Sildenafil in endotoxin-induced pulmonary hypertension: an experimental study

Abstract Background Sepsis and septic shock still represent great challenges in critical care medicine. Sildenafil has been largely used in the treatment of pulmonary arterial hypertension, but its effects in sepsis are unknown. The aim of this study was to investigate the hypothesis that sildenafil can attenuate endotoxin-induced pulmonary hypertension in a porcine model of endotoxemia. Methods Twenty pigs were randomly assigned to Control group (n = 10), which received saline solution; or to Sildenafil group (n = 10), which received sildenafil orally (100 mg). After 30 minutes, both groups were submitted to endotoxemia with intravenous bacterial lipopolysaccharide endotoxin (LPS) infusion (4 µg.kg-1.h-1) for 180 minutes. We evaluated hemodynamic and oxygenation functions, and also lung histology and plasma cytokine (TNFα, IL-1β, IL6, and IL10) and troponin I response. Results Significant hemodynamic alterations were observed after 30 minutes of LPS continuous infusion, mainly in pulmonary arterial pressure (from Baseline 19 ± 2 mmHg to LPS30 52 ± 4 mmHg, p< 0.05). There was also a significant decrease in PaO2/FiO2 (from Baseline 411 ± 29 to LPS180 334 ± 49, p< 0.05). Pulmonary arterial pressure was significantly lower in the Sildenafil group (35 ± 4 mmHg at LPS30, p< 0.05). The Sildenafil group also presented lower values of systemic arterial pressure. Sildenafil maintained oxygenation with higher PaO2/FiO2 and lower oxygen extraction rate than Control group but had no effect on intrapulmonary shunt. All cytokines and troponin increased after LPS infusion in both groups similarly. Conclusion Sildenafil attenuated endotoxin-induced pulmonary hypertension preserving the correct heart function without improving lung lesions or inflammation.

Effects of dexmedetomidine on hemodynamic, oxygenation, microcirculation, and inflammatory markers in a porcine model of sepsis

Purpose: To determine whether dexmedetomidine aggravates hemodynamic, metabolic variables, inflammatory markers, and microcirculation in experimental septic shock. Methods: Twenty-four pigs randomized into: Sham group (n = 8), received saline; Shock group (n = 8), received an intravenous infusion of Escherichia coli O55 (3 × 109 cells/mL, 0.75 mL/kg, 1 hour); Dex-Shock group (n = 8), received bacteria and intravenous dexmedetomidine (bolus 0.5 mcg/kg followed by 0.7 mcg/kg/h). Fluid therapy and/ornorepinephrine were administered to maintain a mean arterial pressure > 65 mmHg. Hemodynamic, metabolic, oxygenation, inflammatory markers, and microcirculation were assessed at baseline, at the end of bacterial infusion, and after 60, 120, 180, and 240 minutes. Results: Compared to Shock group, Dex-Shock group presented a significantly increased oxygen extraction ratio at T180 (23.1 ± 9.7 vs. 32.5 ± 9.2%, P = 0.0220), decreased central venous pressure at T120 (11.6 ± 1 vs. 9.61 ± 1.2 mmHg, P = 0.0214), mixed-venous oxygen saturation at T180 (72.9 ± 9.6 vs. 63.5 ± 9.2%, P = 0.026), and increased plasma lactate (3.7 ± 0.5 vs. 5.5 ± 1 mmol/L, P = 0.003). Despite the Dex-Shock group having a better sublingual vessel density at T240 (12.5 ± 0.4 vs. 14.4 ± 0.3 mL/m2; P = 0.0003), sublingual blood flow was not different from that in the Shock group (2.4 ± 0.2 vs. 2.4 ± 0.1 mL/kg, P = 0.4418). Conclusions: Dexmedetomidine did not worsen the hemodynamic, metabolic, inflammatory, or sublingual blood flow disorders resulting from septic shock. Despite inducing a better sublingual vessel density, dexmedetomidine initially and transitorily increased the mismatch between oxygen supply and demand.

