Cardiorespiratory dynamics of sedated pigs submitted to different inspired oxygen fractions under controlled mechanical ventilation

Background: Individuals submitted to situations of deep sedation have a marked decrease in their ventilatory capacity.The provision of adequate ventilation and oxygenation in critically ill patients submitted to sedation in intensive therapyhas been the subject of special care. In such cases, exposure to low inspired oxygen fractions (FIO2) is a factor that caninfl uence alveolar perfusion and respiratory performance. The aim of this study is to evaluate the effects of three inspiredoxygen fractions (80%, 60% or 40%) on the cardiorespiratory dynamics of pigs submitted to mechanical ventilation byintermittent positive pressure in deep sedation with propofol-remifentanil.Material, Methods & Results: Twenty crossbred pigs weighing between 17 and 25 kg and aged between 60 and 90 dayswere used. Each animal was submitted to deep sedation for 2h in randomly assigned FIO2 (80%, 60% or 40%). Scores suchas heart and respiratory rate, blood pressure, respirometry (PaO2, P(A-a)O2, PIP, Vmin), physiological dead space, pulmonaryshunt and blood gas analysis (pH, PaO2, PaCO2, HCO3) were observed, evaluated and compared. Patients were evaluatedafter sedation was induced with propofol (12 mg.kg-1) and remifentanil (1 mcg.kg-1). To maintain the level of sedation weused propofol (an average of 18 mg.kg-1.h-1) and remifentanil (0.5 mcg.kg-1.min-1). Intubation was preceded after the onsetof sedation to mechanical ventilation - volume-cycled, intermittent positive pressure. Patients received a tidal volume of10 mL.kg-1 and an I:E ratio of 1:2, positive end-expiratory pressure of 4 cmH2O with three inspired oxygen fractions. Patients respiratory rate was adjusted so as to maintain end-tidal carbon dioxide pressure between 35 and 45 mmHg. Datawere subjected to analysis of variance for repeated measures followed by a Tukey test. Patients receiving a 40% oxygenconcentration showed an average heart rate higher than the others. Shunt levels...(AU)

Cardiorespiratory dynamics of sedated pigs submitted to different inspired oxygen fractions under controlled mechanical ventilation

Background: Individuals submitted to situations of deep sedation have a marked decrease in their ventilatory capacity.The provision of adequate ventilation and oxygenation in critically ill patients submitted to sedation in intensive therapyhas been the subject of special care. In such cases, exposure to low inspired oxygen fractions (FIO2) is a factor that caninfl uence alveolar perfusion and respiratory performance. The aim of this study is to evaluate the effects of three inspiredoxygen fractions (80%, 60% or 40%) on the cardiorespiratory dynamics of pigs submitted to mechanical ventilation byintermittent positive pressure in deep sedation with propofol-remifentanil.Material, Methods & Results: Twenty crossbred pigs weighing between 17 and 25 kg and aged between 60 and 90 dayswere used. Each animal was submitted to deep sedation for 2h in randomly assigned FIO2 (80%, 60% or 40%). Scores suchas heart and respiratory rate, blood pressure, respirometry (PaO2, P(A-a)O2, PIP, Vmin), physiological dead space, pulmonaryshunt and blood gas analysis (pH, PaO2, PaCO2, HCO3) were observed, evaluated and compared. Patients were evaluatedafter sedation was induced with propofol (12 mg.kg-1) and remifentanil (1 mcg.kg-1). To maintain the level of sedation weused propofol (an average of 18 mg.kg-1.h-1) and remifentanil (0.5 mcg.kg-1.min-1). Intubation was preceded after the onsetof sedation to mechanical ventilation - volume-cycled, intermittent positive pressure. Patients received a tidal volume of10 mL.kg-1 and an I:E ratio of 1:2, positive end-expiratory pressure of 4 cmH2O with three inspired oxygen fractions. Patients’ respiratory rate was adjusted so as to maintain end-tidal carbon dioxide pressure between 35 and 45 mmHg. Datawere subjected to analysis of variance for repeated measures followed by a Tukey test. Patients receiving a 40% oxygenconcentration showed an average heart rate higher than the others. Shunt levels...

Comparação entre três protocolos de obtenção de plasma rico em plaquetas (PRP) utilizando o coelho como modelo experimental / Comparison of Three Protocols to Obtain Platelet Rich Plasma (PRP) with Rabbits as Experimental Model

