Efeitos do óxido nitroso em hipotensão controlada durante anestesia com baixo fluxo / The effects of nitrous oxide on controlled hypotension during low flow anesthesia / Efectos del óxido nitroso en la hipotensión controlada durante la anestesia con bajo flujo

JUSTIFICATIVA E OBJETIVOS: Investigamos o efeito do óxido nitroso (N2O) em hipotensão controlada durante anestesia com baixo fluxo (isoflurano-dexmedetomidina) em termos de hemodinâmica, consumo de anestésico e custos. MÉTODOS: Quarenta pacientes foram randomicamente alocados em dois grupos. Infusão de dexmedetomidina (0,1 µg.kg-1.min-1) foi mantida por 10 minutos. Subsequentemente, essa infusão foi mantida até os últimos 30 minutos de operação a uma dose de 0,7 µg.kg-1.hora-1. Tiopental (4-6 mg.kg-1) e brometo de vecurônio (0,08 0,12 mg.kg-1) foram administrados na indução de ambos os grupos. Isoflurano (2%) foi administrado para manutenção da anestesia. O Grupo N recebeu uma mistura de 50% de O2-N2O e o Grupo A recebeu uma mistura de 50% de O2-ar como gás de transporte. Anestesia com baixo fluxo (1 L.min-1) foi iniciada após um período de 10 minutos de alto fluxo inicial (4,4 L.min-1). Os valores de pressão arterial, frequência cardíaca, saturação periférica de O2, isoflurano inspiratório e expiratório, O2 inspiratório e expiratório, N2O inspiratório e expiratório, CO2 inspiratório, concentração de CO2 após expiração e concentração alveolar mínima foram registrados. Além disso, as taxas de consumo total de fentanil, dexmedetomidina e isoflurano, bem como de hemorragia, foram determinadas. RESULTADOS: A frequência cardíaca diminuiu em ambos os grupos após a carga de dexmedetomidina. Após a intubação, os valores do Grupo A foram maiores nos minutos um, três, cinco, 10 e 15. Após a intubação, os valores de hipotensão desejados foram alcançados em 5 minutos no Grupo N e em 20 minutos no grupo A. Os valores da CAM foram mais altos no Grupo N nos minutos um, três, cinco, 10 e 15 (p < 0,05). Os valores da FiO2 foram mais altos entre 5 e 60 minutos no Grupo A, enquanto foram mais altos no Grupo N aos 90 minutos (p < 0,05). Os valores de Fi Iso (isoflurano inspiratório) foram menores no Grupo N nos minutos 15 e 30 (p < 0,05). CONCLUSÃO: O uso de dexmedetomidina em vez de óxido nitroso em anestesia com isoflurano pela técnica de baixo fluxo atingiu os níveis desejados de pressão arterial média (PAM), profundidade suficiente da anestesia, estabilidade hemodinâmica e parâmetros de inspiração seguros. A infusão de dexmedetomidina com oxigênio-ar medicinal como gás de transporte é uma técnica anestésica opcional.

