O objetivo desse estudo foi comparar a pressão das varizes (PV), a tensão da parede (TP) e parâmetros endoscópicos, ultra-sonográficos e de Doppler em esquistossomóticos com (grupo I, n=7) e sem (grupo II, n=12) antecedente de sangramento. A PV and a TP no grupo I foi 14,7±3,0 mm Hg e 526,1±234,4, em contraste com 11,0±2,0 and 340,8±103,8 no grupo II (p=0,0053). PV acima de 12 mmHg foi observada em 71% dos casos com sangramento prévio e em 8% daqueles que nunca sangraram (0,0095). A PV correlacionou-se significantemente com a TP (p=0,0022). Nenhum parâmetro endoscópico, ultra-sonográfico ou de Doppler foi capaz de diferenciar os grupos I e II / This study was undertaken to compare variceal pressures (VP), wall tensions (WT), and endoscopic, ultrasound and Doppler parameters in schistosomiasis patients with (group I, n=7) and without (group II, n=12) previous bleeding. The VP and the WT in group I were 14.7±3.0 mm Hg and 526.1±234.4 respectively, in contrast to 11.0±2.0 and 340.8±103.8 in the group II (p=0,0053). VP over 12 mmHg was found in 71% of the patients with previous hemorrhage, compared with 8% of patients who had never bled (0,0095). VP significantly correlated with WT (p=0,0022). No endoscopic, ultrasound or Doppler parameters were shown to be different in patients with and without previous bleeding

A estase de secreção salivar e alimentos deglutidos na luz esofágica de pacientes com megaesôfago chagásico traz como consequências: (1) supercrescimento bacteriano na luz do órgão, (2) episódios de aspiração pulmonar e infecções respiratórias de repetição, (3) aumento do risco dos procedimentos terapêuticos cirúrgicos ou endoscópicos em caso de perfuração pela maior possibilidade de contaminação, (4) desenvolvimento de processos inflamatórios crônicos na mucosa esofágica, que podem predispor ao aparecimento de displasia e câncer. Apesar disto, a microbita esofágica no megaesôfago nunca foi estudado. Esse estudo teve o objetivo de analisar qualitativa e quantitativamente a microbiota presente no líquido de estase esofágico de pacientes portadores de megaesôfago chagásico, comparando-a com a existente em indivíduos sadios. Foram estudados prospectivamente 25 pacientes (10 homens e 15 mulheres) com idades variando de 24 a 74 anos ( &#61507; = 49,1a). Quinze pacientes eram portadores de esofagopatia chagásica, sendo 5 portadores de mega grau I (MG1), 5 portadores de mega grau II (MG2) e 5 portadores de mega grau III (MG3), segundo a classificação de Rezende; e 10 indivíduos sadios, agrupados no Grupo Controle (GC). Utilizou-se método de coleta que permitia aspiração de líquido através de sonda de Levine diretamente da luz esofágica, evitando-se a contaminação com microrganismos da orofaringe. Após análise microbiológica qualitativa e quantitativa, foi feita a descrição dos microrganismos encontrados nos vários grupos e sua classificação em aeróbios Gram positivos, aeróbios Gram negativos, anaeróbios e fungos. A análise estatística visou avaliar diferenças quantitativas entre os microrganismos nos diferentes grupos, sendo para tanto utilizado o teste não paramétrico de Kruskal-Wallis, com nível de rejeição menor 0,05 (5%). A positividade das culturas no Grupo Controle foi 40%, com predomínio do gênero Streptococcus sp, em concentrações que variaram de 101 a 102 ufc/ml. No Grupo Megaesôfago 93,3% da culturas foram positivas, com grande variedade de bactérias, mas predomínio de aeróbios Gram positivos (Streptococcus sp. foi o mais comum) e anaeróbios (Veillonella sp foi a mais freqüente) em concentrações que variaram de 101 a 105 ufc/ml. As concentrações foram geralmente mais elevadas em MG3, quando comparado com MG1, MG2 e GC (p<0,05). Concluiu-se que no megoesôfago, diferentemente dos indivíduos sadios, existe a presença de rica microflora bacteriana, constituída principalmente por aeróbios Gram positivos e anaeróbios, em concentrações tanto maiores quanto maior o seu grau de dilatação. Parte desta microbiota tem capacidade de metabolizar nitratos, etapa importante na formação de nitrosaminas. / The stasis of saliva and swallowed