Background: Platelet rich plasma (PRP) is a blood-derived source of growth factors and several cytokines, which are essential for tissue regeneration and important for wound healing due to their angiogenic, mitogenic, and chemotactic activities. To date no protocol has been established for PRP production. Standardization of this technique should consider fundamental factors such as experimental model used, blood collection method, anticoagulant choice, rotation and amount of centrifugations, elapsed time between sample activation and its clinical use in order to ensure quality and biological effects of the product. This study aimed to compare three protocols for PRP achievement in order to evaluate platelet enrichment ability and method reproducibility for further use in clinical investigations regarding PRP therapeutic properties. Materials, Methods & Results: New Zealand higid rabbit's whole blood was collected in tubes containing sodium citrate. Samples were obtained through exsanguination, via abdominal aortic puncture, and separated in four aliquots designed for PRP processing and basal platelet count. The count was conducted at the time blood was collected and after every concentration protocol. Methods were tested in triplicates, and three different individuals repeated each technique for three times, reaching 27 repetitions. Selected methodologies consisted in two centrifugations protocols: protocol A used 250 g for 10 min for the first separation, and another 10 min at 2000 g during the second centrifugation; protocol B proposed that first centrifugation would last 20 min at 160 g, and the second would last 15 min at 400 g, and protocol C consisted of 10 min at 400 g for the first separation, and 10 min at 800 g during second separation. Protocols were performed at the same time in three similar centrifuges, in order to standardize the variables (operator, time, environment, equipments), and also to diminish biases. Comparison objects in this study include: ability of raising platelet concentration, time required for preparing the final product, reproduction handiness, and need for equipment for proper hemoconcentrated production. Achieved platelet count in each protocol and basal value were analyzed following randomized complete. Kurskal-Wallis test was used for independent samples comparison, considering a 5% significance level. For each tested sample, elapsed time for product preparation was evaluated. Subjective analyzes comprehended execution easiness and the need for special material, and were evaluated through questionnaire after each protocol. Protocol A showed a 25-fold increase in platelet count, whereas protocols B and C had 13 and 7-fold, respectively. Results indicate all protocols were efficient in concentrating the samples at least 3 times more than basal count. Elapsed time for product preparation in each protocol was 35, 52, and 41 min for A, B, and C methods, respectively. Subjective analyzes considered protocols A and C as low complexity, and protocol B was defined as medium complexity in regards to execution. With reference to material accessibility for protocols, all were considered of easy reproducibility. Discussion: Besides analyzing experimental model and most proper way to access blood collection, this study was limited to verify in a quantitative manner the platelet concentration in specific protocols, without evaluating their biological effects. Therefore, in regards to proposed objectives - relation between platelet concentration increase, spent time, and easiness of protocol - we conclude that protocol A, formulated by Nagae et al. (2007), was the method that most fitted the work needs, and greatly suited the challenges posed.

Oxidative stress evaluation of ischemia and reperfusion in kidneys under various degrees of hypothermia in rats

PURPOSE:To design an animal model of ischemia-reperfusion (I/R) in kidneys and evaluate the role that predetermined ranges of local hypothermia plays on markers of stress-oxydative as well as on histologic sections. METHODS: Twenty eight male rats Wistar, under general anesthesia, undergone right nephrectomy (G0, control group) followed by left kidney ischemia during 40 min. Four temperatures groups were designed, with seven animals randomized for each group: normothermic (G1, ±37ºC), mild hypothermia (G2, 26ºC), moderate hypothermia (G3, 15ºC) and deep hypothermia (G4, 4ºC). Left kidney temperature was assessed with an intraparenchymal probe. Left nephrectomy was performed after 240 min of reperfusion. After I/R a blood sample was obtained for f2-IP. Half of each kidney was sent to pathological evaluation and half to analyze CAT, SOD, TBARS, NO3, NO2. RESULTS:Histopathology showed that all kidneys under I/R were significantly more injured than the G0 (p<0.001). TBARS had increased levels in all I/R groups compared with the G0 (p<0.001). CAT had a significant difference (p<0.03) between G1 and G4. Finally, no difference was found on SOD, NO3, NO2 nor on f2-IP. CONCLUSION: This model of I/R was efficient to produce oxidative-stress in the kidney, showing that 4ºC offered significant decrease in free radicals production, although tissue protection was not observed.(AU)

Efeito da presença de um coespecífico no alojamento de ovelhas em novo ambiente, após estresse agudo causado pelo transporte / Effect of the Presence of a Conspecific in the Housing of Sheep in the New Environment, Following Acute Stress Caused by Transportation

Sheep are social and gregarious animals. They feel at ease when free and clustered rather than isolated. In some situations, as in experimental procedures, they need to be separated from the flock and kept without social company. Both instances, separation from the flock and isolation are considered stressful and may impact their well being. As stress can affect the results of the study, special care should be taken when conducting biomedical or veterinary research. The aim of this study was to compare the concentration of cortisol and behavior of ewes housed at a research institution in the presence of a familiar conspecific, an unfamiliar conspecific or in the absence of conspecifics.

