Diffusion Of Nitrous Oxide Research Articles

Inhalation anesthesia in the cat: Development of cuff pressure when using nitrous oxide

During inhalation anesthesia with nitrous oxide in oxygen the pressure in the cuff of the endotracheal tube may increase due to diffusion of nitrous oxide into the cuff. The aim of the study was to investigate the development of cuff pressure during nitrous oxide anesthesia under clinical conditions in feline patients and to identify possible influencing factors such as tube size and gas flow rate. The prospective study included cats scheduled for inhalation anesthesia with nitrous oxide for a minimum duration of 60 minutes at the Department for Small Animals of the University of Leipzig. Cuff pressure was adjusted with a cuff manometer and its development was recorded. In total, the cuff pressure values of 24 cats were recorded. Animals were allocated into groups by tube size (ID 4.0 mm and ID 4.5 mm) and by fresh gas flow rate: low flow rate (0.6 l/min) and high flow rate (3 l/min). During anesthesia, cuff pressure increased over time, with statistical significance occurring from 45 minutes onwards in comparison to the initial cuff pressure (p=0.005). After 60 minutes, there was a mean cuff pressure increase of 3 cmH2O. Despite this moderate mean increase, highly variable pressure values up to 48 cmH2O in individual animals were recorded. No cat reached the termination criterion of 60 cmH2O cuff pressure. Effects of tube size (p=0.63) and flow rate (p=0.334) on the cuff pressure were not evident. After a period of 45 minutes of nitrous oxide administration, a significant increase in cuff pressure occurs in the cat. However, tube size and total gas flow rate do not seem to influence the cuff pressure development. When using nitrous oxide during inhalation anesthesia, regular cuff pressure evaluation and correction are necessary and hence recommended in feline patients. As individual pressure changes may be highly variable, no fixed recommendations for optimal management are possible.

Entropy Generation and Exergy Assessment of Methane–Nitrous Oxide Diffusion Flames in a Triple-Port Burner

A triple-port burner was used in this study, and a numerical simulation was employed to investigate the entropy generation rate of CH4–N2O diffusion flames at the R ratio = 1 . Here, R ratio refers to the ratio of the oxidizer flow velocity to the fuel flow velocity. In order to scrutinize the decomposition effect of N2O on entropy generation, an oxygen-enriched gas with the same nitrogen to oxygen ratio as N2O (N-to- O = 2 ) was used in CH4–N2–O2 diffusion flames. Besides, because the N2O could decompose into the oxygen-enriched gas, the oxygen-enriched effect was also studied by the CH4–air diffusion flames that were conducted in this research. The entropy generation rate comprises of three items in this study, including heat conduction, mass diffusion, and chemical reaction. As a result, the different reaction pathways would take part in the major reaction pathway in CH4–N2O diffusion flames, causing more entropy generation rate being produced through the more intense reactions in CH4–N2O diffusion flames. The irreversibility in CH4–air diffusion flames are dominated through heat conduction and chemical reaction, which is an identical result in CH4–N2–O2 diffusion flames. However, in CH4–N2O diffusion flames, chemical reactions dominated the irreversibility because of the more intense reaction caused by the thermal effect of N2O decomposition. As a result, the decomposition effect of N2O influences the availability of CH4–N2O diffusion flames.

Microcosm Study with Continuous Dynamic Monitoring of Nitrous Oxide Diffusion and Reduction in Agricultural Soil at Variable Moisture

Microcosm Study with Continuous Dynamic Monitoring of Nitrous Oxide Diffusion and Reduction in Agricultural Soil at Variable Moisture

Effect of diffusion of anaesthetic gases on fibre-optic view change of laryngeal mask airway and post-operative laryngo-pharyngeal morbidity in children - A randomised controlled trial.