BACKGROUND AND OBJECTIVES: We investigated the effect of Nitrous Oxide (N2O) on controlled hypotension in low-flow isoflurane-dexmedetomidine anesthesia in terms of hemodynamics, anesthetic consumption, and costs. METHODS: We allocated forty patients randomly into two equal groups. We then maintained dexmedetomidine infusion (0.1 µg.kg-1.min-1) for 10 minutes. Next, we continued it until the last 30 minutes of the operation at a dose of 0.7 µg.kg-1.hour-1. We administered thiopental (4-6 mg. kg-1) and 0.08-0.12 mg.kg-1 vecuronium bromide at induction for both groups. We used isoflurane (2%) for anesthesia maintenance. Group N received a 50% O2-N2O mixture and Group A received 50% O2-air mixture as carrier gas. We started low-flow anesthesia (1 L.min-1) after a 10-minute period of initial high flow (4.4 L.min-1). We recorded values for blood pressure, heart rate, peripheral O2 saturation, inspiratory isoflurane, expiratory isoflurane, inspiratory O2, expiratory O2, inspiratory N2O, expiratory N2O, inspiratory CO2, CO2 concentration after expiration, Minimum Alveolar Concentration. In addition, we determined the total consumption rate of fentanyl, dexmedetomidine and isoflurane as well as bleeding. RESULTS: In each group the heart rate decreased after dexmedetomidine loading. After intubation, values were higher for Group A at one, three, five, 10, and 15 minutes. After intubation, the patients reached desired hypotension values at minute five for Group N and at minute 20 for group A. MAC values were higher for Group N at minute one, three, five, 10, and 15 (p < 0.05). FiO2 values were high between minute five and 60 for Group A, while at minute 90 Group N values were higher (p < 0.05). Fi Iso (inspiratuvar isofluran) values were lower in Group N at minute 15 and 30 (p < 0.05). CONCLUSION: By using dexmedetomidine instead of nitrous oxide in low flow isoflurane anesthesia, we attained desired MAP levels, sufficient anesthesia depth, hemodynamic stability and safe inspiration parameters. Dexmedetomidine infusion with medical air-oxygen as a carrier gas represents an alternative anesthetic technique.

JUSTIFICATIVA Y OBJETIVOS: Investigamos el efecto del óxido nitroso (N2O) en hipotensión controlada durante anestesia con bajo flujo (isoflurano-dexmedetomidina) en términos de hemodinámica, consumo de anestésico y costes. MÉTODOS: Cuarenta pacientes fueron aleatoriamente divididos en dos grupos iguales. La infusión de dexmedetomidina (0,1 µg.kg-1.min-1) se mantuvo entonces por 10 minutos. En secuencia, esa infusión se mantuvo hasta los últimos 30 minutos de operación en una dosis de 0,7 µg.kg-1.hour-1. El tiopental (4-6 mg.kg-1) y el bromuro de vecuronio (0,08 0,12 mg.kg-1) fueron administrados en la inducción de ambos grupos. El Isofluorano (2%) fue administrado para el mantenimiento de la anestesia. El Grupo N recibió una mezcla de un 50% de O2-N2O y el Grupo A recibió una mezcla de un 50% de O2-ar como gas de transporte. La anestesia con bajo flujo (1 L.min-1) fue iniciada después de un período de 10 minutos de alto flujo inicial (4,4 L.min-1). Se registraron los valores de la presión arterial, frecuencia cardíaca, saturación periférica de O2, isoflurano inspiratorio, isoflurano espiratorio, O2 inspiratorio, O2 espiratorio, N2O inspiratorio, N2O espiratorio, CO2 inspiratorio, concentración de CO2 después de la espiración y concentración alveolar mínima. Además, de determinaron las tasas de consumo total de fentanil, dexmedetomidina e isoflurano, como también la de hemorragia. RESULTADOS: La frecuencia cardíaca disminuyó en ambos grupos después de la carga de dexmedetomidina. Después de la intubación, los valores del Grupo A fueron mayores en los minutos 1, 3, 5, 10 y 15. Después de la intubación, los valores de hipotensión deseados se alcanzaron en 5 minutos en el Grupo N y en 20 minutos en el grupo A. Los valores de la CAM fueron más altos en el Grupo N en los minutos 1, 3, 5, 10 y 15 (p < 0,05). Los valores de la FiO2 fueron más altos entre 5 y 60 minutos en el Grupo A, mientras que fueron más altos en el Grupo N a los 90 minutos (p < 0,05). Los valores de Fi Iso (isoflurano espiratorio) fueron menores en el Grupo N en los minutos 15 y 30 (p < 0,05). CONCLUSIONES: El uso de la dexmedetomidina en vez del óxido nitroso en la anestesia con el isoflurano por la técnica de bajo flujo, alcanzó los niveles deseados de presión arterial promedio (PAP), profundidad suficiente de la anestesia, estabilidad hemodinámica y parámetros de inspiración seguros. La infusión de dexmedetomidina con oxígeno / aire medicinal como gas de transporte es una técnica anestésica opcional.

