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Jabur et al. 3 Table 1. Patient demographics+EuroSCORE II+selected details of cardiopulmonary bypass management.
Factor
Age (years)
Gender (male/female)
Body surface area
EuroSCORE II
Bypass time (minutes)c
Aortic cross-clamp time (minutes)d
Open chamber (n = 20), mean (SDa), median (IQRb) or numbers
Closed chamber (n = 20), mean (SDa), median (IQRb) or numbers
63.3 (8.3) 20/0
2.1 (0.2)
0.9 (0.7–1.4) 81.5 (64.5–91.0) 55.5 (44.5–66.0)
2012 Microsoft Corporation) spreadsheet for analysis. As the data were not normally distributed, they were reported as medians with an interquartile range (IQR), and nonparametric tests were used for statistical analy- sis. The Wilcoxon paired signed-rank test was used to compare the emboli counts in the right and left MCA. The two-sample Wilcoxon rank-sum (Mann-Whitney) test was used for comparing the open- and closed- chamber groups. Statistical significance was defined with a p-value < 0.05. The statistical analysis was per- formed using Stata, version 16 (StataCorp LLC, TX, USA). No corrections for multiple comparisons were made.
Results
Of an approximate pool of 1400 potential patients, forty subjects were recruited. In the recruitment process, one subject approached declined to consent, two consented but were found to have an inadequate transtemporal ultrasound window, six were consented but were with- drawn from the study due to technical equipment issues in theatre, and eight were consented but had their sur- gery cancelled on the planned day.
Relevant characteristics of the patients undergoing OCS (n=20) and CCS (n=20) are shown in Table 1. One patient was female, and 39 were male.
Total (median (interquartile range)) emboli counts (both phases) were 898 (499–1366) and 2617 (1007– 5847) in CCS and OCS respectively (Table 2). The vast majority were gaseous; median 794 (CCS) and 2240 (OCS) (Table 3). When normalized for duration, there was no significant difference between emboli exposures in CCS and OCS in phase 1: 6.8 (3.6–15.2) versus 6.4 (2.0–18.1) emboli per minute (p=0.85), respectively (Table 2). In phase 2 CCS cases were exposed to mark- edly fewer emboli than OCS cases: 9.6 (5.1–14.9) versus 43.3 (19.7–60.3) emboli per minute (p < 0.001), respec- tively (See Table 2). Combining data from all cases and both phases, more emboli passed into the right cerebral
64.7 (12.3) 19/1
2.1 (0.2)
1.1 (0.8–2.0) 96.5 (65.5–159.0) 70.5 (46.0–74.5)
aStandard deviation.
bInterquartile range.
cTwo patients in each procedural group had two bypass periods. dOne patient in each procedural group had two cross-clamp periods.
(pulmonary veins) and aortic venting during cardiac filling and ventilation until no further air was observed on the transesophageal echocardiogram. Aortic root and venting of the left heart were continued after termi- nation of CPB in the event of visible remaining air in the heart, or according to surgeon preference. The de- airing vents and the venous cannula were decannulated before the administration of protamine. Decannulation of the aortic cannula took place after protamine admin- istration was complete, and the patient was haemody- namically stable.
Continuous emboli counts in the right and left MCAs were recorded using two 2.25 MHz transducers fitted on a DiaMon head brace (DWL/Compumedics Germany GmbH, Singen, Germany). The head brace was placed on the patient’s head once the patient was fully anaesthetized. The depth of insonation on the TCD transducers was varied between 35–65 mm until bilateral representative spectral MCA flow was identi- fied. High-intensity transient signals representing emboli were defined as short-duration, high intensity signals equal to or greater than 4 dB above background noise. Emboli were automatically counted and differ- entiated into artefact, gaseous (bubbles) or solid in real-time by the DWL Doppler X TCD device’s inte- grated differentiation software (DWL/Compumedics Germany GmbH, Singen, Germany).8,9
Emboli counts (with subdivision into counts of gase- ous and solid emboli) were compiled across two surgi- cal phases: initiation of CPB until aortic cross-clamp removal (phase 1); and aortic cross-clamp removal until 20 minutes after venous decannulation (phase 2). Emboli counts were normalized for the duration of each phase by dividing the count by the duration of the phase to produce an emboli count per minute.
Statistical analysis
The emboli data from each patient were exported into a Microsoft Excel (Microsoft® Office Proofing Tools©
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