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Australas Phys Eng Sci Med. 2019 Mar 13. doi: 10.1007/s13246-019-00746-5. [Epub ahead of print]

Development and validation of a measurement system for continuously monitoring postoperative reservoir levels.

Eichhorn S1,2, Reisinger T3,4, Böhm J3,4, Voss S3,4, Doppler S3,4, Lange R3,4,5, Krane M3,4,5.

Author information

1
Department of Cardiovascular Surgery, German Heart Center Munich at the Technische Universität München, Lazarettstrasse 36, 80636, Munich, Germany. Eichhornst@gmail.com.
2
Department of Cardiovascular Surgery, INSURE (Institute for Translational Cardiac Surgery), Technische Universität München, Lothstrasse 11, 80636, Munich, Germany. Eichhornst@gmail.com.
3
Department of Cardiovascular Surgery, German Heart Center Munich at the Technische Universität München, Lazarettstrasse 36, 80636, Munich, Germany.
4
Department of Cardiovascular Surgery, INSURE (Institute for Translational Cardiac Surgery), Technische Universität München, Lothstrasse 11, 80636, Munich, Germany.
5
DZHK (German Center for Cardiovascular Research), Partner Site Munich Heart Alliance, 80636, Munich, Germany.

Abstract

Following cardiac surgical procedures, multiple drainage systems remain in place inside the patient's chest to prevent the development of pericardial effusion or pneumothorax. Therefore, postoperative bleeding must be diligently observed. Currently, observation of the exudate rate is performed through periodical visual inspection of the reservoir. To improve postoperative monitoring, a measurement system based on load cells was developed to automatically detect bleeding rates. A reservoir retaining bracket was instrumented with a load cell. The signal was digitized by a microcontroller and then processed and displayed on customized software written in LabView. In cases where bleeding rates reach critical levels, the device will automatically sound an alarm. Additionally, the bleeding rate is displayed on the screen with the status of the alarm, as well as the fluid level of the reservoir. These data are all logged to a file. The measurement system has been validated for gain stability and drift, as well as for sensor accuracy, with different in vitro examinations. Additionally, performance of the measurement device was tested in a clinical pilot study on patients recovering from cardiac surgical procedures. The in vitro investigation showed that the monitoring device had excellent gain and drift stability, as well as sensor accuracy, with a resolution of 2.6 mL/h for the bleeding rate. During the clinical examination, bleeding rates of all patients were correctly measured. Continuously recording drainage volume using the developed system was comparable to manual measurements performed every 30 min by a nurse. Implementation of continuous digital measurements could improve patient safety and reduce the workload of medical professionals working in intensive care units.

KEYWORDS:

Measurement system; Postoperative monitoring; Surgical reservoir

PMID:
30868479
DOI:
10.1007/s13246-019-00746-5

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