food in the esophageal lumen of patients with chagasic megaesophagus causes: (1) bacterial overgrowth in the esophageal lumen, (2) recurring pulmonary aspirations and respiratory infections, (3) increased risk of surgical or endoscopic procedures if perforation occurs by the major possibility of contamination, and (4) the development of chronic inflammatory process in esophageal mucosa, that can predispose to the development of dysplasia and cancer. In spite of this, esophageal microbiota in the megaesophagus has never been studied. The aim of this study was to analyze qualitatively and quantitatively the microbiota in chagasic megaesophagus in comparison to the normal esophagus. Twenty-five patients (10 men and 15 women) were prospectively studied, with ages varying from 24 to 74 years (&#61507;=49,1), from March to September 2000. Fifteen patients with chagasic megaesophagus (MG), were divided into three sub- groups according to the grade of esophageal dilation: MG1 – 5 patients with megaesophagus grade I; MG2- 5 patients with megaesophagus grade II; MG3- 5 patients with megaesophagus grade III. Another group of ten patients without any esophageal disease was constituted in the Control Group (CG). The sample collection was performed using a method specially developed to avoid contamination with microorganisms of the oral cavity and oropharynx. After qualitative and quantitative analysis, the microorganisms found were described and classified as Gram positive aerobes, Gram negative aerobes, anaerobes and fungus. Statistical analysis using Kruskal-Wallis non-parametric test was performed in order to find quantitative differences of microorganisms in the different groups. In CG 40% of the cultures were positive with predominance of the genus Streptococcus sp, in concentrations that varied from 101 to 102 cfu/ml. In MG, 93,3% of the cultures were positive, with great bacterial variability and predominance of a variety of aerobic Gram-positive (Streptococcus sp was the most common) and anaerobic bacteria (Veillonella sp was the most frequent), in concentrations that varied from 101 to 105 cfu/ml. The bacterial concentrations were generally more elevated in MG3 in comparison to MG1, MG2 and CG (p<0,05). It was concluded that patients with megaesophagus present a varied microbiota constituted mostly of aerobic Gram positive and anaerobic bacteria, in concentrations that vary with the megaesophagus dilatation degree. Some of the bacteria found in MG are able to metabolize nitrates intro nitrites, an important step in the formation of nitrosamines.

O objetivo deste estudo foi correlacionar as alterações causadas pela doença de Chagas no sistema nervoso autônomo e a possibilidade destas alterações provocarem disfunção erétil. Foram incluídos 60 pacientes, do sexo masculino, entre 40 e 70 anos, sendo 30 com a forma digestiva da doença de Chagas e 30 como grupo controle negativos para tripanossomíase; foram utilizados o questionário auto-aplicável do Índice Internacional de Função Erétil (IIFE) e o algoritmo de pontuação para análise e interpretação do questionário.Os resultados obtidos neste estudo comprovaram que a doença de Chagas não afetou a função erétil dos pacientes, que não há diferença significativa se a lesão é do esôfago ou de esôfago e cólon e que a doença de Chagas não deve ser considerada um fator de risco para a disfunção erétil / The objective of this study was to correlate the alterations caused by the Chagas'disease in the autonomous nervous system and the possibility of these alterations they provoke erectile dysfunction. Sixty men - between 40 and 70 years-old - were selected for the stydy: 30 men with the digestive form of the Chagas'disease and 30 of them had negative serologic findings for T. Cruzi. It was used the questionnaire of the International Index of Erectile Function (IIEF) and the punctuation algorithm for interpretation of the questionnaire. The results this study they proved that the Chagas'disease didn't affect the patients' erectile function, that there is not significant difference if the lesion is of esophagus or esophagus and colon and Chagas'disease should not be considered a risk factor for the erectile dysfunction

