Sedative efficacy of nitrous oxide combined with midazolam in extraction of impacted supernumerary teeth in children / 口腔疾病防治

Objective@#To study the sedative efficacy and safety of nitrous oxide (N2O ) inhalation combined with oral midazolam in children with impacted supernumerary teeth for extraction under sedation and to provide a reference for the selection of anesthetic methods for children undergoing impacted teeth extraction.@*Methods @#Sixty patients aged 5-10 years with maxillary impacted supernumerary teeth were randomly divided into three groups, with 20 in each group, as follows: the N2O group: N2O inhalation sedation before the operation; the midazolam group: oral midazolam sedation before the operation; the combination group: N2O inhalation combined with oral midazolam sedation before the operation. Sedation was performed before extraction under local anesthesia. The Ramsay sedation effect, Houpt behavioral score and incidence of adverse reactions were evaluated after the operation.@*Results@#The Ramsay sedation scale score was significantly higher in the combination group (2.75 ± 0.55) than in the N2O group (2.30 ± 0.47) and the midazolam group (2.40 ± 0.50) (P ＜0.05). Similarly, the Houpt behavioral rating scale score was significantly higher in the combination group (5.25 ± 0.64) than in the N2O group (4.70 ± 0.73) and the midazolam group (4.80 ± 0.69) (P ＜0.05). The adverse reaction rate was lower in the combination group (5%) than in the N2O group (10%) and the midazolam group (10%), but the difference was not significant (χ2=0.436, p=0.804).@*Conclusion@#N2O inhalation combined with oral midazolam sedation in the extraction of impacted supernumerary teeth in children can significantly improve the sedative and therapeutic efficacy and is a safe and effective sedation method.

The effectiveness of methanotrophic bacteria and Ochrobactrum anthropi to reduce CH4 and N2O emissions and to promote paddy growth in lowland paddy fields

Aims: Paddy field is one of the sources of greenhouse gasses such as methane (CH4) and nitrous oxide (N2O), which causes global warming and other negative effects in agricultural sector. An alternative to optimize paddy productivity and reduce emissions of CH4 and N2O is by using methanotrophic bacteria and Ochrobactrum anthropi BL2. Methodology and results: This study consisted of two parts, i.e. positive control and experimental treatments. Positive control consisted of 250 kg/ha NPK inorganic fertilizer NPK (15:15:15) (100% of the recommended normal dose) without any methanotrophic bacteria. Meanwhile the experimental treatment consisted of 50 kg/ha inorganic fertilizers NPK (20% of the recommended normal dose) with methanotrophic bacteria (Methylocystis rosea BGM 1, M. parvus BGM 3, Methylococcus capculatus BGM 9, Methylobacter sp. SKM 14) and N2O reducing bacteria (Ochrobactrum anthropi BL2). Using weight indicator of 1000 grams, all the bacteria are capable of increasing paddy productivity by 42.07%, compared to conventional method which can only increase the productivity by 2.51% (Cepy and Wangiyana, 2011). The increasing productivity and growth of paddy plants were due to the nitrogen fixation activity of M. rosea BGM 1, M. capculatus BGM 9, and Methylobacter sp. SKM 14. In the experimental treatment using bacteria, the emission of CH4 and N2O was reduced with the highest CH4 and N2O sinks of 24018.8 mol CH4/day/ha and 68.48 mol N2O/day/ha, respectively. However, the positive control treatment with 100% of the recommended fertilizer dose showed the highest CH4 and N2O emissions which were up to 74346.45 mol CH4/day/ha and 26.21 mol N2O/day/ha, respectively. Conclusion, significance and impact study: All the methanotropic bacteria and O. anthropi BL2 are significantly increase paddy production, compared to positive control treatment. The addition of bacteria in paddy fields results in CH4 and N2O sinks.

