimulation options
  • Comment fields during or after recording
  • Automation of experimental procedures
  • Data analysis and display features which include: statistical measures, data smoothing, interchannel arithmetic and data exclusion

1.1.3 - Basics of data acquisition

The purpose of the PowerLab system is to acquire, store and analyze data. How does data acquisition occur?

  • Chart records voltage data from an external source (like a pulse transducer) this raw input signal is in the form of an analog voltage whose amplitude varies over time.
  • This voltage is monitored by the hardware and through signal conditioning can amplify, filter, zero… to remove any unwanted steady offset voltage
  • After signal conditioning, the analog voltage is sampled at regular intervals
  • The signal or sampled voltage is then converted from analog to a digital representation
  • The computer software displays the data directly

1.2 – Physiological Setup   top

1.2.1 - General Setup

  • Connect the USB cable from the PowerLab amplifier to the GCRC laptop (See images below)
    The USB cable from PowerLab The USB cable plugged into the laptop
  • Turn the laptop on and start Chart
  • Make sure that all desired peripheral equipment (ECG, EtCO 2, GSR, etc) is attached (see below)
  • When ready for data acquisition, press the “Start” button to begin

1.2.2 - ECG (Electrocardiogram)  top

Reference Range

  • 50 – 100 beats per minute. This varies from one person to the next based on cardiac conditioning, exercise, medications, and anxiety.

Default Settings

  • Check the PowerLab ECG bioamp ( image below left). Make sure the cable is attached to the PowerLab amplifier BNC channel output [see image below on right].
  • Confirm that the BNC input channel matches the channel set for ECG “channel settings” [ see image below on right] in chart (*note: the designated channel for ECG may vary depending on how it was setup)
    Powerlab power cable
    PowerLab amplifier
  • Attach ECG electrodes to the subject in preferred configuration and snap-connect the plastic coated insulated ECG leads to the electrodes on the subject

    The standard configuration is as follows: (facing the subject) upper left=white, upper right=black, lower right=green [see image on right]

    On women, place the lower right electrode directly below the left breast

1.2.3 - EtCO2 (End-tidal Carbon Dioxide) top

  • Attach the nasal cannula (CO 2 respiratory tube) [ image below left] to the port on the Capstar CO 2 sensor pod [ image below right]. There should be a male to male tube adaptor attached to the sensor pod to allow the cannula to attach.
    Nasal cannula Capstar sensor pod
  • Make sure the red “fast” button [ images below left and middle] is pushed in on the blue Capstar-100 C0 2 Analyzer [ image below right]
  • Make sure the cable connected to “EtCO 2” on the Capstar sensor pod is connected to the correct channel on the PowerLab amplifier. This channel should match the channel set for EtCO 2 in “channel settings” [ see image below]
    EtCO 2 channel in “Channel Settings” of Chart

ETCO2 calibration and use for GCRC/Mock Physio Equipment-CapStar-100 ETCO2 analyzer top

    • Turn Unit on for at least 5 minutes before sampling
    • When the instrument is warmed and the SAMPLE INLET port is open to room air, adjust the Zero knob on the front panel to get a reading of 0%
    • Once a stable zero is established, a known calibration gas is introduced to the SAMPLE INLET.
    • Adjust the SPAN knob until the display indicates the concentration of the calibration gas
    • The digital display can report CO2 concentration in either % or mmHg (see DISPLAY MODE on front of Unit)
    • The display can report either a FAST response to changing concentration or an End Tidal (ET) reading. The FAST response display is updated about 3 times per secondand is the preferred mode
    • Once calibration is complete, attach nasal cannula to subject
    • To display data on the Powerlab monitor, follow above steps to convert voltage to mmHg for your display

No condensed water or fluids should enter the sample cell, this will shift the zero or make zeroing impossible. A moisture trap should be used between the sample site and the SENSORPOD sample inlet

1.2.4 - GSR (Galvanic Skin Response) top

Refernce Range

Baseline levels usually 10 – 50 uS

Default Settings

Hardware Setup

  • Attach the GSR banana cables directly into the GSR amp (image on the right).
  • Check the BNC channel output for GSR and make sure this channel matches the channel set in the “channel settings” [ image below] of Chart.

    GSR channel in “Channel Settings” of Chart

GSR Electrodes top

  • Have subject wash their hands in soapy water followed by rinsing and thorough drying.
  • When ready to place the electrodes on the subject, place a little isotonic Biopac 101 gel inside the well on the electrode (fill to top of well) to enhance conductance [ image below left].
  • Use a paper towel to skim off the top – level the gel to fill the well and only the well [ image below right].
  • Go to PowerLab and click on the output for GSR, and select “GSR amplifier”[ see image below].

    getting to “GSR Amplifier” in chart

  • Click “Open Circuit Zero” (do this before connecting the electrodes to the subject) [ see image below]

    Screen grab of “Open Circuit Zero”
  • Connect the electrodes to the tips of the index and ring fingers (or toes) of the subject [ image right]

    Note the subject's GSR level (this may differ for different subjects).

  • Go to Power Lab's “GSR amplifier” [ image below] and click “subject zero”
    Screen grab of “Open Circuit Zero”
  • Access the GSR menu by placing the cursor on the down arrow to the right of the channel title [ image below] top
    Screen grab of subject zero
  • Printer-friendly Files top
  • Plese click here for a Word document.
  • Plese click here for a PDF document.

Key Personnel