Comparison of Efficacy and Safety of Midazolam versus Nitrous Oxide as Sedative Agents during Paediatric Dental Treatment: A Systematic Review

ABSTRACT Objective: To identify and study the existing literature on the efficacy and safety of midazolam compared to inhalation of nitrous oxide in children undergoing dental treatment. Material and Methods: Electronic resources such as PubMed Central, Cochrane Database of Systematic Reviews, Lilacs, Science Direct, and SIGLE were thoroughly searched. The title scan was used to find randomised controlled trials reviewed for inclusion by reading the abstract. Studies comparing the sedative, behavioural, and anxiolytic effects and safety in children undergoing dental treatment under midazolam and nitrous oxide inhalation were included. The Cochrane Reviews system software, Revman 5.4.1, was used to assess the quality of the included studies. Results: 11328 articles were identified by screening the electronic databases, of which 10906 were eliminated after titles were read and duplicates were removed. Ten full-text articles were examined, of which three were excluded as they did not match the eligibility criteria. Hence, a total of 7 studies were included. Midazolam and nitrous oxide inhalation were not statistically different in terms of the success of treatment and behaviour modification. However, midazolam showed a deeper level of sedation and resulted in amnesia in more children when compared to nitrous oxide sedation. All of the included studies were found to have a high risk of bias. Conclusion: Though all the studies included showed an increased risk of bias, midazolam and nitrous oxide inhalation seem equally effective sedative agents for controlling behaviour in children undergoing dental treatment. Midazolam shows a deeper sedation level when given orally and produces a higher rate of anterograde amnesia.

Uso de óxido nitroso como sedação consciente por profissionais de odontologia no Rio Grande do Sul: um estudo transversal / Prevalence of nitrous oxide use as conscious sedation by dentistry professionals in Rio Grande do Sul: a cross-sectional study

Objetivo: Avaliar fatores associados, percepção e prevalência do uso de óxido nitroso por cirurgiões-dentistas do Rio Grande do Sul, Brasil. Metodologia: Realizou-se um estudo transversal, de base eletrônica, com profissionais registrados no Rio Grande do Sul. A coleta de dados baseou-se no envio, por e-mails e campanhas no Instagram, de um questionário via plataforma Google Forms contendo 27 questões acerca do uso de óxido nitroso em atendimentos odontológicos, bem como o perfil e as percepções dos profissionais sobre a técnica. Resultados: Dos 220 participantes, apenas 12,3% utilizava o óxido nitroso em sua prática clínica, sendo as especialidades que mais utilizavam, cirurgia e odontopediatria. Dentre os que reportaram utilizar a técnica, 81,5% tinham mais de 29 anos (p<0,001) e possuíam curso de pós-graduação, sendo que destes, 55,6% realizou o curso de habilitação (p<0,01) e mais da metade (55,6%) relatou utilizar em pacientes adultos (p<0,001). O alto custo do equipamento, bem como a falta de interesse dos profissionais, foram as principais razões para o não uso da técnica. Conclusão: A técnica de sedação consciente com óxido nitroso é pouco usada pelos cirurgiões-dentistas no Estado do Rio Grande do Sul. É possível que a ampliação do conhecimento acerca da indicação e aplicação do óxido nitroso, ainda durante a graduação, possa expandir o uso e contribuir para uma melhor qualidade no atendimento de pacientes com medo e ansiedade odontológicos. (AU)

Objective: The aim of this study is to evaluate associated factors, perception and prevalence of nitrous oxide use by dental surgeons in Rio Grande do Sul, Brazil. Methodology: A cross-sectional, electronic-based study was carried out with professionals registered in Rio Grande do Sul. Data collection was based on sending, via emails and Instagram campaigns, a questionnaire via the Google Forms platform containing 27 questions about the use of nitrous oxide in dental care, as well as the profile and perceptions of professionals about the technique. Results: Of the 220 participants, only 12.3% used nitrous oxide in their clinical practice, the specialties they used most being surgery and pediatric dentistry. Among those who reported using the technique, 81.5% were over 29 years old (p<0.001) and had a postgraduate course, of which 55.6% completed the qualification course (p<0.01) and more than half (55.6%) reported using it in adult patients (p<0.001). The high cost of the equipment, as well as the lack of interest from professionals, were the main reasons for not using the technique. Conclusion: The conscious sedation technique with nitrous oxide is little used by dental surgeons in the State of Rio Grande do Sul. It is possible that expanding knowledge about the indication and application of nitrous oxide, even during graduation, can expand its use and contribute to a better quality of care for patients with dental fear and anxiety. (AU)

