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You searched for:"Luciano César Pontes Azevedo"
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Revista Brasileira de Terapia Intensiva. 2015;27(2):178-184
01-01-2015
DOI 10.5935/0103-507X.20150030
To analyze the correlations of the blood flow/pump rotation ratio and the transmembrane pressure, CO2 and O2 transfer during the extracorporeal respiratory support.
Five animals were instrumented and submitted to extracorporeal membrane oxygenation in a five-step protocol, including abdominal sepsis and lung injury.
This study showed that blood flow/pump rotations ratio variations are dependent on extracorporeal membrane oxygenation blood flow in a positive logarithmic fashion. Blood flow/pump rotation ratio variations are negatively associated with transmembrane pressure (R2 = 0.5 for blood flow = 1500mL/minute and R2 = 0.4 for blood flow = 3500mL/minute, both with p < 0.001) and positively associated with CO2 transfer variations (R2 = 0.2 for sweep gas flow ≤ 6L/minute, p < 0.001, and R2 = 0.1 for sweep gas flow > 6L/minute, p = 0.006), and the blood flow/pump rotation ratio is not associated with O2 transfer variations (R2 = 0.01 for blood flow = 1500mL/minute, p = 0.19, and R2 = - 0.01 for blood flow = 3500 mL/minute, p = 0.46).
Blood flow/pump rotation ratio variation is negatively associated with transmembrane pressure and positively associated with CO2 transfer in this animal model. According to the clinical situation, a decrease in the blood flow/pump rotation ratio can indicate artificial lung dysfunction without the occurrence of hypoxemia.
Abstract
Revista Brasileira de Terapia Intensiva. 2015;27(2):178-184
01-01-2015
DOI 10.5935/0103-507X.20150030
To analyze the correlations of the blood flow/pump rotation ratio and the transmembrane pressure, CO2 and O2 transfer during the extracorporeal respiratory support.
Five animals were instrumented and submitted to extracorporeal membrane oxygenation in a five-step protocol, including abdominal sepsis and lung injury.
This study showed that blood flow/pump rotations ratio variations are dependent on extracorporeal membrane oxygenation blood flow in a positive logarithmic fashion. Blood flow/pump rotation ratio variations are negatively associated with transmembrane pressure (R2 = 0.5 for blood flow = 1500mL/minute and R2 = 0.4 for blood flow = 3500mL/minute, both with p < 0.001) and positively associated with CO2 transfer variations (R2 = 0.2 for sweep gas flow ≤ 6L/minute, p < 0.001, and R2 = 0.1 for sweep gas flow > 6L/minute, p = 0.006), and the blood flow/pump rotation ratio is not associated with O2 transfer variations (R2 = 0.01 for blood flow = 1500mL/minute, p = 0.19, and R2 = - 0.01 for blood flow = 3500 mL/minute, p = 0.46).
Blood flow/pump rotation ratio variation is negatively associated with transmembrane pressure and positively associated with CO2 transfer in this animal model. According to the clinical situation, a decrease in the blood flow/pump rotation ratio can indicate artificial lung dysfunction without the occurrence of hypoxemia.
Abstract
Revista Brasileira de Terapia Intensiva. 2014;26(3):253-262
01-01-2014
DOI 10.5935/0103-507X.20140036
To analyze the cost-utility of using extracorporeal oxygenation for patients with severe acute respiratory distress syndrome in Brazil.
A decision tree was constructed using databases from previously published studies. Costs were taken from the average price paid by the Brazilian Unified Health System (Sistema Único de Saúde; SUS) over three months in 2011. Using the data of 10,000,000 simulated patients with predetermined outcomes and costs, an analysis was performed of the ratio between cost increase and years of life gained, adjusted for quality (cost-utility), with survival rates of 40 and 60% for patients using extracorporeal membrane oxygenation.
