O termo limitação ao fluxo expiratório (LFE) refere-se a uma condição na qual o fluxo expiratório máximo obtido durante um ciclo da respiração espontânea é menor que o previsto e permanece constante apesar do aumento do gradiente pressórico. A LFE pode estar presente durante o envelhecimento pulmonar fisiológico, e em afecções pulmonares obstrutivas, como na doença pulmonar obstrutiva crônica (DPOC). A aferição direta para determinar a LFE requer a mensuração do volume pela relação entre o fluxo e a pressão transpulmonar, porém é um método invasivo. Os testes usualmente empregados estão baseados na comparação da curva fluxo-volume expiratório máximo e corrente, porém estas técnicas requerem alto grau de colaboração do indivíduo e podem gerar alteração do tônus muscular brônquico. Estudos sugerem que a Técnica de Pressão Expiratória Negativa (NEP) pode ser aplicada para detecção da LFE, sendo um método simples, não invasivo e que não requer esforço dos voluntários. Contudo, índices quantitativos para a avaliação deste fenômeno ainda não foram definidos, assim como também não foram estudadas a LFE no processo de envelhecimento e nos diversos estágios de obstrução das vias aéreas na DPOC. Neste contexto, os objetivos deste estudo foram: (1) avaliar o comportamento da LFE durante o processo de envelhecimento e (2) estudar a LFE presente nos portadores de DPOC. Trata-se de um estudo transversal controlado com avaliação de casos prevalentes, tendo como unidade de avaliação o indivíduo. Os exames realizados incluíram medidas de espirometria e NEP. Foram selecionados indivíduos saudáveis para o grupo envelhecimento separados em três grupos: grupo jovem (GJ), n=17; grupo meia idade (GMI), n=17 e grupo idoso (GI), n=17. No grupo DPOC foram selecionados indivíduos tabagistas e com doença obstrutiva, sendo classificados de acordo com o nível de obstrução sugerido pela espirometria. Essa classificação resultou em cinco categorias: indivíduos normais ao exame espirométrico (NE, n= 18); com distúrbio ventilatório obstrutivo leve (DVOL, n=15); distúrbio ventilatório obstrutivo moderado (DVOM, n= 18); distúrbio ventilatório obstrutivo acentuado (DVOA, n= 18) e distúrbio ventilatório obstrutivo muito acentuado (DVOMA, n= 18). Todos os indivíduos realizaram os exames de NEP e posteriormente foram submetidos à espirometria. No estudo sobre envelhecimento o parâmetro LFE% foi o que melhor caracterizou a LFE, apresentando uma correlação moderada com a idade. Os parâmetros ∆EF0-50% e ∆EF25-75% apresentaram uma correlação razoável com o progredir da idade, possivelmente devido a LFE no idoso apresentar componentes relacionadas às vias aéreas superiores. No grupo DPOC a NEP caracterizou adequadamente a LFE, sendo o melhor parâmetro a LFE%. Alterações significativas também foram encontradas com os parâmetros ∆EF0-50% e ∆EF25-75%. Avaliando-se a influência da idade neste grupo, pode-se observar que a idade é um fator de contribui para a LFE, no entanto, o efeito preponderante foi a gravidade da doença. Pode-se concluir que: (1) a NEP é útil no estudo da LFE em idosos saudáveis; (2) nestes indivíduos a LFE ocorre principalmente nas vias aéreas extratorácicas; (3) que a NEP é útil na avaliação de pacientes com DPOC, e: (4) que os efeitos da DPOC se sobrepõe ao efeito do envelhecimento. / The term expiratory flow limitatition (EFL) refers to a condition in which the peak flow obtained during a spontaneous breathing cycle is less than expected and remains constant despite the increased pressure gradient. The EFL may be present during the physiological aging lung and obstructive lung diseases such as chronic obstructive pulmonary disease (COPD). Direct assessment of EFL requires determination of iso-volume relationships between flow and trans-pulmonary pressure, however, this is an invasive method. The conventional method to detect EFL is based on comparison of tidal with maximal flow-volume curves, but this test requires a high degree of pacients cooperation and the maneuvers of forced expiration and inspiration can change the bronchial tone. Previous studies suggest that the Negative Expiratory Pressure