Computer Software Experts Opine on Programming Error in Defective Ventilator System


Computer Software Expert WitnessThis case involves a now-recalled bedside device used to accommodate medical patients with respiratory disorders such as COPD. In this instance a ventilator of this type was being used to supply oxygen to a sleeping patient in an Alaskan hospital who depended on the device for respiration. One week after the device was purchased, it suddenly ceased functioning, but provided no alarm to indicate that anything had gone wrong. As a result, the patient suffocated before assistance could be rendered. It was alleged that the device’s software contained a fatal flaw that allowed the device to cease functioning without providing any kind of alarm.

Question(s) For Expert Witness

  • 1. Are you capable of reading the data stored on the memory card in question to determine whether or not a malfunction was recorded?

Expert Witness Response E-037773

I have examined this model ventilator in the past and know it comes with an SD card for ventilator data. Given the relevant files and data, it is possible for me to determine whether an adverse event is recorded, and maybe even determine the cause of the incident that lead to the decedent’s death. I have a profound understanding of the operating principles of ventilators, having designed and developed these devices over the course of my career. My team, which includes experienced respiratory therapists, reverse engineers, and V&V engineers, conduct objective, 3rd party ventilator investigations, helping ventilator companies to perform independent studies on safety and performance. We possess adult and infant simulated lungs, calibrated flow sensors and other test equipment to perform these studies.

Expert Witness Response E-017517

I am capable of reading the data on the memory card. I am not familiar with this particular device and don’t know what languages or processors are involved, but it should be well within my expertise. It may require specialized equipment to translate the code to some readable form. I have consulted to or served to attorneys on about 25 cases most of which involved computer controls. I also wrote the software and firmware for two ultrasonic medical instruments and consulted to the pharmaceutical industry on compliance of computerized systems including medical devices with applicable regulations. I have examined code and/or control logic on several cases.

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