Combination of inhaled nitrous oxide and oral opioids induces long-lasting analgesic effects in patients with neuropathic pain: ProtoTOP study post hoc exploratory analyses.

ABSTRACT: Experimental studies have suggested that nitrous oxide-induced analgesia depends on interactions with opioids. On the basis of these results, we hypothesized that the effects of inhaled nitrous oxide/oxygen (N 2 O/O 2 ) 50%-50% equimolar mixture (EMONO) on patients with neuropathic pain would be higher in those receiving concomitant opioids. To test this hypothesis, we did exploratory post hoc analyses of our recently published ProtoTOP study to compare the effects of EMONO and placebo in patients with or without concomitant opioid treatment. A total of 92 patients of the 221 (ie, 41.6%) included in the ProtoTOP study were concomitantly treated with opioids. In contrast with our previous analyses, average pain intensity was significantly decreased in comparison with placebo one week after the last treatment administration in patients treated with opioids, but not in those treated without opioid, and this effect was maintained over the 4-week follow-up period. Neuropathic pain symptom inventory (NPSI total and subscores) was also significantly more decreased after inhalation of EMONO in comparison with placebo only in patients receiving opioids. The proportion of patients with at least 30% pain reduction and of those reporting an overall improvement with the Patient Global Impression of Change were significantly higher only in this population of patients. In conclusion, these results complement our previous analyses with the identification of a specific population of responders to EMONO inhalation in patients with neuropathic pain. As suggested by experimental studies, we hypothesized that these long-lasting analgesic effects could depend on the anti-N-methyl-D-aspartate properties of N 2 O.

Procedural analgesia with nitrous oxide at home for epidermolysis bullosa: A case report.

RATIONALE: Epidermolysis bullosa (EB) is an inherited disease characterized by fragile skin with painful blistering, which requires lifelong skin and wound care. This case report describes the use of inhaled nitrous oxide (N2O) for procedural pain control at home during wound care in a young man with severe dystrophic EB. To our knowledge, only 1 case was reported by Ingelmo et al in 2017 regarding the use of N2O at home in a 4-year-old-child. To date, no such attempt has been made in adult patients. PATIENT CONCERNS: Our patient was a 28-year-old man. Frequent blisters appear spontaneously, and are often preceded by erythema and itching. Patient required daily treatment daily consisting of lancing blisters with a needle and emptying them by compression. DIAGNOSES: Severe recessive dystrophic EB diagnosed at the time of delivery. INTERVENTIONS: Procedural pain control was managed by the auto-administration of an inhaled N2O and air gas mixture. OUTCOMES: Conscious sedation with N2O leads to beneficial effects, such as reduction in dressing duration, acute procedural pain, local antibiotic needing, medication memory, anxiety, anticipatory pain, and fatigue after the dressing session. LESSONS: N2O analgesia is safe and effective, resulting in a significant reduction in procedural pain and an improvement in the quality of life of patients and their caregivers.

Multicenter Study Evaluating Nitrous Oxide Use for Labor Analgesia at High- and Low-Altitude Institutions.

BACKGROUND: Nitrous oxide (N2O) has been used nationally as an analgesic in many clinical settings. While neuraxial analgesia is still the most commonly used labor analgesic in the United States, there is increasing use of N2O in labor. Given the reduction in the partial pressure of gases at a higher altitude, N2O has been reported to have reduced analgesic properties. However, there is no study to date evaluating the impact of altitude on labor analgesia and N2O. METHODS: We conducted a multicenter retrospective data analysis of a N2O registry collected from 4 institutions over a 3-year period. We compared the impact of altitude on 50% N2O administration for labor analgesia, conversion rates to another analgesic modality, as well as collected side effect frequencies and conversion predictors. Multivariable regression models were used to compare clinical characteristics and outcomes between parturients at high and low altitudes, while adjusting for race, ethnicity, education, and age (logistic and linear regressions for categorical and quantitative outcomes, respectively). RESULTS: A total of 1856 laboring parturients (age 18-50) were included in the analysis. The odds of converting from 50% N2O to another analgesic modality had no statistically significant difference between high- versus low-altitude institutions (adjusted odds ratio [aOR], 1.13; 95% confidence interval [CI], 0.90-1.42; P = .3). Yet, when parturients at low altitude converted from N2O, they were more likely (aOR, 3.03; 95% CI, 1.59-5.88) to choose neuraxial analgesia instead of another analgesic modality when compared to high-altitude parturients. This is possibly due to higher epidural rates at the low-altitude institutions. When parturients at high altitude did convert into another modality, they were more likely (aOR, 2.19; 95% CI, 1.14-4.21) to convert due to inadequate pain relief compared to low-altitude parturients; however, missing data may have affected this finding. Laboring individuals at low altitude were significantly more likely to experience side effects (aOR, 2.13; 95% CI, 1.45-3.12). Those requiring labor augmentation, assisted vaginal, or cesarean delivery converted to neuraxial analgesia significantly more often than those that delivered via spontaneous vaginal delivery (P < .05) in both high- and low-altitude groups. CONCLUSIONS: This is the first study evaluating 50% N2O as a labor analgesic at high altitude. As expected, we found lower side effects at high altitude, likely due to the lower partial pressure of N2O. However, there was not a statistically significant increase in conversion from N2O to another analgesic modality at high altitude and no clinically significant differences in neonatal outcomes.

