Blood Pressure - Intravascular

Overview:

Blood pressure is regulated by the cardiovascular system and is a widely used parameter in cardiovascular assessment. It is defined as the amount of pressure exerted on the walls of blood vessels by the blood. Blood pressure is accurately measured using invasive techniques that allow pressure to be continually monitored beat-by-beat and a waveform of pressure against time displayed.

Arterial blood pressure is often recorded from a peripheral artery such as the carotid or femoral, and may be used to derive mean arterial pressure (MAP), systolic pressure, diastolic pressure, pulse pressure or used to monitor anaesthesia.

Method:

Fluid-Filled Transducer Technique

Invasive recording of arterial or venous blood pressure in animals is required in a wide range of research and teaching applications. A polyethylene catheter (PE-50 [1 mm O.D.] for rats; PE-10 [0.5 mm O.D.] for mice) is attached to a pressure transducer (both being prefilled with heparinized saline), and inserted into the blood vessel of interest and then tied in place. Pressure fluctuations in the vessel are then transmitted along the catheter tubing to the transducer’s diaphragm, which moves in response. The diaphragm movements are converted into a varying electrical signal that is amplified through a Bridge Amplifier and recorded by a PowerLab system.

Cannula Connection

Details of cannula connection and filling methods vary greatly from laboratory to laboratory. An example includes; the cannula (PE tubing) is connected to one of the Luer fittings (‘cannula port’) on the transducer, with or without an intervening pressure line. Heparinized saline is then introduced through the other Luer fitting (‘filling port’) to fill the transducer and backfill the cannula. Care must be taken during filling to avoid air bubbles being formed. Lastly, a stopcock on the filling port is closed off, leaving the cannula as the only hydraulic connection from the transducer.

After the cannula has been tied into the blood vessel, it is necessary from time to time to inject small quantities of heparinized saline (via the filling port) to prevent clotting of blood in the cannula.

Mikro-Tip Pressure Catheters

Mikro-Tip Pressure Catheters are inserted directly into the blood vessel of interest and tied in place. Pressure fluctuations are measured straight from the source through a high fidelity pressure transducer that is located at the tip of the catheter allowing for precise resolution of the signal. Mikro-Tip pressure catheters are solid-state and resistant to movement artifacts, provide an excellent frequency response (up to 10 kHz) and do not attenuate or dampen the pressure signal.

There is a large selection of Mikro-Tip Catheters available for a variety of animal species (including mice, rats, cats, dogs, pigs, sheep, cattle, horses, etc). Dual pressure sensor catheters are also available for recording two pressure signals simultaneously, for example atrial and ventricular pressure.

Mikro-Tip Catheters connect easily to the PowerLab systems using any ADInstruments Bridge Amp and a Catheter Interface Cable. The Mikro-Tip BP Foundation System is also available.

Calibration
For information on Pressure Transducer Calibration, please refer to the Pressure Transducer Calibration (64 KB) technique note.

Recording Settings
For information on recommended blood pressure sampling rates and filtering options, please refer to the Signal Filtering (199 KB) technique note.

Wireless Recording

Telemetry systems facilitate study in conscious, free moving and unstressed animals and offer a more realistic insight into animal physiology, particularly physiological parameters that may be influenced by the sympathetic nervous system. ADInstruments supplies small animal telemetry systems by Telemetry Research suitable for use with PowerLab systems. The Telemetry Small Animal Foundation System is also available.

Telemeters are selected according to the animal species and signals of interest. Implantation of the telemeters requires specialized surgical training. The innovative power supply enables simultaneous recharging of the implanted telemeter battery while recording.

Analog adapters for interfacing PowerLab systems with a range of DSI Telemetry Transmitters are also available and allow data acquisition and analysis in LabChart.

Related areas of interest include:

Software:

The LabChart Advantage:

(may require additional Modules and Extensions)

  • LabChart data files can be marked with events using the Comments feature
  • Blood pressure parameters such as heart rate, systole (maximum) and diastole (minimum), and mean arterial pressure can be recorded and displayed in real-time using Cyclic Measurements, Arithmetic and the Data Pad
  • The Units Conversion feature can be used to convert signals into relevant units e.g. mmHg
  • Macros can automate many tedious and repetitive analysis tasks
  • Automated extraction of data from recordings using online Timed Add to Data Pad or offline using Multiple Add to Data Pad
  • The LabChart Blood Pressure Module enables beat-by-beat or signal-averaged analyses of arterial and ventricular waveforms.
  • Extracted parameters in the Data Pad or BP Table View can be easily exported for further analysis, e.g in Excel or Matlab

LabChart

LabChart software (for Windows and Macintosh) together with a PowerLab data acquisition system offers up to 32 channels of real-time data acquisition, data integrity, easy selection of hardware settings, powerful online and offline analysis, procedure automation, seamless extraction of experimental data and flexible display options. Additional acquisition and analysis functionality is provided with the use of specialized LabChart Extensions and LabChart Modules. Modules are available as part of LabChart Pro while Extensions are free for download from the website for existing LabChart users.

Blood Pressure Module
The Blood Pressure Module (Windows) automatically detects, analyzes and reports cardiovascular parameters from arterial or ventricular pressure signals.

