|Clinical Evaluation of a New Low Level Sensor
Horgan W J, Richards R D, Milligan P J,
Ishmael J S, Turja S J, Gray R
The LevelSens Safety System, from Rocky Mountain Research, Inc. in Salt Lake City, UT is a new low-level sensor that will alarm and notify the operator when blood or clear liquid in a reservoir has dropped below the sensor. The system incorporates a disposable fluid sensor, a sensor cable and connector and a battery operated control box. There are two models of the LevelSens Safety System, one for use with a flexible reservoir and the other for use with a rigid reservoir. In our clinical evaluation of the system we found that the LevelSens System alerted us each time the reservoir level dropped below the disposable sensor.
The LevelSens was used in more than 200 applications by our group. We evaluated the LevelSens on two different venous reservoirs, two different cardiotomy reservoirs, in two different hospitals. In order to see how well the system operated on a hard shell reservoir we elected to evaluate the system on the cardiotomy reservoirs we use for our cardioplegia reservoirs.
The sensors used on the venous bag operated at temperatures ranging from 13 C to 38.8 C. The sensors used on the cardioplegia cardiotomy reservoirs operated at temperatures ranging from 4.0 C to 38.0 C. The temperature ranges did not affect the LevelSens control box or sensor performance. We saw no effect from hematocrit levels on their system in either position.
The first system we evaluated was the Bentley BMR-1900 Venous Reservoir. After trying the disposable sensor in different locations on the bag we settled on placing the sensor just above the outlet at about 600mls. We then tried the sensor on the Bentley BCR-2000 Cardiotomy Reservoir. We are setting the sensor at about 150ml level on the cardiotomy reservoir. In order to get more experience for everyone in the group we also evaluated the system at another hospital where we used the Medtronic MVR-1600 Venous Reservoir and the Medtronic Intersept Cardiotomy Reservoir. The sensors were set at about the same levels as they were with the Bentley products.
The LevelSens Safety System from Rocky Mountain Research, Inc. was evaluated by our group on two different venous reservoirs and two different cardiotomy reservoirs at two different hospitals on over one hundred open pump cases. Our findings were that the LevelSens Safety System alarmed and alerted us each time the fluid level dropped below the disposable sensor. There was no interference with the sensor because of temperature or hematocrite. We believe that the LevelSens Safety System is a very simple device to set up and operate. It is a reliable safety system for both the flexible and rigid reservoir user. Since this evaluation, our group has incorporated the LevelSens Safety System into our set up for every procedure requiring the use on the Heart-Lung Machine.