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Abstract Background In many countries, nitrous oxide is used in a gas mixture (EMONO) for short-term analgesia. Cases of addiction, with significant misuse, have been reported in hospitalized patients. Patients suffering from sickle cell disease (SCD) could represent a high-risk population for substance use disorder (SUD) due to their significant pain crisis and repeated use of EMONO. The objective of the PHEDRE study was to assess the prevalence of SUD for EMONO in French SCD patients. Results A total of 993 patients were included. Among 339 EMONO consumers, only 38 (11%) had a SUD, with very few criteria, corresponding mainly to a mild SUD due to a use higher than expected (in quantity or duration) and relational tensions with the care teams. Almost all patients (99.7%) were looking for an analgesic effect, but 68% of patients were also looking for other effects. The independent risks factors associated with at least one SUD criterion were: the feeling of effects different from the expected therapeutic effects of EMONO, at least one hospitalization for vaso occlusive crisis in the past 12 months and the presence of a SUD for at least one other analgesic drug. Conclusions The use of EMONO was not problematic for the majority of patients. Manifestations of SUD that led to tensions with healthcare teams should alert and lead to an evaluation, to distinguish a true addiction from a pseudoaddiction which may be linked to an insufficient analgesic treatment related to an underestimation of pain in SCD patients. Trial registration : Clinical Trials, NCT02580565. Registered 16 October 2015, https://clinicaltrials.gov/

Introduction: Dental anxiety is a common problem among children, leading to missed dental appointments and neglect of oral health. Conscious sedation is a technique used in dental clinics to alleviate anxiety and enhance the patient’s experience. However, parents often lack understanding about conscious sedation, which can hinder their consent for the procedure for their child. Aim: To assess parents’ knowledge, attitudes, and perceptions towards conscious sedation in dental care settings. Materials and Methods: This study employed a pre-test/posttest quasi-experimental design and involved 400 parents (aged 21-40 years) whose children, aged 3 to 16 years, were randomly selected to complete a questionnaire survey at the Department of Pedodontics and Preventive Dentistry at Rajarajeswari Dental College and Hospital in Bengaluru, Karnataka, India. The survey was conducted between December 2022 and March 2023, spanning a period of four months. Data collection methods included a pre-education questionnaire and a posteducation questionnaire after an educational intervention. The collected data underwent statistical analysis, utilising mean, Standard Deviation (SD), Analysis of Variance (ANOVA), Wilcoxon's signed rank, and Tukey’s posthoc tests. Results: Prior to education, 393 (98.25%) of the study population were unaware that conscious sedation was safe and easy. It was observed that 368 (92%) of the participants opposed conscious sedation for their child, but following education, 400 (100%) agreed, resulting in a 95.2% shift in perception. Conclusion: The study revealed that, before the intervention, the majority of parents were unaware of and opposed to conscious sedation, indicating a significant knowledge gap. However, the implementation of educational interventions during dental visits, led by dentists, played a crucial role in improving their knowledge and significantly changing their attitude, with 400 (100%) agreeing to the use of conscious sedation.

Introduction: In order to effectively treat children, managing terrified and nervous paediatric dental patients is crucial. The choice of a specific behaviour control strategy is at the operator’s discretion, but it may be influenced by parental approval. Clinically beneficial pharmacological therapies, such as Nitrous Oxide-oxygen Inhalation Sedation (NOIS), have been demonstrated. However, prolonged exposure to specific amounts of these therapies could pose health hazards for medical personnel. Aim: To evaluate the clinical efficacy and safety of utilising N2 O inhalation sedation at a 70% concentration in a paediatric dental setting, compared to administering it at 50% and 60% concentrations. Materials and Methods: A non randomised clinical trial was conducted in the Department of Paediatric and Preventive Dentistry at Saveetha Dental College, Chennai, India. The duration of the study was three months, from June 2022 to August 2022. A total of 42 young patients between the ages of 4 and 10 who required mandibular pulpectomy and crown were selected. During the study, the researchers recorded each patient’s levels of sedation and cooperation at four specific time points while administering a fixed concentration of N2 O. The concentrations at these time points were 50% at the 10th minute, 60% at the 20th minute, 70% at the 30th minute, and 70% at the 40th minute. The study compared the primary outcomes of sedation and cooperation levels, along with the secondary outcome of adverse effects, between the different time intervals using the Kruskal-Wallis test followed by post-hoc tests for pairwise comparison. The level of significance was set at p

Nitrous oxide, commonly known as ‘laughing gas’, has become a popular recreational drug. Whippets, small canisters containing gas in pressurized form, can be easily obtained from a food store. However, inhaling nitrous oxide from these canisters, which contain a 100% concentration, can lead to hypoxia, resulting in seizures or even death. Inhalation of nitrous oxide rarely causes pneumothorax, pneumomediastinum, and pneumopericardium.This case study highlights the potential dangers of recreational abuse of nitrous oxide.