Continuous peritoneal lavage with vacuum peritoneostomy: an experimental study

OBJECTIVE: Despite advances in diffuse peritonitis treatment protocols, some cases develop unfavorably. With the advent of vacuum therapy, the use of laparostomy to treat peritonitis has gained traction. Another treatment modality is continuous peritoneal lavage. However, maintaining this technique is difficult and has been associated with controversial results. We propose a new model of continuous peritoneal lavage that takes advantage of the features and benefits of vacuum laparostomy. METHOD: Pigs (Landrace and Large White) under general anesthesia were submitted to laparostomy through which a multiperforated tube was placed along each flank and exteriorized in the left and lower right quadrants. A vacuum dressing was applied, and intermittent negative pressure was maintained. Peritoneal dialysis solution (PDS) was then infused through the tubes for 36 hours. The stability of peritoneostomy with intermittent infusion of fluids, the system resistance to obstruction and leakage, water balance, hemodynamic and biochemical parameters were evaluated. Fluid disposition in the abdominal cavity was analyzed through CT. RESULTS: Even when negative pressure was not applied, the dressing maintained the integrity of the system, and there were no leaks or blockage of the catheters during the procedure. The aspirated volume by vacuum laparostomy was similar to the infused volume (9073.5±1496.35 mL versus 10165±235.73 mL, p=0.25), and there were no major changes in hemodynamic or biochemical analysis. According to CT images, 60 ml/kg PDS was sufficient to occupy all intra-abdominal spaces. CONCLUSION: Continuous peritoneal lavage with negative pressure proved to be technically possible and may be an option in the treatment of diffuse peritonitis.

Animal model of continuous peritoneal lavage with vacuum peritoneostomy

Abstract Purpose: To establish and evaluate the feasibility of continuous peritoneal lavage with vacuum peritoneostomy in an animal model. Methods: Eight pigs aged 3-4 months, females, were anesthetized and submitted to laparotomy and installation of a continuous peritoneal lavage with vacuum peritoneostomy. The sta-bility of the system, the physiological effects of washing with NaCl 0.9% and the sys-tem clearance were evaluated. Results: Stability of vacuum peritoneostomy was observed, with no catheter leaks or obstructions and the clearance proved adequate, however, the mean volume of fluids aspirated by the peritoneostomy at the end of the experiment was higher than the volume infused by the catheters (p=0.02). Besides that, the animals presented a progressive increase in heart rate (p=0.04) and serum potassium (p=0.02). Conclusion: The continuous peritoneal lavage technique with vacuum peritoneostomy is feasible and presents adequate clearance.

Sevoflurane preconditioning during myocardial ischemia-reperfusion reduces infarct size and preserves autonomic control of circulation in rats

ABSTRACT PURPOSE: To investigate the myocardial ischemia-reperfusion with sevoflurane anesthetic preconditioning (APC) would present beneficial effects on autonomic and cardiac function indexes after the acute phase of a myocardial ischemia-reperfusion. METHODS: Twenty Wistar rats were allocated in three groups: control (CON, n=10), myocardial infarction with sevoflurane (SEV, n=5) and infarcted without sevoflurane (INF, n=5). Myocardial ischemia (60 min) and reperfusion were performed by temporary coronary occlusion. Twenty-one days later, the systolic and diastolic function were evaluated by echocardiography; spectral analysis of the systolic arterial pressure (SAPV) and heart rate variability (HRV) were assessed. After the recording period, the infarct size (IS) was evaluated. RESULTS: The INF group presented greater cardiac dysfunction and increased sympathetic modulation of the SAPV, as well as decreased alpha index and worse vagal modulation of the HRV. The SEV group exhibited attenuation of the systolic and diastolic dysfunction and preserved vagal modulation (square root of the mean squared differences of successive R-R intervals and high frequency) of HRV, as well as a smaller IS. CONCLUSION: Sevoflurane preconditioning better preserved the cardiac function and autonomic modulation of the heart in post-acute myocardial infarction period.

