N2O Inhalation Research Articles

Intraoperative nitrous oxide inhalation to prevent chronic postsurgical pain in video-assisted thoracoscopic surgery: a prospective observational cohort study.

Chronic postsurgical pain (CPSP) is a significant detriment to postsurgical recovery. Previous studies have shown that nitrous oxide (N2O) may produce long-term analgesia and may benefit the prevention of CPSP in Chinese patients. We tested the hypothesis that N2O is a protective factor against chronic pain after video-assisted thoracoscopic surgery (VATS). Two groups of patients with and without N2O inhalation during VATS in Peking Union Medical College Hospital were recruited. Perioperative information was documented, and postsurgical pain was followed up by telephone. The primary outcome was the presence of CPSP at 6 months postoperatively. Odds ratios (ORs) and their 95% confidence intervals (CIs) were estimated using a multivariate logistic regression model adjusted for relevant confounding factors. A total of 833 patients were eligible, among whom 33.6% were male and 66.4% were female, with an average age of 56.3±11.1 years. A total of 387 (46.5%) patients reported incision-related pain at 6 months after surgery, and 160 (40.0%) out of 400 patients with N2O inhalation during surgery and 227 (52.4%) out of 433 patients without N2O inhalation during surgery developed CPSP. After adjusting for confounding factors, N2O inhalation during surgery was associated with lower odds of CPSP (OR =0.654; 95% CI: 0.480-0.890; P=0.007). N2O inhalation during surgery was associated with lower odds of CPSP in VATS patients, and N2O may benefit the prevention of chronic pain after thoracoscopic surgery.

Quantitative determination of nitrous oxide in human blood by HS-GC–MS: forensic application of two fatal poisoning cases

Nitrous oxide (N2O), also known as laughing gas, has a euphoric effect and is becoming increasingly popular as a recreational inhalant drug. Deaths caused by recreational nitrous oxide abuse are rare, but may still occur. Although some methods for the quantification of N2O by GC-MS have been reported, elimination of carbon dioxide interference and the choice of a suitable internal standard remain current limitations to accurate N2O quantification. Here, a validated method using headspace-gas chromatography–mass spectrometry (HS-GC–MS) is described that allows the quantification of N2O in human blood samples: sodium hydroxide is used to remove carbon dioxide, and n-pentane is chosen as a suitable internal standard. Collectively, the validation results show a good linear relationship of N2O in blood within the concentration range of 0.02 ∼ 0.5 mL/mL and an LOD of 0.005 mL/mL. Subsequent application of the validated method to two real mortality cases due to N2O intoxication provided reference values for blood concentrations in forensic cases. Other biological specimens (gaseous samples and tissues) of the deceased were also analyzed to demonstrate that the deaths were caused by asphyxia due to the inhalation of N2O.

Pancytopenia Caused by Nitrous Oxide Toxicity: Two Cases Report

Recreational nitrous oxide (N2O) is increasingly common among young people, leading to attendant health disadvantages. Related complications primarily involve the hematological and neurological systems. We report two relatively uncommon cases of pancytopenia due to substantial N2O inhalation. One possible cause is that N2O toxicity results in vitamin B12 inactivation and an insufficient intake of nutrients. The patient’s symptoms partially improved after cessation of N2O inhalation and supplementation with vitamin B12. In conclusion, if the patients presented with unexplained bone marrow failure, a history of prolonged N2O exposure should be considered, which would greatly help in early diagnosis, therapy, and the reduction of unnecessary costs.

Barriers to Using Advanced and Pharmacological Behavior Management Techniques: A Survey of Pediatric Dentists in Jeddah, Saudi Arabia.

In this study, we assessed the use of advanced pharmacological behavior management techniques (BMTs) among pediatric dentists in Saudi Arabia and the barriers to their clinical application. This cross-sectional study used a self-administered electronic survey that targeted members of the Saudi Society of Pediatric Dentistry. The questionnaire included questions on five techniques of advanced and pharmacological behavior management recommended by the American Academy of Pediatric Dentistry. Descriptive statistics, frequency, Chi-square test, and Fisher's exact test were used to present the outcomes and independent variables. A total of 57 pediatric dentists completed the survey. Nitrous oxide (N2O) sedation, general anesthesia (GA), and protective stabilization were used regularly by pediatric dentists in 70.2%, 68.4%, and 56.1% of the participants, respectively. A few participants reported using oral (14.0%) or intravenous (IV) sedation (10.5%) regularly. The most common barriers to using these techniques were either dentists' discomfort or the non-availability of the equipment/drugs. The most common method used by pediatric dentists was N2O inhalation sedation, followed by GA and protective stabilization. The participants' use of pharmacological BMTs, including IV and oral sedation, was relatively low.

