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You searched for:"Pedro Vitale Mendes"

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  • Original Article

    Factors associated with carbon dioxide transfer in an experimental model of severe acute kidney injury and hypoventilation during high bicarbonate continuous renal replacement therapy and oxygenation membrane support

    Crit Care Sci. 2024;36:e20240005en

    Abstract

    Original Article

    Factors associated with carbon dioxide transfer in an experimental model of severe acute kidney injury and hypoventilation during high bicarbonate continuous renal replacement therapy and oxygenation membrane support

    Crit Care Sci. 2024;36:e20240005en

    DOI 10.62675/2965-2774.20240005-en

    Views54

    ABSTRACT

    Objective

    To investigate the factors influencing carbon dioxide transfer in a system that integrates an oxygenation membrane in series with high-bicarbonate continuous veno-venous hemodialysis in hypercapnic animals.

    Methods

    In an experimental setting, we induced severe acute kidney injury and hypercapnia in five female Landrace pigs. Subsequently, we initiated high (40mEq/L) bicarbonate continuous veno-venous hemodialysis with an oxygenation membrane in series to maintain a pH above 7.25. At intervals of 1 hour, 6 hours, and 12 hours following the initiation of continuous veno-venous hemodialysis, we performed standardized sweep gas flow titration to quantify carbon dioxide transfer. We evaluated factors associated with carbon dioxide transfer through the membrane lung with a mixed linear model.

    Results

    A total of 20 sweep gas flow titration procedures were conducted, yielding 84 measurements of carbon dioxide transfer. Multivariate analysis revealed associations among the following (coefficients ± standard errors): core temperature (+7.8 ± 1.6 °C, p < 0.001), premembrane partial pressure of carbon dioxide (+0.2 ± 0.1/mmHg, p < 0.001), hemoglobin level (+3.5 ± 0.6/g/dL, p < 0.001), sweep gas flow (+6.2 ± 0.2/L/minute, p < 0.001), and arterial oxygen saturation (-0.5 ± 0.2%, p = 0.019). Among these variables, and within the physiological ranges evaluated, sweep gas flow was the primary modifiable factor influencing the efficacy of low-blood-flow carbon dioxide removal.

    Conclusion

    Sweep gas flow is the main carbon dioxide removal-related variable during continuous veno-venous hemodialysis with a high bicarbonate level coupled with an oxygenator. Other carbon dioxide transfer modulating variables included the hemoglobin level, arterial oxygen saturation, partial pressure of carbon dioxide and core temperature. These results should be interpreted as exploratory to inform other well-designed experimental or clinical studies.

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    Factors associated with carbon dioxide transfer in an experimental model of severe acute kidney injury and hypoventilation during high bicarbonate continuous renal replacement therapy and oxygenation membrane support
  • Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model

    Rev Bras Ter Intensiva. 2016;28(1):11-18

    Abstract

    Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model

    Rev Bras Ter Intensiva. 2016;28(1):11-18

    DOI 10.5935/0103-507X.20160006

    Views4

    ABSTRACT

    Objective:

    The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure.

    Methods:

    The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested.

    Results:

    Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL).

    Conclusion:

    In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin.

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    Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model
  • Original Article

    Oxygen delivery, carbon dioxide removal, energy transfer to lungs and pulmonary hypertension behavior during venous-venous extracorporeal membrane oxygenation support: a mathematical modeling approach

    Rev Bras Ter Intensiva. 2019;31(2):113-121

    Abstract

    Original Article

    Oxygen delivery, carbon dioxide removal, energy transfer to lungs and pulmonary hypertension behavior during venous-venous extracorporeal membrane oxygenation support: a mathematical modeling approach

    Rev Bras Ter Intensiva. 2019;31(2):113-121

    DOI 10.5935/0103-507X.20190018

    Views6

    ABSTRACT

    Objective:

    To describe (1) the energy transfer from the ventilator to the lungs, (2) the match between venous-venous extracorporeal membrane oxygenation (ECMO) oxygen transfer and patient oxygen consumption (VO2), (3) carbon dioxide removal with ECMO, and (4) the potential effect of systemic venous oxygenation on pulmonary artery pressure.

    Methods:

    Mathematical modeling approach with hypothetical scenarios using computer simulation.