Abstract Background Nitrous oxide (N2O) is a gas used in medicine for its analgesic, anxiolytic and amnesic properties. It is a drug considered safe if adequately administered. In the literature, accidental N2O-related deaths are rare. They are mostly related to inhalation of this substance for recreational and autoerotic purposes; rarely are reported deaths due to incorrect administration of medical gas in anesthesia. The diagnosis of death from acute N2O intoxication is complex and is generally an exclusion diagnosis: the macroscopic and microscopic post-mortem signs are entirely nonspecific. Furthermore, the circumstantial data are not always supportive and can even be confusing, mainly if the death occurred inside a hospital. Case presentation We describe a particular case of death from acute nitrous oxide poisoning in a hospital environment, of a Caucasian male of 72-years-old. The intoxication occurred during a minimally invasive vascular surgery due to an incorrect assembly of the supply lines of medical gases (O2 and N2O). The identification of the cause of death resulted from the analysis of circumstantial data, macroscopic and microscopic autoptic findings, and immunohistochemical investigations based on the search for antibodies anti E-selectin, P-selectin, and HIF 1-α. Conclusion Although not pathognomonic of asphyxiation by N2O, the latter molecules are a valid and early marker of hypoxic insult. Therefore, in concert with all other findings, it may constitute valid support for the forensic pathologist to ascertain the cause of death in case of suspected intoxication by N2O.

Key Clinical Message Frostbite arising from nitrous oxide (N2O) inhalation is rare. As such, there is no consensus on best treatment for these injuries. In all published reports, judicious use of corticosteroids and antibiotics has resulted in positive clinical outcomes; we endorse these agents in our case of a young man with oropharyngeal burns.

Objective: To find out if the addition of Nitrous Oxide to Sevoflurane significantly reduces induction time and to study the effect of Nitrous Oxide on the frequency of adverse events during induction. Study Design: Quasi-experimental study Place and Duration of Study: Operation Theatre Complex, PAF Hospital Mushaf Sargodha Pakistan from Jul to Sep 2018. Methodology: One hundred adult indoor patients undergoing elective surgeries were included in the study. Their ages were from 18 to 34yrs, and all fell in ASA I and II category. In Group-A, 43 and Group- B, 57 patients were enrolled. Sevoflurane at a high concentration of 8% was given to all patients for induction. In Group-A, 100% oxygen was used as a vehicle, while in Group-B, 70% Nitrous Oxide and 30% oxygen were used as vehicles. Induction time was measured from switching Sevoflurane to when the patients’ arms fell horizontal. We documented adverse effects, including coughing, laryngospasm,bronchospasm, fall in SpO2

Abstract Nitrous oxide abuse can have detrimental effects on the central and peripheral nervous systems. This case study report aims to demonstrate a combination of severe generalized sensorimotor polyneuropathy and cervical myelopathy related to vitamin B12 deficiency following nitrous oxide abuse. We present a clinical case study and literature review examining primary research—published between 2012 and 2022—reporting nitrous oxide abuse affecting the spinal cord (myelopathy) and peripheral nerves (polyneuropathy); 35 articles were included in the review with a total of 96 patients, where the mean “patients” age was 23.9 years and were in a 2:1 male/female ratio. Of the 96 cases, within the review, 56% of patients were diagnosed with polyneuropathy, most commonly impacting the nerves of the lower limb (62%), while 70% of patients were diagnosed with myelopathy, most commonly impacting the cervical region (78%) on the spinal cord. In our clinical case study, a 28‐year‐old male underwent a multitude of diagnostic investigations for bilateral “foot drop” and sense of lower limb stiffness as ongoing complications of a vitamin B12 deficiency secondary to recreational nitrous oxide abuse. Both the literature review and our case report emphasize the dangers of recreational nitrous oxide inhalation, colloquially termed “nanging” and the risks it presents to both the central and peripheral nervous systems, which is erroneously considered by many recreational drug users to be less harmful than other illicit substances.

