The current place of nitrous oxide in clinical practice: An expert opinion-based task force consensus statement of the European Society of Anaesthesiology

Persistent use of nitrous oxide for anaesthesia in European hospitals despite its harmfulness to the climate - how emission taxation can achieve the coupling of cost-effectiveness and climate protection: observational study

BACKGROUND

Health care has the intrinsic obligation to preserve health. This concept is also applicable to planetary health. Nitrous oxide (N2O) lacks clinical indications in modern anaesthesia, while it is a high-potential greenhouse gas. Its seemingly low cost contrasts with the consequential externalised socio-economic costs due to its contribution to the climate crisis, which is approximately €698 per emitted ton of CO2 equivalent. This difference can be internalised through emission taxation. In this study, we aim to evaluate how much N2O - total amount and converted to CO2 equivalent - is used at a German university hospital and compare this amount to that used at European hospitals. Furthermore, how the cost of N2O usage changes under different emission taxation scenarios is calculated.

METHODS

This trial was a retrospective observational study at a German university hospital with approximately 1,250 beds between 2016 and 2020. Additionally, five European hospitals from the Health Care Without Harm Network were used for comparison from a European perspective. The main outcome parameters were the amount of N2O used, in total and converted to CO2 equivalent, and the total cost at emission taxation of €0, €25, €55 and €698 per ton CO2 equivalent.

RESULTS

At the peak, 2,104 tCO2 equivalent in N2O was emitted in 2019. The actual cost was €14,040 in this year, while the corresponding socio-economic damage due to the climate crisis was almost €1.5 million. Other European hospitals showed comparable amounts of emissions.

CONCLUSIONS

The annual peak amount of emitted N2O corresponded to the total annual greenhouse gas emission of 188 people in Germany. To achieve a drastic reduction in use, the abandonment of recommendations by anaesthesiologic societies appears necessary, in addition to an internalisation of future costs via emission taxation, which will cause inadequate cost for a medication without relevant benefit or indication. To that end, the inclusion of health sector emissions within national or international greenhouse gas taxation, for example, the European Union Emissions Trading System, appears necessary and expedient in view of the urgent need to address the ecological transformation.

TRIAL REGISTRATION

The trial was registered with the German Clinical Trials Register, identifier DRKS00024973 on 12/04/2021.

Challenges and current status of children pain management in Spain

Pain in children population is prevalent, but its proper diagnosis and management are frequently insufficient in pediatrics daily practice. Lack of knowledge of the professionals in charge is a recognized barrier to ensure an appropiate approach to pain in this population. Our present study reflects the current status of pain management and the challenges in diagnosis and treatment that pediatricians face in their daily work. This information is obtained from a survey made with a voluntary questionaire, desinged and distributed online by "Grupo Español para el Estudio del Dolor Pediátrico (GEEDP)" to pediatricians in Spain from october 2021 to march 2022. The final objective of the questionaire was to shed some light into the problem and find out which areas of pain management knowledge are in need of improvent.

Beyond the epidural: Alternatives to neuraxial labor analgesia

Labor creates an intense pain experienced by women across the world. Although neuraxial analgesia is the most effective treatment of labor pain, in many cases, it may not be undesired, not available, or have contraindications. In addition, satisfaction with labor analgesia is not only determined by the efficacy of analgesia but a woman's sense of agency and involvement in the childbirth experience are also key contributors. Providing safe choices for labor analgesia and support is central to creating a tailored, safe, and effective analgesic treatment plan with high maternal satisfaction. Healthcare provider knowledge of various nonneuraxial analgesic options, including efficacy, contraindications, safe clinical implementation, and side effects of various techniques is needed for optimal patient care and satisfaction. Future rigorous scientific studies addressing all of these labor analgesia options are needed to improve our understanding. This review summarizes the current published literature for commonly available non-neuraxial labor analgesic options.

