There was a failure to remove CO2 with normal sweep gas flow rates. The patient had a calculated flow of 5LPM. Sweep gas flow rates of between 7.5-9 LPM were required to achieve a pCO2 of 5kPa. These high sweeps were required from the initiation of CPB and for the full duration of the procedure. pO2's were normal throughout.

The case was a CABGx3 with a target temperature of 34degrees Celsius. Total CPB time was 95mins.

The baseline ACT was 86 seconds. 10,000units of heparin were added to prime as per local unit protocol. 30,000 units of heparin were given pre-CPB to achieve an ACT of 466 pre-CPB. The ACT machine and cartridges used (Haemochron Signature Elite) had all been QC'd as per manufacturers recommendations. The Maquet HLM20 was used alongside rotaflow centrifugal head, electronic blender and Terumo CDI.

Baseline pre-op pCO2 was 5.4kPa. Ventilated pre-CPB pCO2 was 5.9kPa. The first ACT on CPB was 526, followed by an ACT of 443, where an additional 5000 units of heparin were administered. This returned an ACT value of 516. There was no CO2 flushing for the case and the outlet of oxygenator was checked for any obstructions.

Drugs administered throughout CPB included heparin, phenylephrine, cardioplegia, magnesium and lignocaine.