Fisiología respiratoria: relación ventilación/perfusión / Respiratory fisiology: ventilation/perfusion relationship

Las alteraciones de la relación entre la ventilación y el flujo sanguíneo (V/Q) en diversas regiones del pulmón alteran el aporte de oxígeno (O2) y remoción del dióxido de carbono (CO2) al organismo. Fisiológicamente existen diferencias regionales en la relación V/Q. Determinadas patologías pueden alterar esta relación, produciendo tres escenarios distintos: Cortocircuito (Shunt), Alteración V/Q y aumento del espacio muerto. Para evaluar estos escenarios y realizar una aproximación diagnostica son de utilidad el estudio de los gases arteriales y venosos, la diferencia alveolo arterial y la respuesta al suministrar O2

Alterations in the ventilation perfusion relationship (V/Q) in various lung regions alter the supply of oxygen (O2) and the removal of carbon dioxide (CO2) in the body. Physiologically, there are regional differences in the V/Q ratio. Certain pathologies can alter this relationship, producing three different scenarios: Shunt, V/Q mismach and dead space increased. To evaluate these scenarios and carry out a diagnostic approach, it is useful to study arterial and venous gasometry, the alveolar arterial difference and the response to oxygen supplying.

Guideline for Ventilation/Perfusion Scintigraphy

This paper is about the Guideline for Ventilation / Perfusion Scintigraphy. It has been developed by the Brazilian Society of Nuclear Medicine to be a best practices guide used in Nuclear Medicine. Its function is to be an educational tool to help the Nuclear Medicine Services in Brazil to guarantee a quality care to the patients

Clinical effect of mometasone furoate nasal spray combined with montelukast in the treatment of children with obstructive sleep apnea hypopnea syndrome / 中国基层医药

Objective@#To explore the clinical effect of mometasone furoate nasal spray combined with montelukast in the treatment of children with obstructive sleep apnea hypopnea syndrome (OSAHS), and to analyze its feasibility and clinical application value.@*Methods@#From August 2017 to March 2019, 64 children with OSAHS who were treated in the People's Hospital of Jinhua were selected in the study.According to the random number table method, they were divided into the observation group and the control group, with 32 cases in each group.The observation group was treated with mometasone furoate nasal spray combined with montelukast for 12 weeks.The control group was treated with surgical treatment to remove hypertrophic tonsils and/or adenoids.The clinical symptom scores, polysomnography(PSG) monitoring index, adenoid and tonsil size index, and the efficacy after 12 weeks of treatment were compared between the two groups.@*Results@#There were no statistically significant differences in symptom scores and minimum arterial oxygen saturation(LSaO2) between the two groups before treatment(all P>0.05). After treatment, the symptom scores and LSaO2 of the control group were (1.90±0.53)points and (94.74±1.54)%, respectively, which of the observation group were (4.00±1.50)points and (85.34±10.57)%, respectively, the differences between the two groups were statistically significant(t=-7.416, 4.972, all P<0.05). There were statistically significant differences in the apnea hypopnea index(AHI) and obstructive apnea index(OAI) between the two groups(all P<0.05). After treatment, the A/N of the adenoids in the observation group was significantly decreased, and the difference in the tonsil classification was statistically significant(Z=-2.602, P<0.05). The effective rate of the observation group was 56.25%(18/32), which was significantly lower than that of the control group [100.00%(32/32)], the difference was statistically significant(χ2=17.920, P<0.05).@*Conclusion@#In summary, non-surgical treatment can alleviate OSAHS-related symptoms, reduce the size of tonsils and adenoids, and achieve the purpose of remission or cure.Non-surgical treatment can be selected when patients' families are reluctant to choose surgical treatment.

Pulmonary thromboembolism: new diagnostic imaging techniques / Novas técnicas no diagnóstico por imagem do tromboembolismo pulmonar

Abstract The accurate diagnosis of pulmonary thromboembolism is essential to reducing the morbidity and mortality associated with the disease. The diagnosis of pulmonary thromboembolism is challenging because of the nonspecific nature of the clinical profile and the risk factors. Imaging methods provide the definitive diagnosis. Currently, the imaging method most commonly used in the evaluation of pulmonary thromboembolism is computed tomography. The recent development of dual-energy computed tomography has provided a promising tool for the evaluation of pulmonary perfusion through iodine mapping. In this article, we will review the importance of diagnosing pulmonary thromboembolism, as well as the imaging methods employed, primarily dual-energy computed tomography.