WHEN LAUGHTER GAS NO LONGER BRINGS LAUGHTER

Introduction: Nitrous oxide (N2O), also dubbed the laughing gas or proto, is a gas used therapeutically in the medical field. However, a recreational trend has emerged, involving the inhalation of N2O from culinary capsules or canisters. Clinical Case: This involves a 23-year-old patient, Hospitalized for psychomotor agitation, the patient has a history of cardiac arrest following extensive inhalation of laughing gas. The patient presented with a manic syndrome that resolved within 2 days. Biological tests returned normal results, including vitamin B12. Brain MRI revealed bilateral bi-fronto-parietal cortical cerebral atrophy. The patient underwent a neurological etiological assessment, which came back normal. Discussion: The majority of literature reviews on the psychiatric complications of NO2 use have indicated that the most frequent symptoms are delirium, hallucinations, and confusion. The prognosis is often favorable, with symptoms typically resolving under antipsychotic treatment. Conclusion: The consumption of nitrous oxide is a recreational practice that is on the rise, and especially among young people. With easy access and low cost.Cases of intoxication are increasing with serious medical complications which can lead to death, regardless of the type of exposure.

Incidence and related factors of chronic neuropathic pain in elderly patients after video-assisted thoracoscopic surgery

Objective: To investigate the incidence and related factors of chronic neuropathic pain (CNP) in elderly patients after thoracoscopic surgery. Methods: A total of 463 elderly patients (aged≥60 years) who underwent elective video-assisted thoracoscopic surgery from November 2020 to May 2021 at Peking Union Medical College Hospital were prospectively recruited. Among them, 283 were males and 180 were females, with an average age of (66.6±4.8) years. Chronic postsurgical pain (CPSP) was assessed by telephone at 6 months after surgery, and then the patients with CNP were screened using the ID-pain scale. Multivariable logistic regression was used to analyze the related factors for CNP in elderly patients after thoracoscopic surgery. Results: The incidence of CPSP was 41.9% (194/463), and the incidence of CNP was 18.8% (87/463). Multivariable logistic regression analysis showed that incision number<3 (OR=0.385, 95%CI: 0.156-0.949, P=0.038) and intraoperative N2O inhalation (OR=0.506, 95%CI: 0.304-0.842, P=0.009) were protective factors for CNP in elderly patients after thoracoscopic surgery, but high numeric rating scale (NRS) score on the first day after surgery (OR=1.180, 95%CI: 1.056-1.318, P=0.003) was a risk factor. Conclusions: The incidence of CNP in elderly patients after thoracoscopic surgery is 18.8%. Incision number<3 and intraoperative N2O inhalation are protective factors for CNP, but high NRS score on the first day after surgery is a risk factor.

The recreational inhalation of N2O “whippits” among college students at a Saudi University: prevalence, patterns, and perceived harm

Background Recreational nitrous oxide (N2O) inhalation is a growing trend among young adults, but few studies have explored its prevalence. We aimed to measure the prevalence of recreational N2O inhalation among Saudi university students, its perceived harm, as well its association with gender, college type and use of tobacco and alcohol. Methods A cross-sectional study was conducted among undergraduate students at King Saud University, Riyadh, in September, 2022. Self-administered questionnaires asked about knowing someone who inhaled N2O, awareness of whippits (cream charger bulbs), its recreational use, and perceived side effects. Results A total of 720 students participated (response rate = 82%). About 13.3% of the students heard about N2O, 15.7% knew someone who inhaled N2O recreationally, 7.9% ever inhaled it (8.3% women, and 7.5% men), and 36.8% thought it had no negative health effects. Whippits were the most common mode inhaled. Being a health-college student increased the odds for lifetime recreational inhalation by 97% (AOR = 1.97; 95% CI = 1.10, 3.55), while hookah use increased the odds around three-fold (AOR = 3.27; 95% CI = 1.01, 10.63). Conclusion Saudi university students have a low perception of harm toward recreational N2O inhalation and are experimenting with it, with greater odds for use among healthy college students. Raising community awareness about this behavior is needed.