ANAESTHETIC MANAGEMENT OF A PATIENT WITH HYPERHOMOCYSTEINEMIA FOR TOTAL ABDOMINAL HYSTERECTOMY

Hyperhomocysteinemia is a disorder caused by a disruption of any of the enzymes or cofactors involved in the pathways of homocysteine metabolism. The resultant high plasma levels of homocysteine increase the risk for thromboembolic events. These patients are frequently anticoagulated in the perioperative setup. Interruption of anticoagulant therapy may subject the patient to an increased risk of thrombosis, infarction, and death. Neuraxial anaesthesia techniques may be relatively contraindicated in anticoagulated patients and nitrous oxide may exacerbate the condition by inhibiting the conversion of homocysteine to methionine. We describe a case of the anaesthetic management of a unique case of hyperhomocysteinemia with multiple recent thrombotic episodes proposed for total abdominal hysterectomy conducted under general anaesthesia, the intraoperative and postoperative monitoring and considerations.

Tillage and nutrient management influence net global warming potential and greenhouse gas intensity in soybean-wheat cropping system

Conservation tillage has proven advantageous in improving soil health and productivity. However, the greenhouse gases (GHGs) emission and intensity from different conservation tillage and nutrient management systems under Indian conditions are less understood. Therefore, here, we compared the effect of tillage and nutrient management on GHGs emissions, net global warming potential (NGWP), and greenhouse gas intensity (GHGI) from a field experiment under five years in a soybean-wheat cropping system in the Vertisols. The tillage treatments comprised of reduced tillage (RT) and no tillage (NT). The three nutrient management treatments included application of 100% NPK (T1), 100% NPK + 1.0 Mg FYM-C ha-1 (T2), 100% NPK +2.0 Mg FYM-C ha-1 (T3). The results showed significantly higher SOC sequestration under NT (1388 kg ha-1 yr-1) followed byRT (1134 kg ha-1 yr-1) with application of FYM (2.0 Mg C ha-1) (T3) every year. Across tillage, integrated nutrient management(T2 and T3) lowered NGWP and GHGI compared to NPK (T1). The GHGI of NT system was less by 33% compared to RT. The results suggest that GHGs mitigation and sustained food production in the soybean-wheat system can be achieved in NT and RT with integrated use of organic and inorganic fertilizer as the major component of nutrient management.

Pasture management and greenhouse gases emissions

Pastures are important environments worldwide because they offer many ecosystem services and sustain meat and milk production. However, pastures ecosystems are responsible for greenhouse gas (GHG) emission. The major GHGs include CO2, CH4, and N2O. The present review summarizes GHG emission from pasture ecosystems and discusses strategies to mitigate this problem. In pastures, emissions originate from animal excretion, fertilization, and organic matter decomposition. Emissions of specific gases can be measured based on certain factors that were recently updated by the United Nation's Intergovernmental Panel on Climate Change in 2019. Urine is the main source of N2O emission. Forage structure is an important factor driving GHG transport. Forage fiber content and animal intake are the key drivers of enteric CH4 emission, and the introduction of forage legumes in pasture systems is one of the most promising strategy to mitigate GHG emission.

Electrophysiological characteristics of subacute combined degeneration of spinal cord in patients with nitrous oxide poisoning / 中国医师进修杂志