Does vitamin B12 deficiency explain psychiatric symptoms in recreational nitrous oxide users? A narrative review.

Background Recreational use of nitrous oxide (N2O) is associated with many side effects, of which neurological complications are most common. Nitrous oxide abuse is also associated with psychiatric symptoms, but these have received less attention so far. Vitamin B12 deficiency may play a role in the development of these psychiatric symptoms.Aims To explore the relationship among the occurrence of recreational nitrous oxide-induced psychiatric symptoms, accompanying neurological symptoms, vitamin B12 status and choice of treatment.Methods A retrospective search for case reports was conducted across multiple databases (Pubmed, Embase, Web of Science, PsycINFO and CINAHL). Keywords included variants of "nitrous oxide", "case report" and "abuse". No restrictions to language or publication date were applied.Results The search retrieved 372 articles. A total of 25 case reports were included, representing 31 patients with psychiatric complications following nitrous oxide abuse. The most often reported symptoms were: hallucinations (n = 16), delusions (n = 11), and paranoia (n = 11). When neurological symptoms were present, patients were treated more frequently with vitamin B12 supplementation.Conclusions This review highlights the need to recognize that psychiatric symptoms may appear in association with nitrous oxide use. Approximately half of the cases that presented with nitrous oxide-induced psychiatric complaints did not show neurological symptoms, and their vitamin B12 concentration was often within the hospital's reference range. Psychiatrists and emergency physicians should be aware of isolated psychiatric symptoms caused by recreational nitrous oxide abuse. We suggest asking all patients with new psychiatric symptoms about nitrous oxide use and protocolizing the management of nitrous oxide-induced psychiatric symptoms.

A retrospective cohort study on red blood cell morphology changes in pre-school age children under nitrous oxide anesthesia.

BACKGROUND: Megaloblastic anemia or bone marrow changes could occur after prolonged nitrous oxide inhalation via vitamin B12 inactivation related DNA synthesis impairment. Previous researches have studied hematological changes with nitrous oxide exposure, but only in adults or adolescents. Pre-school age children with active hematopoietic red bone marrow are more vulnerable to potential side effects of nitrous oxide and might experience growth impairment. The purpose of our study was to analyze red blood cell morphology changes under nitrous oxide anesthesia in pre-school age children. METHODS: One hundred thirty-six children under 5 years old scheduled for hemivertebra resection were analyzed. According to fresh gas type in anesthesia records, 71 children who received nitrous oxide in oxygen during anesthesia maintenance were categorized into the nitrous oxide group and the other 65 who received air in oxygen were the air group. Complete blood counts in perioperative period were assessed for anemia, macrocytosis, microcytosis, anisocytosis, hyperchromatosis and hypochromatosis. The peak value and change percentage were calculated for mean corpuscular volume and red cell distribution width. RESULTS: Forty-two children in the air group (64.6%) and 30 in the nitrous oxide group (42.3%) developed anemia (P = 0.009). None developed macrocytosis in both groups. Postoperative mean corpuscular volume peaked (mean [95% confidence interval]) at 83.7(82.9-84.4) fL, and 83.2(82.4-83.9) fL and postoperative red cell distribution width at 13.8% (13.4-14.2%), and 13.9% (13.6-14.2%) for the air group and the nitrous oxide group. Both the relative change of mean corpuscular volume (P = 0.810) and red cell distribution width (P = 0.456) were similar between the two groups. CONCLUSIONS: No megaloblastic red blood cell changes were observed with nitrous oxide exposure for 4 h in pre-school age children undergoing hemivertebra resection.