Diagnosis and Management of Nitrous Oxide Poisoning: A Case Report

Background: Chronic nitrous oxide (N2O) poisoning induces irreversible inactivation of vitamin B12, affecting two biochemical reactions essential for the proper functioning of the body. The prognosis is excellent when adequately and quickly treated. We present the case of a 23-year-old Caucasian woman with symptoms caused by chronic N2O inhalation. Case Presentation: A 23-year-old Caucasian woman was admitted to the emergency department with complaints of confusion and gait disturbance. Following an in-depth history and laboratory tests, chronic N2O poisoning was confirmed, and vitamin B12 supplementation was initiated promptly. Conclusion: Our case demonstrated the clinical presentation and biological changes typical of N2O poisoning. The misuse of N2O is prevalent due to the easy accessibility of cylinders over-the-counter since a few years. Recreational misuse of N2O has been observed in young populations. It is important to raise awareness among emergency physicians and nursing staff regarding increases in their consumption. Treatment involved vitamin B12 supplementation and long-term addiction monitoring

Comparative Assessment of Anxiety during Inferior Alveolar Nerve Block under Nitrous Oxide + Oxygen and Oxygen Inhalation Sedation in Children Aged 3-12 Years: A Randomized Clinical Trial.

A comparative evaluation of children's anxiety with the use of nitrous oxide-oxygen (N2O-O2) inhalation sedation during the administration of inferior alveolar nerve block (IANB). A total of 60 children between 3 and 12 years of age, with Frankl's behavior rating of 2-3 requiring IANB for any dental procedure were enrolled in this randomized clinical study. Group I (n = 30) received N2O and oxygen inhalation sedation at a concentration in the range of 25-50%, whereas group II (n = 30) received 100% O2 as a placebo. The physiological parameters like pulse rate, respiration, blood pressure, and O2 saturation were measured at the baseline, intraoperatively [during and after administration of local anesthesia (LA)] and postoperatively after the termination of the gases in both groups. The sedation level was measured intraoperatively (before administration of LA) using the Ramsay Sedation Score (RSS). The discomfort and anxiety were measured at the baseline, intraoperatively, and postoperatively using the Face, Legs, Activity, Cry, Consolability (FLACC) behavior scale. The data were evaluated using the statistical software International Business Machines (IBM) Statistical Package for the Social Sciences (SPSS) statistics 20.0. There was a significant difference in the FLACC scores between the two groups, intraoperatively (p-value-0.002), and postoperatively (p-value-0.049). The mean of the RSS for group I was 2.80 + 1.03, and for group II was 1.80 + 0.81. All the physiological parameters recorded were within the normal range. The use of N2O-O2 inhalation improved the anxiety levels in children while receiving the IANB and showed significant anxiolytic and sedative effects as compared to O2 inhalation. Nitrous oxide-oxygen (N2O-O2) inhalation can be used as a nonpharmacological behavior management adjunct for invasive treatments for children with utmost comfort for the child. Thomas PS, Dave BH, Shah DJ, et al. Comparative Assessment of Anxiety during Inferior Alveolar Nerve Block under Nitrous Oxide + Oxygen and Oxygen Inhalation Sedation in Children Aged 3-12 Years: A Randomized Clinical Trial. Int J Clin Pediatr Dent 2023;16(1):30-36.

Pharmacological modelling of dissociation and psychosis: an evaluation of the Clinician Administered Dissociative States Scale and Psychotomimetic States Inventory during nitrous oxide (‘laughing gas’)-induced anomalous states