technique (NEP) can be applied to detect EFL, and that it is a simple and noninvasive technique, which requires no effort of volunteers. However, quantitative indices for evaluating this phenomenon has not been defined, as well as the EFL have not been studied in aging and in various stages of COPD airway obstruction. In this context, the aims of this study were (1) evaluate the EFL during the aging process and (2) study the EFL present in COPD. This is a cross-controlled study evaluation of prevalent cases, with the evaluation unit the individual. The examinations included measurement of NEP and spirometry. We selected healthy individuals divided in three groups: young group (GJ, n = 17); middle aged group (GMI, n = 17) and elderly group (GI, n = 17). In the COPD group we selected smoking subjects and people with obstructive disordered, classified in five categories according to the level of obstruction suggested by spirometry: normal spirometric exam (n = 18); mild obstruction (n = 15); moderate obstruction (n=18), severe obstruction (n = 18) and very severe obstruction (n=18). In the aging group, LFE% parameter was the more adequate to characterize the EFL present during the aging process, showing a moderate correlation. The parameters ∆EF0-50% and ∆EF25-75% showed a reasonable correlation with the progression of age, possibly because the EFL in the elderly have components of the upper airways. In the COPD group, the more adequate parameter to characterize the EFL was the LFE%. Significant changes were also found with the parameters ∆EF0-50% and ∆EF25-75%. Evaluating the influence of age in this group, it can be seen that age contributes for the LFE. However, the effect of the disease was higher than that associated with ageing. It can be concluded that: (1) NEP is a useful tecnique in the study of LFE in healthy elderly people, (2) In these individuals the LFE occurs mainly in the extrathoracic airways, (3) NEP tecnique is useful in evaluating patients with COPD, and: (4) the effects of COPD diseases overlaps the effect of aging.

O termo limitação ao fluxo expiratório (LFE) refere-se a uma condição na qual o fluxo expiratório máximo obtido durante um ciclo da respiração espontânea é menor que o previsto e permanece constante apesar do aumento do gradiente pressórico. A LFE pode estar presente durante o envelhecimento pulmonar fisiológico, e em afecções pulmonares obstrutivas, como na doença pulmonar obstrutiva crônica (DPOC). A aferição direta para determinar a LFE requer a mensuração do volume pela relação entre o fluxo e a pressão transpulmonar, porém é um método invasivo. Os testes usualmente empregados estão baseados na comparação da curva fluxo-volume expiratório máximo e corrente, porém estas técnicas requerem alto grau de colaboração do indivíduo e podem gerar alteração do tônus muscular brônquico. Estudos sugerem que a Técnica de Pressão Expiratória Negativa (NEP) pode ser aplicada para detecção da LFE, sendo um método simples, não invasivo e que não requer esforço dos voluntários. Contudo, índices quantitativos para a avaliação deste fenômeno ainda não foram definidos, assim como também não foram estudadas a LFE no processo de envelhecimento e nos diversos estágios de obstrução das vias aéreas na DPOC. Neste contexto, os objetivos deste estudo foram: (1) avaliar o comportamento da LFE durante o processo de envelhecimento e (2) estudar a LFE presente nos portadores de DPOC. Trata-se de um estudo transversal controlado com avaliação de casos prevalentes, tendo como unidade de avaliação o indivíduo. Os exames realizados incluíram medidas de espirometria e NEP. Foram selecionados indivíduos saudáveis para o grupo envelhecimento separados em três grupos: grupo jovem (GJ), n=17; grupo meia idade (GMI), n=17 e grupo idoso (GI), n=17. No grupo DPOC foram selecionados indivíduos tabagistas e com doença obstrutiva, sendo classificados de acordo com o nível de obstrução sugerido pela espirometria. Essa classificação resultou em cinco categorias: indivíduos normais ao exame espirométrico (NE, n= 18); com distúrbio ventilatório obstrutivo leve (DVOL, n=15); distúrbio