Success rate of nitrous oxide-oxygen procedural sedation in dental patients: systematic review and meta-analysis

The aim of this systematic review was to determine the success rate of nitrous oxide-oxygen procedural sedation (NOIS) in dentistry. A systematic digital search was conducted for publications or reports of randomized controlled trials evaluating the clinical performance of NOIS. Abstracts of research papers were screened for suitability, and full-text articles were obtained for those who met the inclusion and exclusion criteria accordingly. The quality of the studies was assessed using the revised Cochrane risk-of-bias tool (RoB 2). A total of 19 articles (eight randomized clinical trials with parallel intervention groups and 11 crossover trials), published between May 1988 and August 2019, were finally selected for this review. The studies followed 1293 patients reporting NOIS success rates, with a cumulative mean value of 94.9% (95% CI: 88.8–98.9%). Thirteen trials were conducted on pediatric populations (1098 patients), and the remaining six were conducted on adults (195 patients), with cumulative efficacy rates of 91.9% (95% CI: 82.5–98.1%) and 99.9% (95% CI: 97.7–100.0%), respectively. The difference was statistically significant (P = 0.002). Completion of treatment and Section IV of the Houpt scale were the most used efficacy criteria. Within the limitations of this systematic review, the present study provides important information on the efficacy rate of NOIS. However, further well-designed and well-documented clinical trials are required and there is a need to develop guidelines for standardization of criteria and definition of success in procedural sedation. Currently, completion of treatment is the most used parameter in clinical practice, though many others also do exist at the same time. To maximize NOIS efficacy, clinicians should strictly consider appropriate indications for the procedure.

Anesthesia-Induced Oxidative Stress: Are There Differences between Intravenous and Inhaled Anesthetics?

Agents used for the induction of anesthesia have been shown to either promote or mitigate oxidative stress. A fine balance between the presence of reactive oxygen species (ROS) and antioxidants is crucial for the proper normal functioning of the cell. A basal concentration of ROS is essential for the manifestation of cellular functions, whereas disproportionate levels of ROS cause damage to cellular macromolecules such as DNA, lipids, and proteins, eventually leading to necrosis and apoptosis. Increased ROS has been linked with numerous illnesses, such as cardiovascular, immune system, liver, and kidney, and has been shown to promote cancer and accelerate aging. Knowledge of the various pharmacologic agents that increase or reduce oxidative stress may promote a safer way of inducing anesthesia. Furthermore, surgery itself leads to increased ROS production and ischemia/reperfusion injury. Indeed, increased perioperative oxidative stress has been correlated with increased postoperative complications and prolonged recovery. Anesthesiologists care for patients during the whole spectrum of perioperative care and thus are in a unique position to deliver countermeasures to oxidative stress. Using preferentially an induction agent which reduces oxidative stress might lead to better clinical outcomes and fewer postoperative complications. Propofol has been shown in several studies to reduce oxidative stress, which reduces postoperative complications and leads to a faster recovery, and thus might represent the preferred induction agent in the right clinical setting.

The association of nitrous oxide on length of stay in the postanesthesia care unit: a retrospective observational study

PURPOSE

To assess whether intraoperative use of nitrous oxide (N₂O) as an adjunct to general anesthesia is associated with a shorter length of stay in the postanesthesia care unit (PACU).

METHODS

We analyzed data from adult patients who underwent non-cardiothoracic surgery under general anesthesia between May 2008 and December 2018. We assessed the association between intraoperative low- and high-dose N₂O and PACU length of stay.

RESULTS

A total of 148,284 patients were included in the primary analysis. After adjusting for a priori defined confounders, a high dose of N₂O significantly decreased PACU length of stay, with a calculated difference of -9.1 min (95% confidence interval [CI], -10.5 to -7.7; P < 0.001). Patients who received high-dose N₂O had a lower incidence of both short- and prolonged-duration of intraoperative hypotension (adjusted odds ratio [aOR], 0.85; 95% CI, 0.83 to 0.88; P < 0.001 and aOR, 0.76; 95% CI, 0.73 to 0.80; P < 0.001, respectively) and received a lower total intraoperative vasopressor dose (-0.04 mg of norepinephrine equivalents; 95% CI, -0.06 to -0.01; P = 0.01). The effect of high-dose N₂O on PACU length of stay was modified by surgical complexity (adjusted absolute difference: -26.1 min; 95% CI, -29.2 to -23.1; P < 0.001; P for interaction < 0.001), and most pronounced in patients who underwent complex surgery and received intraoperative antiemetic therapy (adjusted absolute difference: -38.9 min; 95% CI, -43.1 to -34.6; P < 0.001; P for interaction < 0.001).