The effect of saline versus air for cuff inflation on the incidence of high intra-cuff pressure in paediatric MicroCuff® tracheal tubes: a randomised controlled trial.

The use of cuffed tracheal tubes in paediatric anaesthesia is now common. The use of nitrous oxide in anaesthesia risks excessive tracheal tube cuff pressures, as nitrous oxide can diffuse into the cuff during the course of surgery. The aim of this single-centre, prospective, randomised controlled trial was to compare the effect of saline versus air for the inflation of tracheal tube cuffs on the incidence of excessive intra-operative cuff pressure in children undergoing balanced anaesthesia with nitrous oxide. Children (age ≤ 16 y) were randomly allocated to receive either saline (saline group) or air (air group) to inflate the cuff of their tracheal tube. The pressure in the tracheal tube cuff was measured during surgery and brought down to the initial inflation level if it breached a safe limit (25 cmH2 O). Post-extubation adverse respiratory events were noted. Data from 48 patients (24 in each group), aged 4 months to 16 y, were analysed. The requirement for reduction in intra-cuff pressure occurred in 1/24 patients in the saline group, compared with 16/24 patients in the air group (p < 0.001). The incidence of extubation-related adverse events was similar in the saline and air groups (15/24 vs. 13/24, respectively; p = 0.770). The use of saline to inflate the cuff of paediatric cuffed tubes reduces the incidence of high intra-cuff pressures during anaesthesia. This may provide a pragmatic extra safety barrier to help reduce the incidence of excessive tracheal cuff pressure when nitrous oxide is used during paediatric anaesthesia.

Recreational Nitrous Oxide Abuse: Prevalence, Neurotoxicity, and Treatment.

Nitrous oxide (N2O), also known as "laughing gas," is a colorless, nonirritating gas. Clinically, it is widely used as an inhaled anesthetic, analgesic, and anxiolytic. In recent years, recreational abuse of N2O has become increasingly common, especially among young adults and adolescents, but many of them lack awareness of the possible side effects associated with this drug. N2O abuse can damage multiple systems, especially the nervous system, but the exact mechanism of N2O toxicity remains controversial. At present, an increasing number of cases of nervous system damage caused by N2O abuse have been reported both at home and abroad. Discontinuation of N2O use and timely supplementation with vitamin B12 are essential for a good prognosis. Long-term abuse without timely treatment will eventually lead to irreversible neurological damage. In this article, we discuss the epidemiology of N2O abuse, neurotoxicity mechanisms, clinical manifestations, relevant auxiliary examinations, treatments, and prognosis to improve social awareness of N2O exposure risk, especially among users and clinicians.

Plaque erosion causing ST-elevation myocardial infarction after consumption of cannabis and N2O in a 27-year old man: a case report.

BACKGROUND: The recreational drugs cannabis and nitrous oxide (N2O) are known for pro-atherogenic effects and are associated with an elevated risk of myocardial infarction. These cardiovascular effects might be underestimated by the public. Culprit-lesion composition of myocardial infarctions associated with cannabis and N2O has been unknown so far. This case report aims to raise the awareness of the adverse cardiovascular effects of cannabis and N2O and reports, for the first time, optical coherence tomography (OCT) findings of the culprit lesion. CASE PRESENTATION: This is a case report of a 27-year old man with anterior ST-segment-elevation myocardial infarction (STEMI) after intoxication with cannabis and N2O. Coronary angiography and OCT revealed plaque erosion with subsequent subtotal thrombotic occlusion of the left anterior descending artery that was successfully treated with 1 drug-eluting stent. The patient was symptom free at 6 months follow-up and had been able to abstain from drug consumption. CONCLUSIONS: This is the first case to demonstrate the association between cannabis and N2O abuse and plaque erosion on OCT in a young man with STEMI. In contrast to smoking, whose adverse effects are well-known, the cardiovascular effects of cannabis and N2O might be underestimated. These adverse effects should gain more awareness in the public to prevent early vascular events in young adults.