Objective:To analyze the electrophysiological characteristics of subacute combined degeneration of spinal cord in 10 patients with nitrous oxide poisoning.Methods:Ten patients with nitrous oxide poisoning (case group) and 20 controls (control group)treated in Dalian Municipal Central Hospital Affiliated of Dalian Medical University from January 2016 to January 2020 were included in this study. MRI and electrophysiological examinations were performed on the head, cervical spine and thoracic spine, including distal motor latency (DML), motor nerve amplitude (CMAP), motor conduction velocity (MNCV), sensory conduction velocity (SNCV), sensory nerve amplitude (SNAP), N20 latency of upper limb cortical somatosensory evoked potential and P40 latency of lower limb cortical somatosensory evoked potential. The above indexes were compared between the two groups.Results:In the case group, DML of motor nerve was prolonged, MNCV was slowed down, CMAP was decreased, SNCV was slowed down and SNAP was decreased compared with the control group, the differences were statistically significant ( P<0.05). The incubation periods of N20 and P40 in the case group were longer than those in the control group: (32.70 ± 3.34) ms vs. (18.85 ± 1.37) ms, (57.00 ± 4.08) ms vs. (38.40 ± 1.54) ms, the differences were statistically significant ( t = 16.20, 18.20, P<0.01). The inverted "V" type T 2 long signal of cervical spinal cord and thoracic spinal cord could be seen on MRI of cervical or cervical and thoracic vertebrae in 5 patients. Conclusions:Nitrous oxide poisoning can cause obvious subacute combined degeneration of spinal cord, involving peripheral nerve and spinal cord damage. Peripheral nerve damage can involve motor fibers and sensory fibers, mainly axonal damage, accompanied by demyelination damage, especially in both lower limbs.

Mielopatía cervical secundaria al consumo recreativo de óxido nitroso una afección emergente / Cervical myelopathy secondary to recreational nitrous oxide use: an emergent pathology

Resumen Se describe el caso de una paciente de 27 años que se presentó al servicio de urgencias por hipoestesia y parestesia de dos meses de evolución. El cuadro se inició en ambos pies, progresó en pocos días hasta las rodillas sin trastornos de la marcha y se acompañó de distonías en pulgar e índice de ambas manos. La analítica sanguínea incluyendo tóxicos fue negativa. La resonancia magnética medular mostró una imagen sugestiva de mielopatía o mielitis (C3-C5) sin otras anomalías sugestivas de enfermedad sistémica. El análisis bioquímico y el bacteriológico del líquido cefalorraquídeo fueron normales. Ante estos elementos se re-interrogó a la paciente en busca de consumo de tóxicos inusuales con la confirmación de consumo de óxido nitroso. La paciente fue internada para la realización de otros estudios que confirmaron la hipótesis diagnóstica del servicio de urgencias.

Abstract We describe the case of a 27-year-old female patient who presented to the emergency ward with hypoesthesia and paresthesia developing over the last two months, initially in both feet and progressing to the knees in a few days without associated gait disorders. Dystonia in the thumb and index finger of both hands was noted. Blood tests including toxic drugs were negative. The spinal magnetic resonance imaging was consistent with (C3-C5) myelopathy or myelitis without other abnormalities suggestive of systemic diseases. The biochemi cal and bacteriological analysis of the cerebrospinal fluid was normal. Because of these findings, the patient was re-interviewed to determine the consumption of unusual drugs, and nitrous oxide consumption was referred. The patient was admitted for further studies, which confirmed the diagnosis.

Nitrous oxide as an adjunctive therapy in major depressive disorder: a randomized controlled double-blind pilot trial

Objective: Major depressive disorder (MDD) is related to glutamatergic dysfunction. Antagonists of glutamatergic N-methyl-D-aspartate receptor (NMDAR), such as ketamine, have antidepressant properties. Nitrous oxide (N2O) is also a NMDAR antagonist. Thus, this study aimed to evaluate the effects of augmenting antidepressant treatment with N2O. Methods: This double blind, placebo-controlled randomized parallel pilot trial was conducted from June 2016 to June 2018 at the Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo. Twenty-three subjects with MDD (aged 18 to 65, on antidepressants, with a score > 17 on the 17-item-Hamilton Depression Rating Scale [HAM-D17]) received 50% N2O (n=12; 37.17±13.59 years) or placebo (100% oxygen) (n=11; 37.18±12.77 years) for 60 minutes twice a week for 4 weeks. The primary outcome was changes in HAM-D17 from baseline to week 4. Results: Depressive symptoms improved significantly in the N2O group (N2O: from 22.58±3.83 to 5.92±4.08; placebo: from 22.44±3.54 to 12.89±5.39, p < 0.005). A total of 91.7% and 75% of the N2O group subjects achieved response (≥ 50% reduction in HAM-D17 score) and remission (HAM-D17 < 7), respectively. The predominant adverse effects of N2O treatment were nausea, vomiting, and headache. Conclusion: N2O treatment led to a statistically significant reduction in HAM-D17 scores compared to placebo. Clinical trial registration: Brazilian Register of Clinical Trials, RBR-5rz5ch