    Results:

    The transition from protective ventilation to ultraprotective ventilation in a patient with severe acute respiratory distress syndrome and a static respiratory compliance of 20mL/cm H2O reduced the energy transfer from the ventilator to the lungs from 35.3 to 2.6 joules/minute. A hypothetical patient, hyperdynamic and slightly anemic with VO2 = 200mL/minute, can reach an arterial oxygen saturation of 80%, while maintaining the match between the oxygen transfer by ECMO and the VO2 of the patient. Carbon dioxide is easily removed, and normal PaCO2 is easily reached. Venous blood oxygenation through the ECMO circuit may drive the PO2 stimulus of pulmonary hypoxic vasoconstriction to normal values.

    Conclusion:

    Ultraprotective ventilation largely reduces the energy transfer from the ventilator to the lungs. Severe hypoxemia on venous-venous-ECMO support may occur despite the matching between the oxygen transfer by ECMO and the VO2 of the patient. The normal range of PaCO2 is easy to reach. Venous-venous-ECMO support potentially relieves hypoxic pulmonary vasoconstriction.

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    Oxygen delivery, carbon dioxide removal, energy transfer to lungs and pulmonary hypertension behavior during venous-venous extracorporeal membrane oxygenation support: a mathematical modeling approach
  • Original Article

    Insights about serum sodium behavior after 24 hours of continuous renal replacement therapy

    Rev Bras Ter Intensiva. 2016;28(2):120-131

    Abstract

    Original Article

    Insights about serum sodium behavior after 24 hours of continuous renal replacement therapy

    Rev Bras Ter Intensiva. 2016;28(2):120-131

    DOI 10.5935/0103-507X.20160026

    Views1

    ABSTRACT

    Objective:

    The aim of this study was to investigate the clinical and laboratorial factors associated with serum sodium variation during continuous renal replacement therapy and to assess whether the perfect admixture formula could predict 24-hour sodium variation.

    Methods:

    Thirty-six continuous renal replacement therapy sessions of 33 patients, in which the affluent prescription was unchanged during the first 24 hours, were retrieved from a prospective collected database and then analyzed. A mixed linear model was performed to investigate the factors associated with large serum sodium variations (≥ 8mEq/L), and a Bland-Altman plot was generated to assess the agreement between the predicted and observed variations.

    Results:

    In continuous renal replacement therapy 24-hour sessions, SAPS 3 (p = 0.022) and baseline hypernatremia (p = 0.023) were statistically significant predictors of serum sodium variations ≥ 8mEq/L in univariate analysis, but only hypernatremia demonstrated an independent association (β = 0.429, p < 0.001). The perfect admixture formula for sodium prediction at 24 hours demonstrated poor agreement with the observed values.

    Conclusions:

    Hypernatremia at the time of continuous renal replacement therapy initiation is an important factor associated with clinically significant serum sodium variation. The use of 4% citrate or acid citrate dextrose - formula A 2.2% as anticoagulants was not associated with higher serum sodium variations. A mathematical prediction for the serum sodium concentration after 24 hours was not feasible.

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    Insights about serum sodium behavior after 24 hours of continuous renal replacement therapy
  • Original Articles

    Blood flow/pump rotation ratio as an artificial lung performance monitoring tool during extracorporeal respiratory support using centrifugal pumps

    Rev Bras Ter Intensiva. 2015;27(2):178-184

    Abstract

    Original Articles

    Blood flow/pump rotation ratio as an artificial lung performance monitoring tool during extracorporeal respiratory support using centrifugal pumps

    Rev Bras Ter Intensiva. 2015;27(2):178-184

    DOI 10.5935/0103-507X.20150030

    Views2

    ABSTRACT

    Objective:

    To analyze the correlations of the blood flow/pump rotation ratio and the transmembrane pressure, CO2 and O2 transfer during the extracorporeal respiratory support.

    Methods:

    Five animals were instrumented and submitted to extracorporeal membrane oxygenation in a five-step protocol, including abdominal sepsis and lung injury.

    Results:

    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).

    Conclusion:

    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.

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    Blood flow/pump rotation ratio as an artificial lung performance
               monitoring tool during extracorporeal respiratory support using centrifugal
               pumps
  • Original Article

    Metabolic acid-base adaptation triggered by acute persistent hypercapnia in mechanically ventilated patients with acute respiratory distress syndrome

    Rev Bras Ter Intensiva. 2016;28(1):19-26

    Abstract

    Original Article

    Metabolic acid-base adaptation triggered by acute persistent hypercapnia in mechanically ventilated patients with acute respiratory distress syndrome

    Rev Bras Ter Intensiva. 2016;28(1):19-26

    DOI 10.5935/0103-507X.20160009

    Views4

    ABSTRACT

    Objective:

    Hypercapnia resulting from protective ventilation in acute respiratory distress syndrome triggers metabolic pH compensation, which is not entirely characterized. We aimed to describe this metabolic compensation.

