Noninvasive Neuromodulation Techniques in Difficult Tracheostomy Weaning of Patients With Spinal Cord Injury: Report of Two Cases.

High spinal cord injured patients (SCI) are susceptible to respiratory muscle impairments. Transcranial direct current stimulation (tDCS) and peripheral electrical stimulation (PES) may influence the diaphragm's central control, but until now they are not described as a therapeutic resource for difficult weaning. We present two case reports of SCI patients (P1 and P2) with long-term tracheostomy (>40 days) and hospital stay (>50 days). In association with respiratory exercise, P1 received a combined application of anodal tDCS over the supplementary motor area plus sensory PES in the thoracic-abdominal muscles, and P2 received isolated excitatory PES in the abdominal muscles, applied daily except on weekends. Maximum inspiratory/expiratory pressure, peak cough flow, diaphragm excursion, and thickening fraction were measured in the first and last days of the protocol. Both patients had improvements, with clinical impact such as cough effectiveness, decannulated after 15 applications of stimulation. Augmentation of neural respiratory drive and corticospinal excitability is suggested.

Characteristics and outcomes of patients with COVID-19 admitted to the ICU in a university hospital in São Paulo, Brazil - study protocol.

OBJECTIVES: We designed a cohort study to describe characteristics and outcomes of patients with coronavirus disease (COVID-19) admitted to the intensive care unit (ICU) in the largest public hospital in Sao Paulo, Brazil, as Latin America becomes the epicenter of the pandemic. METHODS: This is the protocol for a study being conducted at an academic hospital in Brazil with 300 adult ICU beds dedicated to COVID-19 patients. We will include adult patients admitted to the ICU with suspected or confirmed COVID-19 during the study period. The main outcome is ICU survival at 28 days. Data will be collected prospectively and retrospectively by trained investigators from the hospital's electronic medical records, using an electronic data capture tool. We will collect data on demographics, comorbidities, severity of disease, and laboratorial test results at admission. Information on the need for advanced life support and ventilator parameters will be collected during ICU stay. Patients will be followed up for 28 days in the ICU and 60 days in the hospital. We will plot Kaplan-Meier curves to estimate ICU and hospital survival and perform survival analysis using the Cox proportional hazards model to identify the main risk factors for mortality. ClinicalTrials.gov: NCT04378582. RESULTS: We expect to include a large sample of patients with COVID-19 admitted to the ICU and to be able to provide data on admission characteristics, use of advanced life support, ICU survival at 28 days, and hospital survival at 60 days. CONCLUSIONS: This study will provide epidemiological data about critically ill patients with COVID-19 in Brazil, which could inform health policy and resource allocation in low- and middle-income countries.

Characteristics and outcomes of patients with COVID-19 admitted to the ICU in a university hospital in São Paulo, Brazil - study protocol

OBJECTIVES: We designed a cohort study to describe characteristics and outcomes of patients with coronavirus disease (COVID-19) admitted to the intensive care unit (ICU) in the largest public hospital in Sao Paulo, Brazil, as Latin America becomes the epicenter of the pandemic. METHODS: This is the protocol for a study being conducted at an academic hospital in Brazil with 300 adult ICU beds dedicated to COVID-19 patients. We will include adult patients admitted to the ICU with suspected or confirmed COVID-19 during the study period. The main outcome is ICU survival at 28 days. Data will be collected prospectively and retrospectively by trained investigators from the hospital's electronic medical records, using an electronic data capture tool. We will collect data on demographics, comorbidities, severity of disease, and laboratorial test results at admission. Information on the need for advanced life support and ventilator parameters will be collected during ICU stay. Patients will be followed up for 28 days in the ICU and 60 days in the hospital. We will plot Kaplan-Meier curves to estimate ICU and hospital survival and perform survival analysis using the Cox proportional hazards model to identify the main risk factors for mortality. ClinicalTrials.gov: NCT04378582. RESULTS: We expect to include a large sample of patients with COVID-19 admitted to the ICU and to be able to provide data on admission characteristics, use of advanced life support, ICU survival at 28 days, and hospital survival at 60 days. CONCLUSIONS: This study will provide epidemiological data about critically ill patients with COVID-19 in Brazil, which could inform health policy and resource allocation in low- and middle-income countries.

