The use of intraoperative nitrous oxide leads to postoperative increases in plasma homocysteine

Hyperhomocysteinemia is an independent risk factor for coronary artery and cerebrovascular disease, but its significance in the perioperative period is unknown. Nitrous oxide inhibits methionine synthase, which aids in the conversion of homocysteine to methionine. In this prospective, controlled, randomized study, we determined the effect of intraoperative nitrous oxide exposure on postoperative plasma homocysteine concentrations. Twenty ASA physical status I-III patients, aged \u3e18 yr, presenting for elective craniotomy, were randomized to receive general anesthesia with or without nitrous oxide (inspired nitrous oxide \u3e50%). Plasma was sampled before the induction of anesthesia, on arrival in the postanesthesia care unit (PACU) after discontinuation of nitrous oxide, and 24 h after induction. There was a significant increase (22.6 ± 11.4 vs 13.0 ± 4.7 μmol/L; P = 0.0038 for postoperative versus preinduction values) in plasma homocysteine concentrations in the nitrous oxide group on arrival in the PACU and for 24 h. In the nonnitrous oxide group, mean plasma homocysteine concentrations did not change (9.5 ± 1.9 vs 9.8 ± 1.6 μmol/L; P = 0.86 for postoperative versus preinduction values). The change in plasma homocysteine concentrations in the nitrous oxide group was significantly different from that in the nonnitrous group (P = 0.0031). We conclude that the use of intraoperative nitrous oxide leads to significant increases in perioperative plasma homocysteine concentrations. Implications: Short-term exposure to nitrous oxide led to significant increases in plasma homocysteine. Further investigations are required to determine the clinical significance of this change

Optimizing preoperative requirements for outpatient cataract surgery at the Royal Alexandra hospital

Objective: To evaluate preoperative testing for cataract surgery, implement stakeholder-driven change, and increase the number of patients who arrived for surgery with complete preoperative requirements, for the purpose of delivering safe, high-quality, and cost-effective care for patients.Design: Quality improvement.Participants: Cataract surgery patients, health care staff in Ophthalmology Day Surgery, an Ophthalmology improvement team, the Clinical Section Heads of Ophthalmology and Anaesthesia, Quality Consultants, and members of the Quality Council participated in this study.Methods: A lean quality improvement approach was used to define and build understanding of the problem. Between July and November 2016, a chart-based reporting system captured all patients who arrived for cataract surgery with expired or incomplete preoperative requirements. A cost analysis was completed, and evidence was reviewed to ensure alignment with best practice preoperative recommendations.Results: On average, 25% (619/2451 over a 17-week period) of patients per day arrived at the Ophthalmology Day Surgery for cataract surgery with incomplete and/or expired physical history forms and ECGs. An improvement team worked to implement a radical improvement idea and relied on an existing questionnaire to ensure patient safety preoperatively.Conclusions: Based on the literature, best practice guidelines, and a cost analysis, it was decided that patients undergoing routine cataract surgery in Edmonton Zone Hospitals under regional anaesthesia would no longer require physician history and physicals and ECGs. Elimination of the preoperative requirements for all but select high-risk patients meant that 100% of patients who arrived for cataract surgery would not have outstanding presurgery requirements