# Vernier Blood Pressure for NI ELVIS II

Publish Date: Oct 30, 2011 | 0 Ratings | 0.00 out of 5 | Print | Submit your review

## Overview

Students learn basic concepts of acquiring systolic and diastolic blood pressures. Students learn about the various factors which influence blood pressure by working and becoming familiar with Vernier’s blood pressure sensor. This lab also introduces the Noninvasive Blood Pressure Analyzer of the NI Biomedical Startup Kit.

#### Theory

This lab uses the oscillometric method as a way to non-invasively measure blood pressure. This method is based on the principle that blood pumped through the arteries by the heart causes the arterial walls to flex. First, a cuff is placed around the upper arm to occlude the brachial artery. When the cuff is inflated and then slowly deflated at a constant rate, an arterial pressure pulse forms, which passes through the arm and into the cuff itself. When the cuff reaches maximum inflation, the artery becomes highly occluded which stops pulsations of the blood. As the pressure in the cuff slowly decreases, blood pressure increases and the blood is forced through the artery in short pulses. As the pressure in the cuff continues to decrease, the pulses become increasingly significant until maximum amplitude is reached. The cuff pressure corresponding to this amplitude approximates the mean arterial pressure (MAP). At that point, the pulses will begin to decrease with any further decrease in cuff pressure.

These pressure pulses form an oscillating waveform and the peak-to-peak amplitudes of this waveform create a bell shaped “envelope” (Figure 1). The systolic blood pressure (SBP) is calculated by determining the point along the envelope prior to the MAP using a known percentage of the maximum amplitude. Diastolic blood pressure is calculated using the same method but with the portion of the envelope following the MAP.

(Summarized from the Blood Pressure Sensor User Guide; http://www.vernier.com)

Figure 1: Oscillatory Waveform of Blood Pressure Pulses

#### MATERIALS

• NI Biomedical Startup Kit 3.0
• NI ELVIS II Series Benchtop Workstation
• NI ELVIS II Series Prototyping Board
• AC/DC power supply
• NI ELVISmx 4.0 or later CD
• High-speed USB 2.0 cable
• Computer
• Wires to build circuits
• Vernier Analog Proto Board Connector (Order Code BTA-ELV)
• Vernier Blood Pressure Sensor (Order Code BPS-BTA)

To set up the experiment with the Biomedical Startup Kit:

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Attachments:

Instructions for Vernier Blood
Pressure for NI ELVIS II

Requirements

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