RationaleA significant obstacle to an improved understanding of pathological dissociative and psychosis-like states is the lack of readily implemented pharmacological models of these experiences. Ketamine has dissociative and psychotomimetic effects but can be difficult to use outside of medical and clinical-research facilities. Alternatively, nitrous oxide (N2O) — like ketamine, a dissociative anaesthetic and NMDAR antagonist — has numerous properties that make it an attractive alternative for modelling dissociation and psychosis. However, development and testing of such pharmacological models relies on well-characterized measurement instruments.ObjectivesTo examine the factor structures of the Clinician Administered Dissociative States Scale (CADSS) and Psychotomimetic States Inventory (PSI) administered during N2O inhalation in healthy volunteers.MethodsSecondary analyses of data pooled from three previous N2O studies with healthy volunteers.ResultsEffect sizes for N2O-induced dissociation and psychotomimesis were comparable to effects reported in experimental studies with sub-anaesthetic ketamine in healthy volunteers. Although, like ketamine, a three-factor representation of N2O-induced dissociation was confirmed, and a more parsimonious two-factor model might be more appropriate. Bayesian exploratory factor analysis suggested that N2O-induced psychosis-like symptoms were adequately represented by two negative and two positive symptom factors. Hierarchical cluster analysis indicated minimal item overlap between the CADSS and PSI.ConclusionN2O and ketamine produce psychometrically similar dissociative states, although parallels in their psychosis-like effects remain to be determined. The CADSS and PSI tap largely non-overlapping experiences under N2O and we propose the use of both measures (or similar instruments) to comprehensively assess anomalous subjective states produced by dissociative NMDAR antagonists.

Nitrous Oxide Gas May be a Promising Therapy for Acute Priapism in Patients with Sickle Cell Disease: A Case Report

▪Background : Nitrous oxide (N2O) is an inhalational medication that has anxiolytic, amnestic, potent venodilatory and mild-to-moderate analgesic properties commonly used in the emergency department (ED) setting. N2O has a rapid onset of action (<5 minutes) and recovery (< 5 minutes) and can be quickly titrated to effect without the need for IV access. It has few side effects, does not require renal or hepatic metabolism for excretion and has no reports of allergic reaction. Priapism is a serious complication of sickle cell disease (SCD) affecting approximately 35% of males, with an adverse impact on quality of life. Treatment options are limited and not evidence based, including hydration, alkalization, analgesia, oxygenation to prevent further sickling, and exchange transfusion. Patients who do not respond within 4 hours often require a painful invasive procedure that includes aspiration of blood from the corpus cavernosum and phenylephrine injections. Case reports have described a therapeutic benefit from oral pseudoephedrine, sildenafil, and IV arginine, however controlled clinical trials are lacking. Although a 50:50 nitrous oxide/oxygen mix is commonly used in France to enhance analgesia in patients with SCD and vaso-occlusive pain events (VOE) not sufficiently responding to IV morphine, there are no reports of its use to treat priapism.Objective: To describe the effects of N2O for the treatment of acute priapism associated with SCD in a pediatric ED.Methods: This is a case report of a child with Hb-SS who on 2 separate occasions presented to the ED with acute priapism that failed oral therapy (pseudoephedrine and opioids). On each occasion he received standard treatment for VOE pain based on institutional guidelines for SCD that included oral opioids and intranasal fentanyl prior to IV access. N2O gas was utilized to help facilitate IV catheter placement.Results: In each presentation (at ages 8 and 10 years) the patient experienced complete resolution of the priapism within 5-15 min of receiving N2O (max 60%). The patient was discharged from the ED following each presentation and had no recurrence during the subsequent week.Conclusions: Priapism is a challenging complication of SCD associated with long-term morbidity and a paucity of treatment options. Given the risks and inconsistent results of current recommended therapy, N2O may represent a potentially superior treatment option for priapism presenting to the ED that warrants further investigation. Although anecdotal, N2O inhalation is a safe consideration during a time when a treating ED physician has few alternatives. DisclosuresMorris:Pfizer: Consultancy; Lifetrients: Patents & Royalties: I am inventor of IP owned by USCF-Benioff Children's Hospital Oakland, licensed to Lifetrients, generating royalties; Nestle: Consultancy; Calithera Biosciences: Consultancy; MAST Therapeutics: Research Funding.

Neural Dynamics in Primate Cortex during Exposure to Subanesthetic Concentrations of Nitrous Oxide.