Pulse pressure variation and stroke volume variation under different inhaled concentrations of isoflurane, sevoflurane and desflurane in pigs undergoing hemorrhage

OBJECTIVES: Inhalant anesthesia induces dose-dependent cardiovascular depression, but whether fluid responsiveness is differentially influenced by the inhalant agent and plasma volemia remains unknown. The aim of this study was to compare the effects of isoflurane, sevoflurane and desflurane on pulse pressure variation and stroke volume variation in pigs undergoing hemorrhage. METHODS: Twenty-five pigs were randomly anesthetized with isoflurane, sevoflurane or desflurane. Hemodynamic and echocardiographic data were registered sequentially at minimum alveolar concentrations of 1.00 (M1), 1.25 (M2), and 1.00 (M3). Then, following withdrawal of 30% of the estimated blood volume, these data were registered at a minimum alveolar concentrations of 1.00 (M4) and 1.25 (M5). RESULTS: The minimum alveolar concentration increase from 1.00 to 1.25 (M2) decreased the cardiac index and increased the central venous pressure, but only modest changes in mean arterial pressure, pulse pressure variation and stroke volume variation were observed in all groups from M1 to M2. A significant decrease in mean arterial pressure was only observed with desflurane. Following blood loss (M4), pulse pressure variation, stroke volume variation and central venous pressure increased (p <0.001) and mean arterial pressure decreased in all groups. Under hypovolemia, the cardiac index decreased with the increase of anesthesia depth in a similar manner in all groups. CONCLUSION: The effects of desflurane, sevoflurane and isoflurane on pulse pressure variation and stroke volume variation were not different during normovolemia or hypovolemia.

Effect of hypertonic saline treatment on the inflammatory response after hydrochloric acid-induced lung injury in pigs

OBJECTIVES: Hypertonic saline has been proposed to modulate the inflammatory cascade in certain experimental conditions, including pulmonary inflammation caused by inhaled gastric contents. The present study aimed to assess the potential anti-inflammatory effects of administering a single intravenous dose of 7.5% hypertonic saline in an experimental model of acute lung injury induced by hydrochloric acid. METHODS: Thirty-two pigs were anesthetized and randomly allocated into the following four groups: Sham, which received anesthesia and were observed; HS, which received intravenous 7.5% hypertonic saline solution (4 ml/kg); acute lung injury, which were subjected to acute lung injury with intratracheal hydrochloric acid; and acute lung injury + hypertonic saline, which were subjected to acute lung injury with hydrochloric acid and treated with hypertonic saline. Hemodynamic and ventilatory parameters were recorded over four hours. Subsequently, bronchoalveolar lavage samples were collected at the end of the observation period to measure cytokine levels using an oxidative burst analysis, and lung tissue was collected for a histological analysis. RESULTS: Hydrochloric acid instillation caused marked changes in respiratory mechanics as well as blood gas and lung parenchyma parameters. Despite the absence of a significant difference between the acute lung injury and acute lung injury + hypertonic saline groups, the acute lung injury animals presented higher neutrophil and tumor necrosis factor alpha (TNF-α), interleukin (IL)-6 and IL-8 levels in the bronchoalveolar lavage analysis. The histopathological analysis revealed pulmonary edema, congestion and alveolar collapse in both groups; however, the differences between groups were not significant. Despite the lower cytokine and neutrophil levels observed in the acute lung injury + hypertonic saline group, significant differences were not observed among the treated and non-treated groups. ...