Background and Aims:The diffusion of nitrous oxide (N2O) into the air-filled cuff of the classic laryngeal mask airway (LMA) may lead to an increase in cuff pressure (CP) and displacement of LMA affecting its performance. This study was conducted to evaluate the change in optimal position of LMA by fibre-optic bronchoscope, the changes in cuff pressure and oropharyngeal leak pressure (OLP), and post-operative laryngo-pharyngeal morbidity during N2O–oxygen (O2) anaesthesia in children.Methods:After ethics committee approval and written informed consent, 84 children, aged 2 to 8 years undergoing lower abdominal surgery using LMA were included. Anaesthesia was induced with sevoflurane and maintained with either 33% O2 in air (Group 1) or with 33% O2 in 67% N2O (Group 2) along with sevoflurane. The position of LMA using fibre-optic bronchoscope, CP and OLP were recorded at 30, 60 and 90 minutes and at the end of surgery. The incidence of post-operative sore throat, hoarseness of voice and dysphagia was assessed for 24 hours.Results:A mild (Grade 1) change in fibre-optic position of LMA was observed in 6 out of 42 children maintained with N2O–O2 anaesthesia. The cuff pressure was higher than baseline in group 2 at all three time points with the maximum at 90 minutes (93.23 ± 14.86 cm H2O vs. 39.78 ± 7.75 cm H2O; P < 0.05). The OLP was comparable between the groups during the initial 60 minutes and then increased in group 2. The incidence of post-operative sore throat was significantly higher in group 2 (P = 0.008).Conclusion:The diffusion of anaesthetic gases into the air-filled cuff does not change the fibre-optic position of the LMA significantly but increases the cuff pressure and incidence of post-operative laryngo-pharyngeal complications in children.

Changing Diffusion–Convection Modes in Ternary Mixtures with a Diluent Gas

The characteristic features of the diffusion of helium and nitrous oxide diluted by propane to the same extent are experimentally studied at different pressures and concentrations of the diluent gas in the mixture. It is found that, at a certain pressure, convection currents appear in the system which intensify the partial mass transfer, which uncommon for diffusion. An increase in pressure intensifies the mixing of the components of the mixture. An increase in the concentration of the diluent gas in the mixture leads to the stabilization of convection modes. Solving diffusion equations shows that, in systems with a ballast gas, conditions for the nonlinear distribution of the concentrations of the components of the mixture along the length of the channel are implemented which can lead to the appearance of an extremum of the density of the mixture (i.e., inversion of the density gradient of the mixture), which induces the appearance of convection currents. The stability of the mechanical equilibrium of the ternary mixture in a vertical cylindrical channel under the action of gravity and at the predefined concentration gradients of the components is numerically studied. The boundary of the diffusion–convection kinetic transition is determined. The experimental and numerical results are compared in the coordinates of the Rayleigh number and pressure.

Diffusive flux of CH4 and N2O from agricultural river networks: Regression tree and importance analysis

River networks in subtropical agricultural hilly region become an inconvenient greenhouse gas (GHG, methane and nitrous oxide) source because of the influence of human activities, which has caused large uncertainties for refinement of national GHG inventories and their global budget. Based on field monitoring experiments at high temporal resolution, we employed regression tree and importance analysis to identify quantitatively factors that influence the diffusive flux of GHGs to provide a scientific basis for reducing GHG emissions and controlling regional carbon and nitrogen losses. The results indicate that significant spatiotemporal variation of methane (CH4) nitrous oxide (N2O) diffusion occurs in all the four reaches (W1, W2, W3 and W4) of Tuojia river networks. Among them, W1 contributed lowest CH4 (22.55 μg C m−2 h−1) and N2O (5.00 μg N m−2 h−1) diffusive flux than the other three (P < 0.05), while W4 offered highest CH4 (166.15 μg C m−2 h−1) and N2O (30.47 μg N m−2 h−1) diffusive flux but with no statistically significant difference between W2 and W3 due to homogeneous extraneous nutrition loading into the two reaches. W4 also contributed largest cumulative flux of CH4 (14.55 kg C ha−1 yr−1) and N2O (2.69 kg N ha−1 yr−1) in Tuojia River networks (P < 0.05). Furthermore, the regression tree and importance analysis indicate that, in the anaerobic environment, dissolved oxygen saturation controlled the production and diffusion for both CH4 and N2O. The findings of this investigation highlighted that decision support tools provide an effective pathway to enhance the GHG mitigation technology research in agroecosystems and simultaneously shed light on the global campaign on refinement of national GHG inventories as well as regional nutrient management.

