Introduction

The noninvasive blood pressure (NIBP100E/D) system measures blood pressure from the fingers of participants using a double cuff finger sensor. Participants wear a double cuff around two fingers which inflates and takes measurements from one finger at a time. Calibration is done with a cuff on the upper arm. It is a simple and non-invasive system based on continuous non-invasive arterial pressure CNAP™ technology.   

SOLO has both the NIBP100E and NIBP100D systems. The NIBP100E consists of finger cuff and arm cuff hardware that connect to the BIOPAC modules and is controlled via the AcqKnowledge software. The NIBP100D has the same setup, but additionally includes a CNAP monitor that connects to the cuffs and BIOPAC modules. Most instructions in this protocol apply to both systems; however, there are some differences which will be described separately.  

Protocol

Below, a general protocol for measuring blood pressure can be found. Note that an adequate training is required before working with physiological data acquisition equipment and collecting such data from participants. If you are uncertain about the procedure, please contact your supervisor or lab coordinator. For more information, see also NIBP100E & NIBP100E-HD and NIBP100D-HD Manual.

Setup

Equipment

• MP150/160 BIOPAC system

• Computer running AcqKnowledge version 5.0.7 or later (note we currently have AcqKnowledge 5.0.6 installed on most lab computers).

• Finger cuff hardware, consisting of the double-cuff finger sensor, the cuff controller, and finger sensor cable, connected to the NIBP100E or NIBP100D.
  • Note that the double cuff has an expiration date, and its performance may degrade over time. Remaining usage time can be checked for the NIBP100E. Make sure the finger cuff is connected. In Acqknowledge go to MP150/160 > Setup data acquisition > Analog. Choose the wrench icon on the line NIBP100E. Click on the About button, on the tab cuff you can find the info about the currently attached cuff. Remember to check this regularly and to organize new double cuffs in time before the expiration date. 
• Blood pressure arm cuff connected to the NIBP100E or NIBP100D.

Additionally, depending on the system you will need:  

NIBP100E  

• NIBP100E BIOPAC module connected to the MP150/160 

NIBP100D 

• The CNAP monitor, connected to the MP150/160 via a HLT100C and UIM100C Interface Connector

Materials

For SSH researchers, supplies can be picked up at SOLO 1B11 in PdlC or 2.5.01 in Sylvius, see lab supplies for more info.

No particular material is needed for measuring blood pressure, but you can wear gloves if desired. 

Participant Setup

The finger cuffs are very fragile and can easily break. Therefore, to minimize cleaning the cuffs, have the participants wash their hands with soap and preferably warm water before the cuffs are attached. If absolutely necessary, the equipment, including the cuffs can be wiped gently with a slightly moist microfiber cloth.

Make sure the equipment is connected as described at Equipment. Power on the MP160/150 device and power on the NIBP100E (button on the rear of the device) or NIBP100D (Power On/Off).

Make sure the NIBP100E/D module is turned on before continuing. The finger cuff should not be attached to the participant when turning on the NIBP100E/D.

Applying the arm cuff:

• Select an upper arm blood pressure cuff that is the proper fit for the participant. The cuff part number indicates each cuff’s circumference. The dotted line inside the arm cuff should be within the span of the index arrow. 
• Try rolling up the participant's shirt, ensuring that it doesn’t squeeze their upper arm. If it does, place the arm cuff over the participant's shirt. 
• Place the arm cuff on the participant’s upper arm, preferably contralateral to the finger cuff and on heart level.
• The marker arrow on the arm cuff should be above the brachial artery. The word “patient” should be on the inside and the “arrow” should point at the vein.

Applying the double cuff finger sensor:

• Ask the participant to remove all rings/jewelry from fingers and hand.
• Select the correct double cuff finger sensor size by using the sizing graph on the finger cuff controller. Place the base of the finger to the base of the measurement graph. If a participant’s finger size is between two cuff sizes, choose the larger cuff.
• Connect the CNAP double finger cuff to the CNAP controller.
• Apply the double cuff finger sensor on index and middle finger by sliding the participant’s fingers through the cuff. Ensure the finger cuff cable runs along the outside of the participant's arm  
• Place the cuff controller in the slide and attach it to participant’s forearm with the velcro strap and ensure the cable does not apply any additional force to the double cuff finger sensor 
• Please note: Only start measuring when fingers are in the cuffs to avoid mechanical damage of the finger cuffs.