ventilatório obstrutivo moderado (DVOM, n= 18); distúrbio ventilatório obstrutivo acentuado (DVOA, n= 18) e distúrbio ventilatório obstrutivo muito acentuado (DVOMA, n= 18). Todos os indivíduos realizaram os exames de NEP e posteriormente foram submetidos à espirometria. No estudo sobre envelhecimento o parâmetro LFE% foi o que melhor caracterizou a LFE, apresentando uma correlação moderada com a idade. Os parâmetros ∆EF0-50% e ∆EF25-75% apresentaram uma correlação razoável com o progredir da idade, possivelmente devido a LFE no idoso apresentar componentes relacionadas às vias aéreas superiores. No grupo DPOC a NEP caracterizou adequadamente a LFE, sendo o melhor parâmetro a LFE%. Alterações significativas também foram encontradas com os parâmetros ∆EF0-50% e ∆EF25-75%. Avaliando-se a influência da idade neste grupo, pode-se observar que a idade é um fator de contribui para a LFE, no entanto, o efeito preponderante foi a gravidade da doença. Pode-se concluir que: (1) a NEP é útil no estudo da LFE em idosos saudáveis; (2) nestes indivíduos a LFE ocorre principalmente nas vias aéreas extratorácicas; (3) que a NEP é útil na avaliação de pacientes com DPOC, e: (4) que os efeitos da DPOC se sobrepõe ao efeito do envelhecimento. / The term expiratory flow limitatition (EFL) refers to a condition in which the peak flow obtained during a spontaneous breathing cycle is less than expected and remains constant despite the increased pressure gradient. The EFL may be present during the physiological aging lung and obstructive lung diseases such as chronic obstructive pulmonary disease (COPD). Direct assessment of EFL requires determination of iso-volume relationships between flow and trans-pulmonary pressure, however, this is an invasive method. The conventional method to detect EFL is based on comparison of tidal with maximal flow-volume curves, but this test requires a high degree of pacients cooperation and the maneuvers of forced expiration and inspiration can change the bronchial tone. Previous studies suggest that the Negative Expiratory Pressure technique (NEP) can be applied to detect EFL, and that it is a simple and noninvasive technique, which requires no effort of volunteers. However, quantitative indices for evaluating this phenomenon has not been defined, as well as the EFL have not been studied in aging and in various stages of COPD airway obstruction. In this context, the aims of this study were (1) evaluate the EFL during the aging process and (2) study the EFL present in COPD. This is a cross-controlled study evaluation of prevalent cases, with the evaluation unit the individual. The examinations included measurement of NEP and spirometry. We selected healthy individuals divided in three groups: young group (GJ, n = 17); middle aged group (GMI, n = 17) and elderly group (GI, n = 17). In the COPD group we selected smoking subjects and people with obstructive disordered, classified in five categories according to the level of obstruction suggested by spirometry: normal spirometric exam (n = 18); mild obstruction (n = 15); moderate obstruction (n=18), severe obstruction (n = 18) and very severe obstruction (n=18). In the aging group, LFE% parameter was the more adequate to characterize the EFL present during the aging process, showing a moderate correlation. The parameters ∆EF0-50% and ∆EF25-75% showed a reasonable correlation with the progression of age, possibly because the EFL in the elderly have components of the upper airways. In the COPD group, the more adequate parameter to characterize the EFL was the LFE%. Significant changes were also found with the parameters ∆EF0-50% and ∆EF25-75%. Evaluating the influence of age in this group, it can be seen that age contributes for the LFE. However, the effect of the disease was higher than that associated with ageing. It can be concluded that: (1) NEP is a useful tecnique in the study of LFE in healthy elderly people, (2) In these individuals the LFE occurs mainly in the extrathoracic airways, (3) NEP tecnique is useful in evaluating patients with COPD, and: (4) the effects of COPD diseases overlaps the effect of aging.