Accidental endotracheal tube migration following diffusion of nitrous oxide in mastoid surgery

Accidental endotracheal tube migration following diffusion of nitrous oxide in mastoid surgery

Density Effects on Soil‐Water Characteristics, Soil‐Gas Diffusivity, and Emissions of N2O and N2 from a Re‐packed Pasture Soil

Core Ideas A predictive gas diffusivity model for undisturbed soils was modified for sieved‐repacked pasture soils. Density‐induced changes in soil physical attributes along with gaseous fluxes help identify N2O mitigation. Maintaining well‐aerated conditions and a soil‐gas diffusivity of &gt;0.038 may be a mechanism for keeping N2O and N2 fluxes low. Density‐induced soil structural changes may potentially alter both soil total porosity and soil pore size distribution, and thus change the soil's water retention characteristics, gas diffusion and transport properties, and subsequent greenhouse emissions. In this study, we characterized and parameterized water retention, pore size distribution, gas diffusivity and cumulative emissions of nitrous oxide (N2O) and nitrogen (N2) fluxes in a differently compacted silt‐loam sampled from a grazed pasture in Lincoln, New Zealand. The soils used for the simulations were subjected to five different density treatments (1.1, 1.2, 1.3. 1.4, 1.5 Mg m−3), subsequently saturated and successively drained to 11 matric potentials at which water retention, gas diffusivity and flux measurements were performed. Results show strong correlations between best‐fit soil‐water characteristic parameters and the density levels. A recent predictive gas diffusivity model developed for undisturbed soils was modified to better characterize the measured gas diffusivity data in sieved‐repacked pasture soils. Further, two exponential and linear parametric models were developed to adequately parameterize the observed fingerprints of cumulative (35‐d) N2O and N2 fluxes, respectively. Results clearly distinguished the density‐induced changes in pore structure, pore size distribution, gas diffusivity and emission of gas fluxes and hence provide useful implications for pasture management to reduce future emission of greenhouse gases. Results particularly highlighted the importance of ensuring a diffusivity ≥0.038 to limit extensive emission of N2O and N2 fluxes. The improved parametric models and parameter correlations provide valuable numerical insight to better characterize density‐dependent behavior in soil physical properties and functions.

K-Y\u2122 jelly inhibits increase in endotracheal tube cuff pressure during nitrous oxide exposure in vitro

BackgroundThe increase in endotracheal tube cuff pressure due to nitrous oxide diffusion is a well-known risk during general anesthesia using nitrous oxide. We hypothesized that lubricating endotracheal tube cuffs with K-Y™ Jelly might inhibit the increase in cuff pressure that occurs during exposure to nitrous oxide.MethodsWe used two types of endotracheal tube cuffs: one made from ultrathin polyurethane (PU) and another made from conventional polyvinyl chloride (PVC). Using a pediatric trachea model, which consisted of an acrylic cylinder with an internal diameter of 12 mm, we measured changes in the cuff pressure during nitrous oxide exposure in size 5.0-mm internal diameter endotracheal tubes with each type of cuff, with and without lubrication with K-Y™ Jelly.ResultsDuring nitrous oxide exposure, the increase in cuff pressure was significantly lower in the lubricated cuffs than in the non-lubricated cuffs in both types of cuffs (PVC, P < 0.0001; PU, P < 0.0001). However, the cuff compliance in the trachea model was unaffected by lubrication in both types of cuffs.ConclusionsLubrication of endotracheal tube cuffs with K-Y™ Jelly may effectively delay the increase in cuff pressure that occurs during general anesthesia using nitrous oxide.

Soil concentration profiles and diffusion and emission of nitrous oxide influenced by the application of biochar in a rice-wheat annual rotation system.

Field experiments were carried out to determine biochar effects on nitrous oxide (N2O) concentration profiles, diffusion, and emissions in paddy soil under rice-wheat annual rotation in southeastern China. An in situ soil gas device was adapted to measure N2O concentrations at depths of 7, 15, 30, and 50cm. Five treatments were installed as N0B0, N0B1, N1B0, N1B1, and N1B2 (B0, B1, and B2 designated as biochar at 0, 20, and 40tha(-1), respectively, while N0 and N1 as nitrogen at 0 and 250kgNha(-1) crop(-1), respectively). The results showed that N2O concentrations were higher in the 15 and 30cm depths than other depths. With positive diffusive fluxes, the 7cm in the rice season and 15cm in the wheat season were main production sites. The surface N2O emissions and topsoil diffusive fluxes showed good agreement. N application strongly increased soil N2O profiles and surface emissions. Relative to N1B0, N1B1 decreased N2O concentration, surface emissions, and diffusive fluxes by 25.2, 31.8, and 26.5%, respectively, while N1B2 decreased them averagely by 40.7, 43.2, and 44.2%, correspondingly. Therefore, the gas gradient method is effective for estimating N2O emissions, and biochar can decrease N2O production when N was applied.