The decision tree resulted in 16 outcomes with different life support techniques. With survival rates of 40 and 60%, respectively, the increased costs were R$=-301.00/-14.00, with a cost of R$=-30,913.00/-1,752.00 paid per six-month quality-adjusted life-year gained and R$=-2,386.00/-90.00 per quality-adjusted life-year gained until the end of life, when all patients with severe ARDS were analyzed. Analyzing only patients with severe hypoxemia (i.e., a ratio of partial oxygen pressure in the blood to the fraction of inspired oxygen <100mmHg), the increased cost was R$=-5,714.00/272.00, with a cost per six-month quality-adjusted life-year gained of R$=-9,521.00/293.00 and a cost of R$=-280.00/7.00 per quality-adjusted life-year gained.
The cost-utility ratio associated with the use of extracorporeal membrane oxygenation in Brazil is potentially acceptable according to this hypothetical study.
Abstract
Revista Brasileira de Terapia Intensiva. 2014;26(3):253-262
01-01-2014
DOI 10.5935/0103-507X.20140036
To analyze the cost-utility of using extracorporeal oxygenation for patients with severe acute respiratory distress syndrome in Brazil.
A decision tree was constructed using databases from previously published studies. Costs were taken from the average price paid by the Brazilian Unified Health System (Sistema Único de Saúde; SUS) over three months in 2011. Using the data of 10,000,000 simulated patients with predetermined outcomes and costs, an analysis was performed of the ratio between cost increase and years of life gained, adjusted for quality (cost-utility), with survival rates of 40 and 60% for patients using extracorporeal membrane oxygenation.
The decision tree resulted in 16 outcomes with different life support techniques. With survival rates of 40 and 60%, respectively, the increased costs were R$=-301.00/-14.00, with a cost of R$=-30,913.00/-1,752.00 paid per six-month quality-adjusted life-year gained and R$=-2,386.00/-90.00 per quality-adjusted life-year gained until the end of life, when all patients with severe ARDS were analyzed. Analyzing only patients with severe hypoxemia (i.e., a ratio of partial oxygen pressure in the blood to the fraction of inspired oxygen <100mmHg), the increased cost was R$=-5,714.00/272.00, with a cost per six-month quality-adjusted life-year gained of R$=-9,521.00/293.00 and a cost of R$=-280.00/7.00 per quality-adjusted life-year gained.
The cost-utility ratio associated with the use of extracorporeal membrane oxygenation in Brazil is potentially acceptable according to this hypothetical study.
Abstract
Revista Brasileira de Terapia Intensiva. 2014;26(3):287-291
01-01-2014
DOI 10.5935/0103-507X.20140040
To develop experimental models of erythrocyte transfusion, the first step is to ensure the viability of the red blood cells transfused. In this pilot study, we assessed the viability of transfused red blood cells with validation in vitro and in vivo of homologous swine erythrocytes stored for 14 days.
Blood collected from one Agroceres® swine was stored in two red blood cell units. In vivo validation was performed by labeling the red blood cells with Na2 51CrO4 and recovering the viable erythrocytes after 24 hours of infusion in one autologous and four homologous animals. In vitro validation was performed at baseline and after 14 days in sixteen red blood cell units by measuring hemoglobin, hematocrit, hemolysis index and free hemoglobin. A post-mortem splenectomy was performed to evaluate the splenic sequestration of erythrocytes, and the radioactivity of the supernatant samples was counted to evaluate intravascular hemolysis.
After 14 days of storage, the red blood cell units had lower volumes and equivalent total concentrations of hemoglobin and hematocrit compared to human standards. The free hemoglobin concentration increased from 31.0±9.3 to 112.4±31.4mg/dL (p<0.001), and the hemolysis index increased from 0.1±0.1 to 0.5±0.1% (p<0.001). However, these tests were within the acceptable range for human standards. The percentage of radioactivity in supernatant samples was similar at baseline and after 24 hours, thus excluding significant hemolysis. No evidence of splenic sequestration of radioactive erythrocytes was found.
Swine red blood cells stored for 14 days are viable and can be used in experimental studies of transfusion. These validation experiments are important to aid investigators in establishing experimental models of transfusion.