In patients affected by acute respiratory failure or acute respiratory distress syndrome (ARDS) the leading cause of death is failure of different vital organs other than the lungs, so called multiple organ dysfunction syndrome (MODS). The abdominal organs have a crucial role in the pathogenesis of this syndrome. There is a lack of knowledge regarding the mechanisms by which mechanical ventilation can affect the abdominal compartment. One hypothesis is that mechanical ventilation can interfere with abdominal fluid balance causing edema and inflammation. We addressed the question whether different levels of ventilatory support (mechanical ventilation with different levels of positive end-expiratory pressure, PEEP, and spontaneous breathing with or without PEEP) can influence abdominal edema and inflammation in both healthy and endotoxin-exposed animals. The effect on lymphatic drainage from the abdomen exerted by different degrees of ventilatory support was evaluated (paper I). We demonstrated that endotoxin increases abdominal lymph production, that PEEP and mechanical ventilation increase lymph production but also impede lymphatic drainage; spontaneous breathing improves lymphatic drainage from the abdomen. By adapting a non-invasive nuclear medicine imaging technique and validating it (paper II), we have been able to evaluate extravascular fluid accumulation (edema formation) in the abdomen over time (paper III) demonstrating that edema increases during endotoxemia, mimicking a sepsis-like condition, and that spontaneous breathing, compared to mechanical ventilation, reduces extravascular fluid. Pro-inflammatory cytokines TNF-α and IL-6 in intestinal biopsies are reduced during spontaneous breathing compared to mechanical ventilation. Abdominal edema results in increased intra-abdominal pressure (IAP): in paper IV we analyzed the effect of increased intra-abdominal pressure on the respiratory system. Pulmonary shunt fraction increased with high IAP both in healthy and LPS animals, resulting in decreased level of oxygenation. These changes are only partially reversible by reducing IAP. In conclusion, mechanical ventilation is a life-saving tool but the possible side effect at the extra-pulmonary level should be considered, and the introduction of some degree of spontaneous breathing when clinically possible is a suggested choice.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Our study focuses on the connection between existence of a punctum fixum (or point of support) and respiratory muscle strength. Respiratory muscles execute both respiratory and postural function. Therefore, their strength defines both of these functions. We summarize contemporary knowledge about respiratory and postural functions of the respiratory muscles, their interactions and the connection to postural stability. We used a spirometry assesment of maximal respiratory pressures (PImax and PEmax). The values of PImax (PEmax respectively) retrieved in stance and during water immersion without stable support were compared. We found statistically significant differences. PImax was lower in the water immersion situation (p=0,0009; p≤0,05) and so was PEmax (p=0,0076; p≤0,05). Regarding the results, we suppose a significant influence of punctum fixum presence/absence on maximal respiratory muscle strength. Possible reasons are discussed.

Le Syndrome de détresse respiratoire aiguë (SDRA) est une pathologie fréquente et grave. Son traitement fait appel à la ventilation mécanique qui est indispensable pour maintenir une oxygénation suffisante mais elle peut induire des lésions pulmonaires responsables d'une morbidité importante. Le volume pulmonaire est diminué au cours du SDRA ; sa mesure a longtemps été du domaine de la recherche clinique mais une technique de mesure au lit du patient a récemment été proposée : le lavage de l'azote. Ce travail avait pour but de tester la mesure du volume pulmonaire par la technique du lavage de l'azote dans des conditions d'utilisation comparables à celles du SDRA c'est à dire avec des niveaux de pression expiratoire positive (PEP) et de FiO2 élevés. Une fois cette étape préliminaire validée, nous avons utilisé la mesure du volume pulmonaire pour évaluer le recrutement induit par des réglages de PEP différents et lors de changements de position.Nous avons montré dans l'étude n°1 que les mesures étaient suffisamment précises et reproductibles pour une utilisation clinique. La PEP et le niveau d'oxygénation influençaient peu les mesures. Dans l'étude n°2, le recrutement induit par une PEP de type « recrutement maximal » réglée pour obtenir une pression de plateau (Pplat) entre 28 et 32 cmH2O, a été estimé à partir des mesures de volume pulmonaire comparées à l'augmentation minimale prédite du volume pulmonaire. Une bonne corrélation