Resumo A acurácia no diagnóstico de tromboembolismo pulmonar é essencial para reduzir a morbimortalidade causada por esta enfermidade. Devido ao quadro clínico e fatores de risco inespecíficos, o diagnóstico de tromboembolismo pulmonar torna-se um desafio. Os métodos de imagem fornecem o diagnóstico definitivo, sendo a tomografia computadorizada o método mais utilizado atualmente. Nos últimos anos, houve o desenvolvimento da tomografia computadorizada com dupla energia e essa ferramenta tem se mostrado promissora para avaliação da perfusão pulmonar por meio do mapa de iodo. Neste artigo é feita revisão acerca da importância do diagnóstico de tromboembolismo pulmonar, bem como os métodos de imagem disponíveis, com ênfase na tomografia computadorizada com dupla energia.

Efeitos da filtragem de leucócitos sobre a resposta inflamatória e a função pulmonar de pacientes submetidos à revascularização miocárdica com circulação extracorpórea / Effects of leukocyte filtering on the inflammatory response and pulmonary function in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass

INTRODUÇÃO E OBJETIVOS: A Circulação extracorpórea (CEC) é associada a ativação leucocitária, resposta inflamatória e disfunção pulmonar. Objetivou-se avaliar os efeitos da filtragem leucocitária sobre a resposta inflamatória e a função pulmonar em indivíduos submetidos à revascularização do miocárdio (RM) com CEC. MÉTODO: Após aprovação pelo Comitê de Ética Institucional e obtenção do consentimento informado dos indivíduos, foi realizado estudo prospectivo randomizado, para comparar indivíduos adultos submetidos à RM com CEC, utilizando-se filtragem leucocitária (n=09) ou filtro standard (n=11) durante a CEC. Tomografia computadorizada (CT) de tórax, espirometria, análise da oxigenação e hemograma foram realizados antes da cirurgia. A anestesia foi induzida por via venosa com etomidato (0,3 mg.kg-1), sufentanil (0,3 ug.kg-1), pancurônio (0,08 mg.kg-1) e mantida com isoflurano (0,5 - 1,0 CAM) e sufentanil (0,5 ug.kg-1.h-1). A ventilação mecânica utilizou volume corrente de 8 mL.kg-1, com FiO2 de 0,6 e PEEP de 5 cm H2O, exceto durante a CEC. No grupo Filtragem, durante a CEC, foi inserido um filtro de leucócitos na linha arterial do circuito (LG-6, Pall Biomedical Products) e, no grupo Controle, foi utilizado o filtro Standard. Contagem leucocitária foi realizada após a indução, aos 5, 25 e 50 min de CEC, ao final da cirurgia, com 12 e 24 h PO. Dados hemodinâmicos, PaO2/FiO2, fração de Shunt, interleucinas, elastase e mieloperoxidase foram colhidos antes e após a CEC, no final da cirurgia, com 6,12 e 24 h PO. Trinta minutos depois da indução, e trinta após a CEC, três amostras sequenciais de ar exalado foram colhidas para análise de óxido nítrico (NO), por quimiluminescência. Espirometria e CT de tórax foram realizadas no primeiro dia pós-operatório. Os dados foram analisados por meio de ANOVA de duplo fator para medidas repetidas. RESULTADOS: O tempo de CEC foi similar entre os grupos controle e filtragem (86,78 ± 19,58 versus 104,64 ± 27,76 min, p=0,161)...

