Flow & Bubble Detection

The measurement of Blood Flow:

To provide the accurate measurement of blood flow Spectrum Medical uses the latest ultrasonic technologies and the proven concept of “transit time”.

Clamp on probe body

Transit time is the name given to the “phase delay” between a pair of opposing Ultrasonic transmitters and receivers.  Pair one will measure the upstream transit time and pair two will measure the downstream transit time.
The transit time of the ultrasonic signal is decreased when travelling downstream with the blood flow and increased when travelling upstream against the blood flow.  The phase delay between the integrated transit times is a measure of flowing blood.

If the transit times were equal in both the upstream and downstream sensing systems this would indicate that blood flow was static.


The Measurement of Emboli and Gross Emboli (bubbles)

Unlike blood flow, which is detected by changes in signal phase, emboli or gross Emboli (bubbles) is measured by detecting reductions in Ultrasonic signal strength.  Gas as opposed to flowing blood is a poor conductor of ultrasonic energy and as emboli pass through the sensing elements the ultrasonic signal is reduced. 

The level of emboli volume within the flowing blood will be dependent on the level of signal reduction multiplied by the number of signal reduction events.


Using ultra low-noise electronic technologies maximizes system sensitivity and speed of measurement.  With channel specific samplings speeds now in excess of 2500 times per second Spectrum Medical has ensured system sensitivity to the presence of Emboli or Gross Emboli (bubbles).


HCT/SO2 Part Number Tube ID Tube Wall Tube OD Flow Probe Part Number
3003-010-023 3/16 1/16 5/16 H5XLA
3003-010-024 3/16 3/32 3/8 N/A
3003-010-022 1/4 1/16 3/8 H6XLE
3003-010-021 1/4 3/32 7/16 H7XLH
3003-010-020 3/8 3/32 9/16 H9XLM
Venous Only 1/2 3/32 11/16 H11XLD