Tratamento cirúrgico de mesiodentes sob sedação consciente com óxido nitroso: relato de caso clínico / Surgical treatment of mesiodens under conscious sedation with nitrous oxide: clinical case report

Dentes supranumerários são caracterizados como um excesso no número de dentes da série normal. Os mesiodentes, definidos pela sua localização mediana aos incisivos centrais superiores, referem-se ao tipo de dente supranumerário mais comumente encontrado na cavidade oral, normalmente intraósseo e assintomático. A presença desses dentes pode ocasionar alterações na dentição permanente, mas a abordagem cirúrgica na fase da dentição mista mostra resultados satisfatórios no alinhamento dental espontâneo. Em pacientes pediátricos, a sedação consciente com óxido nitroso tem demonstrado ser uma alternativa segura e eficaz no controle do medo e da ansiedade. Objetivo: relatar um procedimento cirúrgico de remoção de dois mesiodentes em paciente pediátrico sob anestesia local associada à sedação com óxido nitroso. Relato de caso: paciente do sexo feminino, 11 anos de idade, necessitava de remoção cirúrgica de dois dentes supranumerários localizados em região anterior de maxila. Com a avaliação da tomografia computadorizada, pôde-se observar a posição em que ambos se encontravam. Realizou-se também a exodontia do elemento dentário 14, como solicitado pela ortodontista, para posterior continuidade do tratamento ortodôntico. Devido à complexidade cirúrgica e ao tempo operatório, considerando a idade da paciente e o possível aumento nos níveis de ansiedade, optou-se pela realização de sedação consciente com óxido nitroso. Conclusão: clinicamente, dentes supranumerários podem causar danos locais. O tratamento cirúrgico associado à sedação consciente mostrou-se bastante seguro e efetivo no controle comportamental, além de poder ser implementado na rotina ambulatorial.(AU)

Supernumerary teeth are defined as those in addition to the normal series. The mesiodens, is the most common supernumerary tooth and it is present in the midline between the two central incisors. It is usually intraosseous and asymptomatic. The presence of these teeth may cause changes in permanent dentition and the surgical approach in the mixed dentition phase shows satisfactory results in spontaneous dental alignment. In pediatric patients, conscious sedation with nitrous oxide has been shown to be a safe and effective alternative in controlling fear and anxiety. Objective. To report a surgical procedure for the removal of two mesiodens in a pediatric patient under local anesthesia associated with nitrous oxide sedation. Case report. 11-year-old female patient required surgical removal of two upper mesiodens. The computed tomography images assisted to indicate their exact position. The extraction of the upper right premolar (tooth #14) was also performed as requested by the orthodontist. Considering the patient's age and the possible increase in anxiety levels, along with surgical complexity and operative time, the conscious sedation with nitrous oxide was selected. Conclusion. Clinically, supernumerary teeth cause local damage and surgical treatment associated with conscious sedation has proved to be quite safe and effective in the behavioral control besides being able to be implemented in the outpatient routine.(AU)

1 429 cases treated with nitrous oxide inhalation sedation in dental clinic: a retrospective study / 口腔疾病防治

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.

Effects of Oral Diazepam or Inhalatory Nitrous OxideOxygen for Conscious Sedation During Third Molar Surgery: A Randomized Controled Trial, Split Mouth Design / Efectos del Diazepam Oral o la Inhalación de Óxido Nitroso-Oxígeno para la Sedación Consciente Durante la Cirugía del Tercer Molar: Un Ensayo Controlado Aleatorio, Diseño de Boca Dividida