BACKGROUND AND OBJECTIVE: The Cardiopulmonary bypass (CPB) is related to leukocyte activation, inflammatory response and lung dysfunction. The aim of this study was to evaluate the effects of CPB-leukocyte filtration on the inflammatory response and lung function after coronary artery bypass grafting (CABG). METHODS: After approval by the institutional ethics committee and informed consent, a prospective randomized study was performed to compare CABG-patients undergoing CPB-leukocyte filtration (n=9) or standard CPB (n=11). Espirometry, chest computed tomography (CT), oxygenation analysis and leukocyte count were performed before surgery. Anesthesia induction was performed intravenously with etomidate (0,3 mg.kg-1), sufentanil (0,3 ug.kg-1), pancuronium bromide (0,08 mg.kg-1) e sustained with isoflurano (0,5 - 1,0 CAM) and sufentanil (0,5 ug.kg-1.h-1). The tidal volume used during mechanical ventilation was 8 mL.kg-1, the FiO2 0.6 and PEEP 5 cm H2O, except during CPB. In Filtered group, during CPB, was inserted a leukocyte filter in the arterial line of CPB circuit (LG-6, Pall Biomedical Products) and, in Control group, the Standard arterial line filter was utilized. Hemodynamic data, PaO2/FiO2, shunt fraction, interleukins, elastase and myeloperoxidase were evaluated before and after CPB, at the end of surgery, and 6, 12 and 24 h PO. Thirty minutes after induction, and Thirty after CPB, three sequential exhaled air samples were collected to perform analysis of nitric oxide (NO), by chemiluminescence technique. Espirometry and chest CT were performed on first PO. Data were analyzed using two-factor ANOVA for repeated measurements. RESULTS: Length of CPB was similar in the filtered and control groups (86.78 ± 19.58 versus 104.64 ± 27.76 min, p = 0.161). The filtered group showed lower neutrophil counts than the control group up to 50 minutes of CPB (3384 ± 2025 versus 6478 ± 3582 U/mm-3, p = 0.036), lower shunt fraction up to 6 hours after surgery (10 ± 2%)...

Análise da estabilidade de uma variável submáxima em teste cardiopulmonar de exercício: ponto ótimo cardiorrespiratório / Analysis of the stability of a submaximal variable in the cardiopulmonary exercise testing: Cardiopulmonary optimal point

O presente estudo teve por objetivo investigar a estabilidade do ponto ótimo cardiorrespiratório (POC) em dois testes cardiopulmonares de exercício máximos (TCPEs), realizados em cicloergômetro de membros inferiores. Para tanto, foram analisados retrospectivamente os dados de 1334 indivíduos avaliados por no mínimo duas vezes entre 1995 e 2013, sendo identificados, a partir de rígidos critérios de inclusão, 222 pacientes (159 homens) com a idade de 55±11,6 anos. Logo, foram verificados os dados do POC obtidos a partir da análise da ventilação e do consumo de oxigênio em cada minuto do TCPE, o VO2 máximo, e as curvas de eficiência do consumo de oxigênio (OUES) e do equivalente ventilatório de dióxido de carbono (VE/VCO2 slope), sendo a estabilidade avaliada pelos coeficientes de correlação intraclasse. A mediana do intervalo de tempo entre os dois TCPEs foi de 1,6 anos. Os valores de cada uma das variáveis obtidas nos dois TCPEs apresentaram altas e significativas associações (p <0,01), sendo: VO2max ri = 0,93 (IC95% = 0,91 a 0,94); POC ri = 0,87; (IC95% = 0,82 a 0,90); OUES ri = 0,90 (IC95% = 0,87 a 0,93) e VE/VCO2 slope ri = 0,74 (IC95% = 0,67 a 0,80). Concluímos que, em condições controladas, o POC é um índice ventilatório bastante estável em TCPEs realizadas em indivíduos adultos, com níveis de estabilidade similar ou superior de outras variáveis ou índices consagrados na literatura, corroborando, dessa forma, seu potencial de utilização em pesquisas fisiológicas e na prática clínica.