O objetivo deste trabalho foi avaliar comparativamente os resultados tardios da esofagectomia transdiafragmática com gastroplastia e da operação de Serra Dória para o tratamento do megaesôfago avançado. Foi realizado estudo coorte em 44 pacientes. O seguimento tardio no Grupo EG foi de 77,0 meses, e no Grupo SD de 62,1 meses. Utilizou-se interrogatório para queixas gastrointestinais, escalas de Schechter e de Visick, assim como dois questionários. Incluíram-se dados antropométricos, bioquímicos e endoscópicos. A satisfação com a cirurgia medida pela escala de Visick foi equivalente nas duas operações praticadas, sem diferenças estatísticas. Também nos questionários o perfil foi equilibrado. Houve maior a incidência de esofagite no grupo EG; Não houve diferenças significativas com relação à avaliação clínica, nutricional, histológica e de qualidade de vida / The objective of the paper was to carry out a comparative evaluation of the late results of a transdiaphragmatic esophagectomy with an associated gastroplasty and of the Serra Dória procedure, for the treatment of advanced megaesophagus. A cohort study was done on 44 patients. Late follow up for the EG Group was 77.0 months, and for the SD Group, 62.1 months. Several tools were used, such as a series of questions for gastrointestinal complaints, the Schechter and the Visick scales. Anthropometric data were included, as well as the biochemical and endoscopic parameters. Satisfaction with the surgery, as measured by the Visick scale, was equivalent in the two types of surgery, and no statistical differences were observed. There was a higher incidence of the esophagitis in the SD group; There were no significant differences with regards to clinical and nutritional evaluation, histology and quality of life

Abstract Incidence of esophageal adenocarcinoma is rising rapidly in Western countries. The main risk factor for esophageal adenocarcinoma is Barrett’s esophagus. Barrett’s esophagus results from long-term gastroesophageal reflux disease. The gastrointestinal tract is colonized by bacteria, fungi and viruses forming the alimentary tract microbiome. Microbiome transformation is involved in pathogenesis of alimentary tract cancer and also in the development of Barrett’s metaplasia. Toll-like receptors (TLR) are molecules of the innate immune system and they are involved in bacterial and viral recognition and regulation of immune functions in the host and cancer cells. This thesis examined the effect of alimentary tract microbiome and cancer- on the function of TLRs in normal gastrointestinal epithelial cells. An additional focus of the thesis was also to assess the carcinogenetic effect of TLRs 1–9 in Barrett’s esophagus metaplasia – dysplasia – carcinoma sequence. Study material consisted of: a patient cohort, organ donors, conventional and germ-free mice. TLRs are expressed also in a “microbe-free” gut. There were significant differences in all TLRs between small- and large intestine of conventional mice and in humans. In germ-free mice that difference was not observed. Normal tissue sampled adjacent to the tumors of cancer patients can be used as controls in immunohistochemical TLR studies in gastrointestinal cancer Clinical data indicate that TLRs linearly increase toward dysplasia in Barrett’s esophagus. High cytoplasmic and nuclear TLR4 expression and TLR1 and 8 nuclear immunoreactivity in esophageal adenocarcinoma are associated with metastatic disease and poor prognosis. Based on our results, bacteria seem to downregulate TLR expression of the intestine. TLRs 1–9 apparently have a role in malignant progression of Barrett’s dysplasia. TLR1, TLR4 and TLR8 may represent a novel therapeutic target in esophageal adenocarcinoma. / Tiivistelmä Ruokatorven adenokarsinooma on länsimaissa nopeasti yleistyvä syöpätyyppi. Tämän syöpätyypin tärkein riskitekijä on Barrettin ruokatorvi, joka kehittyy pitkään jatkuneen gastroesofageaalisen refluksitaudin