CONCLUSIONS

Nitrous oxide was dose-dependently associated with a decreased PACU length of stay. The effect was clinically relevant (> 30 min difference) in patients who underwent complex surgical procedures and received intraoperative antiemetic therapy.

Oxidative stress under general intravenous and inhalation anaesthesia

Oxidative stress occurs when reactive oxygen species (ROS) production overwhelms cell protection by antioxidants. This review is focused on general anaesthesia-induced oxidative stress because it increases the rate of complications and delays recovery after surgery. It is important to know what effects of anaesthetics to expect in terms of oxidative stress, particularly in surgical procedures with high ROS production, because their either additive or antagonistic effect may be pivotal for the outcome of surgery. In vitro and animal studies on this topic are numerous but show large variability. There are not many human studies and what we know has been learned from different surgical procedures measuring different endpoints in blood samples taken mostly before and after surgery. In these studies most intravenous anaesthetics have antioxidative properties, while volatile anaesthetics temporarily increase oxidative stress in longer surgical procedures.

Disruption of Rapid Eye Movement Sleep Homeostasis in Adolescent Rats after Neonatal Anesthesia

BACKGROUND

Previous studies suggest that rapid eye movement sleep rebound and disruption of rapid eye movement sleep architecture occur during the first 24 h after general anesthesia with volatile anesthetics in adult rats. However, it is unknown whether rapid eye movement sleep alterations persist beyond the anesthetic recovery phase in neonatal rats. This study tested the hypothesis that rapid eye movement sleep disturbances would be present in adolescent rats treated with anesthesia on postnatal day 7.

METHODS

Forty-four neonatal rats were randomly allocated to treatment with anesthesia consisting of midazolam, nitrous oxide, and isoflurane or control conditions for 2 h or 6 h. Electroencephalographic and electromyographic electrodes were implanted and recordings obtained between postnatal days 26 and 34. The primary outcome was time spent in rapid eye movement sleep. Data were analyzed using two-tailed unpaired t tests and two-way repeated measures analysis of variance.

RESULTS

Rats treated with midazolam, nitrous oxide, and isoflurane exhibited a significant increase in rapid eye movement sleep three weeks later when compared with control rats, regardless of whether they were treated for 2 h (174.0 ± 7.2 min in anesthetized, 108.6 ± 5.3 in controls, P < 0.0001) or 6 h (151.6 ± 9.9 min in anesthetized, 108.8 ± 7.1 in controls, P = 0.002).

CONCLUSIONS

Treatment with midazolam, nitrous oxide, and isoflurane on postnatal day 7 increases rapid eye movement sleep three weeks later in rats.

A single-centre investigator-blinded randomised parallel-group study protocol to investigate the influence of an acclimatisation appointment on children's behaviour during N2O/O2 sedation as measured by psychological, behavioural and real-time physiological parameters

AIMS AND OBJECTIVES

To describe a study protocol of a randomised control trial (RCT) assessing the effectiveness, in reducing dental anxiety, of an acclimatising nitrous oxide sedation (N₂O) session prior to actual dental treatment with N₂O.

MATERIALS AND METHODS

A single-centre investigator-blinded parallel-group RCT conducted in a postgraduate dental hospital in Dubai, United Arab Emirates (UAE). Anxious children requiring N₂O (aged 5-15 years) will be randomly assigned to; a study group: children who will have a preparatory N₂O trial experience or; a control group: children who will only have N₂O explained to them. Treatment with N₂O for both groups will start at the second visit. The following outcomes will be recorded: completion of dental treatment, anxiety scores at baseline and after treatment (using the Modified Child Dental Anxiety Scale faces), behaviour of the child (using Frankl Rating Behaviour Scale) and the acquisition of real-time physiological anxiety-related parameters (using E4^® electronic wrist devices).