The present study aimed to assess the stability of the cardiorespiratory optimum point (COP) in two maximum cardiopulmonary exercise testing (CPET), performed in a lower limbs cycling ergometer. Therefore, we retrospectively analyzed data from 1334 subjects that were evaluated by at least twice between 1995 and 2013, and identified after rigid inclusion criteria, 222 subjects (159 men) aged 55 ± 11.6 years. COP results were obtained from the ventilation and oxygen consumption data averaged at each minute during CPET as well as maximum oxygen uptake, efficiency curves of oxygen consumption (OUES) and ventilatory equivalent for carbon dioxide (VE/VCO2 slope), and their stability assessed by intraclass correlation coefficients. The median time interval between two CPETs was 1.6 years. The values of the variables obtained in the two CPETs showed high and significant associations (p <0.01), being: VO2max ri = 0.93 (CI95% = 0.91 a 0.94); COP ri = 0.87; (CI95% = 0.82 a 0.90); OUES ri = 0.90 (CI95% = 0.87 a 0.93) and VE/VCO2 slope ri = 0.74 (CI95% = 0.67 a 0.80). We conclude that, under controlled conditions, COP is a very stable ventilatory index in CPET performed in adults, with stability levels similar or higher than other variables well-established in the literature, confirming thus its potential for use in physiological research and clinical practice.

Ponto ótimo cardiorrespiratório: uma variável submáxima do teste cardiopulmonar de exercício / Cardiorespiratory optimal point: a submaximal variable of the cardiopulmonary exercise testing

FUNDAMENTO: No Teste Cardiopulmonar de Exercício (TCPE) máximo são analisadas diversas variáveis ventilatórias, incluindo o equivalente ventilatório de oxigênio (VE/VO2). O valor mínimo do VE/VO2 reflete a melhor integração entre os sistemas respiratório e cardiovascular, podendo ser denominado Ponto Ótimo Cardiorrespiratório (POC). OBJETIVO: Determinar o comportamento do POC em função do gênero e da idade em adultos saudáveis e verificar a associação com outras variáveis do TCPE. MÉTODOS: De 2.237 indivíduos, foram selecionados 624 (62% homens e 48 ± 12 anos de idade), não atletas, saudáveis, submetidos ao TCPE máximo. O POC ou VE/VO2 mínimo foi obtido a partir da análise da ventilação e do consumo de oxigênio em cada minuto do TCPE. Foi verificada a relação entre idade e POC para os dois gêneros, assim como as associações com: VO2máx, VO2 no limiar anaeróbico (VO2LA), eficiência da inclinação de consumo de oxigênio (OUES) e com VE máxima. Comparou-se ainda a intensidade do esforço (MET) no POC, LA e VO2máx. RESULTADOS: O POC aumenta com a idade, sendo 23,2 ± 4,48 e 25,0 ± 5,14, respectivamente, em homens e mulheres (p < 0,001). Há associações moderadas e inversas com VO2máx (r = -0,47; p < 0,001), com VO2LA (r = -0,42; p < 0,001) e com o OUES (r = -0,34; p < 0,001). O POC ocorreu, em média, a (44% do VO2máx) e antes do LA (67% do VO2máx) (p < 0,001). CONCLUSÃO: POC, uma variável submáxima, aumenta com a idade e é discretamente mais alto em mulheres. Sendo modestamente associado a outras medidas ventilatórias, parece haver uma contribuição independente na interpretação da resposta cardiorrespiratória ao TCPE.

BACKGROUND: At the maximal Cardiopulmonary Exercise Testing (CPET), several ventilatory variables are analyzed, including the ventilatory equivalent for oxygen (VE/VO2). The minimum VE/VO2 value reflects the best integration between the respiratory and cardiovascular systems and may be called "Cardiorespiratory Optimal Point (COP)". OBJECTIVE: To determine the behavior of the COP according to gender and age in healthy adults and verify its association with other CPET variables. METHODS: Of 2,237 individuals, 624 were selected (62% men and 48 ± 12 years), non- athletes, healthy, who were submitted to maximal CPET. COP or minimum VE/VO2 was obtained from the analysis of ventilation and oxygen consumption in every minute of CPET. We investigated the association between age and COP for both genders, as well as associations with: VO2max, VO2 at anaerobic threshold (VO2AT), oxygen uptake efficiency slope (OUES) and with maximum VE. We also compared the intensity of exertion (MET) at the COP, AT and VO2max. RESULTS: COP increases with age, being 23.2 ± 4.48 and 25.0 ± 5.14, respectively, in men and women = (p < 0.001). There are moderate and inverse associations with VO2max (r = -0.47; p < 0.001), with VO2AT (r = -0.42; p < 0.001) and with OUES (r = -0.34; p < 0.001). COP occurred, on average, at 44% do VO2max and before AT (67% of VO2max) (p < 0.001). CONCLUSION: COP, a submaximal variable, increases with age and is slightly higher in women. Being modestly associated with other ventilation measures, there seems to be an independent contribution to the interpretation of the cardiorespiratory response to CPET.

