LUIZ FRANCISCO POLI DE FIGUEIREDO

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LIM/26 - Laboratório de Pesquisa em Cirurgia Experimental, Hospital das Clínicas, Faculdade de Medicina - Líder

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  • article 3 Citação(ões) na Scopus
    Evaluation of hemodynamic effects of xenon in dogs undergoing hemorrhagic shock
    (2013) FRANCESCHI, Ruben C.; MALBOUISSON, Luiz; YOSHINAGA, Eduardo; AULER JR., Jose Otavio Costa; FIGUEIREDO, Luiz Francisco Poli de; CARMONA, Maria Jose C.
    OBJECTIVES: The anesthetic gas xenon is reported to preserve hemodynamic stability during general anesthesia. However, the effects of the gas during shock are unclear. The objective of this study was to evaluate the effect of Xe on hemodynamic stability and tissue perfusion in a canine model of hemorrhagic shock. METHOD: Twenty-six dogs, mechanically ventilated with a fraction of inspired oxygen of 21% and anesthetized with etomidate and vecuronium, were randomized into Xenon (Xe; n = 13) or Control (C; n = 13) groups. Following hemodynamic monitoring, a pressure-driven shock was induced to reach an arterial pressure of 40 mmHg. Hemodynamic data and blood samples were collected prior to bleeding, immediately after bleeding and 5, 20 and 40 minutes following shock. The Xe group was treated with 79% Xe diluted in ambient air, inhaled for 20 minutes after shock. RESULT: The mean bleeding volume was 44 mL.kg(-1) in the C group and 40 mL.kg(-1) in the Xe group. Hemorrhage promoted a decrease in both the cardiac index (p<0.001) and mean arterial pressure (p<0.001). These changes were associated with an increase in lactate levels and worsening of oxygen transport variables in both groups (p<0.05). Inhalation of xenon did not cause further worsening of hemodynamics or tissue perfusion markers. CONCLUSIONS: Xenon did not alter hemodynamic stability or tissue perfusion in an experimentally controlled hemorrhagic shock model. However, further studies are necessary to validate this drug in other contexts.
  • article 13 Citação(ões) na Scopus
    Endovascular treatment of peripheral arterial injury with covered stents: an experimental study in pigs
    (2011) BELCZAK, Sergio; SILVA, Erasmo Simao da; AUN, Ricardo; SINCOS, Igor Rafael; BELON, Alessandro Rodrigo; CASELLA, Ivan Benaduce; GORNATI, Vitor; FIGUEIREDO, Luiz Francisco Poli de
    OBJECTIVE: To evaluate the feasibility of using endovascular repair to treat penetrating arterial injuries with covered stents. Feasibility was examined according to the circumferential extent of the injury. INTRODUCTION: Surgical trauma often increases the risk of major morbidity and mortality associated with vascular injury, and endovascular repair has many advantages in such situations. METHODS: Twenty white male domestic pigs weighing 28-38 kg with controlled vascular injuries were divided into four equal groups according to the circumferential extent of their vascular lesion (i.e., no lesion, lesion <50%, lesion >50%, and complete lesion). The left common carotid artery was dissected with proximal and distal control, and this procedure was followed by controlled sectioning of the arterial wall. Local manual compression was applied for 10 min and was followed by endovascular repair with the placement of a 5x50 mm VIABHAN (TM) covered stent using the femoral approach. We also monitored additional variables, such as the duration of the procedures (the mean was 56.3 +/- 19.1 min), ultrasound parameters (e.g., maximum arterial diameter, peak systolic and diastolic velocity, and resistance index), arteriography findings, and fluctuations in vital signs (e.g., cardiac output, arterial pressure, and central venous pressure). RESULTS: The experimental procedure was found to be feasible and reproducible. Repairs were successful in all animals in the control (no lesion) and <50% lesion groups. Success was also achieved in four out of five pigs in the >50% group and in one pig in the complete lesion group. DISCUSSION: The endovascular repair of an arterial injury is possible, but success depends on the circumferential extent of the arterial lesion. The present experimental model, which involved endovascular techniques, highlighted important factors that must be considered in future studies involving similar animals and materials.
