A (b)(6) y/o male pt with a complex medical history underwent a right sided fistulogram.He was given supplemental oxygen via mask.Immediately prior to the start of the procedure, there was a handoff of care between anesthesiologists.The pt was awake at this time.Intravenous medications were administered.Following this, the pt experienced a short period of respiratory distress; an oral airway was placed and mask ventilation was initiated.It was at this point, the anesthesiologist discovered the oxygen delivered through the carestation machine had been set to the bag / ventilator setting rather than the auxiliary / mask setting.He immediately switched the dial in the machine to the correct setting.An lma was placed and the pt was placed on pressure support ventilation.While the pt's oxygen saturation improved, he remained unresponsive following the procedure.During the investigation into this matter, it was discovered in most anesthesia machines, oxygen intended to be delivered via circuit (bag, ventilator) is completely separated from oxygen administered through the auxiliary mode (nasal or mask), with independent flow meters that are not shared so as to not lead one to believe oxygen is being delivered via auxiliary when it is not.However the ge carestation, 650 anesthesia machine is atypical in that - both modes of operation, auxiliary oxygen and bag / ventilator oxygen, share one source of oxygen which requires use of a valve rather than having two different sources of oxygen with no valve.Both modes, auxiliary oxygen and bag / ventilator oxygen, share the same oxygen flow display (electronic and cylinder) which could cause the provider to believe he or she is administering auxiliary oxygen when the flow is actually going through the circuit.The valve modality labeling has small graphics and a faint light which while intended to help distinguish which mode the oxygen is flowing through can potentially be missed.When the machine is in the auxiliary mode, a large yellow warming appears on the screen indicating the ventilator cannot be used; however, when the circuit mode is used, there is no warning that the auxiliary oxygen cannot be used.In addition, when a practitioner performs the asa, apsf pre-anesthesia check out, the machine must be left in the circuit mode which could cause one to easily miss that they had not switched the valve to the auxiliary mode.This machine also requires two valves to be in proper alignment in order to administer oxygen to the ventilator or bag mode which is also very atypical adding to the confusing user interface.It was thought the unusual design of this machine may have contributed to this event.Fda safety report id# (b)(4).
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