Modelling levels of nitrous oxide exposure for healthcare professionals during EMONO usage

BACKGROUND: Computational fluid dynamics (CFD) has been used to compute nitrous oxide (N2O) levels within a room during the administration of an equimolar mix of N2O/oxygen (EMONO) in the clinical setting. This study modelled realistic scenarios of EMONO usage in hospital or primary care, in order to estimate the potential N2O exposure of healthcare professionals (HCP) with routine EMONO use and to provide guidance for EMONO users. METHODS: Sixteen scenarios were defined by carrying out a survey of practitioners. CFD simulations were performed for each scenario and N2O concentrations over time were calculated. N2O exposures (time-weighted average of concentration over 8 h [TWA-8 h]) were calculated at the HCPs’ mouth to be compared with a predefined occupational exposure limit (OEL). RESULTS: Administration duration and ventilation type were the main factors influencing N2O levels; ventilation type also influenced wash-out time between EMONO administrations. N2O concentration showed a plume distribution towards the ceiling and was highly heterogeneous, highlighting the importance of measurement location. Although estimated TWA-8 h varied widely, 13 of the 16 scenarios had an N2O TWA-8 h of <100 parts per million. CONCLUSIONS: Data demonstrate that EMONO usage in well ventilated rooms – as recommended – helps to ensure that N2O exposure does not exceed the OEL and does not signal any major risks for HCPs when recommendations are followed. Although these data are numerical simulations and should be considered as such, they can provide guidance for EMONO users.

Soil attributes and c and n variation in histosols under different agricultural usages in the state of Rio de Janeiro, Brazil / Atributos edáficos e variação de c e n em organossolos sob diferentes usos agrícolas no estado do Rio de Janeiro, Brasil

Histosols are a natural reservoir of C in the soil, and their drainage followed by other farming practices leads to subsidence and soil organic matter transformations. The objective of this study was to evaluate the influence of use and management of Histosols, by means of: characterizing chemical and physical properties, and the content of SOM and humic fractions; and quantifying C and N stocks. In addition, to obtain preliminary data on greenhouse gas emissions (CO2, N2O) in Histosol areas with different agricultural practices. Three areas were selected with similar soil and environment, two in Macaé municipality, under pasture, and with bean annual crop rotation, and the third in Santa Cruz, Rio de Janeiro city, cultivated with cassava (Manihot esculenta). The attributes evaluated were: physical - bulk density (BD), particle density (Dp), organic matter density (OMD), mineral matter (MM), mineral residue (MR), aggregate stability; and chemical - pH, exchangeable cations, soil organic matter (SOM), carbon in the humin (HUM-C), humic acid (HAF-C) and fulvic acid (FAF-C) fractions; stocks of C and N; and flux of CO2 and N2O. In general, the area cultivated with cassava had the highest values for exchangeable cations, as a result of fertilizer and soil management practices. The cassava site showed the highest values of BD and Dp; total volume of pores; MM, MR and OMD and higher degree of transformation of SOM; indicating higher alteration of Histosols properties under this usage. In all sites, the C levels indicated dominance of humin fraction. The SOM and C and N stocks were highest in the pasture, indicating preservation of organic matter, with values from 115.92 to 99.35Mg ha-1 of C e 8.35 to 4.45 Mg ha-1 for N. The values of CO2-C flux were within the range proposed by the IPCC, where the highest emission was 0.09 Mg CO2 ha-1 day-1 in the pasture site. The values of N2O-N flux were lower than proposed by the IPCC, with the highest value (270 g N2O-N m-2 day-1) in the area under beans (crop rotation). In general, the multivariate analyses discriminated the sites and the pasture was the usage that least affected the Histosols properties.