Abstract
Revista Brasileira de Terapia Intensiva. 2014;26(3):287-291
01-01-2014
DOI 10.5935/0103-507X.20140040
To develop experimental models of erythrocyte transfusion, the first step is to ensure the viability of the red blood cells transfused. In this pilot study, we assessed the viability of transfused red blood cells with validation in vitro and in vivo of homologous swine erythrocytes stored for 14 days.
Blood collected from one Agroceres® swine was stored in two red blood cell units. In vivo validation was performed by labeling the red blood cells with Na2 51CrO4 and recovering the viable erythrocytes after 24 hours of infusion in one autologous and four homologous animals. In vitro validation was performed at baseline and after 14 days in sixteen red blood cell units by measuring hemoglobin, hematocrit, hemolysis index and free hemoglobin. A post-mortem splenectomy was performed to evaluate the splenic sequestration of erythrocytes, and the radioactivity of the supernatant samples was counted to evaluate intravascular hemolysis.
After 14 days of storage, the red blood cell units had lower volumes and equivalent total concentrations of hemoglobin and hematocrit compared to human standards. The free hemoglobin concentration increased from 31.0±9.3 to 112.4±31.4mg/dL (p<0.001), and the hemolysis index increased from 0.1±0.1 to 0.5±0.1% (p<0.001). However, these tests were within the acceptable range for human standards. The percentage of radioactivity in supernatant samples was similar at baseline and after 24 hours, thus excluding significant hemolysis. No evidence of splenic sequestration of radioactive erythrocytes was found.
Swine red blood cells stored for 14 days are viable and can be used in experimental studies of transfusion. These validation experiments are important to aid investigators in establishing experimental models of transfusion.
Abstract
Revista Brasileira de Terapia Intensiva. 2012;24(2):137-142
08-01-2012
DOI 10.1590/S0103-507X2012000200007
OBJECTIVE: To investigate the hemodynamic, respiratory and metabolic impact of blood contact with a priming volume and extracorporeal membrane oxygenation circuit, before the initiation of oxygenation and ventilation METHODS: Five animals were instrumented and submitted to extracorporeal membrane oxygenation. Data were collected at the baseline and 30 minutes after starting extracorporeal circulation, without membrane ventilatory (sweeper) flow. RESULTS: After starting extracorporeal membrane oxygenation, there was a non-significant elevation in pulmonary vascular resistance from 235 (178,303) to 379 (353,508) dyn.seg.(cm5)-1 (P=0.065), associated with an elevation in the alveolar arterial oxygen gradient from 235 (178,303) to 379 (353,508) mmHg (P=0.063). We also observed a reduction in the left ventricle stroke work from 102 (94,105) to 78 (71,87) (mL.mmHg)/beat (P=0.064), in addition to a reduction in cardiac output from 7.2 (6.8,7.6) to 5.9 (5.8,6.3) L/min (P=0.188). The right ventricle stroke work was counterbalanced between the pulmonary vascular resistance increment and the cardiac output reduction, maintaining a similar value. CONCLUSIONS: We presented an experimental model that is feasible and safe. Blood contact with the priming volume and extracorporeal membrane oxygenation circuit resulted in non-significant systemic or metabolic changes.
Abstract
Revista Brasileira de Terapia Intensiva. 2012;24(2):137-142
08-01-2012
DOI 10.1590/S0103-507X2012000200007
OBJECTIVE: To investigate the hemodynamic, respiratory and metabolic impact of blood contact with a priming volume and extracorporeal membrane oxygenation circuit, before the initiation of oxygenation and ventilation METHODS: Five animals were instrumented and submitted to extracorporeal membrane oxygenation. Data were collected at the baseline and 30 minutes after starting extracorporeal circulation, without membrane ventilatory (sweeper) flow. RESULTS: After starting extracorporeal membrane oxygenation, there was a non-significant elevation in pulmonary vascular resistance from 235 (178,303) to 379 (353,508) dyn.seg.(cm5)-1 (P=0.065), associated with an elevation in the alveolar arterial oxygen gradient from 235 (178,303) to 379 (353,508) mmHg (P=0.063). We also observed a reduction in the left ventricle stroke work from 102 (94,105) to 78 (71,87) (mL.mmHg)/beat (P=0.064), in addition to a reduction in cardiac output from 7.2 (6.8,7.6) to 5.9 (5.8,6.3) L/min (P=0.188). The right ventricle stroke work was counterbalanced between the pulmonary vascular resistance increment and the cardiac output reduction, maintaining a similar value. CONCLUSIONS: We presented an experimental model that is feasible and safe. Blood contact with the priming volume and extracorporeal membrane oxygenation circuit resulted in non-significant systemic or metabolic changes.