Intracuff pressures in ProSeal and Supreme airways

AnaesthesiaVolume 69, Issue 2 p. 183-183 CorrespondenceFree Access Intracuff pressures in ProSeal and Supreme airways A. Philip, A. Philip [email protected] Leicester Royal Infirmary, Leicester, UKSearch for more papers by this authorV. Kaushik, V. Kaushik Leicester Royal Infirmary, Leicester, UKSearch for more papers by this authorM. Mushambi, M. Mushambi Leicester Royal Infirmary, Leicester, UKSearch for more papers by this author A. Philip, A. Philip [email protected] Leicester Royal Infirmary, Leicester, UKSearch for more papers by this authorV. Kaushik, V. Kaushik Leicester Royal Infirmary, Leicester, UKSearch for more papers by this authorM. Mushambi, M. Mushambi Leicester Royal Infirmary, Leicester, UKSearch for more papers by this author First published: 20 January 2014 https://doi.org/10.1111/anae.12569Citations: 1 No external funding and no competing interests declared. Previously posted on the Anaesthesia correspondence website: www.anaesthesiacorrespondence.com. AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat We read with interest the article by Anand et al. 1 comparing intracuff pressures between the ProSeal® and Supreme® laryngeal mask airways (LMAs) and should like the authors to clarify some issues that are not clear in their article: Did the authors standardise tidal volumes and peak airway pressures for all their patients? The authors mention that the initial intracuff readings were 60 cmH20 in both groups. Were the cuffs intentionally inflated to that value? If so, the authors chose to inflate the cuffs to the upper limit of the manufacturers' recommendations, which is usually unnecessary since an adequate seal can be achieved at lower cuff pressures. Silicone cuff-based ProSeal LMAs are re-used after sterilisation. Did the authors factor this into their standardisation, i.e. a ProSeal LMA that has been sterilised 30 times will presumably allow more diffusion of nitrous oxide than one that has been sterilised, say, 10 times or less? In Zhang et al.'s study 2, referred to by Anand and colleagues in their study, oropharyngeal leak pressure was determined by closing the expiratory valve at a fixed gas flow of 3 l.min−1 and noting the pressure in the circuit at which an audible leak is heard over the mouth. It is not clear how Anand et al. checked the oropharyngeal leak pressure; was it using a similar method? Anand et al. recommend that cuff pressure should be monitored when ProSeal LMAs are used during general anaesthesia involving nitrous oxide. Recommendations to monitor cuff pressures in LMAs should apply to all LMAs, and not just to ProSeal LMAs. References 1Anand LK, Singh M, Kapoor D, Goel N. Intracuff pressure comparison between ProSeal® and Supreme® laryngeal mask airways. Anaesthesia 2013; 68: 1202– 3. 2Zhang L, Seet E, Mehta V, et al. Oropharyngeal leak pressure with the laryngeal mask airway supreme™ at different intracuff pressures: a randomized controlled trial. Canadian Journal of Anesthesia 2011; 58: 624– 9. Citing Literature Volume69, Issue2February 2014Pages 183-183 ReferencesRelatedInformation

Diffusion of nitrous oxide through endotracheal tube cuffs

Nakamura, Y.; Fujiwara, S.; Tsukamoto, M.; Sakamoto, E.; Yokoyama, T. Author Information

ProSeal TM laryngeal mask airway cuff pressure changes with and without use of nitrous oxide during laparoscopic surgery

Background:The ProSeal™ laryngeal mask (PLMA) is increasingly being used as an airway device for laparoscopic surgery. Its silicone cuff allows diffusion of nitrous oxide, carbon dioxide and other gases with resultant rise in its intracuff pressure during anesthesia. The present study was designed to investigate the intracuff pressure changes during anesthesia with and without nitrous oxide in patients undergoing laparoscopic surgery lasting up to two hours.Materials and Methods:One hundred patients, American Society of Anesthesiologists physical status 2 and 3, undergoing general anesthesia with muscle paralysis, were randomized into two groups of 50 patients each to receive an anesthetic gas mixture containing either oxygen and nitrous oxide (group N) or oxygen and air (group A). Following insertion of an appropriate size PLMA, its cuff was inflated with air to an intracuff pressure of 45 mm Hg. The cuff pressure was measured every 10 minutes for the entire course of anesthesia. The position of the device was also assessed fiberoptically and postoperative airway complications were recorded.Results:The maximum intracuff pressure recorded in group N was 103 ± 4.7 mm Hg vs. 45.5 ± 1.5 mm Hg in group A. The percentage rise in cuff pressure every 10 minutes was also highly significant (P < 0.001) being maximum in first 10 min in group N. The incidence of postoperative airway complications was comparable between the two groups.Conclusion:The results of this study demonstrate that the intracuff pressure of the PLMA increases progressively over time when the breathing gas mixture contains nitrous oxide.