Driving pressure and long-term outcomes in moderate/severe acute respiratory distress syndrome.

BACKGROUND: Acute respiratory distress syndrome (ARDS) patients may present impaired in lung function and structure after hospital discharge that may be related to mechanical ventilation strategy. The aim of this study was to evaluate the association between functional and structural lung impairment, N-terminal-peptide type III procollagen (NT-PCP-III) and driving pressure during protective mechanical ventilation. It was a secondary analysis of data from randomized controlled trial that included patients with moderate/severe ARDS with at least one follow-up visit performed. We obtained serial measurements of plasma NT-PCP-III levels. Whole-lung computed tomography analysis and pulmonary function test were performed at 1 and 6 months of follow-up. A health-related quality of life survey after 6 months was also performed. RESULTS: Thirty-three patients were enrolled, and 21 patients survived after 6 months. In extubation day an association between driving pressure and NT-PCP-III was observed. At 1 and 6 months forced vital capacity (FVC) was negatively correlated to driving pressure (p < 0.01). At 6 months driving pressure was associated with lower FVC independently on tidal volume, plateau pressure and baseline static respiratory compliance after adjustments (r2 = 0.51, p = 0.02). There was a significant correlation between driving pressure and lung densities and nonaerated/poorly aerated lung volume after 6 months. Driving pressure was also related to general health domain of SF-36 at 6 months. CONCLUSION: Even in patients ventilated with protective tidal volume, higher driving pressure is associated with worse long-term pulmonary function and structure.

Characterization of patients transported with extracorporeal respiratory and/or cardiovascular support in the State of São Paulo, Brazil. / Caracterização de pacientes transportados com suporte respiratório e/ou cardiovascular extracorpóreo no Estado de São Paulo − Brasil.

OBJECTIVE: To characterize the transport of severely ill patients with extracorporeal respiratory or cardiovascular support. METHODS: A series of 18 patients in the state of São Paulo, Brazil is described. All patients were consecutively evaluated by a multidisciplinary team at the hospital of origin. The patients were rescued, and extracorporeal membrane oxygenation support was provided on site. The patients were then transported to referral hospitals for extracorporeal membrane oxygenation support. Data were retrieved from a prospectively collected database. RESULTS: From 2011 to 2017, 18 patients aged 29 (25 - 31) years with a SAPS 3 of 84 (68 - 92) and main primary diagnosis of leptospirosis and influenza A (H1N1) virus were transported to three referral hospitals in São Paulo. A median distance of 39 (15 - 82) km was traveled on each rescue mission during a period of 360 (308 - 431) min. A median of one (0 - 2) nurse, three (2 - 3) physicians, and one (0 - 1) physical therapist was present per rescue. Seventeen rescues were made by ambulance, and one rescue was made by helicopter. The observed complications were interruption in the energy supply to the pump in two cases (11%) and oxygen saturation < 70% in two cases. Thirteen patients (72%) survived and were discharged from the hospital. Among the nonsurvivors, there were two cases of brain death, two cases of multiple organ dysfunction syndrome, and one case of irreversible pulmonary fibrosis. CONCLUSIONS: Transportation with extracorporeal support occurred without serious complications, and the hospital survival rate was high.