ABSTRACT: Anxiety in dental surgery may lead to behavioral and physiological changes for the patient and constitute a frequent challenge for the oral surgeon. The objective of this study was to compare the effect of inhalatory nitrous oxide and oxygen (N2O/O2) with oral diazepam conscious sedation in vital signs of patients undergone third molar extraction. Outpatients who needed removal of partially impacted, bilateral lower third molars, during the period of one year, were included. Each patient underwent conscious sedation with either oral diazepam or inhalatory N2O/O2 on a randomized controlled trial, split-mouth design. Systolic and diastolic blood pressure, heart rate and oxygen blood saturation were the changes measured before, at the beginning and the end of the procedure. Also, surgical procedure duration was recorded. Data from vital signs were submitted to analysis of variance and the duration of the surgery to paired Student's t-test. Twenty-five healthy outpatients (13 women and 12 men) with a mean age of 21.6 years were studied. There was an increase in systolic and diastolic pressure and in heart rate in the beginning; these values decreased and stabilized at the end of the surgical procedure in both treatments (p < 0.001) being lower in N2O/O2 but without difference between treatments. The surgical procedure duration was lower and occurred an expected increase of oximetry under N2O/O2 sedation (p < 0.001). Both treatments were effective for the conscious sedation but N2O/O2 showed better outcomes, mainly in duration of the surgery.

RESUMEN: La ansiedad en la cirugía dentoalveolar puede conducir a alteraciones fisiológicas y de comportamiento en el paciente, constituyendo así un desafío frecuente para el cirujano maxilofacial. El objetivo de este estudio fue comparar el efecto del óxido nitroso inhalatorio con oxígeno (N2O/O2) y la sedación consciente oral con diazepam por médio de los signos vitales de pacientes sometidos a la extracción del tercer molar. Fueron incluídos pacientes ambulatoriales com necesidad de exodoncia de terceros molares inferiores bilaterales, parcialmente impactados, durante el período de un año. Cada paciente fue sometido a sedación consciente con diazepam oral o N2O/O2 por inhalación en un ensayo controlado aleatorio, diseño de boca dividida. La presión arterial sistólica y diastólica, la frecuencia cardíaca y la saturación de oxígeno en la sangre fueron medidos antes, al inicio y al final del procedimiento. Además, se registró la duración del procedimiento quirúrgico. Los datos de los signos vitales fueron enviados para análisis de varianza y la duración de la cirugía para la prueba t de Student pareada. Se estudiaron 25 pacientes ambulatorios sanos (13 mujeres y 12 hombres) con una edad media de 21,6 años. Al início hubo un aumento en la presión sistólica y diastólica y en la frecuencia cardíaca; estos valores disminuyeron y se estabilizaron al final del procedimiento quirúrgico en ambos tratamientos (p <0,001), siendo más bajos en N2O/ O2 pero sin diferencia entre los tratamientos. La duración del procedimiento quirúrgico fue menor y se produjo un aumento esperado de la oximetría bajo sedación con N2O/O2 (p <0,001). Ambos tratamientos fueron efectivos para la sedación consciente, pero el N2O/O2 mostró mejores resultados, principalmente en la duración de la cirugía.

Literature review of nitrous oxide-induced disease / 中华全科医师杂志

Nitrous oxide (N2O) is an anesthetic which is also known to have abuse potential. Nitrous oxide-induced disease is occasionally encountered in the clinic, and there have been only several case reports about nitrous oxide-induced disease. In this article we review the reported cases of severe nerve injury following N2O abuse.

Literature review of nitrous oxide-induced disease / 中华全科医师杂志

Nitrous oxide (N2O) is an anesthetic which is also known to have abuse potential.Nitrous oxide-induced disease is occasionally encountered in the clinic,and there have been only several case reports about nitrous oxide-induced disease.In this article we review the reported cases of severe nerve injury following N2O abuse.

Detection and prevention of nitrous oxide iatrogenic pollution in dental treatments / 中华口腔医学杂志

Nitrous oxide (N2O), also known as laughing gas, is widely used in the dental offices as a common inhaled sedative analgesic gas to reduce anxiety and pain during treatment. Studies have shown that long-term exposure to higher concentrations of laughing gas may have a certain impact on the health of medical staff, while currently research on iatrogenic pollution in applications of laughing gas in oral therapy is not sufficient. In the United States and Europe, the condition of applications of laughing gas is relativrly mature, and there are related regulations and recommended measures to prevent and control iatrogenic pollution. However, studies in these countries still show that there is iatrogenic pollution in the clinical use of laughing gas and lack of uniform detection measures. While, in China, there is little research on the health effects of laughing gas on medical staff and on how to detect and control nitrous oxide pollution. This review is about the hazards, monitoring and control of clinical application of nitrous oxide.