Measurements and Correlations of Diffusivities of Nitrous Oxide and Carbon Dioxide in Monoethanolamine + Water by Laminar Liquid Jet

The molecular diffusivities of nitrous oxide (N2O) with aqueous monoethanolamine (MEA) solutions up to 12 M were studied over a temperature range from 298.15 to 333.15 K under atmospheric pressure using a laminar liquid jet absorber. The diffusivities of CO2 in aqueous MEA solutions were calculated by the “N2O analogy” method. A simple and effective thermal control technique was used to control the temperatures of gas and liquid in the laminar liquid jet absorber. The rates of absorption were determined by measuring the flow of gas needed to replace the gas absorbed. The results showed that the diffusivities of both N2O and CO2 into aqueous MEA solution decrease with the increase of the concentration of MEA, and increase with an increase of the temperature of the solution. The relationship between the diffusivity and the viscosity of the solution roughly agrees with the modified Stokes–Einstein equation, but an exponent mathematical model was employed to simulate the diffusivity data and shows a better ag...

Solubility and Diffusivity of N2O in Aqueous 4-(Diethylamino)-2-butanol Solutions for Use in Postcombustion CO2 Capture

In this work, the solubility and diffusivity of nitrous oxide (N2O) in aqueous 4-(diethylamino)-2-butanol (DEAB) solutions were measured. Solubility was measured in a stirred cell reactor over the temperature range of 298–343 K and concentration range of 0.68–3.77 M. On the other hand, diffusivity was measured in a laminar jet absorber over the temperature range of 298–318 K and concentration range of 1.0–2.5 M. An attempt was made to correlate the solubility data with well-known models (semiempirical model, Redlich–Kister equation, and polynomial model). It was observed that only the polynomial model correlated the solubility of N2O in aqueous DEAB solution satisfactorily with an AAD of 0.1%. Similarly, an attempt was made to correlate the diffusivity data with well-known models (semiempirical model and modified Stokes–Einstein model). The semiempirical model provided better predicted N2O diffusivity data compared with the experimental data with an AAD of 3.4%. These data can then be used to determine th...

Upward diffusion of nitrous oxide produced by denitrification near shallow groundwater table in the summer: a lysimeter experiment

Movement of nitrous oxide (N2O) produced in subsoil and shallow groundwater is important in determining the direct and indirect N2O emissions from agricultural soils. From the results of our previous study in a lysimeter-contained Gray lowland soil in the summer, we hypothesized that if a large amount of N2O is produced near shallow groundwater table in the summer, it will diffuse upward to the atmosphere. To examine this hypothesis, we conducted a one-year experiment in the same lysimeters for the cultivation of soybean–wheat double cropping (SW) or upland rice (UR). Dissolved N2O concentration in the drainage water in the UR plots exceeded 0.4 mg N L−1 in the summer, whereas that in the SW plots remained <0.1 mg N L−1. Analyses of the concentrations of nitrate and dissolved N2O in the drainage water and their nitrogen and oxygen isotopic compositions (δ15N and δ18O) during the summer revealed that denitrification was the main process for the N2O production near the groundwater table. There was a significant positive correlation between the dissolved N2O concentration and soil-surface N2O flux in the summer. Calculated upward diffusive N2O fluxes at three soil depths by Fick's law also supported our hypothesis. The δ15N values of N2O in the soil-surface flux were similar to those in the shallow groundwater in the UR plots during the summer. Such similarity was not found in the SW plots. We conclude that our hypothesis was confirmed by the above results. Comparison of the monitored data with other seasons indicates that low soil water content was a driving force for the upward N2O diffusion as well as the high dissolved N2O concentration.