avec le recrutement mesuré par la technique des courbes pression - volume était trouvée sous réserve d'une élimination des mesures incohérentes.Parallèlement, la mesure du volume pulmonaire et l'oxygénation de patients en SDRA et Acute Lung Injury (ALI) ont été analysées lors de changements de position (Position demi-assise puis assise). Cette étude montre que le volume pulmonaire est augmenté lors de la verticalisation et particulièrement chez les patients augmentant leur oxygénation > 20%. Les patients ne répondant pas au positionnement avaient des volumes pulmonaires plus élevés et qui variaient peu.Les différents travaux réalisés ont permis de montrer la simplicité d'utilisation de la technique. Ceci offre des perspectives de recherche au lit du patient plus accessibles qu'avec les techniques de référence (scanner et dilution de l'hélium), et également des perspectives cliniques. Une approche de la déformation pulmonaire induite par la ventilation (strain) et potentiellement des lésions induites par la ventilation mécanique est rendue possible par la mise à disposition en clinique de cette technique. / The acute respiratory distress syndrome (ARDS) is a frequent and severe form of acute respiratory failure. Mechanical ventilation is the cornerstone of treatment but it may induce a specific form of lung injury (Ventilator induced Lung Injury) responsible for superimposed morbidity and mortality. Lung volume is dramatically decreased during ARDS. Lung volume measurements remained limited to clinical research until recently when the nitrogen washout/washin technique has been adapted for bedside use and implemented in an intensive care ventilator. The aim of this work was to test the nitrogen washout/washin method in clinical conditions of ARDS treatment with high Positive End Expiratory Pressure (PEEP) and high oxygen fraction (FiO2). Once this preliminary validation study was realised, we used the technique to assess the amount of lung recruitment induced by PEEP and positioning.We showed in the first study that accuracy and reproducibility of the technique were acceptable. PEEP and FiO2 had a minor influence on measurements. In the second study, the recruitment induced by a “maximal recruitment” PEEP set to obtain a plateau pressure between 28-32 cmH2O has been estimated using end-expiratory lung volume (EELV) measurements. A significant correlation was found between the recruitment measured on Pressure/Volume curves and the recruitment estimated comparing the predicted minimal increase in lung volume and the true increase in EELV.In a third study, we have evaluated the concomitant effects of verticalization on EELV and oxygenation following a change from supine to semi recumbent, seated and back to supine position. In this third study, verticalization (seated position) resulted in a significant concomitant increase in lung volume and oxygenation. Interestingly, patients responding to verticalization had lower EELV at baseline than non-responders. Only the group of patients increasing their PaO2/FiO2>20% during verticalization had a significant increase in their EELV compared to non-responders.These three studies confirmed the feasibility of the technique, easier than the gold standard techniques (helium dilution or CT scan), and offering both research and clinical perspectives. This technique should also allow an easier approach of the strain induced by ventilation and assess the risk of ventilation induced lung injury.

Bibliographic identification HAVLIŠTOVÁ, Michaela. Respiratory physiotherapy affects the quality of life of children with SMA - how, when and why? Prague: Charles University, 2nd Faculty of Medicine, Department of rehabilitation and sport medicine, 2012. 81 p. Supervisor Doc. PaedDr. Libuše Smolíková, Ph. D. Annotation This thesis deals with the influence respiratory function in children with spinal muscular atrophy (SMA). The theoretical part provides an overview of respiratory physiotherapy techniques that can be used in the care of the airways in people with SMA. The practical part deals with the question whether it is possible using the selected techniques of respiratory physiotherapy after six weeks of training to affect ventilatory parameters in children with SMA. The group of six probands with SMA I. - III. type in the range of the age from 3.5 to 12 years participated in this study. To objectively assess changes was performed spirometry efore the beginning of the therapy and after its conclusion. The main therapy was daily training with inspiratory breath simulator CliniFlo. After the finishing of therapy there was a positive change in all measured parameters except for vital capacity (VC) and maximal expiratory flow at 75% of FVC (MEF75), where the values didn't change. Statistically significant...