Observation of patients' clinical characteristics during recovery period in low flow and circulation closed pattern anesthesia by ZEUS with isoflurane / 肿瘤研究与临床

Objective To explore the clinical characteristics of patients during recovery period in low flow and circulation closed pattern anesthesia by ZEUS with isoflurane.Methods During elective gynecologic surgery,35 ASA Ⅰ or Ⅱ patients were anesthetized with isoflurane under general anesthesia with tracheal intubation.The ventilation was used with the closed circuit breathing mode (Autocontrol) of ZEUS anesthesia machine.The time of inhale drug,exhale drug and eyes-opend,consumption of drug and complication were recorded during the process.The values of NT stage (NTS),NT index (NTI),the final endexpiratory concentration of isoflurane (EXP),MAC and hemodynamic parameters were recorded during the time of isoflurane stopping inhale,recovery of spontaneous respiration,eyes opening.Results The values of NTI (50±7,74±12,86±10,t =-9.382,t =-16.682,P ＜ 0.01),the EXP [(0.9±0.0)％,(0.1±0.1)％,0,z =-7.262,z =-7.835],MAC [(1.2±0.1)％,(0.2±0.2)％,0,z =-7.186,z =-7.728,P ＜ 0.01] and hemodynamic parameters (SBP,DBP,MAP,HR) [(108.1±13.4) mm Hg (1 mm Hg =0.133 kPa),(66.3±12.1) mm Hg,(84.3± 12.5) mm Hg,(69.8±12.5) /min and (124.6±17.9) mm Hg,(75.7±14.5) mm Hg,(96.0±14.6) mm Hg,(82.8±15.0)/min and (128.0±16.3) mm Hg,(77.1±15.0) mm Hg,(99.8±15.3) mm Hg,(85.2±18.5) bpm] (t =-4.365,t =-2.951,t =-3.574,t =-3.921; t =-5.554,t =-3.309,t =-4.642,t =-4.085,P ＜0.01) during the time of recovery of spontaneous respiration and tracheal extubation were statistically significant compared to the time of isoflurane stopping (P＜ 0.01).None of patients experienced intraoperative was awareness.Conclusion Isoflurane can be used for closed circuit breathing mode of ZEUS anesthesia machine,but consciousness recovery need a long time.

Contaminação do aparelho de anestesia por agentes patógenos / Contamination of anesthesia circuits by pathogens / Contaminación del aparato de anestesia por agentes patógenos

JUSTIFICATIVA E OJETIVOS: Avaliação da contaminação dos aparelhos de anestesia por meio de coletas de 56 amostras para cultura no sistema circular do aparelho de anestesia, em traqueias previamente reprocessadas por desinfecção com hipoclorito à 1 por cento ou glutaraldeído à 2 por cento , após lavagem com sabão e água não estéreis, secas com jato de ar comprimido e armazenadas em papel com grau cirúrgico, e em outros locais do circuito respiratório não reprocessados, antes dos procedimentos anestésicos. MÉTODO: Foram realizadas culturas de amostras das traqueias dos ramos inspiratórios, ramos expiratórios, canister, cal sodada e frasco coletor (dreno), em swab com meio Stuart e semeadas em meio de cultura Agar sangue, Mac Conkey e Sabouraud. RESULTADOS: Nas traqueias reprocessadas dos ramos inspiratórios e expiratórios dos aparelhos de anestesia, o nível de contaminação em alguns sítios foi de até 39,3 por cento, com a presença de fungos e bactérias e, em alguns casos, com a presença de mais de um micro-organismo sendo 75 por cento da contaminação de fungos e 25 por cento de bactérias. Foi encontrada cultura positiva para Candida sp., Dermatophytus sp., Penicillium sp., Aspergillus sp., Staphylococcus aureus, Staphylococcus saprophyticcu e Staphylococcus epidermidis. No canister houve contaminação em 25 por cento com o crescimento de Candida sp., Penicillium sp., Dermatophytus sp., Aspergillus sp. e Fusarium sp. No frasco coletor, observou-se a contaminação de 36 por cento das amostras analisadas com crescimento de Candida sp., Dermatophytus sp., Staphilocccus saprophyticus e Acinetobacter bauman nii. Nas culturas da cal sodada não houve crescimento de micro-organismos. CONCLUSÕES: Em todos os pontos analisados, com exceção da cal sodada, houve crescimento de micro-organismos com a possibilidade de haver contaminação cruzada.