Abstract Nitrous oxide is a gas frequently used in the medical/dental field for anesthesia and analgesic purposes and in the food industry as a spray propellant or foaming agent. Overexposure can lead to subacute combined degeneration (SACD) of the spinal cord through the mechanism of vitamin B12 deficiency. Because this drug is easily accessible, relatively inexpensive, and legal to possess, it has potential to be abused for recreational purposes. The number of published cases of nitrous oxide abuse has been increasing since 2010. Large‐scale and long‐term use of nitrous oxide have been found to cause nerve damage from vitamin B12 deficiency, thromboembolic phenomenon from elevated homocysteine levels, and even death from hypoxia. A 44‐year‐old male patient with past medical history of recently diagnosed type 2 diabetes, on Metformin, presented for 1 month of worsening bilateral upper and lower extremity weakness. On initial physical examination, he demonstrated pertinent abnormal findings of 2/5 hand strength bilaterally, 4/5 strength in his left upper extremity and right lower extremity, impaired coordination, ataxic gait, rigidity, and decreased but symmetrical reflexes. He reported using 50–100 canisters of nitrous oxide per day to obtain a feeling of relaxation and euphoria. Blood work revealed vitamin B12 deficiency, and abnormalities were seen on MRI. He was treated with 1000 μg of intramuscular vitamin B12 every other day for 3 doses, followed by 500 μg oral cyanocobalamin daily. He demonstrated a great amount of improvement in his neuropathy during his stay. However, he was still dependent in basic transfers, activities of daily living, and mobility and was discharged to acute rehabilitation. Vitamin B12 deficiency can lead to subacute combined degeneration, which presents with sensory deficits, weakness, ataxia, spasticity, and gait abnormalities. Treatment for SACD should be aggressive and rapid to prevent irreversible neurological deficits. Amid an opioid epidemic, practitioners can easily overlook the use of nitrous oxide and patients may consider this drug to be relatively harmless. This case demonstrates the importance of thorough history taking, patient education, and early recognition and treatment of vitamin B12 deficiency and the deleterious effects that may result without intervention.

Background: The COMT gene polymorphism is associated with neurological and psychiatric disorders and pain perception. The present study investigates the existence of anxiety and pain perception in relation to the COMT (catechol-O-methyltransferase) gene polymorphism in labouring women (during “natural” childbirth) with or without inhaled analgesia. Methods: A total of 181 women who chose vaginal birth were enrolled in this study. To present the difference in pain perception, the parturients were divided into one group (n = 90) that chose labour analgesia with inhaled nitrous oxide (50% nitrous oxide and 50% oxygen) and one group (n = 91) without analgesia. The blood samples were taken during the pregnancy as a part of routine pregnancy controls in the hospital. The COMT gene polymorphism was detected with the PCR technique. The pain perception of parturients was self-evaluated two times according to the VAS (Visual Analogue Scale), and anxiety as a personality trait was determined with the STAI-T (State Trait Anxiety Inventory). Pain perception as well as anxiety were compared according to COMT genotypes. Results: In the 181 pregnant women, there were 40 women (22%) of wild homozygotes (GG) of COMT, 95 women (53%) of mutant heterozygotes (GA), and 46 women (25%) of mutant homozygotes (AA). A negative association of pain perception with the GA (mutant heterozygote) polymorphism of the COMT gene versus the wild-type (GG polymorphism) was observed. The GA polymorphism of the COMT gene was associated with 0.46 units lower pain perception compared to the wild type (GG). The anxiety trait score in group AA was lower than in groups GA and GG. The difference reached statistical significance only when comparing AA versus GA (p > 0.042). Analgesic efficacy of nitrous oxide was noticed in 22% of labouring women who reported moderate pain (VAS score 4–7). Conclusions: The COMT gene polymorphism was associated with pain perception and anxiety among parturients. The COMT gene polymorphism GA was associated with negative pain perception among labouring women. Nitrous oxide showed statistical significance in anxiolytic efficacy during labour in women with mild anxiety as a personality trait. Anxiolytic efficacy of nitrous oxide has shown better efficacy in parturients with the COMT gene polymorphism AA.

