C. R. Bard, Inc.

James C Han

Morton Wexler

Timothy J Kelly

Paul J Mulhauser

Bradley J Denny

Richard M Kauder

A monitor is disclosed for measuring a liquid discharged from a patient's body. A housing defines a cavity having a floor. A substantially rigid wall container is removably positioned within the cavity, the container having a bottom wall portion supported on the floor of the cavity. A transducer is mounted in the floor of the cavity and engages the bottom wall portion of the container. The transducer is periodically engaged to transmit energy through the bottom wall portion and into a pool. The time duration required for the transmitted energy to travel from the transducer means to the upper surface of the pool and back again is determined, and this time duration is converted into a volume of fluid by reference to a look-up table, a mathematical algorithm, or both. The monitor includes an optical sensor to detect the presence of a container in the housing and provides an indication if no container is detected. The monitor also includes a transducer driving routine which drives the transducer at more than one output energy level, and responsive to detection of a weak return signal, the output energy level of a succeeding pulse is increased. A novel container is disclosed which includes a small well directly above the transducer, which has the effect of concentrating initial small amounts of liquid directly above the transducer to permit accurate readings of minute volumes of liquid.

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Lawrenceville, GA, United States of America

James C Han