Atrofia progressiva generalizada da retina em cães da raça Cocker Spaniel / Generalized progressive retinal atrophy in Cocker Spaniel dogs

Atrofia progressiva generalizada da retina (APGR) é uma doença frequente nos cães da raça Cocker Spaniel, caracterizada pela perda progressiva da função retiniana externa e desaparecimento dos fotorreceptores. A doença é bilateral, hereditária, autossômica recessiva, sem predisposição sexual e está frequentemente associada à catarata. Segundo estudos moleculares, a degeneração ocorre por mutação de diversos genes. Nos cães da raça Cocker Spaniel Americano, a doença é observada entre três e cinco anos de idade e, no Cocker Spaniel Inglês, entre quatro e oito anos de idade. Os sinais clínicos mais encontrados são: nictalopia, hiperreflexia tapetal e catarata. O diagnóstico baseia-se no histórico clínico, exame oftalmológico e em exames complementares, como eletrorretinograma, testes genéticos e ultrassom ocular. Este artigo teve como objetivo realizar uma revisão de literatura a respeito da atrofia progressiva generalizada da retina (APGR) em cães da raça Cocker Spaniel portadores de catarata.

Generalized progressive retinal atrophy (GPRA) is a common disease in Cocker Spaniels dogs characterized by progressive loss of retinal function and disappearance of photoreceptors. The disease is bilateral, hereditary, autosomal recessive, has no sexual predisposition and is frequently associated with cataracts. According to molecular studies the degeneration occurs by a mutation in different genes. In American Cocker Spaniels dogs the disease is observed between three and five years of age and in English Cocker Spaniels between four and eight years old. The clinical signs are: nyctalopia, tapetal hyperreflexia and cataracts. The diagnosis is based on clinical history, ophthalmologic examination and complementary exams such as electroretinography, ocular ultrasound and genetic testing. This article aimed to conduct a review of literature on the generalized progressive retinal atrophy (GPRA) in Cocker Spaniel dogs with cataracts.

Ceratoplastia lamelar em cães usando membrana amniótica equina: Estudo clínico e morfológico / Lamelar keratoplasty in dogs using equine amniotic membrane: Clinical and morphological study

A membrana amniótica (MA) consolidou-se no tratamento de afecções na superfície ocular. O objetivo deste estudo foi avaliar a viabilidade do implante de MA equina em ceratoplastia lamelar de cães. As membranas amnióticas foram preservadas em glicerina (98%). A eficácia do implante foi acompanhada por avaliação clínica, tempo de cicatrização, resposta inflamatória e reconstrução da arquitetura da córnea. Foram selecionados 12 cães, que foram divididos em quatro grupos de três animais. Em cada animal, foi realizada ceratotomia lamelar com 5 mm de diâmetro, seguida de aplicação do implante de MA. Após cirurgia, os animais foram avaliados em diferentes tempos: 2, 7, 21 e 40 dias. Duran- te o período de observação, os exames oftalmológicos foram realizados com intervalo de 48 h e, após a última avaliação, os animais foram submetidos à eutanásia. Os olhos foram enucleados, fixados e corados com hematoxilina-eosina (HE), ácido periódico de Schiff (PAS) e picrossirius. Os implantes foram completamente epitelizados em cerca de 10 dias após a cirurgia. Os neovasos apresentaram involução progressiva a partir de 21 dias e não foram detectados ao final de 40 dias pós-cirurgia, restando apenas uma nébula no local da lesão. À microscopia óptica, observou-se resposta inflama- tória moderada, presença de epitélio pavimentoso estratificado aos sete dias e epitelização completa aos 21 dias. Aos 40 dias, a membrana basal do epitélio apresentou-se reconstituída. Assim, concluímos que a membrana amniótica equina é viável como implante em córnea de cão, sendo incorporada ao estroma e resultando em restabelecimento parcial da transparência.

