Page 11 - ANZCP Gazette AUG 2023

The primary outcomes measured were cardiopulmonary bypass time and aortic cross clamp time. The secondary outcomes measured were change in haemoglobin and time spent in ICU.
Cardiopulmonary bypass strategy
Cardiopulmonary bypass was carried out using the Liva Nova S5 heart-lung machine with a centrifugal pump and an Inspire 8 hollow fibre oxygenator. The circuit was primed with 1200 ml plasmalyte. The induction dose of microplegia was delivered antegrade via an alaris infusion pump at a rate of 400 ml/hour to initiate asystole. Subsequent doses were given at 20-minute intervals and the infusion rate was decreased. In the Del Nido group, arrest was generally achieved using a single antegrade induction dose of 1000ml (20ml/kg). Both cardioplegia solutions was delivered cold (4-10 degrees) and moderate systemic hyperthermia was used.
Table 1: Composition of microplegia and del Nido cardioplegia
The patient demographic and preoperative data were examined for the two groups. There was no statistical difference in the use of cardioplegia by gender, ethnicity, BSA or EURO score. The majority of patients in this group were of NZ European origin. The patient age reached clinical significance in terms of the cardioplegia solution used.
Table 3: Perioperative and postoperative clinical data
Data analysis
Clinical data was recorded by the clinicians and entered into the Dendrite database. The data was then exported into a Microsoft excel spread sheet for analysis. The data was reported as means with their associated standard deviation. The Wilcock ranksum (Mann Whitney) test and the chi-squared test was used to compare the data between the two groups. A P value less than 0.05 was determined as clinically significant, and a P value > 0.05 did not reach clinical significance.
Results:
Table 2: Patient demographic and preoperative data
The patients in the Del Nido group had a shorter bypass time (90.46 ± 27.9 vs 103.527±33.20) and aortic cross clamp time (64.24 ± 23.56 82.60±53.66) when compared to the patients in the microplegia group. The aortic cross clamp time only reached clinical significance (P = 0.0014). In the Del Nido group patients on average spent less time in ICU and fewer patients were discharged with AF compared with the microplegia group. The comparison did not reach clinical significance.
Table 4: Perioperative and postoperative laboratory data
The average preop haemoglobin in the two groups was the same (13.35 g/dL). The lowest mean Hb on CPB was observed in the microplegia group (9.44 g/dl) but did not reach clinical significance. There was a higher amount of blood product usage in the del Nido group (23.9% vs 27.4%).
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