Associations of socio-demographic characteristics, well-being, school absenteeism, and substance use with recreational nitrous oxide use among adolescents: A cross-sectional study.

PURPOSE: A rapid increase of recreational nitrous oxide use (i.e. laughing gas, N2O) has been reported in several countries, while it has received limited attention in scientific research. We aimed to study the association of socio-demographic characteristics, mental well-being, sickness absence, truancy, and substance use with the frequency of lifetime nitrous oxide use among adolescents. METHODS: We used self-reported questionnaire data of adolescents (N = 555) attending secondary schools to cross-sectionally assess the frequency of nitrous oxide use and potential factors associated with nitrous oxide use, such as gender, mental well-being, and binge drinking. Ordinal logistic regression models were applied with lifetime nitrous oxide use (never, once, ≥ two times) as the outcome variable. RESULTS: Adolescents were on average 15.6 years old (SD = 0.83, range 14-18), 47.0% were female. In total, 86 (15.6%) adolescents had used nitrous oxide at least once in their life. In the multivariable ordinal regression model, the risk of having a higher category of lifetime nitrous oxide use was associated with a non-Dutch ethnic background (OR = 2.10, 95% CI 1.22; 3.61), attending pre-vocational education (OR = 1.88, 95% CI 1.06; 3.34), a higher score on the scale of externalizing problems (OR = 1.10, 95% CI 1.01; 1.20), binge drinking twice or more in the past four weeks (OR = 2.49, 95% CI 1.25; 4.94), and cannabis use (OR = 1.98, 95% CI 1.03; 3.79). CONCLUSIONS: Youth Health Care professionals should be aware of nitrous oxide use in adolescents, especially among adolescents with a non-Dutch ethnic background, lower education levels, externalizing problems, frequent binge drinking, and cannabis use.

Nitrous oxide versus lidocaine versus no analgesic for in-office hysteroscopy: a randomised clinical trial.

OBJECTIVE: To compare the effect of inhaled nitrous oxide (INO) on pain control during in-office hysteroscopy with 1% lidocaine paracervical infiltration and no analgesic. DESIGN: Single-blind stratified randomised clinical trial with masked assessment by a third party. SETTING: Department of Obstetrics and Gynaecology in a Spanish hospital. POPULATION: Women who underwent hysteroscopy. METHODS: Patients were stratified into three groups according to the purpose of the hysteroscopy (biopsy, polypectomy or tubal sterilisation) and then assigned to different treatment groups through a permuted-blocks randomisation within strata. Pain scale was provided by a gynaecologist totally blinded to procedures and treatments. Effects were assessed using a one-way analysis of variance following an intention-to-treat approach. MAIN OUTCOME MEASURES: Visual analogue scale (VAS) from 0 to 100 mm. RESULTS: A total of 314 women were included: 105 to INO, 104 to 1% lidocaine and 105 to no analgesic. Baseline characteristics were comparable. Mean VAS score after the procedure was 34.7 ± 25.8 mm, 36.1 ± 22.9 mm (P = 1.0) and 47.3 ± 28.2 mm (P = 0.001) for INO, 1% lidocaine and no analgesic, respectively. No adverse events were reported in 91 (86.7%) patients in the INO group compared with 79 (76%) in the 1%-lidocaine group (P = 0.04) and 85 (81%) in the no-analgesic group (P = 0.26). CONCLUSION: INO was as effective as 1% lidocaine in pain control for in-office hysteroscopy and was better tolerated. The no-analgesic group presented the poorer results, so was the least recommended clinical option.

Utility and safety of low-concentration nitrous oxide anesthesia in ptosis surgery.