Objective The use and effect of nitrous oxide sedation techniques in oral clinics were analyzed retrospectively. Methods Patients who were treated with nitrous oxide inhalation sedation in the clinic of the Affiliated Stomatological Hospital of Guangzhou Medical University from January 1, 2016, to December 30, 2018, were examined. Age and gender of the patients, dental treatments involved, reasons for nitrous oxide inhalation, sedative effects and adverse reactions were compiled. Results A total of 1 429 cases were examined, comprising 587 males and 842 females, and the average age was 32.64±16.34 years old. Among the patients who underwent nitrous oxide inhalation sedation in the oral clinic, 79.98% needed tooth extraction, and 79.50% had a dental fear of procedures. The patients were divided into following 7 age groups: 5-15 years old, 16-25 years old, 26-35 years old, 36-45 years old, 46-55 years old, 56-65 years old and > 65 years old. The sedation satisfaction rate of the 5-15-year-old group was 45.71%, and the sedation satisfaction rate of the other 6 age groups was 90.83%- 96.20% (P < 0.001). The incidence of total adverse reactions was 5.39%; the incidence was higher in females than in males, and the incidence was higher in the 16-25 age group than in the other age groups (P < 0.05). The most frequent adverse reaction was vertigo (81.82%). Conclusion Among the four common oral outpatient treatment programs including the extraction of teeth, dental implants, pulp treatment and periodontal treatment, patients undergoing inhalation sedation of nitrous oxide in the dental extraction most. The most common reason for requiring sedation is dental fear, and the sedative effect of the 5-15-year-old group was significantly worse than that of the other age groups. The incidence of adverse reactions of nitrous oxide sedation was low and manageable.

The recreational use of nitrous oxide (N2O) is a growing public health concern. Increasing numbers of young individuals are presenting to accident emergency departments complaining of adverse neurological symptoms as a result of N2O induced vitamin B12 deficiency. Despite its increasing popularity, many are still not aware of its devastating potential to cause a myriad of severe longstanding neurological impairment. Herein we present a case that highlights the effects of N2O abuse and the best way to investigate and manage such patients.

Lucerne (Medicago sativa L.) is a major component of the crops used in dry-land farming systems in China and its management is associated with notable nitrous oxide (N2O) emissions. A high proportion of these emissions is more likely to occur during periods when the soil undergoes freezing and thawing cycles. In this study, the effects of freeze/thaw cycles on N2O emissions and related factors were investigated in lucerne grasslands. The hypothesis was tested whether increased emissions resulted from a disruption of nitrification or denitrification caused by variations in soil temperatures and water contents. Three days (3 × 24 h) were chosen, where conditions represented freezing and thawing cycles. N2O emissions were measured for a fallow control (F) and two grasslands where lucerne had been cultivated for 4 and 11 years. Soil temperature, soil water content, soil microbial biomass carbon (MBC), soil microbial biomass nitrogen (MBN), soil ammonium nitrogen (NH4+-N), and soil nitrate nitrogen (NO3−-N) contents were measured. Moreover, the quantities of soil nitrification and denitrification microbes were assessed. Variations in N2O emissions were strongly affected by freeze/thaw cycles, and emissions of 0.0287 ± 0.0009, 0.0230 ± 0.0019, and 0.3522 ± 0.0029 mg m−2 h−1 were found for fallow, 4-year-old, and 11-year-old grasslands, respectively. Pearson correlation analyses indicated that N2O emissions were significantly correlated with the soil water content, temperature, NH4+-N content, and the number of nitrosobacteria and denitrifying bacteria at a soil depth of 0–100 mm. The numbers of nitrosobacteria and denitrifying bacteria correlated significantly with soil temperature at this soil depth. MBN and soil NH4+-N contents correlated significantly with soil water content at this depth. Principal component analysis highlighted the positive effects of the number of denitrifying bacteria on N2O emissions during the freeze/thaw period. Furthermore, soil temperature and the number of nitrosobacteria at the tested soil depth (0−100 mm) also played a significant role. This shows that soil freeze/thaw cycles strongly impacted both N2O emissions and the diurnal range, and the number of denitrifying bacteria was mainly influenced by soil temperature and soil NH4+-N content. The number of denitrifying bacteria was the dominant variable affecting N2O emissions from lucerne grasslands during the assessed soil freeze/thaw period on the Loess Plateau, China.