Os Organossolos são reservatório natural de C no solo e sua drenagem seguida por práticas agrícolas leva a subsidência e transformações na matéria orgânica do solo. O objetivo do estudo é avaliar a influencia do uso e manejo de Organossolos, através da: caracterização de propriedades químicas e físicas, conteudo de matéria orgânica do solo e frações húmicas; e quantificação de estoques de C e N. Ainda, obter dados preliminares sobre emissão de gases de efeito estufa (CO2, N2O) em áreas de Organossolos com diferentes usos agrícolas. Foram selecionadas três áreas com solos e ambientes semelhantes, duas no município de Macaé, sob pastagem e feijão com rotação de lavouras, e a terceira em Santa Cruz na cidade do Rio de Janeiro, com mandioca (Manihot esculenta). Os atributos avaliados foram: físicos - densidade do solo (Ds), densidade de partículas (Dp), densidade de matéria orgânica (DMO), material mineral (MM), resíduo mineral (RM), estabilidade de agregados; químicos - pH, cátions trocáveis, matéria orgânica do solo (MOS), carbono nas frações humina (HUM-C), ácido húmico (FAH-C) e ácido fúlvico (FAF-C); estoques de C e N; e fluxo de CO2 e N2O. A área de mandioca apresentou maiores valores de cátions trocáveis como resultado das práticas de adubação e manejo do solo. A área de mandioca apresentou Ds e Dp, volume total de poros, e valores de MM e RM e DMO mais elevados, e maior grau de transformação da matéria orgânica, indicando maior alteração das propriedades do Organossolo com esse uso. Em todas as áreas, os teores de C indicaram predomínio da humina. Os valores de MOS e estoques de C e N foram maiores na pastagem, indicando melhor preservação da matéria orgânica, com valores variando de 115,92-99,35Mg ha-1 de C e 8,35-4,45 Mg ha-1para N. Os valores de fluxo de CO2 estão de acordo com o IPCC, sendo o mais elevado de 0,09 mg de CO2 ha-1 dia- 1 na pastagem. Para N2O os fluxos foram menores que o proposto pelo IPCC, com o maior valor de 270 g N2O -N m-2 dia-1 na área com feijão. Em geral, a análise multivariada discriminou as áreas e a pastagem foi o uso que menos afetou as propriedades dos Organossolos.

Synthesis and characterization of organosoluble ruthenium(ii) complexes bearing schiff base ligands: efficient reusable catalyst for the hydrogenation reactions.

Six new organosoluble ruthenium(II) complexes bearing dibasic tetradentate Schiff base ligands of the general formula [Ru(CO)(PPh3)(L)] (where L = dibasic tetradentate Schiff base ligands derived by condensing actetoacetanilide/acetoacetotoludide with o-aminophenol/oaminothiophenol/ o-aminobenzoic acid in 1:2 molar ratio in ethanolic medium) have been synthesized by reacting [RuHCl(CO)(PPh3)3] with the respective Schiff base ligands in 1:1 molar ratio. The complexes were characterized by physico-chemical and spectroscopic methods. An octahedral structure has been proposed tentatively for all the complexes. These ruthenium(II) complexes possess N2O2/N2S2 metal binding sites and act as a potential catalyst for the hydrogenation reactions. Organosoluble ruthenium(II) complexes have been used as catalysts in the hydrogenation of methoxy benzene and benzaldehyde. From the results it was observed that all the new six complexes proved to be better catalyst in the hydrogenation. All the ruthenium(II) complexes decomposes completely to form ruthenium metal, which in turn forms a active ruthenium hydride in the hydrogenation reaction. The reusability of the ruthenium catalysts have also been evaluated up to six consecutive runs, which does not show much variation in the conversion of the substrate.

Video eyewear and N2O inhalation sedation in dental fear patients for dental extraction / 实用口腔医学杂志

Objective: To observe the behavior therapy efficacy in dental fear patients for dental extraction using video eyewear and N_2O inhalation. Methods: 100 patients were divided into two groups, one group only used N_2O and other group used N_2O with video eyewear. Compared two groups′ Frankl behavior rating scale and Houpt scale after dental extraction. The HR and SpO_2 were measured during dental extraction. Results: Using video eyewear and N_2O showed a significant good sedative effect on patients with dental fear. There were statistical difference in the Frankl behavior rating scale and Houpt scale between experiment group and control group(P<0.01). There were no significant changes in heat rate and SpO_2 before and after in two groups. Conclusion: Video eyewear and N_2O inhalation sedation is good for dental fear patient during dental extraction.