pohjalta. Ruuansulatuskanavassa on suuri määrä bakteereja, sieniä ja viruksia, jotka muodostavat yhdessä ruuansulatuskanavan mikrobiomin. Normaalin mikrobiomin muutokset ovat yhteydessä usean eri ruuansulatuskanavan syövän patogeneesiin ja myös Barrettin ruokatorven muodostumiseen. Tollin kaltaiset reseptorit ovat luontaisen immuniteetin molekyylejä, jotka osallistuvat bakteerien ja virusten tunnistukseen ja sääntelevät immuunivastetta sekä normaalitilanteessa että syövissä. Väitöskirjassa tutkitaan ruuansulatuskanavan mikrobiomin ja syövän vaikutuksia normaalien epiteelisolujen TLR:ien toimintaan. Lisäksi selvitetään TLR:ien karsinogeneettisiä vaikutuksia Barrettin ruokatorven metaplasia- dysplasia -adenokarsinoomasekvenssissä. Tutkimusmateriaalina käytetään potilaskohortista ja elinluovutuksista peräisin olevia potilasnäytteitä sekä normaalien ja bakteerittomien hiirien näytteitä. Tuloksemme osoittavat, että TLR:t ilmentyvät myös bakteerittomassa ruuansulatuskanavassa, ja TLR:en ilmentyminen oli merkittävästi voimakkaampaa ohutsuolessa kuin paksusuolessa normaaleilla hiirillä ja ihmisillä. Tätä eroa ei havaittu bakteerittomilla hiirillä. Ruuansulatuskanavan syöpien viereistä ja sen altistamaa tervettä kudosta voidaan käyttää terveenä kontrollina immunohistokemiallisissa TLR- tutkimuksissa. Kliinisessä aineistossa TLR:ien ilmentyminen kasvaa lineaarisesti kohti dysplasiaa Barrettin ruokatorvessa. TLR4:n korkea ilmentyminen solulimassa ja tumassa sekä TLR8:n ilmentyminen tumassa ovat yhteydessä metastaattiseen tautiin ja huonoon ennusteeseen. Tulosten perusteella bakteerit näyttävät heikentävän TLR:ien toimintaa suolistossa. Lisäksi kaikilla tutkituilla TLR:illä (1–9) näyttää olevan osuutta Barrettin dysplasian etenemisessä kohti syöpää. TLR1, TLR4 ja TLR8 ovat mahdollisia terapeuttisia kohteita ruokatorven adenokarsinoomassa.

Abstract Cancers of the alimentary tract include many common cancer types, some of which have well-established treatment protocols and relatively good prognosis, such as colorectal cancer, and others, which have generally very poor prognosis. The gastrointestinal canal is colonized by a multitude of bacteria, the effects of which are currently poorly understood. Toll-like receptor 9 (TLR9) in cells of the alimentary tract recognizes the bacterial DNA-fragments and regulates immune functions in the host and the cancer. This thesis examines the function and prognostic significance of Toll-like receptor 9 in oral and esophageal squamous cell carcinoma as well as in esophageal, gastric and colorectal adenocarcinoma. The studies were made using tissue samples from patient cohorts and various cell culture techniques. Our data indicate that high expression of Toll-like receptor 9 in cancer cells associates with metastatic properties in oral and esophageal cancers and poor prognosis in esophageal adenocarcinoma and oral squamous cell carcinoma. Cell culture studies further suggest that TLR9 is functional in alimentary tract cancers and mediates cellular invasion when activated. Based on the results, TLR9 is active in alimentary tract cancers and its expression is related to poor cancer prognosis. Thus, TLR9 may represent a novel therapeutic target in alimentary tract cancers and might provide a link between bacteria and oral and gastrointestinal cancer. / Tiivistelmä Ruuansulatuskanavan syöpiin lukeutuu useita yleisiä syöpätyyppejä, kuten kohtalaisen hyväennusteinen paksusuolen syöpä, jonka hoitokäytäntö on vakiintunut. Toisissa ruuansulatuskanavan syövissä puolestaan ennuste on hyvin huono. Mahasuolikanavaa asuttavat moninaiset bakteerikannat, joiden vaikutuksia ymmärretään vielä kehnosti. Tollinkaltainen reseptori 9 (TLR9) tunnistaa näiden bakteerien DNA-rakenteita ja vaikuttaa yksilön ja syövän immuunivasteeseen. Tämä väitöstutkimus selvittää TLR9:n toimintaa ja ennustevaikutusta suun ja ruokatorven levyepiteelisyövissä, sekä ruokatorven, mahalaukun ja paksusuolen adenokarsinoomassa. Tutkimus toteutettiin käyttäen syöpäpotilaiden kudosnäytteitä sekä soluviljelytekniikoita. Tuloksemme osoittavat, että TLR9:n lisääntynyt ilmentyminen syöpäsoluissa yhdistyy metastasointiin suu- ja ruokatorvisyövissä, sekä korkeaan kuolleisuuteen suun levyepiteelisyövässä ja ruokatorven adenokarsinoomassa. Soluviljelykokeidemme tuloksiin nojaten TLR9 toimii ruuansulatuskanavan syövissä ja sen aktivaatio saa aikaan solujen invasoitumisen. Tutkimustuloksiimme vedoten TLR9 on aktiivinen ja toimiva ruuansulatuskanavan syövissä ja sen ilmentyminen liittyy huonoon ennusteeseen. TLR9 saattaa osoittautua uudeksi syöpähoitojen kohteeksi tai yhdistäväksi tekijäksi syövän ja bakteerien välillä ruuansulatuskanavan syövissä tulevaisuudessa.