ABSTRACT: To evaluate the utility of low-concentration nitrous oxide (N2O) anesthesia in ptosis surgeryThis study was a retrospective consecutive case series that included 54 successive patients with blepharoptosis who underwent bilateral levator aponeurosis advancement and on whom skin resection performed by the same surgeon between August 2016 and July 2017. Among these patients, 27 were operated with a local anesthesia injection (air group) and 27 with a local anesthesia injection and low-concentration N2O anesthesia (N2O group). All N2O cases used a total of 6 L of gas comprising 70% oxygen and 30% N2O. Preoperative and postoperative blood pressure (BP) and heart rate (HR) and intraoperative pain, anxiety, nausea, and memory were measured immediately after surgery using visual analog scale score (VASS). Additionally, perioperative side effects were examined.There was no significant difference in age, sex, and preoperative and postoperative margin reflex distance (MRD) between the 2 groups (all P > .05). The intraoperative mean peripheral oxygen saturation was significantly higher (97.5% ±â€Š1.6% vs 99.5% ±â€Š.6%, P < .001), intraoperative HR was significantly lower (78.2 ±â€Š12.8 vs 70.7 ±â€Š11.6 bpm, P = .02), and operation time was significantly shorter (33.1 ±â€Š8.1 vs 29.4 ±â€Š10.3 minutes, P = .03) in the N2O group than in the air group.Difference between intraoperative and preoperative systolic BP (BPs) (+15.8 ±â€Š18.0 vs + 3.1 ±â€Š21.7 mm Hg, P = .02), diastolic BP (BPd) (+7.0 ±â€Š17.4 vs -2.3 ±â€Š13.6 mm Hg, P = .04), and HR (3.2 ±â€Š8.5 vs -3.9 ±â€Š9.4 bpm, P = .01) was significantly lower in the N2O group than in the air group.VASS of intraoperative pain was significantly lower in the N2O group than in the air group (49.5 ±â€Š24.7 vs 22.6 ±â€Š14.9, P < .001), whereas intraoperative anxiety and memory did not present significant differences between the groups (P = .09 and P = .45, respectively). Intraoperative nausea score was 0 for all cases in both groups. There was no other side effect.Ptosis surgery with anesthesia using 30% N2O may effectively suppress intraoperative BP and HR along with pain and shorten the operation time without side effects such as nausea.

Nitrous oxide misuse reported to two United States data systems during 2000-2019.

Background: Nitrous oxide may be misused due to its euphoric, dissociative, and hallucinogenic effects. Nitrous oxide misuse has been reported to be increasing.Objective: The objective of this study is to describe nitrous oxide misuse reported to two United States (US) data systems.Methods: Cases were nitrous oxide misuse during 2000-2019 reported to the National Electronic Injury Surveillance System (NEISS), which collects data on consumer product-related injuries treated in US emergency departments (EDs), and the Food and Drug Administration Adverse Event Reporting System (FAERS), which collects reports of adverse events involving drugs and other biologic products. The distribution of cases was determined for selected variables.Results: Of the 26 NEISS cases, the mean annual number of cases was 0.5 (range 0-2) during 2000-2013 and 3.2 (range 1-5) during 2014-2019. The patients were 92.3% age 13-39 years and 76.9% male. The patient was treated or examined and released from the ED in 84.6% of the cases. Of the 128 FAERS cases, the mean annual number of cases was 0.4 (range 0-2) during 2000-2013 and 20.3 (range 10-34) during 2014-2019. The patients were 90.2%% age 13-39 years and 77.3% male. A serious classification was assigned to 97.7% of the cases.Conclusions: Nitrous oxide misuse reported to NEISS and FAERS both increased during 2000-2019, particularly after 2013. The majority of patients were age 13-39 years and male. Most NEISS patients were treated or examined and released from the ED.

Gene and systemic inflammatory effects and neuroendocrine response in surgical patients anesthetized with desflurane-nitrous oxide or desflurane-nitrous oxide-free: A randomized trial.