OBJETIVO: Caracterizar pacientes graves transportados em suporte respiratório ou cardiovascular extracorpóreo. MÉTODOS: Descrição de uma série de 18 casos registrados no Estado de São Paulo. Todos os pacientes foram consecutivamente avaliados por uma equipe multidisciplinar no hospital de origem. Os pacientes foram resgatados, sendo a oxigenação por membrana extracorpórea instalada in loco. Os pacientes foram, então, transportados para os hospitais referenciados já em oxigenação por membrana extracorpórea. Os dados foram recuperados de um banco de dados prospectivamente coletado. RESULTADOS: De 2011 até 2017, 18 pacientes com 29 (25 - 31) anos, SAPS3 de 84 (68 - 92), com principais diagnósticos de leptospirose e influenza A (H1N1) foram transportados no Estado de São Paulo para três hospitais referenciados. Uma distância mediana de 39 (15 - 82) km foi percorrida em cada missão, em um tempo de 360 (308 - 431) minutos. As medianas de um (0 - 2) enfermeiro, três (2 - 3) médicos e um (0 - 1) fisioterapeuta foram necessárias por missão. Dezessete transportes foram realizados por ambulância e um por helicóptero. Existiram intercorrências: em duas ocasiões (11%), houve falha de fornecimento de energia para a bomba e, em duas ocasiões, queda da saturação de oxigênio < 70%. Treze pacientes (72%) sobreviveram para a alta hospitalar. Dos pacientes não sobreviventes, dois tiveram morte encefálica; dois, disfunção de múltiplos órgãos; e um, fibrose pulmonar considerada irreversível. CONCLUSÕES: O transporte com suporte extracorpóreo ocorreu sem intercorrências maiores, com uma sobrevida hospitalar alta dos pacientes.

Caracterização de pacientes transportados com suporte respiratório e/ou cardiovascular extracorpóreo no Estado de São Paulo - Brasil / Characterization of patients transported with extracorporeal respiratory and/or cardiovascular support in the State of São Paulo, Brazil

RESUMO Objetivo: Caracterizar pacientes graves transportados em suporte respiratório ou cardiovascular extracorpóreo. Métodos: Descrição de uma série de 18 casos registrados no Estado de São Paulo. Todos os pacientes foram consecutivamente avaliados por uma equipe multidisciplinar no hospital de origem. Os pacientes foram resgatados, sendo a oxigenação por membrana extracorpórea instalada in loco. Os pacientes foram, então, transportados para os hospitais referenciados já em oxigenação por membrana extracorpórea. Os dados foram recuperados de um banco de dados prospectivamente coletado. Resultados: De 2011 até 2017, 18 pacientes com 29 (25 - 31) anos, SAPS3 de 84 (68 - 92), com principais diagnósticos de leptospirose e influenza A (H1N1) foram transportados no Estado de São Paulo para três hospitais referenciados. Uma distância mediana de 39 (15 - 82) km foi percorrida em cada missão, em um tempo de 360 (308 - 431) minutos. As medianas de um (0 - 2) enfermeiro, três (2 - 3) médicos e um (0 - 1) fisioterapeuta foram necessárias por missão. Dezessete transportes foram realizados por ambulância e um por helicóptero. Existiram intercorrências: em duas ocasiões (11%), houve falha de fornecimento de energia para a bomba e, em duas ocasiões, queda da saturação de oxigênio < 70%. Treze pacientes (72%) sobreviveram para a alta hospitalar. Dos pacientes não sobreviventes, dois tiveram morte encefálica; dois, disfunção de múltiplos órgãos; e um, fibrose pulmonar considerada irreversível. Conclusões: O transporte com suporte extracorpóreo ocorreu sem intercorrências maiores, com uma sobrevida hospitalar alta dos pacientes.