Titrating positive end-expiratory pressure after recruitment maneuver according to end-tidal carbon dioxide and its related indicators in acute respiratory distress syndrome dog model / 中华内科杂志

Objective To investigate the relationship between end-tidal carbon dioxide with its related indicators and ventilation/perfusion of the acute respiratory distress syndrome (ARDS) lung,and to explore a feasible way to titrate positive end-expiratory pressure (PEEP) in clinical practice.Methods Five mixed-breed dogs with oleic acid lung injury model were mechanically ventilated at a serial PEEP trial including a recruitment maneuver (RM) before each PEEP level changed.The value of blood dynamics,end-tidal carbon dioxide partial pressure ( PetCO2 ) and arterial carbon dioxide pressure under different PEEP levels were recorded.Arterial end-tidal carbon dioxide gradient (Pa-etCO2) and dead space fraction (Vd/Vt％) were calculated.All dogs received CT scan.Lung volume under different pressure levels,and ratio and volume of alveolar closing pressure,collapsed alveoli,sufficiently and insufficiently ventilated alveoli were obtained.Alveolar opening and closing analysis were performed by non-liner regression equation.Results The mean pressure when Vd/Vt％ obtained lowest level were ( 11.2 ± 4.4 ) cm H2O(1 em H2 O =0.098 kPa),which had no significant difference when compared to alveolar closing pressure[ ( 11.5 ± 3.2 ) cm H2O ]( P ＞ 0.05 ).The fraction of insufficiently ventilated and collapsed alveoli showed a significant linear correlation with the Vd/Vt％ when PEEP was lower than Pmin ( r =0.632,P =0.004 ).There was a linear correlation between the Vd/Vt％ and the fraction of over-distended alveoli when PEEP was higher than Pmin ( r =0.770,P =0.001 ).Conclusions Closing pressure is in accordance with PEEP level after RM having reached the best ventilation/circulation ratio.The characteristics of lung collapse can be revealed by Vd/Vt％ changes after RM.To titrate PEEP for the lowest Vd/Vt％ after RM may be a feasible way to match the best ventilation and circulation effects of PEEP.

Difference in the value of arterial and end-tidal carbon dioxide tension according to different surgical positions: Does it reliably reflect ventilation-perfusion mismatch? / 대한마취과학회지

BACKGROUND: Body posture, as a gravitational factor, has a clear impact on pulmonary ventilation and perfusion. In lung units with mismatched ventilation and perfusion, gas exchange and/or elimination of carbon dioxide can be impaired. In this situation, differences in the value of arterial and end-tidal carbon dioxide tension [Delta(PaCO2 - PETCO2)] are expected to increase. This study was conducted to observe how Delta(PaCO2 - PETCO2) changed according to the 3 different surgical positions, and to determine whether Delta(PaCO2 - PETCO2) is a reliable predictor of ventilation/perfusion mismatch when a patient is in different postural positions. METHODS: Fifty-nine patients were divided into either the chronic obstructive pulmonary disease (COPD) group (n = 29) or the non-COPD group (n = 30). PaCO2 and PETCO2 were measured during surgery in the supine, prone, and lateral decubitus positions after a 10 minute stabilization period. The Delta(PaCO2 - PETCO2) were calculated and compared among positions. RESULTS: The Delta(PaCO2 - PETCO2) decreased slightly in the prone position and increased significantly in the lateral decubitus position compared with the supine position in both groups. These patterns almost corresponded with the degree of ventilation/perfusion mismatch from the results of the radiological studies. The Delta(PaCO2 - PETCO2) in the COPD group was significantly greater than that in the non-COPD group at all surgical positions. CONCLUSIONS: Lateral decubitus position is associated with marked increase in Delta(PaCO2 - PETCO2), especially in patients with COPD. The Delta(PaCO2 - PETCO2) is a simple and reliable indicator to predict ventilation/perfusion mismatch at different surgical positions in patients with or without COPD.

