Instruments for physiology and respiration

Home

Data Sheets

Amplifiers

Blood Pressure

Gas Analyzers

Ventilators

Temperature

Mouse products

New Products

Representatives

Meetings

Contact us!

 

Blood Pressure     

Measuring blood pressure (BP) is a common requirement for many experimental procedures. It is typically done in one of two ways: direct or indirect (NIBP).

The direct method is straightforward, but requires catheterization of a major artery. The catheter is connected to a blood pressure transducer and suitable amplifier to produce an analog signal. This signal can be observed on an oscilloscope, or fed into a data acquisition system for recording and analysis.

The NIBP method uses an inflatable cuff around the tail of the animal, a means of inflating/deflating the cuff, and a means of detecting pulsatile blood flow. Depending on the equipment, special software is required to monitor the results, or the measurements can be sent serially to a computer for data collection.

Important note: NIBP systems differ in the means of pulse detection. Mice and rats increase blood flow to their tails as a means of thermoregulation; as the body temperature increases, blood flow is diverted to the tail for heat radiation. The less-sensitive piezo-electric transducers require this heating to get an adequate signal. The more sensitive photoplethysmographic technique normally does not require heating above ambient temperature. It has long been known that heating the animal produces thermostress, and actually increases BP. Thus the well-established photoplethysmographic method produces the most accurate measurements. 

The table below lists the major features and advantages of each of these methods of measuring BP. Click on the highlighted link to go directly to that page.

Direct arterial BP tracing

 NIBP waveforms
Direct BP Indirect BP (NIBP)
 þ  "Gold standard" for accuracy  þ  Good accuracy (<+6mmHg) depending on technique
 þ  Continuous measurement  þ  Intermittent measurement
 þ  Analog signal suitable for data acquisition  þ  Requires software to compute measurements
 þ  Both systolic and diastolic measurement  þ  Both systolic and diastolic measurement
 þ  Mean BP requires processing of raw signal  þ  Provides Mean BP
 þ  Signal must be processed to get heart rate (HR)  þ  Provides heart rate (HR)
 þ  Requires surgery to place catheter  þ  No surgery required
 þ  No special restraints required  þ  Requires restraining animal in holder
 þ  Periodic flushing of catheter required  þ  Periodic inflation/deflation of cuff required
 þ  Does not require warming of animal  þ  Some systems require warming of animal to increase blood flow in extremities (see note)
 þ  MRI-compatible  þ  MRI-compatible
   

Note: The photoplethysmographic NIBP systems sold by CWE are inherently more sensitive than piezo sensor systems, and do not normally require animal heating.

 

A M P L I F Y   Ÿ   A C Q U I R E   Ÿ    M E A S U R E   Ÿ     V E N T I L A T E   Ÿ    M O N I T O R

Send mail to  info@cwe-inc.com  with questions or comments about this site or our instruments.
Last modified: August 09, 2009