RESULTS

The data will be analysed statistically.

DISCUSSION

There is a paucity of research regarding dental N₂O acclimatising appointments. This RCT will supplement existing literature.

CONCLUSIONS

This RCT will report whether prior acclimatising of a child to N₂O sedation is effective, or not, in improving dental treatment behaviour.

Preoperative pregnancy testing in surgical patients: How useful is policy of routine testing

Surgery in a patient with unrecognised pregnancy has serious ethical and medicolegal implications. There are no guidelines in India for preoperative pregnancy testing (POPT) in surgical patients. This review was undertaken to ascertain utility of routine POPT and whether any specific indication for POPT could be suggested. We performed a literature search to identify publications pertaining to POPT in surgical patients. Searches included PubMed, Google Scholar and internet search for national guidelines. Studies pertaining to incidence of unrecognised pregnancy, cost-effectiveness of POPT, effect of surgery and anaesthesia on pregnancy are included. We excluded articles which were available in languages other than English and those whose full texts were unavailable. Most of the literature about reproductive outcomes after anaesthesia exposure is based on old data. The evidence for teratogenic effect of anaesthetic drugs on human foetus is still inconclusive. Apart from anaesthesia and surgery, the outcome after surgery in unrecognised pregnant patient depends on other factors such as indication for surgery, high incidence of foetal loss in early pregnancy, stress and lifestyle of patient. As it is difficult to unsnarl the effect of these factors, POPT should be offered to all patients who based on history could be possibly pregnant. The cost-effectiveness of POPT appears doubtful, but considering costs associated with miscarriages and medicolegal litigations due to unclear association with anaesthesia, it may indeed be cost-effective.

Pro-Con Debate: Nitrous Oxide for Labor Analgesia

This Pro-Con debate will provide the practitioner with an evidence-based knowledge approach to assist the clinician in determining whether to employ (Pro) or not to employ (Con) this technique in the obstetrical suite for labor analgesia. Nitrous oxide has been used safely in dentistry and medicine for many centuries. However, accumulating preclinical and clinical evidence increasingly suggests previously unrecognized adverse maternal and fetal effects of nitrous oxide, which warrants reconsideration of its use in pregnant women and a more detailed informed consent. Nitrous oxide is associated with metabolic, oxidative, genotoxic, and transgenerational epigenetic effects in animals and humans that may warrant limiting its usefulness in labor. This debate will discuss and review the clinical uses, advantages, and disadvantages of nitrous oxide on occupational effects of nitrous oxide exposure, neuroapoptosis, FDA warning on inhalational anesthetics and the developing brain, research limitations, occupational exposure safety limits, effects on global warming, and potential for diversion.

Nitrous oxide anesthetic versus total intravenous anesthesia for functional endoscopic sinus surgery

BACKGROUND

Functional endoscopic sinus surgery is a common procedure for sinonasal disease, frequently performed in the outpatient setting. General anesthesia maintained with total intravenous anesthesia (TIVA) with propofol has been shown to give superior surgical conditions compared to inhaled anesthetics. This study evaluated the effects of TIVA versus a predominantly nitrous oxide (N₂ O)-based anesthetic with a low-dose propofol and remifentanil infusion on sinus surgery.

METHODS

Patients were randomized to either a N₂ O-based (nitrous oxide with propofol and remifentanil) or TIVA (propofol and remifentanil without nitrous oxide) group. The surgeon was blinded to the anesthetic technique. Surgical field grading was performed in real time by the otolaryngologist every 15 minutes with the Boezaart grading system.

RESULTS

There were no statistically significant differences between the Boezaart scores, duration of surgery, or estimated blood loss between the two anesthetic techniques. However, the use of N₂ O provided a statistically significant, 38% reduction in time from surgery end to extubation. The TIVA group had significantly decreased mean and median pain scores in the post-anesthesia care unit (PACU). There was no difference in the rate of postoperative nausea and vomiting between the two groups.