Objetivo: Avaliar os efeitos do uso de dois diferentes níveis de pressão expiratória final positiva (PEEP) em porcos submetidos a transplante pulmonar unilateral através de troca gasosa [pressão parcial de oxigênio (PaO2) e pressão parcial de dióxido de carbono (PaCO2)], hemodinâmica [freqüência cardíaca (FC), pressão arterial média (PAM) e pressão da artéria pulmonar (PAP)], parâmetros ventilatórios [pressão media das vias aéreas (Pmédia); complacência estática (Cst) e resistência das vias aéreas (Rest)], resposta inflamatória [interleuina 8 (IL-8)] e estresse oxidativo [substância reativa ao ácido tiobarbitúrico (TBARS) and superóxido dismutase (SOD)]. Material e Métodos: Doze porcos pesando aproximadamente 30kg foram submetidos a transplante pulmonar esquerdo. Os animais foram randomizados em dois grupos de diferentes valores de PEEP: Grupo 1 (PEEP=5cmH2O) e Grupo 2 (PEEP=10cmH2O). Dados hemodinâmicos, troca gasosa e mecânica respiratória foram medidos em diferentes tempos após o transplante durante 210 minutos. Foi realizada análise histológica, de IL-8 e estresse oxidativo no tecido pulmonar. Resultados: O grupo 2 apresentou aumento significativo da FC (p=0,006) e Cst (p=0.001), diminuição da PAM (p=0.003) e Rest (p=0.001). Não houve diferença entre os grupos na concentração de TBARS, SOD e IL-8. Contudo, após o período de observação, o grupo 2 mostrou um aumento da concentração de TBARS (p=0,001) e IL-8 (p=0,05) e o grupo 1 um aumento da SOD (p=0,05) comparado com os valores iniciais. Conclusão: O uso de altos níveis de PEEP, após o transplante pulmonar unilateral, não resultou em melhora da troca gasosa. Embora apresentasse uma melhora da mecânica respiratória, a PEEP de 10 cmH2O teve impacto negativo nos parâmetros hemodinâmicos, e provocou um aumento da resposta inflamatória e estresse oxidativo. / Objective: Evaluate the effects of two different levels of positive end expiratory pressure (PEEP) on pigs submitted to unilateral lung transplantation through blood gas exchange [partial oxygen arterial pressure (PaO2) and partial carbon dioxide arterial pressure (PaCO2)], hemodynamics [heart rate (HR), mean arterial pressure (MAP) and pulmonary arterial pressure (PAP)], ventilatory parameters [mean airway pressure (P(aw)); static compliance (Cst) and airway resistance (Rest)], inflammatory response [interleukin 8 (IL-8)] and oxidative stress [thiobarbituric acid reactive substances (TBARS) and superoxide dismutase (SOD)]. Material and Methods: Twelve pigs were submitted to left lung transplantation. The animals were randomized into two groups of different PEEP levels: Group 1 (PEEP = 5cmH2O) and Group 2 (PEEP = 10cmH2O). Hemodynamics, gas exchange and respiratory mechanics were measured prior and after surgery for 210 minutes. Cytokines, oxidative stress and histological score were assessed in lung tissue. Results: Group 2 had significantly higher HR (p=0.006), Cst (p=0.001) and lower MAP (p=0.003) and Rest (p=0.001). There were no differences between both groups in TBARS, SOD and IL-8, concentration after transplant. However, at the end of the observation period, group 2 showed higher TBARS (p=0.001) and IL-8 (p=0.05) concentration and group 1 presented higher SOD (p=0.05) when compared to baseline. Conclusion: After unilateral lung transplantation, higher PEEP levels had no effect on gas exchange. Although, 10 cmH2O PEEP improved respiratory mechanics, it had a negative impact on hemodynamics and stimulated a high inflammatory response and production of reactive oxygen species.

