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Review of the logs provided showed that the timing between m540 and cockpit was not aligned.A signature entry following the timing discrepancy was identified (i2c [inter-integrated circuit] master communication error).When this communication error occurs, the cockpit attempts to correct the issue and in the cases it cannot, as a result, the cockpit closes all communications to the m540.When this occurs, the m540 maintains monitoring capability as intended as a stand-alone patient monitor.Notably, discharging the patient from the m540 resolves the issue, re-establishes connection and the patient can be reassigned to the monitor.Attempts to reproduce the disconnect issue at draeger have been unsuccessful in a simulated clinical test setup.Hardware testing was performed including a radio frequency (rf) immunity test on a customer returned system with focus on radio frequency identification (rfid) frequencies and applications.This was performed as it had been observed that systems with a capsule rf card reader nearby had disconnected.This testing was performed at a certified test lab (reference jira case thorsw-59158).The disconnect issue could not be reproduced.Additionally, a comparative study of the m540 i2c bus timing was made on a known good m540 unit as compared to an m540 unit which was returned from the field with a report of a cockpit disconnect.No anomalies were identified.Based on draeger investigation, the following causes of the m540 disconnects were excluded iacs/m540 hardware defects: no returned device malfunctions were identified, use of non-medical grade power cords, iacs/m540s being plugged in through the apollo anesthesia power strip instead directly to the ac wall outlet - this was assessed to isolate the iacs power source and exclude any power quality/degradation factors from obtaining power through the apollo workstation's power strip or impacts from other devices connected to the strip.(e.G., ac wall outlet to apollo workstation power supply to iacs power supply to m500 docking station and cockpit), compatibility of the m500 firmware in the iacs systems (vg4.2 compatible with firmware versions 4.0 or 4.4), emi (electromagnetic interference) from sources in environment, potential electrical interference from the site power line coming in, site patient profiles in use during disconnections were tested during attempts to recreate the issue at draeger.After extensive investigation where no device malfunctions were identified and the above external factors were excluded, specific root cause cannot be definitively established beyond the potential for an environmental anomaly localized to these operating rooms/sites.Though the specific root cause cannot be determined, based on this investigation, draeger has identified an opportunity to develop software code changes that are intended to prevent the cockpit from disconnecting due to timing alignment issues, regardless of the cause, for a future software release.
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