An FiO2 monitor had been removed from a set-up bypass machine due to failure.
A replacement was not put in place.
Bypass machine was used on patient and air escaped through the open port that should have had the FiO2 monitor in place.
The gas pathway had been checked prior to bypass, but it had not been noticed that the FiO2 monitor was absent.
Upon bypass initiation the venous saturations dropped but not immediately as there must have still been a small delivery of gas.
Once they dropped and it was noted that the blood was dark in colour, bypass was terminated, ventilation was restarted.
The FiO2 monitor was found to be missing and replaced. Bypass was re-initiated and the operation was completed successfully.
The Department amended their prebypass checklist to include the full gas pathway check including the presence of FiO2 monitor.
They also now as part of the maintenance form include that a replacement has been put in place when the defected item is removed.
The safety committee has reviewed this incident and the transparency demonstrates that human error can be commonplace and how important effective checklists and engagement is. The new check list will ensure this error can be mitigated, although it must be acknowledged that even with checklists error can happen due to human factors. We would encourage all incidents to consider the human factors that may have led to incidents for review and analysis.