Nitrous oxide (N2O) is a hypnotic gas with antidepressant and psychedelic properties at subanesthetic concentrations. Despite long-standing clinical use, there is insufficient understanding of its effect on neural dynamics and cortical processing, which is important for mechanistic understanding of its therapeutic effects. We administered subanesthetic (70%), inhaled N2O and studied the dynamic changes of spiking rate, spectral content, and somatosensory information representation in primary motor cortex (M1) in two male rhesus macaques implanted with Utah microelectrode arrays in the hand area of M1. The average sorted multiunit spiking rate in M1 increased from 8.1 ± 0.99 to 10.6 ± 1.3 Hz in Monkey W (p < 0.001) and from 5.6 ± 0.87 to 7.0 ± 1.1 Hz in Monkey N (p = 0.003). Power spectral densities increased in beta- and gamma-band power. To evaluate somatosensory content in M1 as a surrogate of information transfer, fingers were lightly brushed and classified using a naive Bayes classifier. In both monkeys, the proportion of correctly classified fingers dropped from 0.50 ± 0.06 before N2O inhalation to 0.34 ± 0.03 during N2O inhalation (p = 0.018), although some fingers continued to be correctly classified (p = 0.005). The decrease in correct classifications corresponded to decreased modulation depth for the population (p = 0.005) and fewer modulated units (p = 0.046). However, the increased single-unit firing rate was not correlated with its modulation depth (R2 < 0.001, p = 0.93). These data suggest that N2O degrades information transfer, although no clear relationship was found between neuronal tuning and N2O-induced changes in firing rate.

Appearance of hypersegmented neutrophils in the peripheral blood associated with subacute combined degeneration of the spinal cord due to nitrous oxide abuse

A 25-year-old man following 1 year of recreational nitrous oxide (N2O) use presented with quadriplegia and decreased sensation in a glove and stocking distribution. The weakness distally was 2/5 and proximally 2–3/5. The spinal cord lesions showed an increased signal in a V-shape within the posterior column on T2-weighted magnetic resonance imaging (MRI) extending posteriorly from the C1–C2 level to the C5 level. Laboratory tests showed: white cell count 4.39 × 109/l, red cell count 3.95 × 109/l, haemoglobin concentration 133 g/l, haematocrit 0.39 l/l, mean corpuscular volume 99.4 fl (normal range 82–100), mean corpuscular haemoglobin 33.8 pg, mean corpuscular haemoglobin concentration 340 g/l, red cell distribution width 16.2% (9.0–17.0), platelet count 175 × 109/l, serum folate 22.82 ng/ml (5.90–24.80), homocysteine 11.3 μmol/l (0.0–20.0), methylmalonic acid 296 nmol/l (73–376), vitamin B12 312 pg/ml (180–914) and thiamine 165.3 nmol/l (66.5–200). The differential white cell count was normal but a peripheral blood film showed hypersegmented neutrophils, 19% having 6 lobes (normal 1–5) (images, ×100 objective, Wright–Giemsa stain). Neutrophil alkaline phosphatase was normal. The morphology of mature red blood cells showed no obvious abnormality. The patient received intensive physiotherapy and vitamin B12 therapy. At outpatient review 6 weeks later, his symptoms had improved considerably. Neurological examination was normal apart from a mild hyporeflexia of the lower limbs. His peripheral blood film no longer showed neutrophil hypersegmentation. The clinical diagnosis of nitrous oxide abuse causing subacute combined degeneration of the spinal cord mainly depends on a history of N2O inhalation. However patients who are generally young men may conceal the N2O abuse history. Hence, clinical staff should be aware not only of the various presentations of neurotoxicity, but also the peripheral blood features related to N2O abuse.

Analysis of application of dental sedation in attention deficit hyperactivity disorder (ADHD) patients using the Korean National Health Insurance data.

BackgroundAttention deficit hyperactivity disorder (ADHD) is characterized by a persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development. It has a worldwide pooled prevalence of 5.29%. The characteristics of ADHD can increase the probability of dental treatment, while special behavior management can be required to allow proper treatment. In South Korea, the use of sedation in dental treatment has rapidly increased in recent decades. The present study aimed to investigate the trend and effects of sedation in patients with ADHD undergoing dental treatment in South Korea.MethodsThe study used customized health information data provided by the Korean National Health Insurance Service. Among patients with the record of sedative use during the period from January 2007 to September 2019, those with International Classification of Diseases-10 codes for ADHD (F90, F91) were selected; the data of their overall insurance claims for dental treatment were then analyzed. The patients' age, gender, sedative use, and dental treatment were analyzed per year. The annual number of general anesthesia or sedation cases was also analyzed, and changes in the method of behavior management with increasing age were examined.ResultsThe study involved 7,654 patients with ADHD (6,270 males; 1,384 females). The total number of dental treatments was 137,778, while the number of sedation cases was 16,109, among which 13,052 involved male patients and 3,057 female patients. The number of general anesthesia cases was 631, among which 538 involved male patients and 93 female patients. The most frequently used sedation method in the dental treatment of patients with ADHD was N2O inhalation. The percentage of sedation cases was highest in patients aged 4 years, and it decreased with increasing age.ConclusionIn South Korea, both sedation and dental treatments were slightly more common in patients with ADHD than in the general population. With increasing age, the frequency of dental treatments and the percentage of sedation cases decreased.