ABSTRACT Objective: To characterize the transport of severely ill patients with extracorporeal respiratory or cardiovascular support. Methods: A series of 18 patients in the state of São Paulo, Brazil is described. All patients were consecutively evaluated by a multidisciplinary team at the hospital of origin. The patients were rescued, and extracorporeal membrane oxygenation support was provided on site. The patients were then transported to referral hospitals for extracorporeal membrane oxygenation support. Data were retrieved from a prospectively collected database. Results: From 2011 to 2017, 18 patients aged 29 (25 - 31) years with a SAPS 3 of 84 (68 - 92) and main primary diagnosis of leptospirosis and influenza A (H1N1) virus were transported to three referral hospitals in São Paulo. A median distance of 39 (15 - 82) km was traveled on each rescue mission during a period of 360 (308 - 431) min. A median of one (0 - 2) nurse, three (2 - 3) physicians, and one (0 - 1) physical therapist was present per rescue. Seventeen rescues were made by ambulance, and one rescue was made by helicopter. The observed complications were interruption in the energy supply to the pump in two cases (11%) and oxygen saturation < 70% in two cases. Thirteen patients (72%) survived and were discharged from the hospital. Among the nonsurvivors, there were two cases of brain death, two cases of multiple organ dysfunction syndrome, and one case of irreversible pulmonary fibrosis. Conclusions: Transportation with extracorporeal support occurred without serious complications, and the hospital survival rate was high.

Transportation of patients on extracorporeal membrane oxygenation: a tertiary medical center experience and systematic review of the literature.

BACKGROUND: Utilization of extracorporeal membrane oxygenation (ECMO) has increased worldwide, but its use remains restricted to severely ill patients, and few referral centers are properly structured to offer this support. Inter-hospital transfer of patients on ECMO support can be life-threatening. In this study, we report a single-center experience and a systematic review of the available published data on complications and mortality associated with ECMO transportation. METHODS: We reported single-center data regarding complications and mortality associated with the transportation of patients on ECMO support. Additionally, we searched multiple databases for case series, observational studies, and randomized controlled trials regarding mortality of patients transferred on ECMO support. Results were analyzed independently for pediatric (under 12 years old) and adult populations. We pooled mortality rates using a random-effects model. Complications and transportation data were also described. RESULTS: A total of 38 manuscripts, including our series, were included in the final analysis, totaling 1481 patients transported on ECMO support. A total of 951 patients survived to hospital discharge. The pooled survival rates for adult and pediatric patients were 62% (95% CI 57-68) and 68% (95% CI 60-75), respectively. Two deaths occurred during patient transportation. No other complication resulting in adverse outcome was reported. CONCLUSION: Using the available pooled data, we found that patient transfer to a referral institution while on ECMO support seems to be safe and adds no significant risk of mortality to ECMO patients.

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

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.

Fatores associados à regulação da pressão parcial de oxigênio e da pressão parcial de gás carbônico durante suporte respiratório com oxigenação por membrana extracorpórea: dados de um modelo em suínos / Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model

RESUMO Objetivo: Explorar os fatores associados aos níveis sanguíneos da pressão parcial de oxigênio e da pressão parcial de gás carbônico. Métodos: Os fatores associados com a regulação do oxigênio e de gás carbônico foram investigados em um modelo com porcos em apneia com suporte de oxigenação por membrana extracorpórea venovenosa. Foi testada uma sequência predefinida de fluxos de sangue e gás. Resultados: A oxigenação associou-se principalmente com o fluxo da oxigenação por membrana extracorpórea (coeficiente beta = 0,036mmHg/mL/minuto), débito cardíaco (coeficiente beta = -11,970mmHg/L/minuto) e shunt pulmonar (coeficiente beta = -0,232mmHg/%). As mensurações iniciais da pressão parcial de oxigênio e da pressão parcial de gás carbônico também se associaram com oxigenação, com coeficientes beta de 0,160 e 0,442mmHg/mmHg, respectivamente. A pressão parcial de gás carbônico se associou com débito cardíaco (coeficiente beta = 3,578mmHg/L/minuto), fluxo de gás (coeficiente beta = -2,635mmHg/L/minuto), temperatura (coeficiente beta = 4,514mmHg/°C), pH inicial (coeficiente beta = -66,065mmHg/0,01 unidade) e hemoglobina (coeficiente beta = 6,635mmHg/g/dL). Conclusão: Elevações nos fluxos de sangue de gás em um modelo de oxigenação por membrana extracorpórea venovenosa durante apneia resultaram em aumento da pressão parcial de oxigênio e redução da pressão parcial de gás carbônico, respectivamente. Ainda, sem a possibilidade de uma inferência causal, a pressão parcial de oxigênio associou-se negativamente com o shunt pulmonar e o débito cardíaco, e a pressão parcial de gás carbônico teve associação positiva com o débito cardíaco, temperatura central e hemoglobina inicial.