BACKGROUND AND OBJECTIVES: Evaluation of contamination of anesthesia circuits by collecting 56 culture samples from the circular system; previously reprocessed tracheas by disinfection with 1 percent hypochlorite or 2 percent glutaraldehyde after being washed in non-sterile water and soap and dried by using compressed air and stored in surgical grade paper; and from other places of the non-reprocessed respiratory circuit, before anesthetic procedures. METHODS: Samples from the inspiratory and expiratory branches of the tracheas, canister, soda-lime, and collector jar (drain) through swab in Stuart medium and streaked in Agar blood, Mac Conkey, and Sabouraud growth media. RESULTS: The level of contamination with fungus and bacteria in the inspiratory and expiratory branches of tracheas reached up to 39.3 percent in some sites; in some cases, more than one microorganism was present, 75 percent fungal and 25 percent bacterial contamination. Cultures were positive for Candida sp., Dermatophytus sp., Penicillium sp., Aspergillus sp., Staphylococcus aureus, Staphylococcus saprophyticus, and Staphylococcus epider midis. Contamination was observed in 25 percent of the canisters with growth of Candida sp., Penicillium sp., Dermatophytus sp., Aspergillus sp., and Fusarium sp. In the collector jar, a contamination rate of 36 percent was observed with growth of Candida sp., Dermatophytus sp., S. saprophyticus and Acinetobacter baumannii. Microorganisms did not grow in soda-lime cultures. CONCLUSIONS: In all sites investigated except for soda-lime growth of microorganisms was observed with the possibility of cross infection.

JUSTIFICATIVA Y OBJETIVOS: Evaluar la contaminación de los aparatos de anestesia a través de recolecciones de 56 muestras para cultivo en el sistema circular del aparato de anestesia, en traqueas previamente reprocesadas por desinfección con hipoclorito al 1 por ciento o glutaraldehido al 2 por ciento, después del lavado con jabón y agua no estériles, secadas con chorro de aire comprimido y almacenadas en papel quirúrgico, y en otros locales del circuito respiratorio no reprocesados, antes de los procedimientos anestésicos. MÉTODO: Fueron realizados cultivos de muestras de las traqueas de los ramos inspiratorios, ramos espiratorios, caníster, cal sodada y frasco recolector (dreno), a través de swab con medio Stuart, y sembradas entre los cultivos Agar sangre, Mac Conkey y Sabouraud. RESULTADOS: En las traqueas reprocesadas de los ramos inspiratorios y espiratorios de los aparatos de anestesia, el nivel de contaminación en algunos sitios fue de hasta un 39,3 por ciento, con la presencia de hongos y bacterias, siendo que en algunos casos había más de un microorganismo, un 75 por ciento de la contaminación por hongos y un 25 por ciento de bacterias. Se encontró un cultivo positivo para Candida sp., Dermatophytus sp., Penicillium sp., Aspergillus sp., Staphylococcus aureus, Staphylococcus saprophyticus y Staphylococcus epidermidis. En el caníster, hubo contaminación en un 25 por ciento, con el aumento de Candida sp., Penicillium sp., Dermatophytus sp., Aspergillus sp. y Fusarium sp. En el frasco recolector, se observó la contaminación de un 36 por ciento de las muestras analizadas, con un crecimiento de Candida sp., Dermatofitus sp., S. saprophyticcus y Acinetobacter baumannii. En los cultivos de la cal sodada no hubo crecimiento de microorganismos. CONCLUSIONES: En todos los puntos analizados, con excepción de la cal sodada, hubo un aumento de los microorganismos, con la posibilidad de contaminación cruzada.