    Methods:

    The data were retrieved from a prospective collected database. Variables from patients' admission and from hypercapnia installation until the third day after installation were gathered. Forty-one patients with acute respiratory distress syndrome were analyzed, including twenty-six with persistent hypercapnia (PaCO2 > 50mmHg > 24 hours) and 15 non-hypercapnic (control group). An acid-base quantitative physicochemical approach was used for the analysis.

    Results:

    The mean ages in the hypercapnic and control groups were 48 ± 18 years and 44 ± 14 years, respectively. After the induction of hypercapnia, pH markedly decreased and gradually improved in the ensuing 72 hours, consistent with increases in the standard base excess. The metabolic acid-base adaptation occurred because of decreases in the serum lactate and strong ion gap and increases in the inorganic apparent strong ion difference. Furthermore, the elevation in the inorganic apparent strong ion difference occurred due to slight increases in serum sodium, magnesium, potassium and calcium. Serum chloride did not decrease for up to 72 hours after the initiation of hypercapnia.

    Conclusion:

    In this explanatory study, the results indicate that metabolic acid-base adaptation, which is triggered by acute persistent hypercapnia in patients with acute respiratory distress syndrome, is complex. Furthermore, further rapid increases in the standard base excess of hypercapnic patients involve decreases in serum lactate and unmeasured anions and increases in the inorganic apparent strong ion difference by means of slight increases in serum sodium, magnesium, calcium, and potassium. Serum chloride is not reduced.

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    Metabolic acid-base adaptation triggered by acute persistent hypercapnia in mechanically ventilated patients with acute respiratory distress syndrome
  • Original Article

    Bedside clinical data subphenotypes of critically ill COVID-19 patients: a cohort study

    Rev Bras Ter Intensiva. 2021;33(2):196-205

    Abstract

    Original Article

    Bedside clinical data subphenotypes of critically ill COVID-19 patients: a cohort study

    Rev Bras Ter Intensiva. 2021;33(2):196-205

    DOI 10.5935/0103-507X.20210027

    Views3

    Abstract

    Objective:

    To identify more severe COVID-19 presentations.

    Methods:

    Consecutive intensive care unit-admitted patients were subjected to a stepwise clustering method.

    Results:

    Data from 147 patients who were on average 56 ± 16 years old with a Simplified Acute Physiological Score 3 of 72 ± 18, of which 103 (70%) needed mechanical ventilation and 46 (31%) died in the intensive care unit, were analyzed. From the clustering algorithm, two well-defined groups were found based on maximal heart rate [Cluster A: 104 (95%CI 99 - 109) beats per minute versus Cluster B: 159 (95%CI 155 - 163) beats per minute], maximal respiratory rate [Cluster A: 33 (95%CI 31 - 35) breaths per minute versus Cluster B: 50 (95%CI 47 - 53) breaths per minute], and maximal body temperature [Cluster A: 37.4 (95%CI 37.1 - 37.7)°C versus Cluster B: 39.3 (95%CI 39.1 - 39.5)°C] during the intensive care unit stay, as well as the oxygen partial pressure in the blood over the oxygen inspiratory fraction at intensive care unit admission [Cluster A: 116 (95%CI 99 - 133) mmHg versus Cluster B: 78 (95%CI 63 - 93) mmHg]. Subphenotypes were distinct in inflammation profiles, organ dysfunction, organ support, intensive care unit length of stay, and intensive care unit mortality (with a ratio of 4.2 between the groups).

    Conclusion:

    Our findings, based on common clinical data, revealed two distinct subphenotypes with different disease courses. These results could help health professionals allocate resources and select patients for testing novel therapies.

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    Bedside clinical data subphenotypes of critically ill COVID-19 patients: a cohort study
  • Letter to the Editor

    Endotracheal intubation in COVID-19 patients in Brazil: a nationwide survey

    Rev Bras Ter Intensiva. 2022;34(1):202-204

    Abstract

    Letter to the Editor

    Endotracheal intubation in COVID-19 patients in Brazil: a nationwide survey

    Rev Bras Ter Intensiva. 2022;34(1):202-204

    DOI 10.5935/0103-507X.20220015-en

    Views7
    To the Editor Endotracheal intubation is a life-saving procedure in acute respiratory distress syndrome. However, complications such as hypoxia, hypotension and cardiovascular collapse may occur in almost 40% of the procedures in the intensive care unit (ICU).() Evidence regarding the best practice of endotracheal intubation in this context is scarce, and most data have been […]
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    Endotracheal intubation in COVID-19 patients in Brazil: a nationwide survey

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