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.

Kinetics of arterial carbon dioxide during veno-venous extracorporeal membrane oxygenation support in an apnoeic porcine model.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) is a technique widely used worldwide to improve gas exchange. Changes in ECMO settings affect both oxygen and carbon dioxide. The impact on oxygenation can be followed closely by continuous pulse oximeter. Conversely, carbon dioxide equilibrates much slower and is not usually monitored directly. METHODS: We investigated the time to stabilization of arterial carbon dioxide partial pressure (PaCO2) following step changes in ECMO settings in 5 apnoeic porcine models under veno-venous ECMO support with polymethylpentene membranes. We collected sequential arterial blood gases at a pre-specified interval of 50 min using a sequence of standardized blood and sweep gas flow combinations. RESULTS: Following the changes in ECMO parameters, the kinetics of carbon dioxide was dependent on sweep gas and ECMO blood flow. With a blood flow of 1500 mL/min, PaCO2 takes longer than 50 min to equilibrate following the changes in sweep gas flow. Furthermore, the sweep gas flow from 3.0 to 10.0 L/min did not significantly affect PaCO2. However, with a blood flow of 3500 mL/min, 50 min was enough for PaCO2 to reach the equilibrium and every increment of sweep gas flow (up to 10.0 L/min) resulted in additional reductions of PaCO2. CONCLUSIONS: Fifty minutes was enough to reach the equilibrium of PaCO2 after ECMO initiation or after changes in blood and sweep gas flow with an ECMO blood flow of 3500 ml/min. Longer periods may be necessary with lower ECMO blood flows.

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

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.

Variação da razão entre fluxo sanguíneo e rotações da bomba centrífuga como ferramenta para monitorar o desempenho do oxigenador durante o suporte respiratório extracorpóreo / Blood flow/pump rotation ratio as an artificial lung performance monitoring tool during extracorporeal respiratory support using centrifugal pumps

RESUMO Objetivo: Analisar as correlações da taxa de fluxo sanguíneo e rotação da bomba com a pressão transmembrana e a transferência de CO2 e O2 durante o suporte respiratório extracorpóreo. Métodos: Cinco animais foram instrumentalizados e submetidos à oxigenação extracorpórea de membrana em um protocolo de cinco fases, as quais incluíam sepse abdominal e lesão pulmonar. Resultados: Este estudo demonstrou que as variações da taxa de fluxo sanguíneo e rotação da bomba dependem, de forma logarítmica positiva, do fluxo sanguíneo na membrana extracorpórea de oxigenação. As variações da taxa de fluxo sanguíneo e rotação da bomba têm associação negativa com a pressão transmembrana (R2 = 0,5 para o fluxo sanguíneo = 1.500mL/minuto e R2 = 0,4 para o fluxo sanguíneo = 3.500mL/minuto, ambos com p < 0,001) e associação positiva com as variações de transferência de CO2 (R2 = 0,2 para o fluxo do gás de varredura ≤ 6L/minuto, p < 0,001, e R2 = 0,1 para o fluxo de gás de varredura > 6L/minuto, p = 0,006). A taxa de fluxo sanguíneo com a rotação da bomba não se associa às variações na transferência de O2 (R2 = 0,01 para o fluxo sanguíneo = 1.500mL/minuto, p = 0,19, e R2 = -0,01 ao fluxo sanguíneo = 3.500mL/minuto, p = 0,46). Conclusão: Neste modelo em animais, a variação da taxa de fluxo sanguíneo e rotação da bomba se associa negativamente com a pressão transmembrana e positivamente com a transferência de CO2. Conforme a situação clínica, uma diminuição na taxa do fluxo sanguíneo e rotação da bomba pode, na ausência de hipoxemia, indicar uma disfunção do pulmão artificial. .