Efeito da presença de um coespecífico no alojamento de ovelhas em novo ambiente, após estresse agudo causado pelo transporte / Effect of the Presence of a Conspecific in the Housing of Sheep in the New Environment, Following Acute Stress Caused by Transportation

Sheep are social and gregarious animals. They feel at ease when free and clustered rather than isolated. In some situations, as in experimental procedures, they need to be separated from the flock and kept without social company. Both instances, separation from the flock and isolation are considered stressful and may impact their well being. As stress can affect the results of the study, special care should be taken when conducting biomedical or veterinary research. The aim of this study was to compare the concentration of cortisol and behavior of ewes housed at a research institution in the presence of a familiar conspecific, an unfamiliar conspecific or in the absence of conspecifics.(AU)

Anesthetic protocol for videolaparoscopic surgery in rabbits / Protocolo anestésico para cirurgia videolaparoscópica em coelhos

PURPOSE: To describe the anesthetic protocol and the intubation technique without visualizing the trachea in rabbits, in order to enable the videolaparoscopic surgical procedure. METHODS: The experiment was performed on 33 female rabbits (Oryctolagus cuniculus), aged from 5 to 7 months. It consisted of general anesthesia and endotracheal intubation by manual palpation of the trachea of the rabbits, without using the laryngoscope, orally, for later videolaparoscopic surgical access to the abdominal cavity. RESULTS: The mean values and standard deviation of vital parameters of the animals were 223.8±15.61 beats per minute for heart rate; 35±9 movements per minute for respiratory rate; 96.94±0.99 percent of oxymetry and 42.82±4.02 mmHg for capnometry; 16.7±4.3 minutes for pneumoperitoneum (duration of surgery) and 1 hour and 14±8.52 minutes for time of observation (from induction to recovery from anesthesia). All animals were intubated in at most three attempts. No animals were lost after the introduction of this anesthetic technique. CONCLUSION: This protocol proved adequate, safe and easy to perform, on rabbits submitted to videolaparoscopic surgery.(AU)

OBJETIVO: Descrever o protocolo anestésico e a técnica de intubação sem visualização da traqueia em coelhos, para viabilização de procedimento cirúrgico videolaparoscópico. MÉTODOS: O experimento foi realizado em 33 coelhas (Oryctolagus cuniculus), com idade entre 5 e 7 meses. Consistiu de anestesia geral e intubação endotraqueal por meio de palpação manual da traquéia das coelhas, sem o uso de laringoscópio, pela via oral, para posterior acesso cirúrgico videolaparoscópico da cavidade abdominal. RESULTADOS: Os valores médios e desvio padrão dos parâmetros vitais dos animais foram de 223,8±15,61 batimentos por minuto para freqüência cardíaca; 35±9 movimentos por minuto para frequência respiratória; 96,94±0,99 por cento de oximetria e 42,82±4,02 mmHg para capnometria; 16,7±4,3 minutos para o pneumoperitônio (tempo de cirurgia) e 1 hora e 14±8,52 minutos para o tempo de observação (desde a indução até a recuperação anestésica). Todos os animais foram intubados em, no máximo, três tentativas. Não houve perda de animais após a introdução dessa técnica anestésica. CONCLUSÃO: Este protocolo mostrou-se adequado, seguro e de fácil realização, para a aplicação em coelhos submetidos à cirurgia videolaparoscópica.(AU)

Experimental model of the formation of pelvic adhesions by videolaparoscopic in female rabbits / Modelo experimental de formação de aderências pélvicas por videolaparoscopia em coelhas

PURPOSE: To verify the frequency of postsurgical pelvic adhesion formation in an experimental animal model using videolaparoscopy. METHODS: Experimental study in a sample of 11 non-pregnant female rabbits, aged 5 to 7 months. After general anesthesia, access to the abdominal cavity was performed by an open puncture technique, with 10mm optics, placing two other 5 mm trochars under direct visualization, in the iliac fossae. Then a fragment of peritoneum was resected, followed by electrocauterization. In 21 days, the videolaparoscopy was repeated, and adhesion formation and score was looked at, with biopsies at the surgical site. RESULTS: 54 percent of adhesion formation was observed, and the median score of adhesions was 6 (minimum of 3 and maximum of 10), all of them found in the bladder and the anterior abdominal wall. CONCLUSION: The method used presents a high frequency of intra-abdominal adhesion formation.(AU)

OBJETIVO: Verificar a freqüência da formação de aderências pélvicas pós-cirúrgicas, em um modelo experimental animal, por videolaparoscopia. MÉTODOS: Estudo experimental, em uma amostra de 11 coelhas, não prenhas, com idade entre cinco e sete meses. Após anestesia geral, o acesso da cavidade abdominal foi efetuado por técnica de punção aberta, com óptica de 10 mm, colocando-se outros dois trocateres de 5 mm, sob visão direta, nas fossas ilíacas. Realizou-se, então, ressecção de fragmento de peritônio, seguida de cauterização com eletrocautério. Em 21 dias, foi repetida a videolaparoscopia, verificando-se a formação e escore de aderências e realizando-se biópsias do local da cirurgia. RESULTADOS: Observou-se 54,5 por cento de formação de aderências, sendo o escore total mediano de aderências seis (mínimo de três e máximo de 10), todas encontradas na bexiga e na parede abdominal anterior. CONCLUSÃO: O procedimento utilizado apresentou alta freqüência de formação de aderências intra-abdominais.(AU)