Perioperative Factors Associated with Severe Pain in Post-Anesthesia Care Unit after Thoracolumbar Spine Surgery: A Retrospective Case-Control Study

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 <7 in every PACU assessment). The data collected comprised patient factors, anesthetic factors, surgical factors, PACU pain score, and PACU pain management. RESULTS: A total of 197 patients underwent thoracolumbar spine surgery with an incidence of early postoperative severe pain of 53.3%. The case-control study revealed no differences in the factors related to pain intensity. A subgroup analysis was performed for failed back surgery syndrome (FBSS), spinal stenosis, and spondylolisthesis. After multivariate analyses, only the age group of 19–65 years and the baseline Oswestry Disability Index (ODI) were found to be significant risk factors for early postoperative severe pain in the PACU (odds ratio [OR], 2.86; 95% confidence interval [CI], 1.32–6.25; OR, 1.03; 95% CI, 1.01–1.05, respectively). CONCLUSIONS: Nitrous oxide, anesthetic agents, and surgical techniques did not affect the early postoperative pain severity. Age under 66 years and the baseline ODI were the significant risk factors for pain intensity during the early postoperative period of the FBSS, spinal stenosis, and spondylolisthesis subgroups.

Subacute Combined Degeneration Caused by Nitrous Oxide Intoxication: A Report of Two Cases

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.

Comparison of endotracheal tube cuff pressure changes using air versus nitrous oxide in anesthetic gases during laparoscopic abdominal surgeries / Comparação de alterações na pressão do balonete do tubo endotraqueal usando ar versus óxido nitroso nos gases anestésicos durante cirurgias abdominais laparoscópicas

Abstract Background and objectives The purpose of this study was to compare the endotracheal tube cuff pressure changes during laparoscopic surgeries using air versus nitrous-oxide in anesthetic gas mixture; and to observe the incidences of postoperative sore throat, hoarseness and dysphagia. Methods Total 100 patients scheduled for elective laparoscopic abdominal surgery were allocated into two groups. Group A (n = 50) received air while Group N (n = 50) received nitrous-oxide in anesthetic gas mixture. After endotracheal intubation, cuff was inflated with air to achieve sealing pressure. Cuff pressure at baseline (sealing pressure), 30 min, 60 min and 90 min was recorded with a manometer. Incidence of sore throat, hoarseness and dysphagia was noted at the time of discharge from post-anesthesia care unit and 24 h after extubation. Results Cuff pressure increased from baseline in both the groups. The increase in cuff pressure in Group N was greater than that in Group A at all time points studied (p < 0.001). Within Group A, cuff pressure increased more at 90 min than at 30 min (p < 0.05). Within Group N, increase in cuff pressure was more at each time point (30, 60 and 90 min) than its previous time point (p < 0.05). The incidence of sore throat in post-anesthesia care unit was higher in Group N than in Group A. Conclusion Use of nitrous-oxide during laparoscopy increases cuff pressure resulting in increased incidence of postoperative sore throat. Cuff pressure should be monitored routinely during laparoscopy with nitrous-oxide anesthesia.

Resumo Justificativa e objetivos O objetivo deste estudo foi comparar as alterações na pressão do balonete do tubo endotraqueal durante cirurgias laparoscópicas usando ar versus óxido nitroso na mistura dos gases anestésicos e observar a incidência de dor de garganta, rouquidão e disfagia no pós-operatório. Métodos No total, 100 pacientes agendados para cirurgia abdominal laparoscópica eletiva foram alocados em dois grupos: Grupo A (n = 50) recebeu ar e Grupo N (n = 50) recebeu óxido nitroso na mistura de gases anestésicos. Após a intubação endotraqueal, o balonete foi insuflado com ar para obter a pressão de vedação. As pressões do balonete na fase basal (pressão de vedação), aos 30 min, 60 min e 90 min foram registradas com um manômetro. A incidência de dor de garganta, rouquidão e disfagia foi observada no momento da alta da sala de recuperação pós-anestésica e 24 horas após a extubacão. Resultados A pressão do balonete aumentou em ambos os grupos, comparada à pressão basal. O aumento da pressão do balonete foi maior no Grupo N do que no Grupo A em todos os tempos avaliados (p < 0,001). No Grupo A, o aumento da pressão do balonete foi maior aos 90 min do que aos 30 min (p < 0,05). No Grupo N, o aumento da pressão do balonete foi maior em cada um dos tempos (30, 60 e 90 min) do que no tempo anteriormente mensurado (p < 0,05). A incidência de dor de garganta na sala de recuperação pós-anestésica foi maior no Grupo N do que no Grupo A. Conclusão O uso de óxido nitroso durante a laparoscopia aumenta a pressão do balonete, resulta em aumento na incidência de dor da garganta no pós-operatório. A pressão do balonete deve ser rotineiramente monitorada durante a laparoscopia sob anestesia com óxido nitroso.