The effects of climate change such as dry spells, floods and erosion heavily impact agriculture especially smallholder systems on the Northwestern Loess Plateau of China. Nonetheless agriculture also contributes to global warming through the emission of greenhouse gases such as CO2, CH4 and N2O. Yet this complex conundrum can be alleviated and mitigated through sound soil and water management practices. Despite considerable literature on Conservation Agriculture (CA) as a strategy to improve the resilience and mitigation capacity of agroecosystems, there is still paucity of information on the impacts of CA on crop production and environmental quality on the Plateau. In order to fill this gap this study examined the effects of no-till and straw mulch on crop productivity and greenhouse gas fluxes in agroecosystems on the Plateau where farmers’ common practice of conventional tillage (CT) was tested against three CA practices: conventional tillage with straw mulch (CTS), no-till (NT) and no-till with straw mulch (NTS). The results indicated that all three CA practices (CTS, NT and NTS) markedly increased soil water content (SWC), soil organic carbon (SOC) and soil total nitrogen (STN) but reduced soil temperature (ST). Average grain yields were 854.46 ± 76.51, 699.30 ± 133.52 and 908.18±38.64 kg ha-1 respectively under CTS, NT and NTS indicating an increase by approximately 33%, 9% and 41% respectively compared with CT (644.61 ± 76.98 kg ha−1). There were significant (p

We report two cases of subacute combined degeneration (SCD) caused by nitrous oxide (N2O) gas intoxication, which is rarely reported in Korea. Two patients recreationally inhaled N2O gas daily for several months. They presented with paresthesia of limbs, voiding difficulty, and gait disturbance. The initial vitamin B12 levels were normal or decreased, but homocysteine levels of the two patients were increased. Magnetic resonance imaging of the cervical spine showed T2-weighted hyperintensity in the bilateral dorsal columns of the cervical spinal cord. Electromyography and somatosensory evoked potential tests for both patients suggested posterior column lesion of the spinal cord combined with sensorimotor polyneuropathy. According to these findings, we concluded that the two patients had SCD. The patient’s symptoms partially improved after cessation of N2O gas inhalation and the receiving of vitamin B12 supplementation therapy. As the incidence of recreational N2O gas inhalation is increasing in Korea, physicians must be alert to the N2O induced SCD in patients presenting with progressive myelopathy.

Background and purpose: Nitrous oxide (N2O) is an anesthetic widely used in operating rooms. Chronic exposure to N2O causes decrease in mental performance, peripheral neuropathy, and polyneuropathy. The aim of this study was to compare neurological complications caused by N2O exposure between operating room staff and other hospital staff. Materials and methods: In this multicenter cohort study, operating room staff (n=110) and non-operating room staff (n= 224) in Arak Valiasr Hospital and Isfahan Al-zahra Hospital were randomly selected and individually matched. Both groups were examined for neuropathic symptoms and their medical history was recorded. Clinical neurological exams such as Romberg test were used in both groups. Patients with neuropathic sign and symptoms were referred to a neurology clinic to confirm any diagnosis. Results: The two groups were significantly different in ataxia, numbness, weakness and paresthesia of upper and lower limb, Romberg test score, and levels of Vitamin B12 (P

Study Design A retrospective case-control study. Purpose To evaluate the effect of nitrous oxide and anesthetic and operative factors associated with severe pain in the early postoperative period after thoracolumbar spine surgery. Overview of Literature Thoracolumbar spine surgery is the most common procedure in spine surgery, and up to 50% of the patients suffer from moderate to severe pain. Nitrous oxide has analgesic, anxiolytic, and anesthetic effects; nevertheless, its benefits for early postoperative pain control and opioid consumption remain to be established. Methods The medical records of eligible participants who underwent thoracolumbar spine surgery between July 2016 and February 2017 were reviewed. Enrolment was performed consecutively until reaching 90 patients for the case (severe pain) group (patients with a pain score of >7 out of 10 at least once during the post-anesthesia care unit [PACU] admission), and 90 patients for the control (mild-to-moderate pain) group (patients with a pain score of

Lumbar puncture (LP) is stressful and often painful. We evaluated the efficacy of a fixed 50% nitrous oxide–oxygen mixture (50%N2O-O2) versus placebo to reduce immediate procedural pain and anxiety during LP performed in an emergency setting. We conducted a randomized controlled trial involving adults who needed a cerebrospinal fluid analysis in an emergency department. Patients were randomly assigned to inhale either 50%N2O-O2 or medical air. The primary endpoint, assessed using a numerical scale, was the maximum pain felt by the patient during the procedure and the maximum anxiety and satisfaction as secondary outcomes. Eighty-eight patients were randomized and analyzed (ITT). The maximal pain was 5.0 ± 2.9 for patients receiving air and 4.2 ± 3.0 for patients receiving 50%N2O-O2 (effect-size = −0.27 [−0.69; 0.14], p = 0.20). LP-induced anxiety was 4.7 ± 2.8 vs. 3.7 ± 3.7 (p = 0.13), and the proportion of patients with significant anxiety (score ≥ 4/10) was 72.7% vs. 50.0% (p = 0.03). Overall satisfaction was higher among patients receiving 50%N2O-O2 (7.4 ± 2.4 vs. 8.9 ± 1.6, p < 0.001). No serious adverse events were attributable to 50%N2O-O2 inhalation. Although inhalation of 50%N2O-O2 failed to reduce LP-induced pain in an emergency setting, it tended to reduce anxiety and significantly increased patient satisfaction.