CONCLUSION

A N₂ O-based anesthetic for functional endoscopic sinus surgery provides similar intraoperative and postoperative conditions when compared to TIVA, while being superior in terms of time to extubation. Although the TIVA group had significantly decreased pain scores, this did not lead to a decrease in pain medicine received in the PACU, and there was no difference between groups in time to discharge.

LEVEL OF EVIDENCE

1b Laryngoscope, 130:E299-E304, 2020.

A study protocol of a single-center investigator-blinded randomized parallel group study to investigate the effect of an acclimatization visit on children's behavior during inhalational sedation in a United Arab Emirates pediatric dentistry postgraduate setting as measured by the levels of salivary Alpha Amylase and Cortisol

INTRODUCTION

Inhalation sedation is a proven safe method for reducing children's dental anxiety and has been used worldwide for decades. There is controversy regarding the use of acclimatization or familiarization visits for dental sedation treatment pathways for children. This may increase acceptance to the treatment based on desensitization and acclimatization principles underpinning many behavior management techniques. This study aims to identify whether, an inhalation sedation acclimatization visit is effective in reducing the stress level in anxious children as measured by salivary Alpha Amylase and Cortisol levels.

METHODS

The study is a single-center, single blinded, parallel group 2 arm clinical trial. Children in need of inhalation sedation aged 5 to 15 years from September 2019 through March 2020 attending the Postgraduate Pediatric Clinic at the Hamdan Bin Mohammed College of Dental Medicine, in Dubai, will be allocated randomly and equally to either:At the initial visit a salivary sample will be collected at the beginning of the visit and the sedation need score will be recorded using the pediatric indicator of sedation need. Treatment for both groups will commence at the second visit. Salivary samples will be collected 15 minutes before the start of the treatment and 15 minutes after the conclusion of the treatment. The following outcomes will be recorded: completion of dental treatment, anxiety scores at baseline and after treatment using Frankl rating behavior scale and physiological anxiety related changes will be recorded using salivary Alpha Amylase and Cortisol levels. Mean changes of physiologic anxiety levels and corresponding 95% confidence intervals will be determined to compare the 2 treatments (sedation with familiarization and sedation without familiarization).

DISCUSSION

This is will be the first study to measure the effect of the acclimatization visit of nitrous oxide inhalation sedation on the level of physiological anxiety and the behavior of the pediatric patients during treatment.

Non-Neuraxial Labor Analgesia: Options

Although it is the most effective method to treat labor pain, neuraxial analgesia may be undesired, contraindicated, unsuccessful, or unavailable. Providing safe choices for labor pain relief is a central goal of health care providers alike. Consequently, knowledge of the efficacy, clinical implementation, and side effects of various non-neuraxial strategies is needed to provide appropriate options for laboring patients. In addition to nonpharmacologic alternatives, inhaled nitrous oxide and systemic opioids represent two broad classes of non-neuraxial pharmacologic labor analgesia most commonly available. This review summarizes the current published literature for these non-neuraxial labor analgesic options.

Past, present, and future of nitrous oxide

INTRODUCTION

For a drug that has been omnipresent for nearly 200 years, nitrous oxide's (N2O) future seems less certain than its illustrious past. Environmental concerns are coming to the fore and may yet outweigh important clinical benefits.

SOURCES OF DATA

After determining the scope of the review, the authors used PubMed with select phrases encompassing the words in the scope. Both preclinical and clinical reports were considered.

AREAS OF AGREEMENT

The analgesic and anaesthetic advantages of N2O remain despite a plethora of newer agents.

AREAS OF CONTROVERSY

N2O greenhouse gas effect and its inhibition of key enzymes involved in protein and DNA synthesis have provided further fuel for those intent on eliminating its further clinical use.

GROWING POINTS

The use of N2O for treatment-resistant depression has gained traction.

AREAS TIMELY FOR DEVELOPING RESEARCH

Comparative studies for N2O role in combatting the prescription opioid analgesic epidemic may well provide further clinical impetus.

