Hemodynamic effects of intraoperative 30% versus 80% oxygen concentrations: an exploratory analysis

BackgroundSupplemental oxygen leads to an increase in peripheral vascular resistance which finally increases systemic blood pressure in healthy subjects and patients with coronary artery disease, heart failure, undergoing heart surgery, and with sepsis. However, it is unknown whether this effect can also be observed in anesthetized patients having surgery. Thus, we evaluated in this exploratory analysis of a randomized controlled trial the effect of 80% versus 30% oxygen on intraoperative blood pressure and heart rate.MethodsWe present data from a previous study including 258 patients, who were randomized to a perioperative inspiratory FiO2 of 0.8 (128 patients) versus 0.3 (130 patients) for major abdominal surgery. Continuous arterial blood pressure values were recorded every three seconds and were exported from the electronic anesthesia record system. We calculated time-weighted average (TWA) and Average Real Variability (ARV) of mean arterial blood pressure and of heart rate.ResultsThere was no significant difference in TWA of mean arterial pressure between the 80% (80 mmHg [76, 85]) and 30% (81 mmHg [77, 86]) oxygen group (effect estimate −0.16 mmHg, CI –1.83 to 1.51; p = 0.85). There was also no significant difference in TWA of heart rate between the 80 and 30% oxygen group (median TWA of heart rate in the 80% oxygen group: 65 beats.min−1 [58, 72], and in the 30% oxygen group: 64 beats.min−1 [58; 70]; effect estimate: 0.12 beats.min−1, CI –2.55 to 2.8, p = 0.94). Also for ARV values, no significant differences between groups could be detected.ConclusionIn contrast to previous results, we did not observe a significant increase in blood pressure or a significant decrease in heart rate in patients, who received 80% oxygen as compared to patients, who received 30% oxygen during surgery and for the first two postoperative hours. Thus, hemodynamic effects of supplemental oxygen might play a negligible role in anesthetized patients.Clinical Trail Registrationhttps://clinicaltrials.gov/ct2/show/NCT03366857?term=vienna&cond=oxygen&draw=2&rank=

Effect of Supplemental Oxygen on von Willebrand Factor Activity and Ristocetin Cofactor Activity in Patients at Risk for Cardiovascular Complications Undergoing Moderate-to High-Risk Major Noncardiac Surgery—A Secondary Analysis of a Randomized Trial

Increased von Willebrand Factor (vWF) activity mediates platelet adhesion and might be a contributor to the development of thrombotic complications after surgery. Although in vitro studies have shown that hyperoxia induces endovascular damage, the effect of perioperative supplemental oxygen as a possible trigger for increased vWF activity has not been investigated yet. We tested our primary hypothesis that the perioperative administration of 80% oxygen concentration increases postoperative vWF activity as compared to 30% oxygen concentration in patients at risk of cardiovascular complications undergoing major noncardiac surgery. A total of 260 patients were randomly assigned to receive 80% versus 30% oxygen throughout surgery and for two hours postoperatively. We assessed vWF activity and Ristocetin cofactor activity in all patients shortly before the induction of anesthesia, within two hours after surgery and on the first and third postoperative day. Patient characteristics were similar in both groups. We found no significant difference in vWF activity in the overall perioperative time course between both randomization groups. We observed significantly increased vWF activity in the overall study population throughout the postoperative time course. Perioperative supplemental oxygen showed no significant effect on postoperative vWF and Ristocetin cofactor activity in cardiac risk patients undergoing major noncardiac surgery. In conclusion, we found no significant influence of supplemental oxygen in patients undergoing major non-cardiac surgery on postoperative vWF activity and Ristocetin cofactor activity.</jats:p

Perioperative Supplemental Oxygen and Postoperative Copeptin Concentrations in Cardiac-Risk Patients Undergoing Major Abdominal Surgery&mdash;A Secondary Analysis of a Randomized Clinical Trial

Noncardiac surgery is associated with hemodynamic perturbations, fluid shifts and hypoxic events, causing stress responses. Copeptin is used to assess endogenous stress and predict myocardial injury. Myocardial injury is common after noncardiac surgery, and is often caused by myocardial oxygen demand-and-supply mismatch. In this secondary analysis, we included 173 patients at risk for cardiovascular complications undergoing moderate- to high-risk major abdominal surgery. Patients were randomly assigned to receive 80% or 30% oxygen throughout surgery and the first two postoperative hours. We evaluated the effect of supplemental oxygen on postoperative Copeptin concentrations. Copeptin concentrations were measured preoperatively, within two hours after surgery, on the first and third postoperative days. In total, 85 patients received 0.8 FiO2, and 88 patients received 0.3 FiO2. There was no significant difference in postoperative Copeptin concentrations between both study groups (p = 0.446). Copeptin increased significantly within two hours after surgery, compared with baseline in the overall study population (estimated effect: &minus;241.7 pmol&middot;L&minus;1; 95% CI &minus;264.4, &minus;219.1; p &lt; 0.001). Supplemental oxygen did not significantly attenuate postoperative Copeptin release. Copeptin concentrations showed a more immediate postoperative increase compared with previously established biomarkers. Nevertheless, Copeptin concentrations did not surpass Troponin T in early determination of patients at risk for developing myocardial injury after noncardiac surgery