The participant must be comfortable and sit in a natural posture with both feet on the floor. The finger cuffs are usually applied to the participant’s non-dominant hand, so that they can use their dominant hand to control the mouse or keyboard. For optimal data recording, the participant should move their hand to which the cuffs are attached as little as possible throughout the experiment.

Start AcqKnowledge and open your template. The NIBP100E will start with a calibration window. For the NIBP100D, the calibration needs to be started on the CNAP monitor. After calibrating, make sure to start the recording in AcqKnowledge.

Calibration Procedures

The NIBP100E/D is calibrated by taking blood pressure measurement from the arm cuff and using this value for calibration.

NIBP100E

Calibration is performed via AcqKnowledge. When setting up your template, the NIBP100E needs to be configured (see NIBP100E Configuration below), and you can choose the finger cuff alternation interval and arm cuff calibration settings.

After opening your AcqKnowledge template, the signal preview window will pop up and start automatic calibration. The finger and arm cuff will inflate and the signal in the preview window will be red. When calibration is complete, the signal will turn green. A countdown will appear until the window closes automatically, but you can also choose to close it manually by clicking on the close button.  

When the finger cuff switches fingers during the experiment, it will be recalibrated with the arm cuff. The finger cuff alternation interval can be set in the NIBP100E Configuration when creating a template. You can also switch fingers manually in AcqKnowledge during the recording. As shown in the picture below, you can click Turn NIBP Off to turn the module off, and Turn NIBP On if it is turned off. The middle button with a picture of the arm cuff starts a new arm cuff calibration. The timer next to it indicates the time until the next calibration. The button on the right with a picture of two fingers, allows you to switch fingers, which also starts a new arm cuff calibration. The timer next to it indicates the time until the next finger switch.

NIBP100D

Calibration is performed via the CNAP monitor. Start a new calibration by pressing the Start/Stop button on the monitor and selecting the New Patient - Adult Defaults feature. Note that while calibration is performed, no measurements are taken and recorded. Once calibration is performed successfully, you will see a bar displaying remaining time before the next calibration on the top of the monitor display. 

To change fingers during the experiment, select the left bottom quadrant and click on it. As shown in the picture below, a new window will open and you can select CNAP: Change Finger to change fingers and recalibrate. 

For more information on using the CNAP monitor, see NIBP100D-HD Manual.

Cleaning Up

NIBP100E

When the experiment is finished, press Stop in AcqKnowledge. Make sure to remove the cuffs only when they are not inflated, as it will damage them. Turn off the NIBP100E (either in AcqKnowledge or on the NIBP100E itself). 

NIBP100D

When the experiment is finished, press Stop in AcqKnowledge and turn off the CNAP monitor. Next, remove the arm and finger cuffs from the participant. Make sure to remove the cuffs only when they are not inflated, as it will damage them.

Safety Information

• Make sure the finger cuff is not positioned on the finger joints. 

• If the pressure of the finger cuff becomes too uncomfortable, you can switch the fingers.  

• If there is an emergency and you have to stop the measurement, try stopping the NIBP100E/D system to release pressure from the finger cuffs.

Tips & Tricks

• Ask participants to sit relaxed and avoid finger movements to obtain the best measurements.  

• It is important to choose the correct size for finger and arm cuff - using a size that is too big or too small can distort the blood pressure measurement.

• The cuffs can be used for a maximum of 60 minutes until they have to be recalibrated. However, the pressure can get quite uncomfortable for the participant after some time. The optimal amount of (re)calibration depends on a trade-off between experiment design (no data can be recorded during calibration) and participant comfort.  

• If you experience poor quality of the measurement, you can: 
  • Check (and fix) the position of the finger cuff.
  • Warm up cold fingers to improve the blood circulation and improve quality of measurements.
  • If the quality does not improve, try to apply finger cuffs to different fingers. 

More Information

• NIBP100E: Check the BIOPAC manual: NIBP100E & NIBP100E-HD 
• NIBP100D: Check the BIOPAC manual: NIBP100D and NIBP100D-HD Manual 
• Practical Tips for taking accurate measurements: Ensuring Error-free NIBP Measurements & Accurate Data - BIOPAC Blog 
• BIOPAC Webinar on the NIBP100E: New Integration > NIBP & BIOPAC Physiology Research System | BIOPAC
• BIOPAC Webinar on the NIBP100D: Integrating Noninvasive Blood Pressure Monitoring with Human Physiology Measurements | BIOPAC and Simplify BP & Hemodynamics Measurement | BIOPAC
• Manual for using AcqKnolwedge software including NIBP100E: AcqKnowledge 5 Software Guide