Page 16 - ANZCP Gazette AUG 2023

data from a homogenous group, patients with atretic pulmonary artery, atrio-ventricular septal defects and clear double outlet right ventricles were excluded from the study. There were 1140 consecutive patients who constituted the study group.
The previously published data2,3 was re-examined, expanded upon with respect to bypass and length of stay data. Follow-up post 2005 was limited to RCH records and RMH Adult Congenital records. In general, most patients under the age of 18 had complete admission histories. Those with incomplete histories were usually interstate or overseas patients. Once transited to the Adult system many have been lost to follow-up as they are assumed to be attending adult services other than the RMH congenital clinic.
General analysis of data showed a good deal of it to be skewed, therefore medians rather than means are used. 25th and 75th percentiles as well as medians have been charted where appropriate.
Results:
Looking firstly at patient parameters there is a noticeable reduction in median age at repair up to around 2011 from where it seems relatively consistent. It has been our policy to perform the Tetralogy of Fallot repair after 4 months of age when possible.
Age at Repair (months).
Body Surface Area (BSA, DuBois and DuBois) at repair (m2).
Bypass Temperature
Analysis of bypass data clearly showed the shift from hypothermic to low hypothermic bypass and the reduced use of deep hypothermic circulatory arrest. The transition through bubbler oxygenators to plate membrane to wound fibre membrane and the resulting decrease circuit sizes and thus priming volumes and prime constituents is also shown.
DHCA was pretty much gone by the late eighties. There was only very occasional use thereafter and has not been needed since 2003. Temperature data for the first 4 years was unavailable, but I will speculate that the median temp was rising if the DHCA rate was dropping. The initial spike in the DHCA rate coincided with the adoption of TA repair and, as the surgeons became more adept with the approach the rate of DHCA dropped.
Bubblers VPCML RX05, FX05
Temperature and DHCA
As with age, median weight at repair appears to be relatively stable since around 2011. It looks like the 75th percentile might still be dropping while the 25th is relatively stable.
Weight at Repair (kg).
Prime Volume
The first 4 years of data was not available. The drop in prime volume reflects the change in patient size as the primes were calculated individually as opposed to the periods of 1988 to 2002 where the Terumo VPCML oxygenator was the most used and from 2003 where the Terumo RX05 and FX05 series of oxygenators were used, and we moved to mast mounted pump systems. These changes allowed us to shorten tubing lengths and prime volumes. Post 1989 set prime volumes irrespective of patient size have been used. It is unit policy to start bypass using these oxygenators with 80-100 mls in the venous reservoir. These volumes are post prebypass filtration with 80-100 mls in the venous reservoir.
As expected, BSA shows the same trend as weight.
14 SEPTEMBER 2023 3SCTS SPECIAL EDITION | www.anzcp.org