  • article
    Use of small volume hypertonic acetate dextran during aortic occlusion in pigs: assessment of blood flow and antioxidant status in tissues
    (2014) DUBICK, Michael A.; FIGUEIREDO, Luis F. Poli de; KRAMER, George C.
    BACKGROUND Hypertonic/hyperoncotic fluids may reduce overall fluid requirements and tissue edema, improve perfusion and reduce the incidence of paraplegia associated with aortic cross-clamping and subsequent reperfusion. OBJECTIVE We evaluated potential benefits of a hypertonic saline acetate solution on reperfusion injury following ischemia. We examined blood flow and plasma antioxidant status, spinal cord and skeletal muscle above and below the cross-clamp, as well as in the liver and the kidney. METHOD The aorta of anesthetized swine (n=5-6/group) was cross-clamped at the level of T9 for 30 min; animals were infused with 4 ml/kg of hypertonic acetate dextran (HAD) or 8.4% NaHCO3 (Control). Pigs were euthanatized 1h later. RESULTS As blood flow fell to zero in lower spinal cord and muscle, it doubled in the upper cord and increased 6-fold in upper muscle. Upon reperfusion, blood flow in all regions returned to baseline levels, with no statistical differences between HAD and Controls. Lipid peroxidation in plasma was lower in HAD than Controls. Lower muscle had 41% lower glutathione levels and significantly lower activities of the antioxidant enzymes glutathione peroxidase and reductase, catalase, superoxide dismutase versus upper muscle. The lower spinal cord had 2.5 fold higher malondialdehyde levels and 50% higher catalase activity than upper spinal cord. Within a tissue, any significant differences in antioxidant status or evidence of lipid peroxidation favored HAD over Control. CONCLUSION HAD offered only minor advantages over NaHCO3 with respect to blood flow and antioxidant status of spinal cord and muscle following this period of aortic cross-clamping and reperfusion.
  • article 17 Citação(ões) na Scopus
    N-acetylcysteine (NAC) Protects Against Acute Kidney Injury (AKI) Following Prolonged Pneumoperitoneum in the Rat
    (2012) SEGURO, Antonio Carlos; FIGUEIREDO, Luiz F. Poli de; SHIMIZU, Maria Heloisa M.
    Background. Acute kidney injury (AKI) following prolonged laparoscopy is a documented phenomenon. Carbon dioxide pneumoperitoneum induces oxidative stress. Previous experimental studies have shown that the antioxidant, N-acetylcysteine, protects the rat from AKI following ischemia-reperfusion. The aim of this study was to evaluate the effects of N-acetylcysteine (NAC) on rat renal function after prolonged pneumoperitoneum. Methods. Normal rats treated or not with NAC were submitted to abdominal CO2 insufflation of 10 mmHg, at short and long periods of time of 1 and 3 h, respectively, and evaluated at 24, 72 h, and 1 wk after deinsufflation. Glomerular filtration rate (GFR) was measured by inulin clearance and oxidative stress was evaluated by serum thiobarbituric acid reactive substances (TBARS) Results. No significant alterations in GFR were observed in normal animals submitted to the pneumoperitoneum of 1 h and evaluated after 24 h desufflation. With 3 h of pneumoperitoneum, a significant and progressive decrease in GFR occurred 24 and 72 h after desufflation with an increase in serum TBARS. GFR returned to normal levels a week later. In the NAC-treated rats, a complete protection against GFR drops was observed 24 and 72 h following 3 h of pneumoperitoneum associated with a decrease in TBARS. Conclusion. These results suggest that NAC protects against acute kidney injury following prolonged pneumoperitoneum. These findings have significant clinical implications.
