Comparison of the effects of on-pump and off-pump coronary artery bypass surgery on cerebral oxygen saturation using near-infrared spectroscopy

The effects of on-pump and off-pump coronary artery bypass surgery on oxidative stress and cerebral oxygenation: a prospective observational study

Background/aim

In this prospective observational study, our goal was to investigate the relationship between serum levels of oxidative stress (OS) parameters and regional cerebral oxygen saturation (rSO2) in addition to evaluating postoperative clinical outcomes among patients undergoing coronary artery bypass graft surgery (CABG).

Materials and methods

This study comprised 64 adult patients undergoing elective CABG (on-pump [n = 48] and off-pump [n = 16]) procedures. Serum OS levels and rSO2 values were measured intraoperatively at three specific time points: T1 (after induction), T2 (15 min before aortic cross-clamp removal or the final distal anastomosis), and T3 (15 min after aortic cross-clamp removal or the last distal anastomosis).

Results

Serum OS and lactate values demonstrated higher levels at T2 and T3 (p < 0.001), while rSO2 values were lower at T2 (p = 0.024) in the on-pump CABG group compared to the off-pump CABG group. The rSO2 values at T2 exhibited a negative correlation with OS parameters, lactate levels at T2 and T3, aortic clamp time, postoperative mechanical ventilation time, and intensive care unit stay length. In the multivariate linear regression analysis (R2 = 0.181, p = 0.001), lactate values at T2 emerged as the sole factor affecting the OS index at T2 (t = 2.843, p = 0.006).

Conclusion

In our study, we observed elevated OS values and relatively low rSO2 values during on-pump CABG procedures, with rSO2 showing an association with increased OS parameters. Close monitoring of the OS response level and rSO2 during CABG could potentially enhance postoperative clinical outcomes.

Evaluation of preoperative oral carbohydrate administration on insulin resistance in off-pump coronary artery bypass patients: A randomised trial

BACKGROUND

In fasting cardiac surgery patients, preoperative carbohydrate (CHO) drink intake attenuated insulin resistance and improved cardiac metabolism, although its beneficial effects were not evident after cardiac surgery possibly due to cardiopulmonary bypass-related extreme systemic inflammation.

OBJECTIVE

We aimed to evaluate whether preoperative CHO intake affected insulin resistance and free-fatty acid (FFA) concentrations in off-pump coronary revascularisation.

DESIGN

A randomised controlled trial.

SETTING

Primary care in a university hospital in Korea from January 2015 to July 2016.

PATIENTS

Sixty patients who underwent elective multi-vessel off-pump coronary revascularisation were randomised into two groups. Three patients were excluded from analysis and 57 patients completed study.

INTERVENTION

The CHO group received oral CHO (400 ml) the prior evening and 2 to 3 h before surgery, and the control group was fasted from food and water according to standard protocol.

MAIN OUTCOME MEASURES

Insulin resistance was assessed twice, after anaesthetic induction and after surgery via short insulin tolerance test. FFA, C-reactive protein and creatine kinase-myocardial band concentrations were determined serially for 48 h after surgery.

RESULTS

Insulin sensitivity was greater (P = 0.002) and plasma FFA concentrations were lower (P = 0.001) after anaesthetic induction in the CHO group compared with the Control group, although there were no intergroup differences after surgery. The postoperative peak creatine kinase-myocardial band concentration was significantly lower in the CHO group compared with the Control group [8.8 (5.4 to 18.2) vs. 6.4 (3.5 to 9.7) ng ml, P = 0.031].

CONCLUSION

A preoperative CHO supplement significantly reduced insulin resistance and FFA concentrations compared with fasting at the beginning of the surgery, but these benefits were lost after off-pump coronary revascularisation. Despite their transient nature, these beneficial effects resulted in less myocardial injury, mandating further studies focused on the impact of preoperative CHO on myocardial ischaemia and cardiac function after coronary revascularisation.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT 02330263.