Amniotic membranes have been successfully used in the treatment of superficial corneal diseases. The purpose of this study was to assess the feasibility of use of equine amniotic membrane (AM) in lamellar keratoplasty of dogs. Amniotic membranes were preserved in glycerol (98%). Implant efficacy was assessed by clinical evaluation, time of healing, in-flammatory response, and the corneal architectural configuration. Twelve dogs were divided into four groups of three animals. In each animal, a 5-mm diameter lamellar keratectomy was performed, and followed by implantation of the AM. The animals were evaluated at the 2th, 7th, 21th, and 40th days after surgery. During this period, ophthalmological exams were performed at 48-h intervals, and the animals were euthanized after the last evaluation. The eyes were enu-cleated, included, fixed, and stained with hematoxylin-eosin (HE), periodic acid-Schiff (PAS), and picrosirius. Epitheli-zation of the implants was completed in about ten days after surgery. New vessels progressively diminished from 21 days on, were not detected on day 40 after surgery, and only a nebula was observed in the implant area. Optical microscopy revealed a mild inflammatory response, presence of squamous epithelium on day seven, and total epithelization on day 21 after surgery. On day 40, the basal epithelial membrane was shown to be reformed. Therefore, we conclude that use of equine amniotic membranes is feasible as implant for dog cornea since it is incorporated to the corneal stroma, and a relative transparency can be obtained.

Determinação dos valores normais do eletrorretinograma de campo total em cães da raça Poodle portadores de catarata de acordo com a faixa etária / Determination of normal values of full-field electroretinogram in Poodle dogs with cataract according to age

Eletrorretinograma (ERG) é um meio diagnóstico objetivo, não invasivo e capaz de avaliar a função retiniana, detectando precocemente, em diversas espécies, lesões nas camadas mais externas. Tem como uma das principais indicações a avaliação pré-cirúrgica em pacientes portadores de catarata. A determinação dos valores normais do ERG é indispensável quando se objetiva, pela mensuração dos valores, o auxílio no diagnóstico das degenerações retinianas, mesmo quando apresentam opacidade de meios (catarata). Este estudo teve como objetivo padronizar os valores das respostas do eletrorretinograma em cães da raça Poodle portadores de catarata madura ou hipermadura, submetidos ao mesmo protocolo de sedação, adaptação ao escuro e eletrodo, utilizando aparelho portátil BPM 200. Em todos os animais, o exame oftalmológico precedeu o ERG. Os animais foram separados em quatro grupos de acordo com a faixa etária: um a três anos (GI), quatro a sete anos (GII), oito a 11 anos (GIII) e 12 anos ou mais (GIV). Foram mensuradas a amplitude pico a pico (pico da onda-a até o pico da onda-b) e o tempo de culminação da onda-b na resposta de bastonetes, máxima resposta e resposta de cones. Cães com respostas atenuadas ou extintas foram excluídos deste trabalho. Observou-se diminuição das amplitudes das três respostas quando se comparou GI com os demais grupos. Houve aumento do tempo de culminação da onda-b na comparação da resposta de bastonetes de GI com os outros grupos. O tempo de culminação da onda-b na máxima resposta e resposta de cones manteve-se praticamente inalterado nos quatro grupos testados. Concluiu-se que houve alteração dependente de idade nos parâmetros eletrorretinográficos, com diminuição da amplitude na resposta de bastonetes, máxima resposta e resposta de cones, enquanto que, no tempo de culminação da onda-b, apenas a resposta de bastonetes foi estatisticamente significante nos animais submetidos ao mesmo protocolo na execução do ERG.

Electroretinogram (ERG) is an objective and noninvasive diagnostic tool for the evaluation of retinal function, capable to detect early, lesions of the outermost layers in several species of animals. One of its main indications is to evaluate pre-surgical patients for cataract surgery. The determination of normal ERG values is essential if the aim is, by measuring the values; aid the diagnosis of retinal degeneration, despite of the presence of media opacity (cataract). The objective of this study was to standardize the values of electroretinogram responses in Poodle dogs with mature or hypermature cataract, submitted to the same sedation and dark adaptation protocol, using a portable electrodiagnostic system, BPM 200. In all animals, the ophthalmologic examination preceded ERG. Animals were divided into four groups according to age: 1 to 3 years (GI), 4 to 7 years (GII), 8 to 11 years (GIII) and 12 or more years (GIV). Peak-to-peak amplitude (peak of a-wave to peak of b-wave) and b-wave implicit time were measured in rod response and in maximal response and cone response. Dogs with decreased or absent responses were excluded from the study. GI presented decrease in amplitudes of the three responses and increase in b-wave implicit time of rod response when compared with the other groups. B-wave implicit times in maximal response and cone response were practically unaltered in all four groups. It was concluded that there was age-dependent changes in electroretinographic parameters, with decreased amplitudes in rod response, maximal response and cone response. Delay in b-wave implicit time was observed in rod response and unchanged in the two others tested responses of animals subjected to the same ERG protocol.