  • article 19 Citação(ões) na Scopus
    Impact of Stent-Graft Oversizing on the Thoracic Aorta: Experimental Study in a Porcine Model
    (2011) SINCOS, Igor Rafael; AUN, Ricardo; SILVA, Erasmo Simao da; BELCZAK, Sergio; HIGUCHI, Maria de Lourdes; GORNATI, Vitor Cervantes; GIGGLIO, Pedro Nogueira; BAPTISTA, Anna Paula Weinhardt; FIGUEIREDO, Luiz Francisco Poli de
    Purpose: To analyze in an experimental animal model the effect of 4 different levels of stents-graft oversizing on non-atherosclerotic aortas such as those found in young individuals who undergo stent-graft repair for traumatic aortic injuries. Methods: The diameter of the porcine thoracic aorta is similar to the aorta of young adults (18-20 mm), so 25 pigs were randomized into 5 groups: 1 control (without stent-graft) and 4 oversizing groups (A: 10%-19%, B: 20%-29%, C: 30%-39%, and D: >40%). Two types of biomechanical tests were performed on all aortas 4 weeks after endoprosthesis deployment. Results: The results of the detachment test, which analyzed the strength necessary to remove the stent-graft from the aorta, were similar in the 4 groups (A: 42 N, B: 41 N, C: 46 N, and D: 46 N). However, 2 aortas ruptured during the tests (groups C and D). The second test was performed in 3 aortic segments. Maximum shear strength, maximum stress, and maximum tension supported by the aortic wall had a negative and linear correlation with oversizing. There were significant differences in all 4 groups when compared with the control group. Strain, which reflects the elastic properties of the aortic wall, was very similar in all 4 groups, but a great difference was found when compared with the control group (p<0.0001). Conclusion: The study showed an important subacute change in the biomechanical properties of the aortic wall after implantation of an oversized endoprosthesis. This weakness of the aortic wall was confirmed by 2 ruptures during the detachment test. These results partially explain the interaction of stent-grafts with non-atherosclerotic thoracic aortas and may serve as a basis for further studies and the development of specific material to be used in vascular trauma and young patients. J Endovasc Ther. 2011; 18: 576-584
  • article 191 Citação(ões) na Scopus
    Comparison of methods to detect the in vitro activity of silver nanoparticles (AgNP) against multidrug resistant bacteria
    (2015) CAVASSIN, Emerson Danguy; FIGUEIREDO, Luiz Francisco Poli de; OTOCH, Jose Pinhata; SECKLER, Marcelo Martins; OLIVEIRA, Roberto Angelo de; FRANCO, Fabiane Fantinelli; MARANGONI, Valeria Spolon; ZUCOLOTTO, Valtencir; LEVIN, Anna Sara Shafferman; COSTA, Silvia Figueiredo
    Background: Multidrug resistant microorganisms are a growing challenge and new substances that can be useful to treat infections due to these microorganisms are needed. Silver nanoparticle may be a future option for treatment of these infections, however, the methods described in vitro to evaluate the inhibitory effect are controversial. Results: This study evaluated the in vitro activity of silver nanoparticles against 36 susceptible and 54 multidrug resistant Gram-positive and Gram-negative bacteria from clinical sources. The multidrug resistant bacteria were oxacilin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus spp., carbapenem-and polymyxin B-resistant A. baumannii, carbapenem-resistant P. aeruginosa and carbapenem-resistant Enterobacteriaceae. We analyzed silver nanoparticles stabilized with citrate, chitosan and polyvinyl alcohol and commercial silver nanoparticle. Silver sulfadiazine and silver nitrate were used as control. Different methods were used: agar diffusion, minimum inhibitory concentration, minimum bactericidal concentration and time-kill. The activity of AgNPs using diffusion in solid media and the MIC methods showed similar effect against MDR and antimicrobial-susceptible isolates, with a higher effect against Gram-negative isolates. The better results were achieved with citrate and chitosan silver nanoparticle, both with MIC90 of 6.75 mu g mL(-1), which can be due the lower stability of these particles and, consequently, release of Ag+ ions as revealed by X-ray diffraction (XRD). The bactericidal effect was higher against antimicrobial-susceptible bacteria. Conclusion: It seems that agar diffusion method can be used as screening test, minimum inhibitory concentration/minimum bactericidal concentration and time kill showed to be useful methods. The activity of commercial silver nanoparticle and silver controls did not exceed the activity of the citrate and chitosan silver nanoparticles. The in vitro inhibitory effect was stronger against Gram-negative than Gram-positive, and similar against multidrug resistant and susceptible bacteria, with best result achieved using citrate and chitosan silver nanoparticles. The bactericidal effect of silver nanoparticle may, in the future, be translated into important therapeutic and clinical options, especially considering the shortage of new antimicrobials against the emerging antimicrobial resistant microorganisms, in particular against Gram-negative bacteria.
