A 6 year-old boy presented for redo surgery with a sub aortic obstruction. He had previously undergone aortic surgery 4 years prior and the subsequent planned operation was either further relief within the sub-aortic region or possibly a Ross procedure.The patient was 19.5kg and 107cm with a BSA of 0.76m2 His calculated flow was 2lpm The chosen circuit consisted of a preconnected Liva Nova D101,3/8” venous line and 1/4” arterial line (departmental protocol describes this up to 2.5lpm). CDI venous and arterial inline monitoring were used.The patient was anaesthetised as per usual protocol. After a re-do sternotomy heparin was administered, and bypass was started initially with a single SVC cannula, reaching 2/3 of full flow. During this time ventilation was maintained. Following IVC cannulation full bypass was reached and the ventilation stopped. Cooling to 34°C was commenced. It was noted that the inline arterial pO2 was low, FiO2 was increased but 100%was required to produce an adequate pO2 i.e. >20kPa. Attempts to reduce the FiO2 to expected levels were unsuccessful. Venous oxygen saturations were adequate throughout. An arterial blood gas confirmed the inline readings. An inline oxygen gas analyser confirmed the oxygen content. An independent gas flow analyser confirmed the gas supply. The gas line and supply were checked for leaks. The isoflurane vaporiser was temporarily turned off. An emergency oxygen cylinder was attached to the oxygenator, good oxygenation occurred. The blender was attached to emergency oxygen and air cylinders but on reducing the FiO2 below 100% the pO2 again dropped to<10kPa. The blender was changed however the issue did not resolve. The aortic cross clamp had not been applied. Circuit pressures and ACTs were acceptable.
Following discussion with the surgeon and anaesthetist and due to the potential for a prolonged bypass case the decision was made to change the oxygenator. The patient was rewarmed. A new full circuit was set up and primed on another HLM incorporating a preconnected Liva Nova Inspire 6 oxygenator 3/8” venous and 1/4” arterial line. Bypass was terminated in the usual manner and the new circuit attached to the cannula. Full bypass was established and oxygenation was good with FiO2 of 40-50%. The blood from the initial circuit was added to the new circuit and filtered.
The operation continued uneventfully, undergoing a sub-aortic resection. The patient recovered well and went home on day 5.
Following change out the anaesthetist commented that during intubation the patient had higher than expected oxygen demands.
Due to operational demands the oxygenator was not kept for investigation. It was decided that the oxygenator, although rated to greater than the patients expected need was not adequate to oxygenate with a good safety capability for prolonged surgery. Whether the oxygenator was working at full capacity is unknown. It is unusual for this oxygenator to require such a high FiO2 gas supply at the beginning of the operation even for larger patients.
The incident was reported it to the company but unfortunately the Oxy could not be sent. They asked to take note of the lot number in case there were further instances, however, without the device nothing could be concluded.
The department did experience another incidence recently with the same oxy, and same size patient struggling after a longer period of time on bypass.
The safety committee has reviewed the incident and commend the team on identifying the issue and applying appropriate corrective measures. When these measures showed that the Oxygenator was potentially to small for effective perfusion the decision was taken to change the circuit. This was done in a safe and effective manner with excellent team work and communication.