Colonoscopy quality with Entonox®vs intravenous conscious sedation: 18608 colonoscopy retrospective study

AIM

To compare colonoscopy quality with nitrous oxide gas (Entonox®) against intravenous conscious sedation using midazolam plus opioid.

METHODS

A retrospective analysis was performed on a prospectively held database of 18608 colonoscopies carried out in Lothian health board hospitals between July 2013 and January 2016. The quality of colonoscopies performed with Entonox was compared to intravenous conscious sedation (abbreviated in this article as IVM). Furthermore, the quality of colonoscopies performed with an unmedicated group was compared to IVM. The study used the following key markers of colonoscopy quality: (1) patient comfort scores; (2) caecal intubation rates (CIRs); and (3) polyp detection rates (PDRs). We used binary logistic regression to model the data.

RESULTS

There was no difference in the rate of moderate-to-extreme discomfort between the Entonox and IVM groups (17.9% vs 18.8%; OR = 1.06, 95%CI: 0.95-1.18, P = 0.27). Patients in the unmedicated group were less likely to experience moderate-to-extreme discomfort than those in the IVM group (11.4% vs 18.8%; OR = 0.71, 95%CI: 0.60-0.83, P < 0.001). There was no difference in caecal intubation between the Entonox and IVM groups (94.4% vs 93.7%; OR = 1.08, 95%CI: 0.92-1.28, P = 0.34). There was no difference in caecal intubation between the unmedicated and IVM groups (94.2% vs 93.7%; OR = 0.98, 95%CI: 0.79-1.22, P = 0.87). Polyp detection in the Entonox group was not different from IVM group (35.0% vs 33.1%; OR = 1.01, 95%CI: 0.93-1.10, P = 0.79). Polyp detection in the unmedicated group was not significantly different from the IVM group (37.4% vs 33.1%; OR = 0.97, 95%CI: 0.87-1.08, P = 0.60).

CONCLUSION

The use of Entonox was not associated with lower colonoscopy quality when compared to intravenous conscious sedation using midazolam plus opioid.

Effects of Inhaled Nitrous Oxide on the Induction Dose and Time Requirements of Propofol: A Prospective, Randomized, Double-blind Study

Context:

Propofol is a commonly used induction agent during general anesthesia. As a sole agent, it does not provide any strong analgesic effect. The nitrous oxide (N₂O) used along with propofol for induction of anesthesia augments the induction characteristics and reduces the dose of propofol.

Aims:

To study the effects of inhaled N₂O on the induction dose and time of propofol during general anesthesia and also its hemodynamic response and adverse effects.

Settings and Design:

The present research is a prospective, randomized, double-blind comparative study.

Subjects and Methods:

The study population consisted of eighty patients aged 18–60 years from either sex, American Society of Anesthesiologists physical status 1 and 2 which were scheduled for various elective surgical procedures under general anesthesia. The patients were randomly allocated into two groups comprising forty patients in each group. All patients were premedicated with glycopyrrolate 0.2 mg, ondansetron 4 mg, and fentanyl 1 μg/kg intravenously. Group FN received breathing mixture of gases (67% N₂O @ 4 L/min and 33% O₂ @ 2 L/min), and propofol and Group FO received 100% O₂ @ 6 L/min and propofol. The different hemodynamic parameters (heart rate, mean arterial pressure, systolic blood pressure, diastolic blood pressure, and SpO₂) were measured.

Statistical Analysis:

All observations were analyzed using Chi-square test, Student's t-test, and analysis of variance.

Results:

The mean induction time and dose were significantly less in Group FN as compared to Group FO (P < 0.05). The mean induction time was 172 ± 32 s in Group FN as compared to 242 ± 43 s in Group FO (P < 001), whereas the mean induction dose was 56.10 ± 13.92 mg in Group FN as compared to 81.67 ± 17.64 mg in Group FO (P < 0.05). The hemodynamic parameters remained stable with no complications.

Conclusion:

The coadministration of N₂O during induction of anesthesia with propofol not only reduced the induction dose of propofol but also reduced induction time significantly. Furthermore, it provided stable hemodynamics without any complications.