The Settings dialog allows the user to select arterial or ventricular pressure for analysis and the Classifier View allows for easy selection of pressure waveforms for further analyses. Pressure signals with unusual cycle height and duration can be easily excluded using the data selection tool within the Classifier View.

The Analysis View displays pressure cycles as beat-by-beat or as the average of a specified number of cycles. The calculated parameters are logged in the Table View for easy exporting.

Features and benefits include:

  • Suitable for analysis of pressure signals from humans as well as large and small animals
  • Pressure signals can be analyzed in real time during acquisition
  • The BP Classifier simplifies detection and exclusion of atypical waveforms
  • Parameters can be displayed as continuous data on separate channels
  • Values are logged to the Table View
  • Averages any number of pressure waveforms

Calculated arterial parameters include:

  • Systolic, Diastolic and Mean Pressure
  • Pulse Pressure
  • Dichrotic Notch Pressure
  • Ejection and Non-ejection duration
  • Cycle Duration
  • Heart Rate
  • Time to Peak
  • Mean Diastolic Pressure

Calculated ventricular parameters include:

  • Maximum Pressure
  • Maximum dP/dt
  • Isovolumetric relaxation time constant (tau)
  • linear fit (IRP Average dP/dt)
  • exponential fit
  • Minimum Pressure
  • Minimum dP/dt
  • Mean Pressure
  • End Diastolic Pressure (EDP)
  • Maximum-Minimum Pressure
  • Contractility Index
  • Systolic, Diastolic, Cycle Durations
  • Pressure Time Index
  • Heart Rate

GLP and 21 CFR Part 11
For those researchers working within a laboratory requiring GLP and 21 CFR Part 11 compliance, the GLP Client and GLP Server are available for use with LabChart (Windows only) and PowerLab data acquisition systems. For more information, visit the Good Laboratory Practice application page or contact your nearest ADInstruments representative.

Hardware:

PowerLab Data Acquisition Systems

The PowerLab is a high-performance data acquisition unit capable of recording at speeds of up to 400,000 samples per second continuously to disk (aggregate). PowerLab units are compatible with instruments, signal conditioners and transducers supplied by ADInstruments, as well as many other third-party companies. In addition to standard single-ended BNC inputs, 4 differential Pod ports are also available for direct connection of Pod signal conditioners and appropriate transducers. Research PowerLab units include:

Research Systems

Mikro-Tip Blood Pressure System

Telemetry Foundation Systems

Note: Telemeters are NOT included in research systems and must be purchased separately.

Signal Conditioners

Bridge Amplifiers

Mikro-Tip Pressure Catheters and fluid-filled blood pressure transducers can connect to PowerLab data acquisition systems via our software-controlled bridge amplifiers including:

BP Amplifier (Human use)

Transducers and Accessories

Mikro-Tip Pressure Catheters

ADInstruments offers the full line of Millar Mikro-Tip Pressure Catheters ranging from 0.8F (for small animals) through to 7F (for large animals). These catheters are for use ONLY in animal research. Mikro-Tip Pressure Catheters may be interfaced to a PowerLab through ADInstruments Bridge Amplifiers (using either an AEC-10C Catheter Interface Cable (Viking) or AEC-10D Catheter Interface Cable (Low-profile).

These include:


Fluid-filled Pressure Transducers

Intravascular blood pressure may be recorded using fluid-filled catheters (typically made from polyethylene tubing) attached to any of the following transducers:

Bridge Amplifier Catheter Interface Cables

Calibration

  • MLA1052 Pressure Gauge For use with conventional fluid-filled pressure transducers and Millar Mikro-Tip pressure catheters

Other Fluid-filled Transducer Accessories

Blood Pressure Telemeters
The pressure telemeters are suitable for measuring intravascular or intraluminal pressure. These include:

Telemetry Blood Pressure Consumables

Analog Adapters for DSI Transmitters

The acute effect of atrioventricular pacing on sympathetic nerve activity in patients with normal and depressed left ventricular function
Segerson N M, Wasmund S L, Daccarett M, Fabela M L, Hammond C H, Stoddard G, Smith M L, Hamdan M H, American Journal of Physiology: Heart and Circulatory Physiology, H1076–H1080, 2008

Expression Of Group I Metabotropic Glutamate Receptors On Phenotypically Different Cells Within The Nucleus Of The Solitary Tract In The Rat
J. R. Austgen, A. Y. Fong, C. M. Foley, P. J. Mueller, D. D. Kline, C. M. Heesch and E. M. Hasser , Neuroscience, 701-716, 2009

Lack of S100A1 in mice confers a gender-dependent hypertensive phenotype and increased mortality after myocardial infarction
Desjardins JF, Pourdjabbar A, Quan A, Leong-Poi H, Teichert-Kuliszewska K, Verma S, Parker TG, American Journal of Physiology: Heart and Circulatory Physiology, H1457-H1465, 2009

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The material on this page is provided in good faith and believed accurate at the time of writing. No responsibility will be taken, or liability accepted, for damages arising from the use of information herein. Readers are urged to check with respective manufacturers the accuracy of all product related information.

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