Noninvasive Blood Pressure Monitoring System
User's Manual 1. Introduction
1.1. General Description
The NIBP250 noninvasive blood pressure monitor is a stand-alone device for measuring the blood pressure of
small animals. The NIBP250 has a convenient touch screen LCD user interface and includes a built-in Tail Cuff
Sensor pump that automatically inflates the cuff to occlude the blood vessels in the tail of a rat or similar small
animal. Once the pump reaches maximum inflation point the cuff slowly deflates, providing a linear drop in
pressure. Using the simple touch screen interface, the blood pressure points are easily marked for analysis. The
NIBP250 returns marked values for systolic and diastolic blood pressures and calculated values for mean blood
pressure and heart rate. The NIBP250 does not require a data acquisition system or computer to analyze the
data, but can interface with existing BIOPAC data acquisition platforms and third-party systems when combining
other physiological signals.
1.2. Theory of Measurement
The NIBP250 noninvasive blood pressure system uses an adapted version of the well-known ‘Oscillometric
Technique
. Oscillometric Technique was first demonstrated in 1876 and involves the observation of oscillations in
the sphygmomanometer cuff pressure, which are in turn caused by the oscillations of blood flow, i.e., the pulse.
An electronic version of this method is sometimes used in long-term measurements and general practice. This
method relies on a sphygmomanometer cuff with an electronic pressure sensor (transducer) to observe cuff
pressure oscillations. By use of this type of sensor, the NIBP250 automatically acquires BP data, and controls the
automatic inflation and deflation of the cuff.
The cuff is initially inflated to a pressure in excess of the systolic arterial pressure and then reduced over a period
of about 30 seconds to just below diastolic pressure. When blood flow is nil (cuff pressure exceeding systolic
pressure) or unimpeded (cuff pressure below diastolic pressure), cuff pressure will be essentially constant. When
blood flow is present but restricted, the cuff pressure (monitored by the pressure sensor,) will vary periodically in
synchrony with the cyclic arterial expansion and contraction, i.e., it will oscillate. The systolic and diastolic
pressures are computed using an algorithm, and the computed results displayed.
For human use, blood pressure cuffs are snugly wrapped around the upper arm at roughly heart level. The blood
flow rate in the upper arm is measured to determine whether the flow is impeded (systolic) or unimpeded
(diastolic). For use in small laboratory animals, the cuff is placed around the tail. However, the blood flow rate in
the tail is normally too low for the oscillations to be detected with a sphygmomanometer cuff. The NIBP250
system accurately measures systolic and diastolic pressure levels using a Tail Cuff Infrared Pulse Sensor to
detect blood flow pulsations. To enhance measurement accuracy, it’s advisable to gradually heat the tail of the
animal using the optional Tail Heating Unit.
1.3. What’s Included in System
Each NIBP250 system includes:
1 - amplifier unit (switching power supply works for 110 V or 220 V)
1 - cuff/sensor
o
size 11 mm is included, but can be specified as 9.5 mm or 13 mm when ordering
o
optional MRI-compatible cuff/sensors available as add-ons: 9.5 mm, 11 mm, or 13 mm
1 - restrainer (size medium is included, but can be specified as small or large when ordering)
1 - Pulse cable to MP System or third-party A/D hardware
1 - Pressure cable to MP System or third-party A/D hardware
1 Pickering, TG; Hall, JE; Appel, LJ et al. (2005). "Recommendations for blood pressure measurement in humans
and experimental animals: Part 1: blood pressure measurement in humans: a statement for professionals from
the Subcommittee of Professional and Public Education of the American Heart Association Council on High
Blood Pressure Research". Hypertension 45 (5): 142–61.
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