Effects of intraoperative inspired oxygen fraction (FiO2 0.3 vs 0.8) on patients undergoing off-pump coronary artery bypass grafting: the CARROT multicenter, cluster-randomized trial.

BACKGROUND: To maintain adequate oxygenation is of utmost importance in intraoperative care. However, clinical evidence supporting specific oxygen levels in distinct surgical settings is lacking. This study aimed to compare the effects of 30% and 80% oxygen in off-pump coronary artery bypass grafting (OPCAB). METHODS: This multicenter trial was conducted in three tertiary hospitals from August 2019 to August 2021. Patients undergoing OPCAB were cluster-randomized to receive either 30% or 80% oxygen intraoperatively, based on the month when the surgery was performed. The primary endpoint was the length of hospital stay. Intraoperative hemodynamic data were also compared. RESULTS: A total of 414 patients were cluster-randomized. Length of hospital stay was not different in the 30% oxygen group compared to the 80% oxygen group (median, 7.0 days vs 7.0 days; the sub-distribution hazard ratio, 0.98; 95% confidence interval [CI] 0.83-1.16; P = 0.808). The incidence of postoperative acute kidney injury was significantly higher in the 30% oxygen group than in the 80% oxygen group (30.7% vs 19.4%; odds ratio, 1.94; 95% CI 1.18-3.17; P = 0.036). Intraoperative time-weighted average mixed venous oxygen saturation was significantly higher in the 80% oxygen group (74% vs 64%; P < 0.001). The 80% oxygen group also had a significantly greater intraoperative time-weighted average cerebral regional oxygen saturation than the 30% oxygen group (56% vs 52%; P = 0.002). CONCLUSIONS: In patients undergoing OPCAB, intraoperative administration of 80% oxygen did not decrease the length of hospital stay, compared to 30% oxygen, but may reduce postoperative acute kidney injury. Moreover, compared to 30% oxygen, intraoperative use of 80% oxygen improved oxygen delivery in patients undergoing OPCAB. Trial registration ClinicalTrials.gov (NCT03945565; April 8, 2019).

Effects of transcutaneous electrical nerve stimulation on myocardial protection in patients undergoing aortic valve replacement: a randomized clinical trial.

BACKGROUND: Cardiopulmonary bypass-related myocardial ischemia-reperfusion injury is a major contributor to postoperative morbidity. Although transcutaneous electrical nerve stimulation (TENS) has been found to have cardioprotective effects in animal studies and healthy volunteers, its effects on cardiac surgery under cardiopulmonary bypass patients have not been evaluated. We investigated the effects of TENS on myocardial protection in patients undergoing aortic valve replacement surgery using cardiopulmonary bypass. METHODS: Thirty patients were randomized to receive TENS or sham in three different anesthetic states - pre-anesthesia, sevoflurane, or propofol (each n = 5). TENS was applied with a pulse width of 385 µs and a frequency of 10 Hz using two surface electrodes at the upper arm for 30 min. Sham treatment was provided without stimulation. The primary outcome was the difference in myocardial infarct size following ischemia-reperfusion injury in rat hearts perfused with pre- and post-TENS plasma dialysate obtained from the patients using Langendorff perfusion system. The cardioprotective effects of TENS were determined by assessing reduction in infarct size following treatment. RESULTS: There were no differences in myocardial infarct size between pre- and post-treatment in any group (41.4 ± 4.3% vs. 36.7 ± 5.3%, 39.8 ± 7.3% vs. 27.8 ± 12.0%, and 41.6 ± 2.2% vs. 37.8 ± 7.6%; p = 0.080, 0.152, and 0.353 in the pre-anesthesia, sevoflurane, and propofol groups, respectively). CONCLUSIONS: In our study, TENS did not show a cardioprotective effect in patients undergoing aortic valve replacement surgery. TRIAL REGISTRATION: This study was registered at clinicaltrials.gov ( NCT03859115 , on March 1, 2019).

Effects of low versus high inspired oxygen fraction on myocardial injury after transcatheter aortic valve implantation: A randomized clinical trial.

BACKGROUND: Oxygen therapy is used in various clinical situation, but its clinical outcomes are inconsistent. The relationship between the fraction of inspired oxygen (FIO2) during transcatheter aortic valve implantation (TAVI) and clinical outcomes has not been well studied. We investigated the association of FIO2 (low vs. high) and myocardial injury in patients undergoing TAVI. METHODS: Adults undergoing transfemoral TAVI under general anesthesia were randomly assigned to receive FIO2 0.3 or 0.8 during procedure. The primary outcome was the area under the curve (AUC) for high-sensitivity cardiac troponin I (hs-cTnI) during the first 72 h following TAVI. Secondary outcomes included the AUC for postprocedural creatine kinase-myocardial band (CK-MB), acute kidney injury and recovery, conduction abnormalities, pacemaker implantation, stroke, myocardial infarction, and in-hospital mortality. RESULTS: Between October 2017 and April 2022, 72 patients were randomized and 62 were included in the final analysis (n = 31 per group). The median (IQR) AUC for hs-cTnI in the first 72 h was 42.66 (24.82-65.44) and 71.96 (35.38-116.34) h·ng/mL in the FIO2 0.3 and 0.8 groups, respectively (p = 0.066). The AUC for CK-MB in the first 72 h was 257.6 (155.6-322.0) and 342.2 (195.4-485.2) h·ng/mL in the FIO2 0.3 and 0.8 groups, respectively (p = 0.132). Acute kidney recovery, defined as an increase in the estimated glomerular filtration rate ≥ 25% of baseline in 48 h, was more common in the FIO2 0.3 group (65% vs. 39%, p = 0.042). Other clinical outcomes were comparable between the groups. CONCLUSIONS: The FIO2 level did not have a significant effect on periprocedural myocardial injury following TAVI. However, considering the marginal results, a benefit of low FIO2 during TAVI could not be ruled out.