In response to rising interest over the years, many experiments and several models have been devised to understand emission of nitrous oxide (N2O) from agricultural soils. Notably absent from almost all of this discussion is iron, even though its role in both chemical and biochemical reactions that generate N2O was recognized well before research on N2O emission began to accelerate. We revisited iron by exploring its importance alongside other soil properties commonly believed to control N2O production in agricultural systems. A set of soils from California's main agricultural regions was used to observe N2O emission under conditions representative of typical field scenarios. Results of multivariate analysis showed that in five of the twelve different conditions studied, iron ranked higher than any other intrinsic soil property in explaining observed emissions across soils. Upcoming studies stand to gain valuable information by considering iron among the drivers of N2O emission, expanding the current framework to include coupling between biotic and abiotic reactions.

Nitrous oxide (N2O) is a weak anesthetic gas that was first used in 1844 in the field of dental anesthesia. However, currently, N2O is being abused for entertainment purposes in the form of N2O-filled balloons, called funky balls, which can cause many adverse effects, especially nervous system injury. This study aimed to investigate the detailed clinical and subclinical features associated with N2O intoxication. We retrospectively reviewed 47 patients diagnosed with N2O intoxication, from May 2018 to July 2019, and collected demographic data, clinical and laboratory tests, and spinal cord magnetic resonance imaging (MRI) findings. The mean time of funky ball use was 8.8 months, with a mean use of 36.3 balls per day. All patients presented with superficial sensory disorders. Reductions in muscle strength, decreased vibration sensation, and decreased or lost tendon reflexes were the most common clinical signs of N2O intoxication. Romberg sign and Lhermitte sign were observed in 39 patients (83%) and 21 patients (44.7%), respectively. Spinal cord lesions on MRI were observed in 32 patients (68.1%), which mostly presented with an inverted V sign. The total duration of N2O use, the number of days of using N2O per week, and the presence of Lhermitte sign (P

Aim: When N2Ois used for general anaesthesia, it diffuses into the air-filled endotracheal cuff causing the cuff pressure to rise by over inflating the cuff, which results in tracheal damage. This study aimed to estimate changes in the endotracheal-cuff pressure with time during oxygen-air- and oxygen-N2O -induced anaesthesia and to determine its sore throat and hoarseness incidence. Methods: Fifty patients with American Society of Anesthesiologists physical status 1-2, aged 18-60 years were icluded to our study. Orotracheal intubation was performed using polyvinyl chloride high volume-low pressure endotracheal tubes. The AIR group 40% O2/60% air and N2O group 40% O2/60% N2O was used. The endotracheal cuff pressure at 5, 10, 15, 20 minutes immediately after intubation and at 10-minute intervals were recorded. When the cuff pressure reached 45 cm H2O, was attenuated to 25-30-cm H2O. At the post operative first and the 24th hour, the patients were queried for sore throat and hoarseness. Results: The N2O -group cuff pressure rose from the fifth minute onwards. Also, the N2O group had a higher incidence of sore throat and hoarseness. Conclusion: N2O results in elevated cuff pressure and tracheal morbidities. Cuff-pressure should be routinely monitored during anaesthesia using N2O.