Equianalgesic Concentration of Fentanyl Comparable to 67% N2O during Propofol Based General Anesthesia / 대한마취과학회지

BACKGROUND: When using a target controlled infusion (TCI) of propofol, combination with N2O or fentanyl as an analgesic adjuvant is common in clinical practice. In a previous study, a minimal steady state plasma concentration necessary to prevent a response in 50% of the patients following a skin incision (Cp50i) for propofol was reduced from 6ng/ml to 4.5ng/ml with 67% nitrous oxide/oxygen compared to air/oxygen. The goal of this study was to quantify the effect site concentration of fentanyl required to replace 67% N2O at a propofol effect site target concentration of 4.5ng/ml. METHODS: Forty six ASA class I or II adult patients scheduled for lower extremity surgery were randomly allocated to one of three groups according to assigned effect site concentration of fentanyl. Group 1, n = 15; 0.5 ng/ml, Group 2, n = 15; 1.0 ng/ml, Group 3, n = 15; 1.5 ng/ml. Patients received propofol with target concentration 4.5ng/ml and predetermined target concentration of fentanyl in three groups. A laryngeal mask airway was placed after anesthesia induction and all patients were controlled ventilation with 67% air/33% oxygen. The response to the skin incision was observed and the patients categorized as movers or non-movers according to Eger's criteria. Cp50i for fentanyl was evaluated using nonlinear regression analysis. RESULTS: Non-movers to skin incision was 20%, 43.7%, 73.7% in groups 1 3 respectively. Cp50i for fentanyl combined with propofol 4.5ng/ml was 1.08 ng/ml. CONCLUSIONS: We concluded that the MAC for 67% N2O is equivalent to an effect site target fentanyl concentration of 1.08 ng/ml in terms of no movement to skin incision.

The Effect of Inhaled Concentration of N2O (Nitrous Oxide) during Emergenceon Awakening Time after Propofol-N2O-O2 Anesthesia / 대한마취과학회지

BACKGROUND: N2O has a unique analgesic effect and reduces the amount of hypnotics for preventing surgical stimuli during maintenance of anesthesia. Also, it was reported that high concentrations of N2O affect level of consciousness. The aim of this study was to evaluate the effect of inhaled concentrations of N2O during emergence on awakening time after propofol-N2O-O2 anesthesia. METHODS: Sixty ASA class I or II patients scheduled for lower extremity surgery were randomly allocated to one of three groups according to inhaled concentration of N2O during emergence. Group 1: 0% N2O (n = 20), group 2: 33% N2O (n = 20) and group 3: 50% N2O (n = 20). Anesthesia was induced and maintained with propofol (Ct: 3.5 6 microgram/ml)-67% N2O-33% O2 and the target concentration of propofol was kept at 4 microgram/ml at least 30 min before the end of infusion of propofol using TCI. At the time of skin closure, we discontinued the propofol, maintained the allocated concentration of N2O and continuously checked vital signs, current/effect concentration of propofol, bispectral index (BIS), and elapsed time until eye opening to verbal contact (awakening time). RESULTS: Awakening time and bispectral index significantly increased as the inhaled concentration of N2O was higher. At awakening time, The predicted current/effect site concentrations of propofol significantly decreased as the inhaled concentrations of N2O were increased. CONCLUSIONS: Continuous inhalation of N2O after discontinuation of propofol infusion significantly delayed the awakening time after propofol-N2O-O2 anesthesia using TCI.

A Suspected Case of Central Anticholinergic Syndrome after N2O-O2-Propofol Anesthesia / 대한마취과학회지

Central anticholinergic syndrome (CAS) is the clinical picture of the central cholinergic blockade. Many drugs used in anesthesia may cause blockade of central cholinergic neurotransmission. Early diagnosis of CAS is very important clinically, CAS's effects are broad and life-threatening. However, it is difficult to find physostigmine in Korea, which is essential to confirm a diagnosis for CAS. An 18-year-old female who was diagnosed with hyperhydrosis underwent a thoracoscopic sympathicotomy. She received N2O-O2-Propofol anesthesia. The anesthesia was unevenful, but postoperatively, she suffered from drowsiness, fever, mydriasis, stiffness of the left upper and lower extremities, and seizures. All tests to seek the cause of CAS such as blood chemistry, brain CT, brain MRI, and CSF test, were normal. She completely recovered without any sequelae after 3 days in ICU. Though it was not confirmed with physostigmine, we report the case to be suspected CAS by all other indications.