Comparison of Nitrous Oxide-Oxygen as Inhalation Agent, Midazolam, Ketamine alone and in Combination as Oral Sedative Agents for In-office Paediatric Patients- A Randomised Control Trial

Introduction: In-office pharmacological sedation techniques are best applied to manage an extremely fearful preschooler, especially during primary dentition or a child’s early mixed dentition period. These should be used when non pharmacological behavioural management techniques fail either due to lack of communication or in children with special care needs. Aim: To compare the efficacy of oral administrations of midazolam, ketamine, combination of midazolam-ketamine (M+K) and nitrous oxide-oxygen (N2O) inhalational sedation in achieving favorable behavioural outcome compared by using the Houpt scale in the treatment of anxious and uncooperative paediatric patients. Materials and Methods: A randomised clinical trial was conducted in the Department of Paediatric and Preventive Dentistry, SGT University, Haryana, India between September 2018 to December 2019. The study included 100 anxious children (Venham’s picture scale) aged three to five years, who required procedures under local anaesthesia administration were divided into four groups using envelop method. Each group was given either oral midazolam (M) (0.3 mg/kg) or oral ketamine (K) (3 mg/kg) or oral combination of midazolam+ketamine (M+K) (0.3 mg/kg and 2 mg/kg) or inhalational nitrous oxide-oxygen (N2O). The behaviour response of the child was recorded using the Houpt scale. The oxygen saturation level and heart rate of each patient were also recorded before, after, and during the procedure. Adverse drug reactions post-treatment was also recorded. Analysis of Variance (ANOVA), Chi-square test and Mann-Whitney U test was used for statistical analysis. Results: The study comprised of 100 anxious children (mean age was 4.1±0.5 years) requiring administration of local anaesthesia with intent to complete in-office treatment. Statistically, a significant difference was found among behaviour outcomes of four groups (p-value=0.047). Acceptable behaviour was seen best in K+M group (88%), followed by oral ketamine (K) (68%), N2O (59%), and oral midazolam (M) (52%). Adverse reactions were most commonly seen in the oral ketamine group. Conclusion: Oral M+K combination group is significantly better than oral ketamine (K), oral midazolam (M) or N2O inhalation sedation to achieve the required behaviour for dental treatment in three to five years old patients.

Clinical-radiological dissociation in a patient with nitrous oxide-induced subacute combined degeneration: a case report

BackgroundSeveral recent studies have reported subacute combined degeneration (SCD) induced by nitrous oxide (N2O) abuse. However, the association between the evolution of dynamic neuroimaging and clinical manifestations has not been reported in patients with N2O-induced SCD.Case presentationWe described the case of a 24-year-old man who developed SCD with inverted V-sign hyperintensities over the posterior aspect of the spinal cord caused by frequent, excessive N2O inhalation. One month after treatment, his weakness and paresthesia resolved and serum vitamin B12 levels exceeded the normal levels. However, the hyperintensities had extended horizontally and longitudinally on T2-weighted magnetic resonance imaging (MRI), compared to those on the initial scan. Two months after treatment, the patient experienced some residual numbness in the distal limbs, and his serum homocysteine levels were normal, but the abnormal signals seen on cervical T2-weighted MRI had decreased only slightly compared to those seen on the one-month follow-up MRI. The evolution of conventional MRI findings lagged compared to the clinical manifestation, which was suggestive of a clinical-radiological dissociation.ConclusionsClinical-radiological dissociation might have occurred in this case because T2-weighted imaging was not sensitive enough to reveal cytotoxic edema. Moreover, the serum vitamin B12 level is not a good indicator of cellular vitamin B12. Thus, clinicians should recognize this phenomenon, comprehensively assess the condition of patients with N2O-induced SCD, and avoid terminating treatment based on the resolution of clinical symptoms and serological results.