PhD (Department of Biotechnology, Faculty of Applied and Computer Sciences), Vaal Universtiy of Technology / The genus Tulbaghia has been used in traditional medicine to treat various ailments such as fever, earache, tuberculosis and esophageal cancer. However, there is limited scientific evidence to support its use. Therefore the objectives of this study were to perform phytochemical analysis, investigate the antioxidant, antimicrobial, anticancer, immunomodulatory activities and toxicity of crude acetone and water extracts from selected Tulbaghia species. Standard methods were used for preliminary phytochemical analysis. The total phenolic content of the plant extracts was determined using the folin ciocalteu method whereas the total flavonoids were determined by using the aluminium chloride colorimetric method. DPPH and ABTS assays were used to evaluate the antioxidant activity. The antimicrobial activity was assessed by agar well diffusion, microtiter dilution and time kill assays. For anticancer studies, the antiproliferative activity of the extracts was evaluated using the MTT assay on Hkesc-1 and KB cells. Morphological changes of the cancer cells treated with extracts were examined using light microscopy. Induction of apoptosis was assessed using fluorescence microscopy and acridine orange/ethidium bromide staining. Flow cytometry analysis was conducted to examine the multicaspase activity and cell cycle arrest. For immunomodulatory activity, the Greiss reagent and Luminex cytokine assays were used to determine the effect of the extracts on NO production and the concentration of the cytokines in the treated cells, respectively. Toxicity of selected Tulbaghia species was examined by investigating the effect of the extracts on the metabolic activity and cell membrane integrity on the treated RAW264.7 cells using the MTT and LDH assays, respectively. The zebrafish assay was used to evaluate the embryotoxicity and teratogenic effects of crude acetone and water extracts of T. violacea at 24 h intervals for 96 h post fertilisation (hpf). The percentage mortality, hatchability and heart rate were examined. Phytochemical screening of eight Tulbaghia species demonstrated the presence of flavonoids, glycosides, tannins, terpenoids, saponins and steroids. The amount of total phenol and flavonoid content varied in different plant extracts ranging from 4.50 to 11.10 milligrams gallic acid equivalent per gram (mg GAE/g) of fresh material and 3.04 to 9.65 milligrams quercetin equivalent per gram (mg QE/g) of fresh material respectively. The IC50 values based on DPPH and ABTS for T. alliacea (0.06 and 0.06 mg/mL) and T. violacea (0.08 and 0.03 mg/mL) were generally lower showing potential antioxidant activities. For antimicrobial activity, the acetone extracts of T. acutiloba, T. alliacea, T. leucantha, T. ludwigiana, T. natalensis and T. simmleri showed moderate antimicrobial activity against all test organisms while the water extracts showed moderate to no activity. One species, T. cernua, showed poor activity against all the tested microbes. The acetone and water extracts of T. violacea showed the greatest antibacterial and antifungal activity against all the tested microorganisms with minimum inhibitory concentration ranging from 0.1 mg/mL to 3.13 mg/mL. The acetone extracts of T. violacea also exhibited both bacteriostatic/fungistatic and bactericidal/fungicidal activity depending on the incubation time and concentration of the extract. The