The Effects of Nitrous Oxide on Volume and Pressure of Endotracheal Tube Cuffs during General Inhalation Anesthesia / 대한마취과학회지

BACKGROUND: Many studies have demonstrated that nitrous oxide diffuses into the cuffs of endotracheal tubes and increases cuff volumes and pressures. Such increments of cuff pressure maybe result in damage to the trachea. We evaluated the increase of intracuff pressure, volume and the statistical significance was analyzed with personal computer. METHODS: Fourty-nine patients ranging in age 37+/-15 years, in ASA physical status class 1~2 , they were 26 males and 23 females. They divided into two groups, group I(n=25) were anesthesia with nitrous oxide : oxygen (2 L/min : 2 L/min), group II were(n=24) anesthesia with nitrous oxide : oxygen (4 L/min : 2 L/min). The cuff pressure was measured every 30 minutes and compared with each others and group I and II. RESULTS: Our results suggest that a significant intracuff volume and pressure changes developed between two groups (p<0.05), more significant intracuff pressure changes occured at group II than group I (p=0.001) and significant increment changes according to time and different concentration of nitrous oxide between two groups (p<0.05). CONCLUSIONS: This study was conducted to determine the degree of intracuff pressure and volume changes during general inhalation anesthesia with different concentration of nitrous oxide. These results suggest that a nitrous oxide significantly increases cuff pressure and volume in a concentration and time related fashion.

The Effects of Different Oxygen Flow on End-Tidal N2O after Nitrous Oxide/Oxygen Anesthesia / 대한마취과학회지

Nitrous oxide is the most commonly used inhaled anesthetic in the part of anesthesia and used up to 75% of concentrations. Diffusion hypoxia among the disadvantages or harmful damages due to nitrous oxide exposure must be prevented by moderate flow (4-6 liters/minute) of oxygen for a few minutes. This study was investigated the effect of the amount of oxygen flow on the speed of removal of exposed nitrous oxide followed by oxygen flow rate of 2, 4, and 6 liters/minute when halted the administration of nitrous oxide. These variables were taken in 57 patients of 16 to 60 years old, who were performed the elective surgery. All patients were anesthetized with the 0.5-1.5 MAC of enflurane or isoflurane combined with nitrous oxide(2 liters/minute) and oxygen(2 liters/minute), and paralyzed with IV route pancuronium 0.07-0.08 mg/kg. Ventilation was controlled with Ohmeda 7000 ventilator (BOC Health Care Inc, Madison, USA), using a constant tidal volume of 10 ml/Kg of ideal body weight. Ventilatory rate was adjusted 12 times/minute to maintain the end-tidal CO2 of 20-35 mmHg. After 60 to 90 minutes of anesthesia, the nitrous oxide/oxygen mixture was changed to 100% oxygen, but ventilation being held constant. The results were as follows; 1) After the first 30 seconds, the end-tidal nitrous oxide concentration was 39.6+/-+3.7% in 2 liters/minute of oxygen flow, 28.2+/-5% in 4 liters/minute and 23.4+/-6.3% in 6 liters/minute. 2) After the 2 minutes, the end-tidal nitrous oxide concentration was 29.1+/-3.6% in 2 liters/minute of oxygen flow, 14.4+/-3.2% in 4 liters/minute and 10.13+/-2% in 6 liters/minute. 3) After the 5 minutes and 30 seconds, the end-tidal nitrous oxide concentration was 16.4+/-3.3% in 2 liters/minute of oxygen flow, 5.5+/-1.9% in 4 liters/minute and 4.0+/-1.7% in 6 liters/minute. 4) After 15 minutes, the end tidal nitrous oxide was 7.5+/-2.1% in 2 liters/minute of oxygen flow, 2.3+/-0.7% in 4 liters/minute and 2.0+/-0.8% in 6 liters/minute. In conclusion, the larger size of oxygen flow, the more rapid elimination of nitrous oxide. The removal rate of nitrous oxide was greatest at first 30 seconds after halting the nitrous oxide administration in all cases.

