Two separate incidents of oxygenator failure in afternoon cases following pump standby. In both cases, a pre-primed pump (at 0800 on the same day) was utilised for an afternoon case following on from a pump standby morning case, which is within our current SOP.
Case 1 - It was noted that oxygen delivery responded sluggishly to increases in FiO2 and an excessive FiO2 delivery (up to 100% O2 delivery) was required to maintain sufficient PaO2. The case (combined AVR+CABGx3) required beating heart bypass for the CABGx3 element, during this time the perfusionist continued to assess the deteriorating oxygenator and prior to applying the cross clamp for the AVR component a decision was made to electively wean from bypass, complete an oxygenator changeout and re-establish bypass. This was carried out without incident and the new oxygenator resolved the oxygen delivery issues with acceptable FiO2 parameters.
Case 2 - Upon establishing bypass, Pa02 responded sluggishly to changes in FiO2, whilst Pa02 were below SOP targets remained adequate to oxygenate the patient. Again excessive FiO2 was required to achieve this. The oxygenator was continually monitored and function deteriorated during the bypass run, requiring over 90% O2 delivery to keep adequate oxygen delivery. Whilst there was a decision to not exchange this oxygenator electively, the team had prepared for a potential oxygenator changeout.
Supplier of Oxygenator informed, devices kept for analysis. Internal incident forms completed. Perfusion team aware of potential risk of poor functioning oxygenators when utilising wet build pumps. PRONTO loops discussed, and PRONTO requested from supplier.
The pronto loop will go between the arterial pump outlet (roller or centrifugal as we use both)and oxygenator, this will enable the ability to monitor pre-membrane pressures and enables a replacement oxygenator to be cut in, primed, and exchanged without coming off bypass. Wetlab practice and drills have been effective. Pre-membrane pressure monitoring is now standard in the pronto loop.
The department had a lower confidence in a few other cases where the required FiO2 concentrations are not in keeping with our standard practice and as a result and in discussion with the manufacture have removed the batch from use and using a new batch of oxygenators. The only similarities with the two cases are that the circuit has been primed for a few hours before use in afternoon cases due to covering off pump cases in the morning.
Additionally, the department have started CO2 flushing their circuits when they are covering off-pump work and are therefore they are likely to be wet for a few hours, as there is evidence in the literature that this may reduce the risk of high-pressure excursions.
The safety committee have reviewed this incident and will review if there has been a trend with this device in other centres contacting the manufacturers.
Awaiting report form the manufacturers.