Carbon monoxide produced from degradation of desflurane reacting with different carbon dioxide absorbents in a closed anesthesia circuit / 中华麻醉学杂志

soda lime). It took significant less time to reach the peak CO concentration with baralyme than with the other two CO2 absorbents. The temperature of top canister went up faster than that of the bottom one with soda lime; whereas with baralyme the temperature of the bottom canister went up faster. Conclusion In a simulated closed circuit the risk of CO poisoning was higher with baralyme than with soda lime. But KOH-free soda lime which still contains NaOH, such as sofnolime, may produce more CO than standard soda lime.

Comparison of respiratory dynamics of closed circuit ventilation and Jackson-Rees circuit ventilation / 中华麻醉学杂志

Objective To evaluate the feasibility of performing closed circuit ventilation with Ohmeda Excel 210 plus ventilator 7900 in the infant anesthesiaMethods Thirty lip cleft or palate cleft infants with body weight under 10 kg were enrolled into the studyIn a sequence of before and after, the parameters of respiratory dynamics were compared between closed circuit ventilation and Jackson-Rees circuit ventilation RR 22 frequency/min, I:E 1:15 and P ETCO 2 40mmHg were set as constant parameters, tidal volume (VT) was adjusted accordinglyThe total respiratory compliance (CT), airway peak pressure (Ppeak), positive end-expiratory pressure (PEEP), fractional concentration of CO 2 in inspiratory gas (FiCO 2), first second forced expiratory volume rate (FEV 10%) were measured during closed circuit and Jackson-Rees circuit ventilationsResults As compared with those during the Jackson-Rees circuit ventilation, PEEP increased significantly and FiCO 2 decreased markedly during the closed circuit ventilationThere were no significant differences in Ppeak, VT, CT, FEV 10%, MAC, SpO 2, HR and MAP between closed circuit ventilation and Jackson-Rees circuit ventilationConclusions It is feasible to perform closed circuit ventilation with Ohmeda Excel 210 plus ventilator 7900 in the infant anesthesia

Effects of closed-circuit desflurane and sevoflurane anesthesia on postoperative renal function in neurosurgical patients / 中华麻醉学杂志

Objective To compare the renal function after neurosurgery performed under closed-circuit anesthesia with sevoflurane and desflurane and determine the safety of the closed-circuit sevoflurane anesthesia. Methods 36 ASA Ⅰ or Ⅱ patients aged 18-60 years were randomly divided into 2 groups to receive either sevoflurane (group S, n = 18) or desflurane (group D, n = 18) . The duration of surgery was expected to be ≥90 min. The patients were premedicated with intramuscular midazolam 0.07 mg?kg-1 . Anesthesia was induced with midazolam 0.1 mg?kg-1, fentanyl 1.5-2.0 ?g?kg-1 , propofol 1-2 mg?kg-1 and vecuronium 0.1-0.15 mg? kg-1. The patients were mechanically ventilated (VT = 8-12 ml?kg-1) after tracheal intubation. PET CO2 was maintained a 35-45 mm Hg. Fresh gas flow (FGF) was first set at 1-5 L?min-1 for 2-3 min, then reduced to 0.18-0.3 L?min-1. In group D end-tidal desflurane concentration was maintained at 6%-10% ; whereas in group S the end-tidal sevoflurane concentration was maintained at 2.7%-4.0% . BP, HR, ECG, SpO2 PET CO2, inspiratory and expiratory O2 , desflurane and sevoflurane concentrations and the temperature in the center of soda-lime canister were continuously monitored during the operation. Gases were collected from breathing circuit for determination of compound A concentration (by gas chromatography) before anesthesia, at the end of 2-3 min wash-in, every 30 min during maintenance of anesthesia and at the end of anesthesia. Venous blood samples were taken before anesthesia (baseline) , at the end of surgery (T1) and at 2, 24 and 72 h after operation (T2-4) for determination of serum F-, creatinine (Cr) and blood urea nitrogen (BUN) concentrations. Urine specimens were taken for determination of total protein (TP), ?2-microglobulin (?2-MG) and ?-N-acetyl-glucuronidase (NAG) levels, before operation (baseline) at the end of operation and at 24, 48 and 72 h after operation. TP/Cr, ?2-MG/ Grand NAG/Cr were calculated to eliminate the influence of the volume of urine.Results There were no significant differences between the two groups with respect to age, sex, body weight, height, duration of anesthesia and temperature in the center of soda-lime canister. The inspiratory O2 concentration was ≥ 75% during anesthesia. There was no significant difference in serum Cr and BUN concentrations and NAG/Cr in urine before and after operation as well as between the two groups. TP/Cr and ?2-MG/Cr in urine were significantly increased after operation compared to the baseline values but there was no significant difference between the two groups. There was no significant correlation between postoperative TP/Cr, ?-MG/Cr and compound A. Conclusion Closed-circuit sevoflurane ansthesia does not affect postoperative renal function.