The Effects of N2O on the Changes in the Cuff Pressure of the Laryngeal Mask Airway during General Inhalation Anesthesia / 대한마취과학회지

The laryngeal mask airway(LMA) is an alternative to tracheal intubation, especially in out-patient surgery or securing emergency airway. Several studies show that N2O diffuses into the cuffs of endotracheal tubes and increases the cuff pressures. Because LMA also has an air-filling cuff, the cuff pressure of LMA may be increased during general anesthesia with N2O. The purpose of this study was to evaluate the effects of LMA on the changes in the cuff pressure of the LMA during general inhalation anesthesia. In this study, we measured the cuff pressure of LMA after administration of 0%(group A), 50%6(group B), 60%(group C) or 66.7%o(group D) N2O with the air-inflated cuffs, and also measured the cuff pressure of LMA after administration of 66.7% N2O(group E) with the 66.7% N2O-inflated cuffs during general inhalation anesthesia. In group A, there was no significant cuff pressure change throughout the study period. In group B, C and D, the cuff pressures gradually increased as time elapsed and the more increased the concentration of N2O, the more increased the cuff pressures. In group E, the cuff pressure abruptly decreased until the first five minute, but recovered gradually and slightly increased than the baseline value for the rest of the measurement period. These findings demonstrate that N2O administration during general inhalation anesthesia significantly increases the cuff pressure of LMA in a concentration- and time-related fashion with the air-inflated cuffs but not with the N2O-inflated cuffs, and suggest that such increases may result in ischemia on cuff-related laryngeal area, and N2O-inflated cuffs may prevent increasing the cuff pressure of LMA.

Arterial Oxygen Tension Measurements during Nitrous Oxide - Oxygen Anesthesia / 대한마취과학회지

In 30 ASA class I patients aged 15-30 undergoing peripheral operations, PaO2 and SaO2 were determined while the mixture of nitrous oxide and oxygen was administered at the inspired oxygen concentration of 21%. Anesthesia was maintained with 75% or so nitrous oxide and small dose fentanyl, and ventilation was adjusted to maintain normoventilation with tidal volume increased to 15 ml/kg. PaO2 and SaO2 during anesthesia were increased significantly when compared to those which were measured immediately prior to anesthetic induction, that is to say, no one developed hypoxemia despite administration of the same inspired oxygen concentration as that of room air. These results indicate that, in case rapid emergence from anesthesia is required, balanced anesthesia with high concentration nitrous oxide and small dose fentanyl should be very useful and safe so long as we make good selections of patients and deliver large tidal volumes to them during artificial ventilation.

Changes of Mean Arterial Pressure, Intracranial Pressure, Blood Gas and Serum Electrolytes during N2O - Halothane Anesthesia in Rabbits / 대한마취과학회지

This experiment was undertaken to study the effects of different ratios of N2O-O2 in N2O- halothane anesthetized rabbits weighing about 4-4.5 Kg. The N2O-O2 ratios were 2:1 (group 1), 3:1 (group 2) and 4:1 (group 3). We measured the mean arterial pressure, intracranial pressure and cerebral pressure and analysed the blood gas and electrolytes in each group and compared each group to the other two. The results are summarized as follow; The mean arterial pressure was 101.7+/-14.6, 92.7+/-11.0 and 89.4+/-15.1mmHg in each group respectively. The mean arterial pressure of the group 3 decreased more significantly than that of group 1. The intracranial pressure was 12.7+/-4.3, 11.8+/-4.2 and 13.6+/-4.6mmHg in each group respectively and was non-significant as compared to other groups. The cerebral perfusion pressure was 90.8+/-13.3, 82.6+/-9.9 and 76.9+/-16.9mmHg in each group respectively and the cerebral perfusion pressure of group 3 decreased more significantly than that of group l. In the blood gas analysis, PaQ2 was 162+/-27, 119+/-13 and 105+/-8 mmHg in each group respectively and was non-significant in respect to other groups. PaCO2 and O2 content were not different significantly in each group and were within normal values. The oxygen saturation was 98.9+/-0.3, 97.8+/-0.4 and 97.6+/-1.1% in each group respectively and group 2 and 3 decreased more significantly than group 1. Na+, Cl-, HCO-(3), pH and BE were not different significantly in each group, pH, BE and HCO-(3) were measured as being slightly low values, but PaCO2 was kept within normal values. These are explained as probably being due to metabolic acidosis. The serum K' was 2.94+/-0.46, 3.07+/-0.44 and 3.40+/-0.7 mEq/1 in each group respectively and the serum K+ of group 3 increased more significantly than groups 1 and 2. With these results, it is suggested that a ratio above a 2:1 ratio of N2O-O2 is more dangerous in halothane-N2O anesthesia.