Role Of Nitrous Oxide Research Articles

Fixation of nitrous oxide (N2O) by 1, 4, 2, 5‐diazadiborinine: A DFT study

AbstractThe role of nitrous oxide (N2O) in stratospheric ozone depletion and as a greenhouse gas has inspired the scientific community across the globe in understanding the capture, activation, and decomposition of it. Very recently people have started fixing N2O using frustrated Lewis pairs. In this study, we have tried to analyze the fixation of N2O by 1,4,2,5‐diazadiborinine by applying various computational tools and techniques associated with density functional theory. 1,4,2,5‐Diazadiborinine is taken as the fixing agent because of the ambiphilic nature of the two boron centers within it as reported by Wang et al. There are three possible ways of binding of N2O within it as observed in this study. A free energy surface is also generated for the three possible paths representing their thermochemical as well as kinetic stability. The fixation of N2O may become possible using this species as demonstrated by the current results. The nature of bonding between them is also explored through NBO, EDA, and electron density analyses.

The role of nitrous oxide in stroke.

Stroke that is caused by poor blood flow into the brain results in cell death, including ischemia stroke due to lack of blood into brain tissue, and hemorrhage due to bleeding. Both of them will give rise to the dysfunction of brain. In general, the signs and symptoms of stroke are the inability of feeling or moving on one side of body, sometimes loss of vision to one side. Above symptoms will appear soon after the stroke has happened. If the symptoms and signs happen in 1 or 2 hours, we often call them as transient ischemic attack. Moreover, hemorrhagic stroke often leads to severe headache. It is known that neuronal death can happen after stroke, and it depends upon the activation of N-methyl-D-aspartate (NMDA) excitatory glutamate receptor which is the goal for a lot of neuroprotective agents. Nitrous oxide was discovered by Joseph Priestley in 1772, and then he and his friends, including the poet Coleridge and Robert Sauce, experimented with the gas. They found this gas could make patients loss the sense of pain and still maintain consciousness after inhalation. Shortly the gas was used as an anesthetic, especially in the field of dentists. Now, accroding to theme of Helene N. David and other scientists, both of nitrous oxide at 75 vol% and xenon at 50 vol% could reduce ischemic neuronal death in the cortex by 70% and decrease NMDA-induced Ca2+ influx by 30%. Therefore, more clinical and experimental studies are important to illuminate the mechanisms of how nitrous oxide protects brain tissue and to explore the best protocol of this gas in stroke treatment.

A prospective, randomised, controlled clinical trial to evaluate the effect of nitrous oxide on propofol requirement in elective craniotomy in which entropy was used to measure depth of anaesthesia

Background: Propofol is known to have a favourable effect on cerebral haemodynamics. The role of nitrous oxide (N2O) in neurosurgical anaesthesia is still being debated. The primary aim of this study was to assess the dose-sparing effect of N2O on propofol infusion maintenance dosing.Method: Fifty American Society of Anesthesiology (ASA) grade I and II adults scheduled for elective craniotomies for supratentorial tumours were enrolled in the study. The patients received a standard anaesthetic comprising a fentanyl 2 μg/kg bolus prior to propofol induction. Anaesthesia was maintained with an infusion of fentanyl (2 μg/kg/hour), atracurium and propofol. The patients were randomised into two groups. Group A received 67% N2O. Group B did not receive N2O concomitantly with the propofol infusion. Entropy was used to guide the titration of the propofol infusion in both groups.Results: The propofol maintenance dose requirements were 47% lower in Group A (54.30 ± 11.47 μg/kg/minute) vs. Group B (102.30 ± 14.00 μg/...

Early Cognitive Decline In Pituitary Surgery: Is Nitrous Oxide the Culprit?

ABSTRACT Aim: Pituitary tumors have been found to produce cognitive dysfunctions predominantly related to memory and attention. There exists a potential interaction between surgical and anesthetic factors in producing cognitive changes. Therefore we aim to investigate the incidence of cognitive decline and role of nitrous oxide (N2O) on immediate cognitive changes in patients undergoing transsphenoidal removal of pituitary tumors. Patients & methods: Ninety patients between 18 and 65 years of age, undergoing transsphenoidal surgery for pituitary tumor removal, were enrolled and divided into two (air and N2O-based anesthetic regime) groups. Cognitive functions were noted using the Hindi Mini Mental State Examination at baseline and three times in the postoperative period (1-h, 24-h postextubation and at the time of hospital discharge). Results: Both groups were comparable with respect to demographics, baseline parameters and cognitive scores. Significant number of patients (73%) showed cognitive decline in both the groups within 24 h postoperatively. In the factor analysis, thyroid-stimulating hormone and fentanyl consumption were linked with changes in cognitive scores. Conclusion: Patients undergoing pituitary surgery have significantly immediate cognitive decline in the short followup, but N2O-based anesthesia alone does not increase the risk of postoperative cognitive decline.