As vídeo-cirurgias realizadas na cavidade torácica requerem o colapso total ou parcial do pulmão ipsilateral, geralmente obtido pela ventilação pulmonar seletiva (VPS). Uma alternativa à VPS é a ventilação pulmonar não-seletiva (VPNS) em combinação com insuflação torácica (IT) com dióxido de carbono (CO2) no hemitórax do pulmão ipsilateral, o que acarreta alterações cardiorrespiratórias significativas. Para manutenção da homeostasia respiratória nestes pacientes, pode-se utilizar a pressão positiva expiratória final (PEEP), a fim de aumentar a PaO2. Este estudo avaliou, pela primeira vez, os efeitos cardiorrespiratórios de diferentes níveis de IT com CO2 (0, 5 e 10 mm Hg) associado a diferentes níveis de PEEP (5 e 10 cm H2O) em 12 suínos sob anestesia com isoflurano (1 x concentração alveolar mínima) e ventilação convencional durante toracoscopia direita. Um cateter de Swan-Ganz e um analisador de gases foram utilizados para monitorar os parâmetros cardiorrespiratórios durante o experimento. Os dados basais foram obtidos sob VM, sem uso de IT com CO2 e PEEP. Cada animal foi anestesiado uma única vez, recebendo três tratamentos e servindo como seu próprio controle. A indução anestésica foi realizada com bolus de propofol, pela via intravenosa (5 mg/kg). Subseqüentemente à intubação orotraqueal, os animais foram posicionados em decúbito dorsal, conectados ao circuito anestésico reinalatório e instrumentados para registro dos parâmetros das variáveis estudadas. Após a estabilização do plano anestésico, administrou-se pancurônio (0,1 mg/kg, IV) com imediato início da ventilação controlada à pressão com uma FiO2 de 1, objetivando-se a manutenção do valor de ETCO2 entre 35 e 45 mm Hg. As medidas foram divididas em seis momentos (M), com incrementos graduais da pressão de IT: M1 (PEEP de 5 cm H2O e IT de 0 mm Hg); M2 (PEEP 10 e IT 0); M3 (PEEP 5 e IT 5); M4 (PEEP 10 e IT 5); M5 (PEEP 5 e IT 10) e M6 (PEEP 10 e IT 10). Os animais foram ainda divididos em 2 grupos (n=6), onde um recebeu tratamento para manutenção da pressão arterial média (PAM) ≥ 60 mm Hg (grupo não-tratado, GNT; grupo tratado, GTH). Os valores foram submetidos à análise de variância para medidas repetidas para avaliar os efeitos do tratamento nas variáveis hemodinâmicas e pulmonares (p < 0,05). O uso de IT de 10 mm Hg, independente do valor da PEEP associada, induziu uma redução significativa do índice cardíaco, do volume sistólico, do índice de trabalho do ventrículo direito, da complacência dinâmica, do pH arterial e da diferença arteriovenosa de oxigênio, além de aumento na freqüência cardíaca. O uso de PIT de 10 mm Hg, independente do valor da PEEP associada e o uso de PIT de 5 mm Hg associada à PEEP de 5 cm H2O induziu um aumento significativo da diferença alvéolo-arterial de oxigênio, além de redução do conteúdo arterial de oxigênio e da pressão parcial de oxigênio arterial. Ocorreu ainda aumento progressivo da pressão de pico inspiratória, do espaço morto fisiológico, da pressão venosa central, da pressão média da artéria pulmonar e da pressão parcial de CO2 arterial, de acordo com o incremento da IT, além de manutenção das pressões arteriais, em ambos os grupos. Com exceção à associação de PEEP de 5 cm H2O e PIT direita com CO2 de 5 mm Hg, a estratégia ventilatória com PEEP de 5 ou 10 cm H2O e PIT direita com CO2 em níveis pressóricos ≤ a 5 mm Hg pode ser uma ferramenta eficaz para futuros estudos em toracoscopia, em suíno submetido à toracoscopia sob ventilação não-seletiva e FiO2 = 1. / Video-assisted thoracoscopy surgery (VATS) requires lung collapse, at least partially. This condition is usually obtained by one-lung ventilation (OLV). An alternative method is associate two-lung ventilation with carbon dioxide (CO2) insufflation in the operated hemithorax, but this is accompanied by an increased risk of hemodynamic and respiratory deterioration. PEEP can be used in this patients for improve arterial oxygenation. The hemodynamic, ventilatory and blood gases effects of different levels of carbon dioxide insufflations (0, 5 and 10 mm Hg) associated with