Función respiratoria en la senectud / Pulmonary function in aging

Aging generates four important changes in the structure and function of the respiratory system. There is a reduction in the elastic recoil of the lung causing "senile emphysema", a condition characterized by reduction in the alveolar surface area without alveolar destruction, which is associated with hyperinflation, increased lung compliance and reduction in alveolar-capillary diffusing capacity. There is a decrease in the compliance of the chest watt, due to calcification of its articulations, dorsal kyphosis and "barrel chest". There is a decrease in the strength of respiratory muscles which correlates with cardiac Index, nutritional status and hyperinflation, and there is a reduction in the ventilatory response to hypoxia and hypercapnia as well as in the perception of increased airway resistance. The increased static lung compliance combined with the decreased chest watt compliance leads to an increase in the functional residual capacity with aging. On the other hand, the loss of alveolar and airways elastic recoil combined with the reduction in the strength of the expiratory muscles, leads to an increase in residual volume and decreased maximal expiratory airflow rates and vital capacity. Despite these changes, the respiratory system maintains an adequate gas exchange at rest and during exercise during the whole life span, showing a normal PaCO2 and a slight decline in PaO2 (-0,3 mmHg per year) which is attenuated to become almost undetectable over the age of 70.

Temporary interventional pneumonectomy used as an emergency treatment for acute massive pulmonary embolism: the initial experimental results / 介入放射学杂志

Objective To evaluate regional airway obstruction with balloon catheter in stabilizing the vital signs in experimental animals suffered from acute massive pulmonary embolism. Methods Pulmonary embolism of right lung artery by using auto-blood clots or detachable latex balloons was established in 27 healthy sheep. When the blood oxygen saturation decreased by 25% compared to that before the procedure,the placement of balloon catheter in corresponding right main bronchus was carried out in 18 sheep (study group). Five sheep were used as control group. The blood oxygen saturation in the remaining four sheep did not reach the intervention level. The pulmonary arterial pressure, the peripheral arterial pressure, the central venous pressure, the heart rate, the blood oxygen saturation, the arterial partial pressure of oxygen as well as of carbon dioxide were invasively determined. Results The experimental model of acute massive pulmonary embolism was successfully established in 23 sheep. After the establishment of pulmonary embolism, increased heart rate, tachypnea, a decrease of ≥ 25% in blood oxygen saturation within 30 minutes and a rise in pulmonary arterial pressure were detected. After the placement of balloon catheter in study group, a reduction of the pulmonary arterial pressure and an elevation of the blood oxygen saturation as well as the arterial partial pressure of oxygen rose. were observed. The difference between study group and control group was statistically significant (P < 0.05). Conclusion The result of this animal experiment indicates that obstruction of airway with balloon can be served as a first aid for acute massive pulmonary embolism, which can stabilizes the animal's vital signs and, therefore, can help gain precious time for the follow-up thrombolysis treatment.

Temporary interventional pneumonectomy used as an emergency treatment for acute massive pulmonary embolism:the initial experimental results / 介入放射学杂志

Objective To evaluate regional airway obstruction with balloon catheter in stabilizing the vital signs in experimental animals suffered from acute massive pulmonary embolism.Methods Pulmonary embolism of right lung artery by using auto-blood clots or detachable latex balloons was established in 27 healthy sheep.When the blood oxygen saturation decreased by 25%compared to that before the procedure, the placement of balloon catheter in corresponding right main bronchus was carried out in 18 sheep(study group).Five sheep were used as control group.The blood oxygen saturation in the remaining four sheep did not reach the intervention level.The pulmonary arterial pressure,the peripheral arterial pressure,the central venous pressure,the heart rate,the blood oxygen saturation,the arterial partial pressure of oxygen as well as of carbon dioxide were invasively determined.Results The experimental model of acute massive pulmonary embolism was successfully established in 23 sheep.After the establishment of pulmonary embolism,increased heart rate,tachypnea,a decrease of≥25%in blood oxygen saturation within 30 minutes and a rise in pulmonary arterial pressure were detected.After the placement of balloon catheter in study group,a reduction of the pulmonary arterial pressure and an elevation of the blood oxygen saturation as well as the arterial partial pressure of oxygen rose were observed.The difference between study group and control group was statistically significant(P