Does Anaesthesia With Nitrous Oxide Affect Mortality or Cardiovascular Morbidity? A Systematic Review With Meta-analysis and Trial Sequential Analysis

Background. The role of nitrous oxide in modern anaesthetic practice is contentious. One concern is that exposure to nitrous oxide may increase the risk of cardiovascular complications. ENIGMA II is a large randomized clinical trial currently underway which is investigating nitrous oxide and cardiovascular complications. Before the completion of this trial, we performed a systematic review and meta-analysis, using Cochrane methodology, on the outcomes that make up the composite primary outcome. Methods. We used conventional meta-analysis and trial sequential analysis (TSA). We reviewed 8282 abstracts and selected 138 that fulfilled our criteria for study type, population, and intervention. We attempted to contact the authors of all the selected publications to check for unpublished outcome data. Results. Thirteen trials had outcome data eligible for our outcomes. We assessed three of these trials as having a low riskof bias. Using conventional meta-analysis, the relative riskof short-term mortality in the nitrous oxide group was 1.38 [95% confidence interval (CI) 0.22–8.71] and the relative risk of long-term mortality in the nitrous oxide group was 0.94 (95% CI 0.80–1.10). In both cases, TSA demonstrated that the data were far too sparse to make any conclusions. There were insufficient data to perform meta-analysis for stroke, myocardial infarct, pulmonary embolus, or cardiac arrest.

Ceasing routine use of nitrous oxide'a follow up

The role of nitrous oxide in modern anaesthesia is questioned. The routine use of nitrous oxide was almost completely stopped in our department after November 1, 2000, and we now report some consequences. Staff completed a questionnaire after 6 months, and we analysed the use of hypnotics and opioids after 12 months. The cost of drugs for the year after stopping nitrous oxide was compared with the cost 2 yr before. Less than half of the 55 staff members who answered the questionnaire used nitrous oxide in the 6 months after the stop, and they did so on only a few occasions. Half of the staff members thought the benefit of nitrous oxide was small. Most supported the change. The use of opioids was stable during the study period, and there was an annual increase of 12-14% in the use of hypnotics during the 3 yr. The staff questionnaire showed a strong acceptance of the new policy, and the use of other anaesthetic agents did not increase as expected. Has the value of nitrous oxide been overestimated?

Discharge criteria and complications after ambulatory surgery.

I n recent years, the emphasis in providing surgical services has undergone remarkable change. Previously, patients undergoing surgical procedures remained in a hospital for many days after the operation. In 1994, 66% of all elective operations in the United States were performed on an outpatient basis (1). More complex ambulatory procedures are being performed on sicker patients (2). With the increased emphasis on early discharge after surgery and anesthesia, it is important to identify criteria that can be used to determine when patients can safely go home under the care of a friend or relative. In this article, we review current knowledge regarding the assessment of home-readiness after ambulatory surgery and discuss potential complications and appropriate treatment regimens.

Discharge Criteria and Complications After Ambulatory Surgery

Discharge Criteria and Complications After Ambulatory Surgery

The role of nitrous oxide in postoperative nausea and recovery in patients undergoing upper abdominal surgery

The effect of nitrous oxide on postoperative nausea/vomiting and alertness were studied in 50 patients undergoing elective upper abdominal surgery. The study period lasted 20 h. Patients were randomly assigned to receive thiopentone-fentanyl-isoflurane-pancuronium anaesthesia with either 70% nitrous oxide-oxygen (Group I) or air-oxygen (Group II). There were no differences between the groups regarding age, sex, weight or amount or per- and postoperative analgetics given. The mean inspiratory isoflurane concentrations were 0.6% and 1.15% in Groups I and II, respectively. The postoperative alertness was tested by a visual analogue scale (0-10) for 6 h postoperatively. Omitting nitrous oxide did not decrease the frequency of postoperative nausea, although the symptoms were milder in the air group. The patients without nitrous oxide were alert earlier, in spite of a higher isoflurane concentration: VAS from 5 to 8.7 vs from 2.8 to 6.9 during the first 6 postoperative hours.

15N-depleted N2O as a product of nitrification

Recent interest in the role of nitrous oxide in the natural nitrogen cycle has focused on its production through the nitrification process1. Nitrous oxide depleted in 15N has been found in the shallow water column of the eastern tropical Pacific Ocean2, suggesting that 15N is depleted during N2O production. Here we report significant 15N depletion in N2O produced by bacterial nitrification, implying that N2O is produced via NO–2 rather than directly from NH+4 and that N2O should be very depleted in 15N where nitrification is the predominant production process for N2O. The magnitude of the isotope depletion is so large that this work should lead to further use of data on the natural abundance of 15N for assessing the sources and sinks of nitrogenous compounds.

Role of Nitrous Oxide and Other Factors in Postoperative Nausea and Vomiting

Postoperative nausea and vomiting have been reported to be associated with the use of nitrous oxide. To further investigate this possibility, 780 patients undergoing anesthesia and surgery were randomly divided into four groups: group I: enflurane/nitrous oxide/oxygen; group II: enflurane/air/oxygen; group III: isoflurane/nitrous oxide/oxygen; and group IV: isoflurane/air/oxygen. The frequency of postoperative nausea and vomiting was ascertained in the recovery room and at 24-h follow-up by blinded observers. Other data collected included gender, age, body mass index, previous history of postoperative nausea and vomiting, and postoperative narcotic use. The authors found no association between the use of nitrous oxide and subsequent development of postoperative nausea and vomiting. Use of the 95% confidence interval allowed the authors to project a maximum potential increase in the frequency of postoperative nausea and vomiting associated with nitrous oxide to be 5.4% with enflurane and 9.7% with isoflurane in the immediate postoperative period. Female gender, younger age, and a previous history of postoperative nausea and vomiting, but not body mass index, were found to be associated with postoperative nausea and vomiting (P less than 0.05). It is concluded that there is no association between the use of nitrous oxide and the development of postoperative nausea and vomiting.