Method and apparatus for ultrasonic detection of air bubbles
US5394732A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 10, 1993 |
| Grant date | Mar 7, 1995 |
| Priority date | — |
| Expiry date | Sep 10, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/102
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Inclusions in a liquid flow, such as air bubbles in a blood flow, are detected by transmitting a signal through the fluid and receiving and interpreting the received signal based on the expected degree of attenuation for the liquid and the inclusions. The amplitude of the transmitted signal is automatically adjusted to maintain a constant average amplitude of the detected signal, thus compensating for changes in the detection environment. The average amplitude of the transmitted signal is controlled by integrating the received signal using an integrator with a time constant longer than the time constant of the expected inclusion signals, and comparing the integrated signal to a constant reference level. The presence of microbubbles is detected and a signal comprising a string of high frequency pulses is generated while the microbubbles are present. By counting the pulses, in conjunction with knowledge about the flow of liquid and the anticipated size of the microbubbles, an estimate of the total amount of air infused into the patient within a given time period is calculated. A tubing holder for retaining a flexible tube in an inclusion detector has tubing retention grooves formed i…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.