different levels of PEEPs (5 and 10 cm H2O) under two-lung ventilation were evaluated in twelve isoflurane (1 minimum alveolar concentration) anesthetized pigs during right-sided thoracoscopy. An arterial catheter, Swan-Ganz catheter and multianesthetic gas analyser were used to monitor the cardiopulmonary parameters during the experiment. Baseline data were obtained before intrathoracic pressure (IP) and PEEP elevation. Induction of anesthesia was performed using propofol (5 mg/kg) intravenously. After, the pigs were placed in a dorsal recumbent position and were mechanically ventilated with intermittent positive pressure ventilation. The respiratory rate was adjusted to maintain the end-tidal CO2 concentration between 35 and 45 mm Hg. The measurements were divided in six moments (M), with gradual increment of the IP: M1 (5 cm H2O of PEEP and 0 mm Hg of IP); M2 (10 PEEP and 0 IP); M3 (5 PEEP and 5 IP); M4 (10 PEEP and 5 IP); M5 (5 PEEP and 10 IP) and M6 (10 PEEP and 10 IP). The animals were allocated in two different groups (n=6) which one was treated for maintenance of the mean blood pressure (MBP) ≥ 60 mm Hg. The values were compared among the various time points by use of ANOVA for repeated measures (p < 0,05). IP of 10 mm Hg, independently of the associated PEEP, induced a significant decrease in cardiac index, stroke volume, right ventricular stroke work index, dynamic complacency, arterial pH and arteriovenous oxygen difference, in addition to significant increase in heart rate. IP of 10 mm Hg, independently of the associated PEEP and the application of IP of 5 mm Hg associated with PEEP of 5 cm H2O induced a significant increased in alveolar-arterial oxygen difference, whereas decrease the arterial oxygen content and the partial pressure of arterial oxygen. Peak airway pressure, physiologic dead space, central venous pressure, mean pressure pulmonary artery and partial pressure of arterial CO2 decreased significantly, according with increment of the IP, in addition to maintenance of arterial pressures in both groups. The exception of the combined use of 5 PEEP with 10 IP (M3), the ventilatory strategy with 5 or 10 PEEP associated to carbon dioxide insufflation into the right hemithorax with an intrapleural pressure ≤ 5 mm Hg in 1 MAC isoflurane anesthetized pig under two-lung ventilation with FiO2 = 1, can be an useful adjunct for futures studies in thoracoscopy.

<p>The extension of laparoscopic procedures into the chest may induce specific pathophysiologic effects.</p><p>In pigs, we have demonstrated how devastating a combined thoraco-laparoscopic approach can be for gas exchange. Furthermore, the transmission of elevated pressure intra-cranially is a potential danger. The application of positive end-expiratory pressure (PEEP) was found to improve gas exchange and, more importantly, hypoxemia could be avoided. The application of PEEP did not increase intra-cranial pressure further; nor did it adversely affect cerebral circulation.</p><p>Even before the introduction of the laparoscopic technique, there was a substantial increase in the annual number of antireflux procedures. Therefore, the threefold increase of the incidence of antireflux surgery recorded during the past decade cannot solely be explained by the introduction of minimal access surgery. However, a clear shift in the preferred methodology took place. This change was not scientifically supported at the time of the transition and, surprisingly, it is still not supported today. In comparison with open surgery, patients do not seem to derive significant long-term benefits from having the antireflux procedure done laparoscopically. As was demonstrated, laparoscopy might even be an inferior approach in some patients. Nevertheless, it is reasonable to assume that laparoscopy can yield equally good results as open surgery despite our failure to confirm that in our studies. Determination of the effectiveness of minimal access surgery in the treatment of GORD is critical, before minimal access techniques become the standard for antireflux surgery in the community.</p>