bactericidal/fungicidal activity was observed at x2 MIC. The results for anticancer activity showed that treatment of Hkesc-1 cells with acetone and water crude extracts had anti-proliferative activity with IC50 values of 0.4 mg/mL and 1.625 mg/mL, respectively while KB had 0.2 mg/mL and 1 mg/mL, respectively. Morphological changes such as blebbing, cell shrinkage and rounding were observed in the treated cells suggesting that apoptosis was taking place. AOEB staining showed that the level of apoptosis was dependent on the concentration of the extracts. The activation of multicaspase activity in both Hkesc-1 and KB treated cells was also concentration dependent leading to cell death by apoptosis and the induction of cell cycle arrest at the G2/M phase. Immunomodulatory activity results indicated that cell viability was above 80% when concentrations of 50 µg/mL or less of both acetone and water crude was used. Treatment with the acetone extract had no significant effect (p>0.05) on the LPS induced NO production in RAW264.7 cells except at 50 µg/mL where significant inhibition was observed. The water extract had no significant effect (p>0.05) on NO production at all the concentrations. Treatment of LPS–induced RAW264.7 cells with acetone extract stimulated the production of IL-1α, IL-6 and TNF-α, but had no significant effect (p > 0.05) on IL-1β. On the other hand, treatment with the water extracts stimulated the production of IL-1α, IL-6 but had no significant effect (p>0.05) on TNF-α and IL-1β. Treatment of LPS-induced RAW264.7 cells with the acetone extract had very little stimulatory effect on IL-4, IL-5 and IL-13 and no significant effect on IL-10 whereas for the water extract a significant stimulatory effect was only observed for IL-4 after 48 h of treatment. High concentrations (>10000 pg/mL) of MCP-1, MIP1-α, MIP1-β, MIP-2, GCSF, GM-CSF, RANTES and IP-10 were also observed in acetone and water extract treated RAW264.7 cells. For toxicity studies, acetone and aqueous crude leaf extracts from T. alliacea, T. simmleri, and T. violacea had a significant inhibitory (p<0.05) effect on the RAW264.7 cells after 48h treatment. Acetone extracts from T. alliacea, T. simmleri and T. violacea resulted in IC50 values of 0.48 mg/mL, 0.72 mg/mL and 0.1 mg/mL, respectively. Treatment with water extracts showed minimal toxic effect indicated by higher IC50 values of 0.95 mg/mL, 2.49 mg/mL and 0.3 mg/mL for T. alliacea, T. simmleri and T. violacea, respectively. The LDH release by macrophages after 24 h treatment with acetone extracts was observed to be concentration dependent while treatment with water extracts did not induce LDH release. The zebra fish assay showed a lethal dose (LD50) for the T. violacea acetone crude extract of 20 μg/mL whereas that for water extract was 85 μg/mL. The observed teratogenic effects included scoliosis, edema of the pericardial cavity, retarded yolk resorption, hook-like/bent tail and shorter body length. In conclusion, the results from this study indicate that the extracts from the eight Tulbaghia species examined contain phytochemicals that may have the antioxidant, antimicrobial, anticancer and immunomodulatory properties. Extracts from T. violacea were observed to be the most potent. This study thus supports the use of T. violacea in treating bacterial and fungal infections in traditional medicine. The results of this study also confirm the anticancer potential of T. violacea. The immunomodulatory activity of the acetone and water extracts from T. violacea indicated a dominantly pro-inflammatory activity. Traditional medicine prepared form T. violacea may be of benefit to individuals with weak immune systems. The toxicity of selected Tulbaghia species was observed to be concentration, extract and time dependent. Therefore, traditional medicine prepared from Tulbaghia extracts should be taken with caution preferably in small doses over a short period of time. Future studies will focus on the identification of the bioactive compound(s) responsible for the antimicrobial, anticancer and immunomodulatory activities.