Abstract
Revista Brasileira de Terapia Intensiva. 2011;23(4):426-433
04-04-2011
DOI 10.1590/S0103-507X2011000400006
OBJECTIVE: To investigate the correlation of organ dysfunction and its progression with inflammatory response during the early phases of septic shock by assessing baseline cytokine concentrations. METHODS: This study included patients over 18 years old with septic shock within the first 48 hours after the onset of organ dysfunction. Interleukin 6 (IL-6), interleukin 8 (IL-8), interleukin 10 (IL-10) and C-reactive protein levels were assessed at inclusion and after 24 hours, and the differences between these values were calculated. The progression of organ dysfunction was assessed using the Sequential Organ Failure Assessment (SOFA) score upon admission and 24 hours later for a delta-SOFA determination and were categorized as either worsened or improved. The results were expressed as means + standard deviation or median (25-75% percentiles). Values with descriptive p values of 0.05 or less were considered significant. RESULTS: Overall, we included 41 patients with median SOFA scores of 8.0 (6.5-10.0) upon admission (T0) and 8.0 (6.0-10.0) 24 hours later (T1). Worsened, improved or unchanged SOFA scores were observed in 11 (Group 1), 17 (Group 2) and 13 (Group 3) patients, respectively. For Group 1, the baseline IL-6, IL-8 and IL-10 values were higher, and a significant increase of IL-8 levels was found after 24 hours. The change in the SOFA score after 24 hours was significantly, although weakly, correlated with baseline IL-6 and IL-8 concentrations. CONCLUSIONS: Higher baseline IL-6, IL-8 and IL-10 levels are associated with unfavorable organ dysfunction outcomes. Increased IL-8 levels within the first 24 hours are correlated with a worsening dysfunction.
Abstract
Revista Brasileira de Terapia Intensiva. 2011;23(4):426-433
04-04-2011
DOI 10.1590/S0103-507X2011000400006
OBJECTIVE: To investigate the correlation of organ dysfunction and its progression with inflammatory response during the early phases of septic shock by assessing baseline cytokine concentrations. METHODS: This study included patients over 18 years old with septic shock within the first 48 hours after the onset of organ dysfunction. Interleukin 6 (IL-6), interleukin 8 (IL-8), interleukin 10 (IL-10) and C-reactive protein levels were assessed at inclusion and after 24 hours, and the differences between these values were calculated. The progression of organ dysfunction was assessed using the Sequential Organ Failure Assessment (SOFA) score upon admission and 24 hours later for a delta-SOFA determination and were categorized as either worsened or improved. The results were expressed as means + standard deviation or median (25-75% percentiles). Values with descriptive p values of 0.05 or less were considered significant. RESULTS: Overall, we included 41 patients with median SOFA scores of 8.0 (6.5-10.0) upon admission (T0) and 8.0 (6.0-10.0) 24 hours later (T1). Worsened, improved or unchanged SOFA scores were observed in 11 (Group 1), 17 (Group 2) and 13 (Group 3) patients, respectively. For Group 1, the baseline IL-6, IL-8 and IL-10 values were higher, and a significant increase of IL-8 levels was found after 24 hours. The change in the SOFA score after 24 hours was significantly, although weakly, correlated with baseline IL-6 and IL-8 concentrations. CONCLUSIONS: Higher baseline IL-6, IL-8 and IL-10 levels are associated with unfavorable organ dysfunction outcomes. Increased IL-8 levels within the first 24 hours are correlated with a worsening dysfunction.