Nitrous Oxide Diffusion and the Second Gas Effect on Emergence from Anesthesia

Rapid elimination of nitrous oxide from the lungs at the end of inhalational anesthesia dilutes alveolar oxygen, producing "diffusion hypoxia." A similar dilutional effect on accompanying volatile anesthetic agent has not been evaluated and may impact the speed of emergence. Twenty patients undergoing surgery were randomly assigned to receive an anesthetic maintenance gas mixture of sevoflurane adjusted to bispectral index, in air-oxygen (control group) versus a 2:1 mixture of nitrous oxide-oxygen (nitrous oxide group). After surgery, baseline arterial and tidal gas samples were taken. Patients were ventilated with oxygen, and arterial and tidal gas sampling was repeated at 2 and 5 min. Arterial sampling was repeated 30 min after surgery. Sevoflurane partial pressure was measured in blood by the double headspace equilibration technique and in tidal gas using a calibrated infrared gas analyzer. Time to eye opening and time extubation were recorded. The primary endpoint was the reduction in sevoflurane partial pressures in blood at 2 and 5 min. Relative to baseline, arterial sevoflurane partial pressure was 39% higher at 5 min in the control group (P < 0.04) versus the nitrous oxide group. At 30 min the difference was not statistically significant. Time to eye opening (8.7 vs. 10.1 min) and time to extubation (11.0 vs.13.2 min) were shorter in the nitrous oxide group versus the control group (P < 0.04). Elimination of nitrous oxide at the end of anesthesia produces a clinically significant acceleration in the reduction of concentrations of the accompanying volatile agents, contributing to the speed of emergence observed after inhalational nitrous oxide anesthetic.

Inability to ventilate while using a silicone-based endotracheal tube

We present a complication associated with herniation of a specially designed silicone-based endotracheal tube (ETT) cuff used for laryngeal nerve monitoring (electromyographic [EMG] ETT). Lung ventilation in our patient was initially unimpeded. However, 30 minutes after initiation of anesthesia with desflurane and nitrous oxide, there was a sudden inability to ventilate due to the herniation of the ETT cuff presumably caused by diffusion of nitrous oxide into the silicone-based cuff. In vitro testing has shown that the increase in intracuff pressure during ventilation with nitrous oxide in the silicone-based EMG ETT is much greater (approximately 50 mmHg) than that in the polyvinyl chloride–based ETT (approximately 10 mmHg) routinely used in our department.

Visual Loss Following Intraocular Gas Injection

The range of indications for vitreoretinal surgery has widened in recent years, and intraocular gas application is frequently performed as part of retinal surgery, with the aim of achieving long-acting tamponade. Selective literature review. An intraocular gas bubble containing perfluoropropane (C(3)F(8)) or sulfur hexafluoride (SF(6)) can expand during anesthesia due to nitrous oxide diffusion and cause retinal ischemia and postoperative blindness. A decrease in atmospheric pressure associated with travel to high altitude can have the same effect. Case reports suggest that, considering physical properties of these gases and ocular physiology, patients remain at risk for at least three months after intraocular gas application. Both doctors and patients need to be well informed about the hazards of intraocular gas application as good communication may prevent complications. If in doubt, the anesthesiologist should avoid nitrous oxide, in particular in the unconscious patient.

The Effects of the Alkalinization of Intracuff Lidocaine after Nitrous Oxide Anesthesia

Background: Diffusion of nitrous oxide into the cuff of the endotracheal tube (ETT) results in an increase in cuff pressure. This method was used to test whether tracheal morbidity is related to fill the cuff of the endotracheal tube with alkalinized lidocaine instead of air or lidocaine only. Methods: Adult patients scheduled for total thyroidectomy surgery were randomly enrolled (n = 30 for each group). The ETT cuff was filled with air 6 ml (Group C), with 2% lidocaine 6 ml (Group L), or with alkalinized lidocaine (4 ml or 2 ml of 2% lidocaine) using 2 ml (Group A) or 4 ml (Group B) of 8.4% NaHCO3. After tracheal extubation, sore throat was evaluated by visual analog scale as the main end-point of the study. Results: Compared with group air or lidocaine only, the alkalinized-lidocaine groups had a significant reduction in sore throat during the 24-h postoperative period (P ＜ 0.001). The difference was not significant between the two alkalinized lidocaine groups. Cough before tracheal extubation, nausea, postoperative vomiting, dysphonia, and hoarseness after extubation were decreased in the alkalinized-lidocaine groups compared with Group C and L, and a better tolerance was recorded with alkalinized-lidocaine groups compared with Group C and L. Conclusions: We concluded that use of intracuff alkalinized lidocaine is an effective adjunct to endotracheal intubation instead of air or lidocaine only during nitrous oxide anesthesia, however there were no differences between two alkalinizations. (Korean J Anesthesiol 2008; 54: 384∼8)