No description available.

Law / LL.M.

INTRODUÇÃO: O uso de níveis elevados da pressão expiratória final positiva (PEEP) na Síndrome do desconforto respiratório agudo (SDRA), visando reduzir a quantidade de pulmão colapsado, tornando a ventilação mais homogênea, tem sido apontado por estudos clínicos randomizados e metaanálises como uma estratégia eficaz na melhora de alguns desfechos clínicos. Atualmente, não existe um método ideal para ajuste da PEEP na SDRA. Dois métodos distinguem-se pela racionalidade fisiológica e possibilidade de serem usados na prática clínica usual: ajuste da PEEP guiado por Pressão Esofágica (Pes) e ajuste da PEEP guiado por Tomografia de Impedância Elétrica (TIE). Os objetivos do estudo foram: (1) Avaliar, através de tomografia computadorizada de tórax (raios X), qual estratégia induz uma melhor aeração pulmonar: maior recrutamento pulmonar e menor hiperdistensão; (2) Avaliar as alterações da distribuição regional da ventilação, do volume pulmonar e da complacência regional medidos pela tomografia de impedância elétrica; (3) Avaliar as alterações na mecânica pulmonar e nas trocas gasosas produzidas por ambas as estratégias de titulação da PEEP. MÉTODOS: Dez porcos foram submetidos a um modelo de SDRA grave: depleção de surfactante mais lesão pulmonar induzida pelo ventilador. Após uma manobra de recrutamento (MR), duas estratégias de titulação da PEEP foram testadas em uma sequência aleatória: 1) Utilizando a tomografia por impedância elétrica para calcular a menor PEEP que mantem um colapso pulmonar menor de 1%; 2) Utilizando a pressão esofágica para calcular a PEEP necessária para atingir uma pressão transpulmonar final expiratória (PLexp) entre 5-6 cmH2O. Em seguida, os animais foram ventilados durante 1 hora com a PEEP ótima estimada por cada método. Foram registrados parâmetros fisiológicos e de tomografia computadorizada (TC) antes da MR (tempo basal) e após ventilação com a PEEP ótima (15 min e 60 min). RESULTADOS: Aos 60 min, ambas as estratégias reduziram o colapso pulmonar, mas com efeitos significativamente maiores (P < 0,05) no grupo TIE: tecido não-aerado (20,3 ± 11,8% vs. 38,6 ± 13,1%, TIE vs. Pes respectivamente), recrutamento cíclico (4,8 ± 3,7% vs. 8,7 ± 2,7%), PaO2/FIO2 (289 ± 78 vs. 209 ± 92 mmHg), pressão de distensão (14,5 ± 2,3 vs. 16,1 ± 2,3 cmH2O), e pressão de distensão transpulmonar (11,9 ± 1,7 vs. 13,6 ± 1,8 cmH2O). Apesar da escolha de uma maior PEEP ótima no grupo TIE, a pressão platô (33,2 ± 3,7 vs. 31,5 ± 3,1 cmH2O), a pressão transpulmonar inspiratória final (20,0 ± 2,8 vs. 19,2 ± 1,7 cm H2O) e a complacência das áreas não dependentes do pulmão medidas pela TIE (0,07 ± 0,04 vs 0,06 ± 0,05 unidades arbitrárias/cmH2O) ou TC (1,52 ± 0,90 vs. 1,41 ± 0,98 mL/cmH2O) variaram de forma semelhante nos dois grupos (P > 0,05). O tecido hiperaerado e a hipedistensão cíclica foram baixos em ambos os grupos. CONCLUSÕES: Neste modelo animal de SDRA grave o ajuste da PEEP guiado por TIE produz um