Abstract
Revista Brasileira de Terapia Intensiva. 2011;23(3):283-290
10-24-2011
DOI 10.1590/S0103-507X2011000300005
OBJECTIVES: Although fluid resuscitation guided by central venous oxygen saturation (SvcO2) is currently considered the gold standard in sepsis therapy, few studies have described hemodynamic and perfusion parameters during this procedure. This study aims to describe these parameters during septic shock without resuscitation and after 12 hours of goal-directed resuscitation. METHODS: Thirteen anesthetized pigs (35-45 kg) had peritonitis caused by fecal inoculation (0.75 g/kg). After developing persistent hypotension, both groups were given antibiotics and randomized either to the control group (n=7) or the experimental group (n=6). In the control group, hemodynamic control was optimized to maintain a central venous pressure of 8-12 mmHg, a urinary output above 0.5 mL/kg/hour and a mean arterial blood pressure above 65 mmHg. The experimental group received the above target therapy in addition to maintaining a SvO2 above 65%. The interventions included lactated Ringer's solution and norepinephrine for both groups and dobutamine in the SvO2 group. The animals were treated for 12 hours or until death. RESULTS: Untreated sepsis was associated with significant reductions in SvO2, PvO2, cardiac output and central venous pressure in addition to increased arteriovenous oxygen saturation and veno-arterial CO2 differences. Following resuscitation, these parameters were corrected in both groups. Goal-directed resuscitation was associated with a better hemodynamic profile, characterized by higher SvO2, cardiac output and central venous pressure. CONCLUSIONS: Non-resuscitated sepsis showed a hemodynamic profile suggesting hypovolemia, with worsened perfusion and hemodynamics, which is reversed upon fluid resuscitation. Goal-directed resuscitation is associated with significantly improved hemodynamic and perfusion parameters
Abstract
Revista Brasileira de Terapia Intensiva. 2011;23(3):283-290
10-24-2011
DOI 10.1590/S0103-507X2011000300005
OBJECTIVES: Although fluid resuscitation guided by central venous oxygen saturation (SvcO2) is currently considered the gold standard in sepsis therapy, few studies have described hemodynamic and perfusion parameters during this procedure. This study aims to describe these parameters during septic shock without resuscitation and after 12 hours of goal-directed resuscitation. METHODS: Thirteen anesthetized pigs (35-45 kg) had peritonitis caused by fecal inoculation (0.75 g/kg). After developing persistent hypotension, both groups were given antibiotics and randomized either to the control group (n=7) or the experimental group (n=6). In the control group, hemodynamic control was optimized to maintain a central venous pressure of 8-12 mmHg, a urinary output above 0.5 mL/kg/hour and a mean arterial blood pressure above 65 mmHg. The experimental group received the above target therapy in addition to maintaining a SvO2 above 65%. The interventions included lactated Ringer's solution and norepinephrine for both groups and dobutamine in the SvO2 group. The animals were treated for 12 hours or until death. RESULTS: Untreated sepsis was associated with significant reductions in SvO2, PvO2, cardiac output and central venous pressure in addition to increased arteriovenous oxygen saturation and veno-arterial CO2 differences. Following resuscitation, these parameters were corrected in both groups. Goal-directed resuscitation was associated with a better hemodynamic profile, characterized by higher SvO2, cardiac output and central venous pressure. CONCLUSIONS: Non-resuscitated sepsis showed a hemodynamic profile suggesting hypovolemia, with worsened perfusion and hemodynamics, which is reversed upon fluid resuscitation. Goal-directed resuscitation is associated with significantly improved hemodynamic and perfusion parameters
Abstract
Revista Brasileira de Terapia Intensiva. 2011;23(3):374-379
10-24-2011
DOI 10.1590/S0103-507X2011000300017
There are few reports in the literature regarding the use of venoarterial extracorporeal membrane oxygenation (ECMO) for double-dysfunction from both heart and lung contusions in polytrauma patients. This article reports a 48-year-old patient admitted after a traffic accident. He rapidly progressed to shock with low cardiac output due to myocardial contusion and refractory hypoxemia due to pulmonary contusion, an unstable chest wall and bilateral pneumothorax. ECMO was an effective rescue procedure in this dramatic situation and was successfully discontinued on the fourth day after the trauma. The patient also developed an extensive brain infarction and eventually died on the seventh day after admission