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. Objetivo: Analisar as correlações da taxa de fluxo sanguíneo e rotação da bomba com a pressão transmembrana e a transferência de CO2 e O2 durante o suporte respiratório extracorpóreo. .

Síndrome da angústia respiratória aguda associada à varicela em paciente adulto: exemplo de suporte respiratório extracorpóreo em doenças endêmicas brasileiras / Varicella associated acute respiratory distress syndrome in an adult patient: an example for extracorporeal respiratory support in Brazilian endemic diseases

Descreveu-se aqui o caso de um homem de 30 anos de idade com quadro de varicela grave, hipoxemia refratária, vasculite do sistema nervoso central e insuficiência renal anúrica. Foi necessário transporte por ambulância com suporte respiratório extracorpóreo veno-venoso, sendo este utilizado até a recuperação do paciente. Discute-se o potencial uso de oxigenação por membrana extracorpórea em países em desenvolvimento para o controle de doenças comuns nestas áreas.

A case of a 30 year-old man presenting with severe systemic chickenpox with refractory hypoxemia, central nervous system vasculitis and anuric renal failure is described. Ambulance transportation and support using veno-venous extracorporeal membrane oxygenation were necessary until the patient recovered. Ultimately, the potential use of extracorporeal membrane oxygenation support in low-middle income countries to manage common diseases is discussed.

Severe hypoxemia during veno-venous extracorporeal membrane oxygenation: exploring the limits of extracorporeal respiratory support.

OBJECTIVE: Veno-venous extracorporeal oxygenation for respiratory support has emerged as a rescue alternative for patients with hypoxemia. However, in some patients with more severe lung injury, extracorporeal support fails to restore arterial oxygenation. Based on four clinical vignettes, the aims of this article were to describe the pathophysiology of this concerning problem and to discuss possibilities for hypoxemia resolution. METHODS: Considering the main reasons and rationale for hypoxemia during veno-venous extracorporeal membrane oxygenation, some possible bedside solutions must be considered: 1) optimization of extracorporeal membrane oxygenation blood flow; 2) identification of recirculation and cannula repositioning if necessary; 3) optimization of residual lung function and consideration of blood transfusion; 4) diagnosis of oxygenator dysfunction and consideration of its replacement; and finally 5) optimization of the ratio of extracorporeal membrane oxygenation blood flow to cardiac output, based on the reduction of cardiac output. CONCLUSION: Therefore, based on the pathophysiology of hypoxemia during veno-venous extracorporeal oxygenation support, we propose a stepwise approach to help guide specific interventions.

Severe hypoxemia during veno-venous extracorporeal membrane oxygenation: exploring the limits of extracorporeal respiratory support

OBJECTIVE: Veno-venous extracorporeal oxygenation for respiratory support has emerged as a rescue alternative for patients with hypoxemia. However, in some patients with more severe lung injury, extracorporeal support fails to restore arterial oxygenation. Based on four clinical vignettes, the aims of this article were to describe the pathophysiology of this concerning problem and to discuss possibilities for hypoxemia resolution. METHODS: Considering the main reasons and rationale for hypoxemia during veno-venous extracorporeal membrane oxygenation, some possible bedside solutions must be considered: 1) optimization of extracorporeal membrane oxygenation blood flow; 2) identification of recirculation and cannula repositioning if necessary; 3) optimization of residual lung function and consideration of blood transfusion; 4) diagnosis of oxygenator dysfunction and consideration of its replacement; and finally 5) optimization of the ratio of extracorporeal membrane oxygenation blood flow to cardiac output, based on the reduction of cardiac output. CONCLUSION: Therefore, based on the pathophysiology of hypoxemia during veno-venous extracorporeal oxygenation support, we propose a stepwise approach to help guide specific interventions. .

Varicella associated acute respiratory distress syndrome in an adult patient: an example for extracorporeal respiratory support in Brazilian endemic diseases.