AIMS OF THE STUDY The spectrum of agents available for procedural analgosedation (PAS) in paediatric emergency departments (EDs) has increased over the last few decades, yet the pharmacological agents most used in our ED are ketamine and nitrous oxide (N2O). The aim of this study was to assess which patient characteristics in an ambulatory setting were associated with physicians selecting N2O 70% or ketamine as the sedating agent in our paediatric ED, after N2O 70% was introduced. METHODS Patients aged 0 to 16 years who received PAS in a tertiary children’s hospital ED in 2007 (before N2O 70% implementation) and 2016 (after N2O implementation) were included in this retrospective, single-centre cohort study. Data were collected by querying the outpatient ED database for N2O 70% and ketamine. Obtained data included patient characteristics, procedure type and sedation medication. RESULTS 1168 patients were included; 59.8% (699) were male. The overall mean age was 6.3 (± 4.0) years; in the ketamine subgroup, 4.6 (± 4.0) years and in the N2O subgroup, 7.8 (± 3.4) years. In 2016, N2O was chosen in 86.7% of cases involving children aged 4 to 16 years, compared to 28.5% of cases involving children three years and younger. The most apparent shift from ketamine to N2O occurred in patients with displaced upper extremity fractures, with an increase of N2O 70% from 0% in 2007 to 90.8% in 2016. CONCLUSIONS The use of ketamine PAS shifted to N2O PAS, especially in children older than three years and for the reduction of displaced upper extremity fractures.

Salt marshes are highly effective carbon (C) sinks and bury more C per square meter annually than any other ecosystem. Reclamation and anthropogenic impacts, however, have resulted in extensive losses of salt marshes. Carbon credits can be generated and sold by restoring marshes, but only if C sequestration and net reductions in greenhouse gases (GHG) are reliably quantified. Restored marshes, however, may exhibit different patterns of GHG emissions than natural marshes and it is possible that they could temporarily become sources of N2O even in the usually N-limited estuarine environment. Research on short-term GHG flux following salt marsh restoration is limited to studies of two restored marshes which examined GHG flux more than six months after the return of tidal flooding. Here we report on a laboratory experiment in which soil cores collected from a drained agricultural marsh on the St. Lawrence Estuary were flooded with estuary water. Gas flux measurements immediately after flooding revealed small increases in N2O and CH4, but a large decline in CO2 yielding, from a climatic perspective, a net cooling effect over the observation period. In addition to restoring the land’s capacity to sequester C once a marsh develops, returning tidal flooding thus appears to have the added benefit of stemming large ongoing C losses. With more than 400 km2 of undeveloped dykeland, Eastern Canada is well positioned to restore large sections of marsh and contribute to reducing atmospheric CO2 concentrations.

Background Denitrification is one of the main pathways of the N-cycle, during which nitrate is converted to dinitrogen gas, in four consecutive reactions that are each catalyzed by a different metalloenzyme. One of the intermediate metabolites is nitrous oxide, which has a global warming impact greater then carbon dioxide and which atmospheric concentration has been increasing in the last years. The four denitrification enzymes have been isolated and biochemically characterized from Marinobacter hydrocarbonoclasticus in our lab. Methods Bioinformatic analysis of the M. hydrocarbonoclasticus genome to identify the genes involved in the denitrification pathway. The relative gene expression of the gene encoding the catalytic subunits of those enzymes was analyzed during the growth under microoxic conditions. The consumption of nitrate and nitrite, and the reduction of nitric oxide and nitrous oxide by whole-cells was monitored during anoxic and microoxic growth in the presence of 10 mM sodium nitrate at pH 7.5. Results The bioinformatic analysis shows that genes encoding the enzymes and accessory factors required for each step of the denitrification pathway are clustered together. An unusual feature is the co-existence of genes encoding a q- and a c-type nitric oxide reductase, with only the latter being transcribed at similar levels as the ones encoding the catalytic subunits of the other denitrifying enzymes, when cells are grown in the presence of nitrate under microoxic conditions. Using either a batch- or a closed system, nitrate is completely consumed in the beginning of the growth, with transient formation of nitrite, and whole-cells can reduce nitric oxide and nitrous oxide from mid-exponential phase until being collected (time-point 50 h). Discussion M. hydrocarbonoclasticus cells can reduce nitric and nitrous oxide in vivo, indicating that the four denitrification steps are active. Gene expression profile together with promoter regions analysis indicates the involvement of a cascade regulatory mechanism triggered by FNR-type in response to low oxygen tension, with nitric oxide and nitrate as secondary effectors, through DNR and NarXL, respectively. This global characterization of the denitrification pathway of a strict marine bacterium, contributes to the understanding of the N-cycle and nitrous oxide release in marine environments.

Birth of a child is an unique time in the life of every woman. Unfortunately, labor is often one of the most painful and traumatic experiences suffered in woman’s life. In the modern obstetrics pain of labor and methods of its mitigation are the main problem for both, patients and medical staff. In this paper the most important steps of the development of labor analgesia were described.