Abstract
Revista Brasileira de Terapia Intensiva. 2011;23(3):374-379
10-24-2011
DOI 10.1590/S0103-507X2011000300017
There are few reports in the literature regarding the use of venoarterial extracorporeal membrane oxygenation (ECMO) for double-dysfunction from both heart and lung contusions in polytrauma patients. This article reports a 48-year-old patient admitted after a traffic accident. He rapidly progressed to shock with low cardiac output due to myocardial contusion and refractory hypoxemia due to pulmonary contusion, an unstable chest wall and bilateral pneumothorax. ECMO was an effective rescue procedure in this dramatic situation and was successfully discontinued on the fourth day after the trauma. The patient also developed an extensive brain infarction and eventually died on the seventh day after admission
Abstract
Revista Brasileira de Terapia Intensiva. 2011;23(2):164-169
08-01-2011
DOI 10.1590/S0103-507X2011000200008
OBJECTIVE: To evaluate the effects of hemodynamic, respiratory and metabolic changes on intracranial pressure in a model of acute lung injury and abdominal compartment syndrome. METHODS: Eight Agroceres pigs were submitted to five different clinical scenarios after instrumentation: 1) a baseline condition with low intra-abdominal pressure and healthy lungs; 2) pneumoperitoneum with 20 mmHg intra-abdominal pressure; 3) acute lung injury induced by pulmonary lavage with surfactant deactivation; 4) pneumoperitoneum with 20 mmHg intra-abdominal pressure with lung pulmonary injury and low positive end-expiratory pressure; and 5) 27 cmH2O positive end-expiratory pressure with pneumoperitoneum and acute lung injury. Respiratory and hemodynamic variables were collected. A multivariate analysis was conducted to search for variables associated with increased intracranial pressure in the five scenarios. RESULTS: Only plateau airway pressure showed a positive correlation with intracranial pressure in the multivariate analysis. In the models with acute lung injury, plateau airway pressure, CO2 arterial pressure, end tidal CO2 and central venous pressure were positively correlated with increased intracranial pressure. CONCLUSION: In a model of multiple organ dysfunction with associated clinical conditions causing increased intra-thoracic and abdominal pressure, increased intracranial pressure triggered by elevated intra-abdominal pressure is apparently caused by worsened respiratory system compliance and a reduced brain venous drainage gradient due to increased central venous pressure.
Abstract
Revista Brasileira de Terapia Intensiva. 2011;23(2):164-169
08-01-2011
DOI 10.1590/S0103-507X2011000200008
OBJECTIVE: To evaluate the effects of hemodynamic, respiratory and metabolic changes on intracranial pressure in a model of acute lung injury and abdominal compartment syndrome. METHODS: Eight Agroceres pigs were submitted to five different clinical scenarios after instrumentation: 1) a baseline condition with low intra-abdominal pressure and healthy lungs; 2) pneumoperitoneum with 20 mmHg intra-abdominal pressure; 3) acute lung injury induced by pulmonary lavage with surfactant deactivation; 4) pneumoperitoneum with 20 mmHg intra-abdominal pressure with lung pulmonary injury and low positive end-expiratory pressure; and 5) 27 cmH2O positive end-expiratory pressure with pneumoperitoneum and acute lung injury. Respiratory and hemodynamic variables were collected. A multivariate analysis was conducted to search for variables associated with increased intracranial pressure in the five scenarios. RESULTS: Only plateau airway pressure showed a positive correlation with intracranial pressure in the multivariate analysis. In the models with acute lung injury, plateau airway pressure, CO2 arterial pressure, end tidal CO2 and central venous pressure were positively correlated with increased intracranial pressure. CONCLUSION: In a model of multiple organ dysfunction with associated clinical conditions causing increased intra-thoracic and abdominal pressure, increased intracranial pressure triggered by elevated intra-abdominal pressure is apparently caused by worsened respiratory system compliance and a reduced brain venous drainage gradient due to increased central venous pressure.