The uptake of desflurane during closed-circuit anesthesia with low initial fresh-gas-flow / 中华麻醉学杂志

0.05 ). Conclusions With low initial FGF addition of N2O does not affect the uptake of desflurane. The low-flow desflurane anesthesia is safe and economical.

Clinical study on inhalation anesthetic techniques with low-flow and high inspired concentration / 中华麻醉学杂志

Objective Using accurate monitoring,and high precision anesthetic machine and vapourizer,and guided with a simple mathematics formula to implement low-flow inhaled anesthetic techniques.Methods Ten healthy patients under going craniotomy,thoracotomy or laparotomy were assigned to receive isoflurane by low-flor of fresh gas and high vapourizer output.After intubation,the vapourizer dial was set at 5% and the patients were delivered with 1L/min total fresh gas flow of oxygen.The expiratory(F E) and inspired(F 1) concentration of isoflurane were monitored continuously.The data were recorded with computer once every 10. The concentrations were plotted against the time and the predicted regression equation were calculated.Results The F E reached 1.05% 10 min after inhalation of isoflurane ,which could be predicted by curvilinear(y=0 4092(1nx)+0 0172) and lineal (y=0 083x+0 1385) regression equations from 1 to 10 min,The predicted concentration by curvilinear regression equation appeared to estimate the measured value more accurately than linear regression equation.However segmental lineal regression equation cluld predict the measured value as accurately as curvilinear regression equation.Conclusions The inhalation anesthetic induction can be completed within 10 min with low-flow of fresh gas flow and high output of vapourizer dial setting.The measured value of anesthetic can be predicted accurately.

Predictive and intelligent control of sevoflurane closed circuit anesthesia / 中华麻醉学杂志

Objective To evaluate the efficacy of servo controlled sevoflurane closed-circuit anesthesia and the feasibility of the predictive and intelligent control.Methods One hundred and forty-three ASA Ⅰ-Ⅲ patients (90 males, 53 females) aged between 3-77 yrs undergoing elective surgery were studied. Anesthesia was induced with intravenous fentanyl 2-3 ?g ?kg-1 , midazolam 0.12 mg?kg-1 and vecuronium 0.1 mg?kg-1 . After tracheal intubation the tracheal tube was connected to the servo-controlled closed-circuit system composed of IBM computer, O2 mass flow controller and electrically controlled sevoflurane injection pump and multifunctional monitor. The fresh gas flow of O2 = [body weight (kg)3/4 ? 10 + 20] ml?min-1 . The end-expired sevoflurane concentration was maintained at 1.3 MAC by predictive and intelligent control.Results The average wash-in time to reach the target concentration was (5.2 ?2.4) min. The O2 flow rate was(0.22?0.04) L?min-1 . The cumulative uptake of sevoflurane was 5.16 ml, 7.74ml, 9.17ml, 11.08ml, 12.57ml, 13.00ml, 14.18ml, 15.60ml, 18.56ml and 24.6 ml at 30, 60, 90, 120, 150, 180, 210, 240, 300 and 420 min respectively. The uptake rate of fluid sevoflurane was equivalent to (0.2673e-0.0598t + 0.2269e-0.0597t + 0.1150e-0.002t) ml?min-1 . Conclusion The servo controlled sevoflurane closed-circuit system can effectively control the pre-set end-tidal sevoflurane concentration in spite of the influence of multiple factors and is safe and effective.