The Association Between Nitrous Oxide and Postoperative Mortality and Morbidity After Noncardiac Surgery
ABSTRACT Background:Nitrous oxide (N(2)O) has been widely used in clinical anesthesia for >150 years. However, use of N(2)O has decreased in recent years because of concern about the drug's metabolic side effects. But evidence that routine use of N(2)O causes clinically important toxicity remains elusive. We therefore evaluated the relationship between intraoperative N(2)O administration and 30-day mortality as well as a set of major inpatient postoperative complications (including mortality) in adults who had general anesthesia for noncardiac surgery.Methods:We evaluated 49,016 patients who had noncardiac surgery at the Cleveland Clinic between 2005 and 2009. Among 37,609 qualifying patients, 16,961 were given N(2)O ("nitrous," 45%) and 20,648 were not ("nonnitrous," 55%). Ten thousand seven hundred fifty-five nitrous patients (63% of the total) were propensity score-matched with 10,755 nonnitrous patients. Matched nitrous and nonnitrous patients were compared on 30-day mortality and a set of 8 in-hospital morbidity/mortality outcomes.Results:Inhalation of N(2)O intraoperatively was associated with decreased odds of 30-day mortality (odds ratio [OR]: 97.5% confidence interval, 0.67, 0.46-0.97; P = 0.02). Furthermore, nitrous patients had an estimated 17% (OR: 0.83, 0.74-0.92) decreased odds of experiencing major in-hospital morbidity/mortality than nonnitrous (P < 0.001). Among the individual morbidities, intraoperative N(2)O use was only associated with significantly lower odds of having pulmonary/respiratory morbidities (OR, 95% Bonferroni-adjusted CI: 0.59, 0.44-0.78).Conclusions:Intraoperative N(2)O administration was associated with decreased odds of 30-day mortality and decreased odds of in-hospital mortality/morbidity. Aside from its specific and well-known contraindications, the results of this study do not support eliminating N(2)O from anesthetic practice.
Article: This Wonder-Working GasAnesthesia and analgesia 05/2013; 116(5):955-8. DOI:10.1213/ANE.0b013e318271fafb · 3.42 Impact Factor
- Anesthesia and analgesia 05/2013; 116(5):959-61. DOI:10.1213/ANE.0b013e31826e7632 · 3.42 Impact Factor
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ABSTRACT: Conflicting reports about adverse events following nitrous oxide (N(2)O) application have spurred a discussion whether N(2)O should be abandoned from clinical practice. Concurrently, N(2)O is increasingly used as a single anesthetic agent in medical procedures. This article reviews and discusses reports about the present use of N(2)O. RECENT FINDINGS: Multiple publications demonstrate an increasing use of N(2)O as a procedural analgesic and sedative. Results from the Evaluation of Nitrous Oxide in the Gas Mixture for Anesthesia trial have been contrasted by recent studies reporting no increased risk for perioperative complications, particularly related to the cardiovascular and cerebrovascular system. Recent studies show that electroencephalogram-based anesthesia depth monitoring is not compatible with the use of N(2)O because of its distinct influence on electroencephalogram wave patterns. The clinical relevance of the proposed neurotoxicity, immunosuppression and influence on methionine metabolism remains unclear. Recently, its acute and long-term analgesic potency has been proven. Occupational exposure might pose a relevant health hazard. SUMMARY: Based on the present literature, abolishment of N(2)O is controversial. When avoided in patients at risk for adverse events, N(2)O is still a valuable supplement to general anesthesia and a potent procedural analgesic drug. In the latter, its use by nonanesthesiologists should be discouraged.Current Opinion in Anaesthesiology 06/2013; 26(3):354-60. DOI:10.1097/ACO.0b013e32835f8151 · 2.53 Impact Factor