The Southern Ocean is an important region for global nitrous oxide (N2O) cycling. The contribution of different source and sink mechanisms is, however, not very well constrained due to a scarcity of seawater data from the area. Here we present high-resolution surface N2O measurements from the Atlantic sector of the Southern Ocean, taking advantage of a relatively new underway setup allowing for collection of data during transit across mesoscale features such as frontal systems and eddies. Covering a range of different environments and biogeochemical settings, N2O saturations and sea-to-air fluxes were highly variable: Saturations ranged from 96.5% at the sea ice edge in the Weddell Sea to 126.1% across the Polar Frontal Zone during transit to South Georgia. Negative sea-to-air fluxes (N2O uptake) of up to −1.3 µmol m−2 d−1 were observed in the Subantarctic Zone and highest positive fluxes (N2O emission) of 14.5 µmol m−2 d−1 in Stromness Bay, coastal South Georgia. Although N2O saturations were high in areas of high productivity, no correlation between saturations and chlorophyll a (as a proxy for productivity) was observed. Nevertheless, there is a clear effect of islands and shallow bathymetry on N2O production as inferred from supersaturations.

Background Methylophaga nitratireducenticrescens strain JAM1 is a methylotrophic, marine bacterium that was isolated from a denitrification reactor treating a closed-circuit seawater aquarium. It can sustain growth under anoxic conditions by reducing nitrate ( ${\mathrm{NO}}_{3}^{-}$ NO 3 − ) to nitrite ( ${\mathrm{NO}}_{2}^{-}$ NO 2 − ). These physiological traits are attributed to gene clusters that encode two dissimilatory nitrate reductases (Nar). Strain JAM1 also contains gene clusters encoding two nitric oxide (NO) reductases and one nitrous oxide (N2O) reductase, suggesting that NO and N2O can be reduced by strain JAM1. Here we characterized further the denitrifying activities of M. nitratireducenticrescens JAM1. Methods Series of oxic and anoxic cultures of strain JAM1 were performed with N2O, ${\mathrm{NO}}_{3}^{-}$ NO 3 − or sodium nitroprusside, and growth and N2O, ${\mathrm{NO}}_{3}^{-}$ NO 3 − , ${\mathrm{NO}}_{2}^{-}$ NO 2 − and N2 concentrations were measured. Ammonium ( ${\mathrm{NH}}_{4}^{+}$ NH 4 + )-free cultures were also tested to assess the dynamics of N2O, ${\mathrm{NO}}_{3}^{-}$ NO 3 − and ${\mathrm{NO}}_{2}^{-}$ NO 2 − . Isotopic labeling of N2O was performed in 15NH4+-amended cultures. Cultures with the JAM1ΔnarG1narG2 double mutant were performed to assess the involvement of the Nar systems on N2O production. Finally, RT-qPCR was used to measure the gene expression levels of the denitrification genes cytochrome bc-type nitric oxide reductase (cnorB1 and cnorB2) and nitrous oxide reductase (nosZ), and also nnrS and norR that encode NO-sensitive regulators. Results Strain JAM1 can reduce NO to N2O and N2O to N2 and can sustain growth under anoxic conditions by reducing N2O as the sole electron acceptor. Although strain JAM1 lacks a gene encoding a dissimilatory ${\mathrm{NO}}_{2}^{-}$ NO 2 − reductase, ${\mathrm{NO}}_{3}^{-}$ NO 3 − -amended cultures produce N2O, representing up to 6% of the N-input. ${\mathrm{NO}}_{2}^{-}$ NO 2 − was shown to be the key intermediate of this production process. Upregulation in the expression of cnorB1, cnorB2, nnrS and norR during the growth and the N2O accumulation phases suggests NO production in strain JAM1 cultures. Discussion By showing that all the three denitrification reductases are active, this demonstrates that M. nitratireducenticrescens JAM1 is one of many bacteria species that maintain genes associated primarily with denitrification, but not necessarily related to the maintenance of the entire pathway. The reason to maintain such an incomplete pathway could be related to the specific role of strain JAM1 in the denitrifying biofilm of the denitrification reactor from which it originates. The production of N2O in strain JAM1 did not involve Nar, contrary to what was demonstrated in Escherichia coli. M. nitratireducenticrescens JAM1 is the only reported Methylophaga species that has the capacity to grow under anoxic conditions by using ${\mathrm{NO}}_{3}^{-}$ NO 3 − and N2O as sole electron acceptors for its growth. It is also one of a few marine methylotrophs that is studied at the physiological and genetic levels in relation to its capacity to perform denitrifying activities.