Perioperative Supplemental Oxygen and Plasma Catecholamine Concentrations After Major Abdominal Surgery – a Substudy of a Randomized Clinical Trial

Abstract BackgroundIncreased sympathetic nerve activity due to perioperative stress is associated with higher plasma catecholamine concentrations that lead to an increase in heart rate and blood pressure. This fact plays a pivotal role in the development of perioperative myocardial ischemia. A previous study in healthy volunteers has shown that the administration of supplemental oxygen attenuated sympathetic nerve activity, which was associated with lower plasma catecholamine concentrations. However, in patients undergoing surgery evidence is still lacking. We therefore tested the hypothesis that perioperative supplemental oxygen attenuates sympathetic nerve activity estimated by plasma catecholamines in patients at risk for cardiovascular complications undergoing major abdominal surgery.MethodsWe randomly assigned 81 patients to receive either 80% versus 30% inspired oxygen concentration throughout surgery and for the first two postoperative hours. We assessed noradrenaline, adrenaline and dopamine plasma concentrations as surrogate parameters for sympathetic nerve activity before induction of anesthesia, two hours after surgery and on the third postoperative day.Results41 patients received 80% oxygen and 40 patients received 30% oxygen. There was no significant difference in postoperative noradrenaline (effect estimated:-41.5 ng.L-1, 95%CI -134.3, 51.2; p=0.38), adrenaline (effect estimated:11.2 ng.L-1, 95%CI -7.6, 30.1; p=0.24) and dopamine (effect estimated:-1.61 ng.L-1, 95%CI -7.2, 3.9; p=0.57) concentrations between both groups. ConclusionsWe found no significant difference in postoperative plasma catecholamine concentration between the 80% and 30% oxygen group in patients at risk for cardiovascular complications undergoing major abdominal surgery. Based on our results, it seems likely that supplemental oxygen did not influence sympathetic nerve activity in the perioperative setting.Trial RegistrationClinicalTrials.gov (NCT 03366857)European Clinical Trial Database (EudraCT 2017-003714-68)</jats:p

Perioperative Supplemental Oxygen and Plasma Catecholamine Concentrations after Major Abdominal Surgery—Secondary Analysis of a Randomized Clinical Trial

Perioperative stress is associated with increased sympathetic activity that leads to increases in heart rate and blood pressure, which are associated with the development of perioperative myocardial ischemia. In healthy volunteers, it was shown that the administration of supplemental oxygen attenuated sympathetic nerve activity and subsequently led to lower plasma catecholamine concentrations. We therefore tested the hypothesis that perioperative supplemental oxygen attenuates sympathetic nerve in patients at risk for cardiovascular complications undergoing major abdominal surgery. We randomly assigned 81 patients to receive either 80% or 30% inspired oxygen concentration throughout surgery and the first two postoperative hours. We assessed noradrenaline, adrenaline, and dopamine plasma concentrations before the induction of anesthesia, two hours after surgery and on the third postoperative day. There was no significant difference in postoperative noradrenaline (effect estimated: −41.5 ng·L−1, 95%CI −134.3, 51.2; p = 0.38), adrenaline (effect estimated: 11.2 ng·L−1, 95%CI −7.6, 30.1; p = 0.24), and dopamine (effect estimated: −1.61 ng·L−1, 95%CI −7.2, 3.9; p = 0.57) concentrations between both groups. Based on our results, it seems unlikely that supplemental oxygen influences endogenous catecholamine release in the perioperative setting.</jats:p

Perioperative Supplemental Oxygen and Postoperative Copeptin Concentrations in Cardiac-Risk Patients Undergoing Major Abdominal Surgery—A Secondary Analysis of a Randomized Clinical Trial

Noncardiac surgery is associated with hemodynamic perturbations, fluid shifts and hypoxic events, causing stress responses. Copeptin is used to assess endogenous stress and predict myocardial injury. Myocardial injury is common after noncardiac surgery, and is often caused by myocardial oxygen demand-and-supply mismatch. In this secondary analysis, we included 173 patients at risk for cardiovascular complications undergoing moderate- to high-risk major abdominal surgery. Patients were randomly assigned to receive 80% or 30% oxygen throughout surgery and the first two postoperative hours. We evaluated the effect of supplemental oxygen on postoperative Copeptin concentrations. Copeptin concentrations were measured preoperatively, within two hours after surgery, on the first and third postoperative days. In total, 85 patients received 0.8 FiO2, and 88 patients received 0.3 FiO2. There was no significant difference in postoperative Copeptin concentrations between both study groups (p = 0.446). Copeptin increased significantly within two hours after surgery, compared with baseline in the overall study population (estimated effect: −241.7 pmol·L−1; 95% CI −264.4, −219.1; p &lt; 0.001). Supplemental oxygen did not significantly attenuate postoperative Copeptin release. Copeptin concentrations showed a more immediate postoperative increase compared with previously established biomarkers. Nevertheless, Copeptin concentrations did not surpass Troponin T in early determination of patients at risk for developing myocardial injury after noncardiac surgery.</jats:p