There is growing interest in assessing possible immunotoxicological effects in anesthetized patients. There are controversial findings concerning the effect of nitrous oxide (N2O) anesthetic gas effect on inflammatory response. We tested the hypothesis that N2O associated with desflurane (inhalational anesthetic) was likely to worsen neuro-immune-endocrine effects when compared with desflurane alone in this randomized trial. The primary endpoint of this study was to evaluate the systemic proinflammatory interleukin (IL)-6, and the secondary endpoints included other systemic (IL-1ß, TNF-α, IL-8, IL-10, IL-17A and high-sensitivity C-reactive protein - hs-CRP) and genetic inflammatory markers (NF-kB, IL-6 and COX-2) as well as hormones (adrenocorticotropic hormone, cortisol and prolactin) comparing patients undergoing minor surgery with or without N2O-desflurane. As a second aim, we assessed whether there were changes in the neuro-immune-endocrine profiles within each group. Blood samples were collected before anesthesia, 90 min after anesthesia induction, and the day after surgery. We assessed serum cytokines using a cytometric bead array and hs-CRP by chemiluminescent immunoassay. Expression of three proinflammatory transcripts was assessed by real-time quantitative polymerase chain reaction, and neuroendocrine hormones were detected by chemiluminescent microparticle immunoenzymatic assay. There were no significant between-group differences for any analyzed biomarkers. However, there was a significant increase in: (a) systemic IL-6 and hs-CRP values one day after surgery in both groups and (b) prolactin levels in the intraoperative period compared to baseline and postoperative period levels for both groups. In conclusion, N2O does not impair the inflammatory profile and neuroendocrine response compared to patients who receive only desflurane anesthesia.

Combined intranasal fentanyl and dexmedetomidine plus inhaled nitrous oxide sedation in children needing myringotomy and ventilation tube insertion with a specific handheld device.

OBJECTIVES: We report a case series of one-time 4 mcg/kg dose of intranasal dexmedetomidine and 1 mcg/kg of intranasal fentanyl plus inhaled nitrous oxide for procedural sedation in children with otitis media with effusion (OME) for tympanostomy tube placement with a specific handheld device (Solo TTD, AventaMed ®). METHODS: A retrospective review was conducted in a tertiary paediatric teaching hospital on patients with OME referred from December 2018 to December 2019 in need of procedural sedation for myringotomy and ventilation tube insertion (VTI). Sixteen of twenty-four consecutively admitted subjects received a one-time dose (4 mcg/kg) of intranasal dexmedetomidine and 1mcg/Kg of intranasal fentanyl followed by inhaled nitrous oxide (iN2O) at 50% with the intended goal to achieve a Ramsay Sedation Score 4 allowing a motionless procedure with adequate analgesia. Parents' satisfaction for the procedure was measured by mean of a Likert scale (from 0 to 5 points). RESULTS: Sixteen patients underwent procedural sedation for myringotomy with VTI. Sedation was achieved successfully in fifteen patients (93,75%), with a mean induction time of 29 min (range 19-43) and a mean recovery time of 74 min (range 54-110). The patient who did reach an adequate sedation level underwent an intravenous line positioning and a dose of ketamine. No adverse effects were reported, and the parents' judgment average on the Likert scale was 4,93. VTI procedure was successful in all ears. CONCLUSIONS: A combination of intranasal dexmedetomidine, fentanyl, and iN2O could be considered as a possible option for procedural sedation in children with OME undergoing procedural sedation for tympanostomy tube placement in children with Solo TTD device.

The fraction of nitrous oxide in oxygen for facilitating lung collapse during one-lung ventilation with double lumen tube.

BACKGROUND: The ideal fraction of nitrous oxide (N2O) in oxygen (O2) for rapid lung collapse remains unclear. Accordingly, this prospective trial aimed to determine the 50% effective concentration (EC50) and 95% effective concentration (EC95) of N2O in O2 for rapid lung collapse. METHODS: This study included 38 consecutive patients undergoing video-assisted thoracoscopic surgery (VATS). The lung collapse score (LCS) of each patient during one-lung ventilation was evaluated by the same surgeon. The first patient received 30% N2O in O2, and the subsequent N2O fraction in O2 was determined by the LCS of the previous patient using the Dixon up-and-down method. The testing interval was set at 10%, and the lowest concentration was 10% (10, 20, 30, 40%, or 50%). The EC50 and EC95 of N2O in O2 for rapid lung collapse were analyzed using a probit test. RESULTS: According to the up-and-down method, the N2O fraction in O2 at which all patients exhibited successful lung collapse was 50%. The EC50 and EC95 of N2O in O2 for rapid lung collapse were 27.7% (95% confidence interval 19.9-35.7%) and 48.7% (95% confidence interval 39.0-96.3%), respectively. CONCLUSIONS: In patients undergoing VATS, the EC50 and EC95 of N2O in O2 for rapid lung collapse were 27.7 and 48.7%, respectively. TRIAL REGISTRATION: http://www.chictr.org/cn/ Identifier ChiCTR19 00021474 , registered on 22 February 2019.