A case of a 30 year-old man presenting with severe systemic chickenpox with refractory hypoxemia, central nervous system vasculitis and anuric renal failure is described. Ambulance transportation and support using veno-venous extracorporeal membrane oxygenation were necessary until the patient recovered. Ultimately, the potential use of extracorporeal membrane oxygenation support in low-middle income countries to manage common diseases is discussed.

Very early passive cycling exercise in mechanically ventilated critically ill patients: physiological and safety aspects--a case series.

INTRODUCTION: Early mobilization can be performed in critically ill patients and improves outcomes. A daily cycling exercise started from day 5 after ICU admission is feasible and can enhance functional capacity after hospital discharge. In the present study we verified the physiological changes and safety of an earlier cycling intervention (< 72 hrs of mechanical ventilation) in critical ill patients. METHODS: Nineteen hemodynamically stable and deeply sedated patients within the first 72 hrs of mechanical ventilation were enrolled in a single 20 minute passive leg cycling exercise using an electric cycle ergometer. A minute-by-minute evaluation of hemodynamic, respiratory and metabolic variables was undertaken before, during and after the exercise. Analyzed variables included the following: cardiac output, systemic vascular resistance, central venous blood oxygen saturation, respiratory rate and tidal volume, oxygen consumption, carbon dioxide production and blood lactate levels. RESULTS: We enrolled 19 patients (42% male, age 55 ± 17 years, SOFA = 6 ± 3, SAPS3 score = 58 ± 13, PaO2/FIO2 = 223 ± 75). The median time of mechanical ventilation was 1 day (02), and 68% (n=13) of our patients required norepinephrine (maximum concentration = 0.47 µg.kg(-1).min(-1)). There were no clinically relevant changes in any of the analyzed variables during the exercise, and two minor adverse events unrelated to hemodynamic instability were observed. CONCLUSIONS: In our study, this very early passive cycling exercise in sedated, critically ill, mechanically ventilated patients was considered safe and was not associated with significant alterations in hemodynamic, respiratory or metabolic variables even in those requiring vasoactive agents.

Determinants of oxygen and carbon dioxide transfer during extracorporeal membrane oxygenation in an experimental model of multiple organ dysfunction syndrome.

Extracorporeal membrane oxygenation (ECMO) has gained renewed interest in the treatment of respiratory failure since the advent of the modern polymethylpentene membranes. Limited information exists, however, on the performance of these membranes in terms of gas transfers during multiple organ failure (MOF). We investigated determinants of oxygen and carbon dioxide transfer as well as biochemical alterations after the circulation of blood through the circuit in a pig model under ECMO support before and after induction of MOF. A predefined sequence of blood and sweep flows was tested before and after the induction of MOF with fecal peritonitis and saline lavage lung injury. In the multivariate analysis, oxygen transfer had a positive association with blood flow (slope = 66, P<0.001) and a negative association with pre-membrane PaCO(2) (slope = -0.96, P = 0.001) and SatO(2) (slope = -1.7, P<0.001). Carbon dioxide transfer had a positive association with blood flow (slope = 17, P<0.001), gas flow (slope = 33, P<0.001), pre-membrane PaCO(2) (slope = 1.2, P<0.001) and a negative association with the hemoglobin (slope = -3.478, P = 0.042). We found an increase in pH in the baseline from 7.50[7.46,7.54] to 7.60[7.55,7.65] (P<0.001), and during the MOF from 7.19[6.92,7.32] to 7.41[7.13,7.5] (P<0.001). Likewise, the PCO(2) fell in the baseline from 35 [32,39] to 25 [22,27] mmHg (P<0.001), and during the MOF from 59 [47,91] to 34 [28,45] mmHg (P<0.001). In conclusion, both oxygen and carbon dioxide transfers were significantly determined by blood flow. Oxygen transfer was modulated by the pre-membrane SatO(2) and CO(2), while carbon dioxide transfer was affected by the gas flow, pre-membrane CO(2) and hemoglobin.