Comparison of the effects of isoflurane and propofol in conjunction with thoracic epidural block on oxygenation and shunt fraction during one-lung anesthesia / 中华麻醉学杂志

Objective To compare the effects of isoflurane and propofol on arterial oxygenation and intrapulmonary shunt during one-lung ventilation (OLV) when combined with continuous thoracic epidural block. Methods Twenty-four ASA Ⅰ -Ⅱ patients with normal ventilatory function undergoing elective thoracic surgery were enrolled in this study. Patients with abnormal cardiac, liver or kidney function were excluded. The patients were premedicated with scopolamine 0. 3mg I. M. .Epidural block was performed at T7-8 or T8-9 . An epidural catheter was placed and its position confirmed by epidural 1% lidocaine 5 ml. General anesthesia was induced with propofol l.5mg?kg-1, fentanyl 3?g?kg-1 and vecuronium 0.lmg?kg-1 . Double-lumen catheter was inserted and its correct position was confirmed by a combination of unilateral lung ventilation and auscultation in both supine and lateral position. The patients were mechanically ventilated. Tidal volume was set at 8-10 ml?kg-1, FiO2 = 1, I:E=1:1.5, RR=10-12bpm and PETCO2 was maintained between 35-45 mm Hg. The parameters remained unchanged during one-lung ventilation. The patients were assigned to one of two groups : propofol group and isoflurane group. Anesthesia was maintained with propofol infusion in propofol group and isoflurane inhalation in isoflurane group and BIS was maintained at 45-55. A bolus of 0.5 % ropivacaine 7-9ml was given epidurally followed by 0.5% ropivacaine infusion at a rate of 3-5ml?h-1 in both groups during maintenance of anesthesia. Besides ECG, BP and BIS, continuous cardiac output(CCO Baxter) was monitored during operation. Blood samples were taken from radial artery and pulmonary artery simultaneously before anesthesia when patients were lying supine and breathing spontaneously (T0 ), in lateral position when both lungs were ventilated (T1 ), at 5,15, 30, 60 min of one-lung ventilation(T2-5 ) and when both lungs were ventilated again for 30min(T6) for blood gas analysis. Qs/Qt was calculated.Results (1) The two groups were comparable with respect to demographic data. Propofol infusion was maintained at 4-6 mg?kg-1?h-1 in propofol group and end-tidal isoflurane was maintained between 0.3%-0.5% in isoflurane group. (2) Venous admixture increased significantly at T1 and further increased after T2 and reached its peak at T3(31.1% ?4.2%) in propofol group and at T4 (33.5% ? 7.8% ) in isoflurane group. Shunt fraction was significantly lower in propofol at T4-5 than that in isoflurane group. (3) PaO2 decreased significantly during OLV in both groups, but there was no significant difference in PaO2 between the two groups. Conclusions When combined with thoracic epidural block, intravenous propofol infusion exerts less effect on intrapulmonary shunt than isoflurane inhalation during OLV but there was no significant difference in arterial oxygenation between the two groups.

The difference In intrapuimonary shunt during one-lung ventilation under general anesthesia with isoflurane or propofol-remifentanil / 中华麻醉学杂志