  • article 4 Citação(ões) na Scopus
    The Retrograde Ventriculosinusal Shunt in an Animal Experimental Model of Hydrocephalus
    (2016) PINTO, Fernando Campos Gomes; BECCO, Rodrigo; ALHO, Eduardo Joaquim Lopes; POLI-DE-FIGUEIREDO, Luiz Francisco; SOUZA, Podalyro Amaral de; OLIVEIRA, Matheus Fernandes de; TEIXEIRA, Manoel Jacobsen
    Currently, hydrocephalus treatment is performed mainly with ventriculoperitoneal shunting. This experimental study aims at assessing whether the experimental model of hydrocephalus in dogs is applicable to the laboratory study of the retrograde ventriculosinusal shunt (RVSS). Four mongrel dogs were assessed. After randomization, the animals were divided into two groups: an experimental group that underwent the induction of hydrocephalus/RVSS and a control group, for the measurement of the mean arterial pressure, intracranial pressure and pressure in the superior sagittal sinus (SSS). The controls presented a mean arterial pressure of 68 mm Hg (71 and 65), an intracranial pressure of 163 mm H2O (149.6 and 176.8) and a pressure at the SSS of 40 mm H2O (40 and 40). The kaolin injection into the cisterna magna at a concentration of 0.3 mg/ml was capable of inducing the clinical and radiological mechanism of hydrocephalus (intracranial pressure = 250 mm H2O, pressure at the SSS = 50 mm H2O). The caliber of the SSS was 2.5 +/- 1.0 mm. The fact that the SSS caliber of the dog was the same size as the external diameter of the catheter used resulted in the complete obstruction of the SSS when the catheter was inserted. We believe we could design and perform an experimental model to test the RVSS. It is applicable and feasible. The model of hydrocephalus, the surgical apparatus and the scenario were adequate, but the shunt system needs to be proportionally made to the canine anatomy. (C) 2016 S. Karger AG, Basel
  • article 32 Citação(ões) na Scopus
    Modified Nissen fundoplication: laparoscopic anti-reflux surgery after Roux-en-Y gastric bypass for obesity
    (2012) KAWAHARA, Nilton T.; ALSTER, Clarissa; MALUF-FILHO, Fauze; POLARA, Wilson; CAMPOS, Guilherme M.; POLI-DE-FIGUEIREDO, Luiz Francisco
  • article 37 Citação(ões) na Scopus
    Replacement of fentanyl infusion by enteral methadone decreases the weaning time from mechanical ventilation: a randomized controlled trial
    (2012) WANZUITA, Raquel; POLI-DE-FIGUEIREDO, Luiz F.; PFUETZENREITER, Felipe; CAVALCANTI, Alexandre Biasi; WESTPHAL, Glauco Adrieno
    Introduction: Patients undergoing mechanical ventilation (MV) are frequently administered prolonged and/or high doses of opioids which when removed can cause a withdrawal syndrome and difficulty in weaning from MV. We tested the hypothesis that the introduction of enteral methadone during weaning from sedation and analgesia in critically ill adult patients on MV would decrease the weaning time from MV. Methods: A double-blind randomized controlled trial was conducted in the adult intensive care units (ICUs) of four general hospitals in Brazil. The 75 patients, who met the criteria for weaning from MV and had been using fentanyl for more than five consecutive days, were randomized to the methadone (MG) or control group (CG). Within the first 24 hours after study enrollment, both groups received 80% of the original dose of fentanyl, the MG received enteral methadone and the CG received an enteral placebo. After the first 24 hours, the MG received an intravenous (IV) saline solution (placebo), while the CG received IV fentanyl. For both groups, the IV solution was reduced by 20% every 24 hours. The groups were compared by evaluating the MV weaning time and the duration of MV, as well as the ICU stay and the hospital stay. Results: Of the 75 patients randomized, seven were excluded and 68 were analyzed: 37 from the MG and 31 from the CG. There was a higher probability of early extubation in the MG, but the difference was not significant (hazard ratio: 1.52 (95% confidence interval (CI) 0.87 to 2.64; P = 0.11). The probability of successful weaning by the fifth day was significantly higher in the MG (hazard ratio: 2.64 (95% CI: 1.22 to 5.69; P < 0.02). Among the 54 patients who were successfully weaned (29 from the MG and 25 from the CG), the MV weaning time was significantly lower in the MG (hazard ratio: 2.06; 95% CI 1.17 to 3.63; P < 0.004). Conclusions: The introduction of enteral methadone during weaning from sedation and analgesia in mechanically ventilated patients resulted in a decrease in the weaning time from MV.