Clinical Trial of Manual Reduction of Temporomandibular Joint Dislocation After Inhalation of Nitrous Oxide.

The aim of this study was to evaluate the efficiency of inhaled nitrous oxide (N2O) for manual reduction of acute nontraumatic temporomandibular joint (TMJ) dislocation in the supine position technique. This clinical trial included a total of 51 patients presenting with acute nontraumatic TMJ dislocation. The patients were grouped randomly. The supine position technique was applied in both N2O group (experimental group) and control group (without N2O). The visual analogue scale scores (VAS scores) of the pain perception and the operation time were recorded. All patients with dislocated mandible were successfully managed. The VAS scores of pain perception were significantly reduced in N2O group. It was 1.63 compared to 4.00 in control group. The average operation time was also significantly reduced in N2O group (Supplemental Digital Content, Table 2, http://links.lww.com/SCS/A716). It was 129.92 seconds compared to 170.04 seconds in control group. Inhalation of N2O helps to reduce the pain perception and the operation time of manual reduction of acute nontraumatic TMJ dislocation using the supine position technique. It is beneficial to both patients and doctors.

Longevity of posterior composite and compomer restorations in children placed under different types of anesthesia: a retrospective 5-year study

The aims of this study were (i) to assess cumulative survival rates of class II resin-based composite and compomer restorations in primary molars with a 5-year observation period and (ii) to analyze the influence of different types of anesthesia and different localizations of the restorations in the teeth. Patient charts of a private practice for pediatric dentistry were screened for class II resin-based composite (Spectrum TPH3) and compomer (Dyract Posterior; both Dentsply DeTrey) restorations in primary molars with a 5-year observation period used with Adper Prompt L-Pop (3M-ESPE). One restoration per patient (age ≤ 6years at placement) was randomly selected. Two hundred sixty restorations were included (43% resin-based composites, 57% compomers). After 5years, cumulative survival rates were 43% for resin-based composite and 49% for compomer restorations with no statistically significant differences. There was a tendency for higher survival rates for restorations placed under N2O inhalation sedation or general anesthesia. Distal-occlusal compomer restorations showed significantly lower survival rates (p = 0.003) as compared to mesial-occlusal compomer restorations. Within the limitations of the study, we conclude that type of restorative material as well as the type of anesthesia do not influence restoration survival rates, although restorations placed in patients receiving N2O inhalation sedation or general anesthesia tend to perform better as compared with patients receiving no anesthesia or only local infiltration. Resin-based composite and compomer restorations show similar survival rates of more than 43% (annual failure rates less than 11.5%) after 5years for restoration of primary molars.

Combined nitrous oxide 70% with intranasal fentanyl for procedural analgosedation in children: a prospective, randomised, double-blind, placebo-controlled trial

ObjectiveNitrous oxide 70% (N2O 70%) is an excellent medication for procedural analgosedation (PAS), yet the limit of its analgesic power remains uncertain; therefore, a combination with intranasal fentanyl (INF) was...

Imaging appearance of myelopathy secondary to nitrous oxide abuse: a case report and review of the literature

Purpose The abuse of nitrous oxide (N2O) can induce Vitamin B12 deficiency that subsequently leads to central nervous demyelination, myelopathy and peripheral neuropathy. Although myelopathy has been reported in the past, the specific locations and prognosis of the disease are still unclear.Materials and methods: We report the case of a 22-year-old male who presented with quadriplegia that began after a 3-month history of inhalation of N2O. We summarized the clinical data of this entity and performed a comprehensive literature review of various presentations and MRI features of myelopathy secondary to N2O abuse.Results: In combination with previous reports of 14 cases, we found that the onset of the disease was usually subacute, and the majority of patients (92.85%) were young men. There was no definite relationship between myelopathy and the amount or duration of N2O inhalation. The most common clinical manifestation was sensory ataxia, and the cervical spinal cord was the most frequently impaired area of the whole spinal cord. The spinal cord lesions had a high signal intensity on T2-weighted MRI and usually involved more than three spinal segments and impaired the posterior column more significantly. Most patients recovered well after vitamin B12 supplementation.Conclusions: Myelopathy secondary to N2O abuse is generally seen in young men. The clinical diagnosis mainly depends on a history of N2O inhalation and the characteristic imaging changes in the posterior cervical spinal cord. Early diagnosis and intervention are important for a satisfactory prognosis.