Objective To determine if propofol-remifentanil and isoflurane have any different effects on intrapulmonary shunt during one-lung ventilation (OLV). Methods Twenty-four ASA Ⅰ or Ⅱ patients (18 male, 6 female) aged 42-69 yr undergoing radical esophagus cancer resection via left thoracotomy were randomly divided into 2 equal groups ( n = 8 each) : propofol group (Pro) and isoflurane group (Iso) . The preoperative lung function was normal in both groups. The patients were premedicated with intramuscular diazepam 10 mg and atropine 0.5 mg. Radial artery was cannulated and S-G catheter was placed via right internal jugular vein in pulmonary artery. Anesthesia was induced with propofol 1.5-2.0 mg?kg-1, fentanyl 4 ?g?kg-1 and succinylcholine 1.5 mg?kg-1 and maintained with TCI of propofol and remifentanil (target plasma concentration was set at 3.2 ?g?ml-1 and 4.5 ng?ml-1 ) or isoflurane inhalation ( end- tidal isoflurane concentration = 1.5% -2.5 % ) and intermittent i. v. boluses of fentanyl. The patients were mechanically ventilated after endobronchial intubation with double-lumen tube (VT = 8-10 ml, RR= 10-12 bpm, I:E = 1:2) . During OLV VT was reduced to 6-8 ml and RR increased to 14-16 bpm.PaCO2 was maintained at 35-45 mm Hg. ECG, HR, MAP, SpO2, auditory-evoked potential index (AAI), cardiac index (CI), airway pressure and end-tidal isoflurane concentration were continuously monitored during operation. Blood samples were taken from radial artery and pulmonary artery at 10 min after S-G catheter placement (T0, baseline) at 10 min bilateral ventilation (in right lateral position) (T1) at 15, 30, 60, 90 min of OLV (T2-5) for measurement of blood gases and calculation of Qs/Qt.Results The two groups were comparable with respect to age, M/F ratio, body weight and preoperative lung function. AAI was below 30 during operation and PaCO2 and pH were within normal range in both groups. Qs/Qt was significantly increased while PaO2 was significantly decreased during operation (from T1 to T5 ) as compared to baseline values (T0) but Qs/Qt was gradually decreasing while PaO2 was gradually increasing from T2-5 in both groups. Qs/Qt was significantly lower in Pro group than in Iso group at each interval (T2-5) but there was no significant difference in PaO2 at T2-5 between the two groups. Conclusion There is less intrapulmonary shunt during OLV under general anesthesia with propofol-remifentanil than with isoflurane but the difference is not significant enough to affect PaO2.

Effect of lobe bronchus blockade on intrapulmonary shunt during radical esophagus cancer resection / 中华麻醉学杂志

Objective To evaluate the effect of lobe bronchus blockade with a branchial blocker on intrapulmonary shunt during radical esophagus cancer resection. Methods Twenty four ASA Ⅰ-Ⅲ patients with normal lung function aged 18-69 yrs undergoing elective radical esophagus cancer resection were randomized into 2 groups ( n = 12 each): group A one-lung ventilation (OLV) and group B lobe bronchus blockode. Radial artery and right internal jugular vein were cannulated for BP and CVP monitoring and blood sampling. Anesthesia was induced with midazolam 50 ?g?kg-1, fentanyl 4 ?g?kg-1, propofol 2 mg?kg-1 and vecuronium 0.1 mg?kg-1. In group A double-lumen tube (DLT) was used while in group B a single lumen endotracheal tube was placed first, then a bronchial blocker was inserted fiberoptically into the bronchus of lower lobe of the operated side. The patients were mechanically ventilated (FiO2= 100%, VT = 8 ml?kg-1 , RR = 10-15 bpm, I: E = 1:2). PaCO2 was maintained at 30-35 mm Hg. Anesthesia was maintained with 1.5%-2.0% isoflurane and intermittent Ⅳ boluses of fentanyl and vecuronium. BP, HR, CVP, SpO2, PETCO2 and airway pressure were monitored during operation. Blood samples were taken simultaneously from radial artery and central vein for blood gas analysis before induction of anesthesia when the patients were lying supine and breathing spontaneously (T0), after the lungs on both sides were ventilated for 30 min in lateral position (T1) and 30 min after OLV (group A) or lower lobe bronchus was blocked off (group B) in lateral position (T2). Qs/Qt was calculated (blood from central vein was used instead of mixed venous blood from pulmonary artery) . Blood concentrations of TXB2 and 6-k-PGF1 were determined by radioimmunoassay at T0, T1 and T2. Results There was no significant difference in demographic data between the two groups. At T2 the airway pressure in group A was significantly higher than that in group B. At T2 PaO2 was significantly higher in group B than in group A. Qs/Qt was significantly increased at T1 and T2 as compared to the baselines in both groups. Qs/Qt was significantly increased at T2 compared to that at T1 in group A only, while there was no significant difference between Qs/Qt at T1 and T2 in group B. The TXB2 concentration at T2 was significantly increased as compared to that at T0 and T1 in group A and was significantly higher than that at T2 in group B. Conclusion Lower lobe bronchus blockade was superior to OLV in terms of Qs/Qt and PaO2 during esophagus cancer resection.