Estudo comparativo entre sutura mecânica e manual em brônquio após pneumonectomia esquerda em cães (Canis familiaris): uma avaliação anatomopatológica / Comparative study between mechanical and manual sutures in the bronchus after left pneumonectomy in the dogs (canis familiaris): a pathological-anatomic evaluation

O objetivo deste estudo foi realizar um estudo experimental comparando-se sob o ponto de vista anatomopatológico as suturas manual e mecânica em brônquio principal após pneumonectomia esquerda em cães. Foram utilizados 18 cães, sadios, machos e fêmeas, adultos, sem raça definida, pesando entre 9 e 27,5 kg. Foram separados em 2 grupos de 9 cães, de acordo com o tipo de sutura empregada: Grupo A - sutura manual com fio polipropileno 5-0; Grupo B sutura mecânica com grampeador mecânico modelo TL- 30. Cada grupo foi subdividido em 3 subgrupos de 3 animais, sendo estabelecido estudo temporal aos 7, 15 e 36 dias de pós-operatório, onde foi realizada avaliação anatomopatológica da cicatrização das suturas manual e mecânica. Na avaliação histopatológica foram avaliados, qualitativamente e semi-quantitativamente, intensidade da inflamação, fibrose, vasos neoformados e presença ou não de tecido de granulação, granuloma tipo corpo estranho e necrose. Os resultados encontrados foram analisados estatisticamente. Com relação à análise rustopatológica, ocorreu a formação de granuloma tipo corpo estranho no coto brônquico esquerdo em 88,9% dos cães submetidos à sutura manual e em nenhum dos cães submetidos à sutura mecânica. Houve, ainda, diferença estatística significativa nos cães dos Grupos A e B em relação à intensidade da inflamação, sendo de maior intensidade nos cães submetidos à sutura manual. Concluiu-se que os 2 tipos de sutura promoveram cicatrização adequada do coto brônquico principal esquerdo, embora tenha ocorrido maior intensidade de inflamação e maior ocorrência de granuloma tipo corpo estranho nos cães submetidos à sutura manual.

Estudo comparativo entre sutura manual e mecânica de coto brônquico em cães submetidos à pneumonectomia esquerda: avaliação histopatológica do pulmão direito e avaliação eletrocardiográfica / Comparative study between manual and mechanical suture of bronchial stamp in dogs submited to left pneumonectomy: histopahological evaluation of right lung and electrocardiographical evaluation

O presente estudo teve como objetivo avaliar as possíveis alterações eletrocardiográficas e as alterações histopatológicas no pulmão de cães submetidos à pneumonectomia esquerda em abordagem comparativa entre dois tipos de sutura de coto brônquico (manual e mecânica). Foram utilizados doze cães, machos e fêmeas, adultos, sem raça definida, pesando entre quinze e vinte quilos sendo avaliados as alterações microscópicas apresentadas pelo pulmão direito e as alterações do eletrocardiograma. Todos os animais apresentaram-se em condições clínicas satisfatórias no período pós-operatório. As principais alterações eletrocardiográficas observadas no período pós-operatório foram desvio de eixo cardíaco, bloqueio sinoatrial e isquemia de miocárdio. No exame histopatológico, constatou-se atelectasia pulmonar, proliferação de epitélio de bronquíolo tendendo à obliteração, bronquiolite obliterante e enfisema pulmonar. O estudo sugere ainda que o pulmão direito foi submetido à hipertensão pulmonar.