maior recrutamento pulmonar e sinais fisiológicas de melhor proteção pulmonar quando comparado com o ajuste da PEEP guiado por Pes / INTRODUCTION: The use of higher levels of positive end-expiratory pressure (PEEP) in the acute respiratory distress syndrome (ARDS), aimed at reducing the amount of lung collapse, making the ventilation more homogeneous, has been pointed out by randomized clinical trials and meta-analysis as an effective strategy to improve some clinical outcomes. Currently, there is no ideal method for adjustment PEEP in ARDS. Two methods are distinguished by their physiological rationality and the possibility of being used in the clinical practice: PEEP titration guided by Esophageal Pressure (Pes) and PEEP titration guided by Electrical Impedance Tomography (EIT). The objectives of the study were: 1) To evaluate through computed tomography of thorax (X-ray), which strategy induces better pulmonary aeration: greater lung recruitment and less hyperdistension; (2) To evaluate changes in the regional distribution of ventilation, pulmonary volume and regional compliance, measured by electrical impedance tomography; (3) To assess changes in lung mechanics and gas exchange produced by both PEEP titration strategies. METHODS: Ten pigs were submitted to a two-hit model of severe ARDS: Surfactant depletion plus ventilator-induced lung injury. After a recruitment maneuver (RM), two strategies of PEEP titration were tested in a randomized sequence: 1) Using electric impedance tomography to calculate the lowest PEEP keeping recruitable-lungcollapse < 1%; 2) Using esophageal pressure to calculate the PEEP needed to achieve an end-expiratory transpulmonary pressure between 5-6 cmH2O. Then, animals were ventilated for 1 hour with the optimum-PEEP estimated by each method. Physiological and computed tomography (CT) parameters were recorded before RM (baseline) and after ventilation at optimum-PEEP (15 min and 60 min). RESULTS: At 60 min, both strategies reduced lung collapse but with significantly (P < 0.05) greater effects in EIT-group: nonaerated tissue (20.3 ± 11.8% vs 38.6 ± 13.1%, EIT vs. Pes, respectively), tidal recruitment (4.8 ± 3.7% vs 8.7 ± 2.7%), PaO2/FIO2 (289 ± 78 vs 209 ± 92 mmHg), driving-pressure (14.5 ± 2.3 vs 16.1 ± 2.3 cmH2O) and transpulmonary driving-pressure (11.9 ± 1.7 vs 13.6 ± 1.8 cmH2O). Despite the choice for a higher optimum-PEEP in the EIT-group; plateau pressure (33.2 ± 3.7 vs 31.5 ± 3.1 cmH2O), end-inspiratory transpulmonary pressure (20.0 ± 2.8 vs 19.2 ± 1.7 cmH2O) and compliance of non-dependent areas measured by EIT (0.07 ± 0.04 vs 0.06 ± 0.05 arbitrary units/cmH2O) or CT (1.52 ± 0.90 vs 1.41 ± 0.98 mL/cmH2O) varied similarly in both groups (P > 0.05). Hyperaerated tissue and tidal hyperinflation were very low in both groups. CONCLUSION: In this model, the choice of PEEP guided by EIT leads to higher lung recruitment and physiological signals of a better lung protection, when compared to the strategy guided by Pes