COVID-19 et protoxyde d'azote pendant l'accouchement / COVID-19 and nitrous oxide during childbirth

PRÉSENTATION SOMMAIRE DE LA DEMANDE: Il a été demandé à l'INESSS de rechercher dans la littérature les données relatives à l'utilisation du protoxyde d'azote pendant l'accouchement en contexte de pandémie à la COVID-19 chez les femmes atteintes ou non du coronavirus afin d'en faire une utilisation optimale en contexte de pandémie et de crise. Le protoxyde d'azote (aussi appelé gaz hilarant ou oxyde nitreux) est un gaz incolore qui est utilisé, entre autres, en maintien de l'anesthésie générale ou comme analgésique (à dose subanesthésique) en obstétrique pendant l'accouchement. Lorsqu'il est utilisé comme analgésique, il doit être mélangé à de l'oxygène (50 %-50 %) et administré par inhalation par l'entremise d'un masque muni d'une valve à demande. Puisque ce gaz tend à dilater les cavités de l'organisme renfermant des gaz, le protoxyde d'azote serait contre-indiqué en présence d'air dans la plèvre, le péricarde ou le péritoine, de même que lors d'affection des voies aériennes chronique obstructive ou d'emphysème. MÉTHODOLOGIE: Questions d'évaluation: Quelles sont l'innocuité et les modalités d'utilisation du protoxyde d'azote pendant l'accouchement en contexte de pandémie à COVID-19? Critères de sélection: Population: Femmes atteintes ou non de la COVID-19. Intervention: Utilisation du protoxyde d'azote pendant l'accouchement Comparateur : Placebo ou autre analgésique Résultat d'intérêt : Innocuité, modalités d'utilisation. Types de documents retenus: Tout document contenant des informations pertinentes, que ce soit de la littérature scientifique ou de la littérature grise. Méthodes de recension: Date de recherch : 23 et 27 mars 2020. Une recherche rapide a été effectuée en utilisant les bases de données PubMed, MEDLINE, Embase, EBM Reviews et le moteur de recherche Google avec les mots-clés suivants: Coronavirus, pneumonia virus, 2019 ncov, COVID-19, nitrous Oxide, laughing gas, nitrogen protoxide, delivery, obstetric, childbirth, parturition, sage*-femme*, midwife*, midwives. Une recherche manuelle de la littérature a également été effectuée en consultant les sites Web des agences règlementaires, d'agences d'évaluation des technologies de la santé ainsi que ceux d'organismes gouvernementaux, d'associations ou ordres professionnels en lien avec le thème des travaux. Consultation menée: Aucune consultation d'experts n'a été menée dans le cadre de ces travaux. CONSTATS DE L'INESSS: Basé sur la documentation scientifique disponible au moment de sa rédaction, malgré l'incertitude existante dans cette documentation et dans la démarche utilisée de recension, il ressort que: Les recommandations liées à l'utilisation du protoxyde d'azote pendant l'accouchement chez les femmes confirmées ou suspectées COVID-19 sont divergentes selon les sociétés savantes ou organismes: Certains recommandent d'utiliser le protoxyde d'azote pendant l'accouchement en utilisant un filtre microbiologique pour prévenir la contamination du système d'inhalation du gaz; Certains recommandent d'utiliser le protoxyde d'azote pendant l'accouchement sans précision sur les précautions particulières; Certains recommandent d'évaluer les risques et bénéfices de l'utilisation du protoxyde d'azote pendant l'accouchement avant son utilisation vu les incertitudes entourant le nettoyage, les filtres à utiliser ainsi que le potentiel d'aérosolisation du produit; Certains ne mentionnent aucune opposition sur l'utilisation du protoxyde d'azote pendant l'accouchement puisqu'il n'existe aucune évidence que l'administration de ce médicament est une procédure pouvant générer des aérosols. Les incertitudes soulevées quant à la possibilité pour ce médicament de générer des aérosols rendent potentiellement nécessaire le port d'un équipement de protection approprié pour le personnel médical si utilisé par une personne avec statut COVID-19 positif ou suspecté. Or, ces équipements sont des ressources dont il serait judicieux de réserver l'usage pour des situations de nécessité absolue. De plus, le risque théorique de contamination par le virus du système d'administration du protoxyde d'azote est une considération importante.