  • article 6 Citação(ões) na Scopus
    The Effects of Low and High Tidal Volume and Pentoxifylline on Intestinal Blood Flow and Leukocyte-Endothelial Interactions in Mechanically Ventilated Rats
    (2011) AIKAWA, Priscila; ZHANG, Haibo; BARBAS, Carmen S. V.; PAZETTI, Rogerio; CORREIA, Cristiano; MAUAD, Thais; SILVA, Eliezer; SANNOMIYA, Paulina; POLI-DE-FIGUEIREDO, Luiz F.; NAKAGAWA, Naomi Kondo
    BACKGROUND: The combination of high PEEP and low tidal volume (V(T)) decreases some risks of mechanical ventilation, including pulmonary overdistention, damage due to cyclic opening and closing of the alveoli, and inflammatory responses that can lead to multiple-organ dysfunction. We hypothesized that high V(T) and high PEEP induce mesenteric microcirculatory disturbances and that those disturbances would be attenuated by pentoxifylline, which is anti-inflammatory. METHODS: We anesthetized (isoflurane 1.5%), tracheostomized, and mechanically ventilated 57 male Wistar rats with PEEP of 10 cm H(2)O and F(IO2) of 0.21 for 2 hours. One group received low V(T) (7 mL/kg), another group received high V(T) (10 mL/kg), and a third group received high V(T) plus pentoxifylline (25 mg/kg). We measured mean arterial pressure, respiratory mechanics, mesenteric blood flow, and leukocyte-endothelial interactions. RESULTS: The mean arterial pressure was similar among the groups at baseline (108 mm Hg [IQR 94-118 mm Hg]) and after 2 hours of mechanical ventilation (104 mm Hg [IQR 90-114 mm Hg]). Mesenteric blood flow was also similar between the groups: low V(T) 15.1 mL/min (IQR 12.4-17.7 mL/min), high V(T) 11.3 mL/min (IQR 8.6-13.8 mL/min), high-V(T)/pentoxifylline 12.4 mL/min (10.8-13.7 mL/min). Peak airway pressure after 2 hours was lower (P = .03) in the low-V(T) group (10.4 cm H(2)O [IQR 10.2-10.4 cm H(2)O]) than in the high-V(T) group (12.6 cm H(2)O [10.2-14.9 cm H(2)O]) or the high-V(T)/pentoxifylline group (12.8 cm H(2)O [10.7-16.0 cm H(2)O]). There were fewer adherent leukocytes (P = .005) and fewer migrated leukocytes (P = .002) in the low-V(T) group (5 cells/100 gm length [IQR 4-7 cells/100 mu m length] and 1 cell/5,000 mu m(2) [IQR 1-2 cells/5,000 mu m(2)], respectively) and the high-V(T)/pentoxifylline group (5 cells/100 mu m length [IQR 3-10 cells/100 mu m length] and 1 cell/5,000 mu m(2) [IQR 1-3 cells/5,000 mu m(2)], respectively) than in the high-V(T) group (14 cells/100 mu m length [IQR 11-16 cells/100 mu m length] and 9 cells/5,000 mu m(2) [IQR 8-12 cells/5,000 mu m(2)], respectively). CONCLUSIONS: Low V(T) with high PEEP was lung-protective, and early pentoxifylline reduced the inflammatory response to high V(T) with high PEEP (and presumed lung overdistention) during mechanical ventilation.