Emisión de óxido nitroso, nitrificación, desnitrificación y mineralización de nitrógeno durante el cultivo del arroz en 2 suelos de Uruguay / Nitrous oxide emission, nitrification, denitrification and nitrogen mineralization during rice growing season in 2 soils from Uruguay

Los procesos microbianos como la mineralización, la nitrificación y la desnitrificación regulan la dinámica del nitrógeno en el suelo. Estos 2 últimos son los principales responsables de la emisión de óxido nitroso (N2O). En este trabajo se determinaron los flujos de N2O en momentos clave del ciclo de cultivo del arroz en 2 sitios que diferían principalmente en el contenido de materia orgánica del suelo (MO), en las localidades de Salto (mayor MO) y de Treinta y Tres. Dichos momentos clave fueron a la siembra, en macollaje, en primordio floral y a la madurez. También se determinó el potencial de mineralización neta de N y las actividades y los números más probables (NMP) de oxidantes de NH4+ y de desnitrificantes. El potencial de mineralización de N, así como la actividad y el NMP de oxidantes de NH4+, no variaron con el tipo de suelo. Sin embargo, la actividad y el NMP de desnitrificantes fueron mayores en el suelo con mayor contenido de MO, independiente de la etapa del cultivo. A su vez, en las etapas finales del ciclo del cultivo, el NMP de desnitrificantes aumentó coincidiendo con el mayor potencial de mineralización y el mayor contenido de N mineral del suelo. Solo se observó un incremento en el flujo de N2O en el suelo de Salto a la madurez del arroz y cuando el suelo ya había sido drenado (44,2g N-N2O/ha d, frente a 20,8g N-N2O/ha d en Treinta y Tres). Esta investigación señala la importancia de estudiar las emisiones en distintos tipos de suelos y de continuar la medición luego del drenaje del cultivo de arroz para la elaboración de los inventarios de gases de efecto invernadero.

Microbial processes such as mineralization, nitrification and denitrification regulate nitrogen dynamics in the soil. The last two processes may produce nitrous oxide (N2O). In this work N2O fluxes were quantified at four moments of the rice cycle, sowing, tillering, panicle initiation and maturity, in two sites that differed mainly in their soil organic matter (OM) content, Salto (higher OM) and Treinta y Tres. Potential net N mineralization, ammonium oxidation and denitrification as well as the most probable numbers (MPN) of ammonia oxidizers and denitrifiers were determined. Potential N mineralization did not vary with the soil type and increased at rice maturity. Neither ammonia oxidation potential nor MPN were different among the soils. However, the soil with higher OM exhibited higher activity and MPN of denitrifiers, irrespective of the rice stage. In turn, at the latest phases of the crop, the MPN of denitrifiers increased coinciding with the highest mineralization potential and mineral N content of the soil. Significant differences in N2O flux were observed in Salto, where the highest emissions were detected at rice maturity, after the soil was drained (44.2 vs 20.8g N-N2O/ha d in Treinta y Tres). This work shows the importance of considering the soil type and end-of-season drainage of the rice field to elaborate GHGs (greenhouse gases) inventories.

Complications caused by nitrous oxide in dental sedation

The first clinical application of nitrous oxide (N₂O) was in 1844, by an American dentist named Horace Wells who used it to control pain during tooth extraction. Since then, N₂O has shared a 170-year history with modern dental anesthesia. N₂O, an odorless and colorless gas, is very appealing as a sedative owing to its anxiolytic, analgesic, and amnestic properties, rapid onset and recovery, and, in particular, needle-free application. Numerous studies have reported that N₂O can be used safely and effectively as a procedural sedation and analgesia (PSA) agent. However, N₂O can lead to the irreversible inactivation of vitamin B12, which is essential for humans; although rare, this can be fatal in some patients.