Alveolar recruitment maneuvers for children with cancer and acute respiratory distress syndrome: a feasibility study / Manobras de recrutamento alveolar em crianças com câncer e síndrome do desconforto respiratório agudo: um estudo de viabilidade

ABSTRACT Objective: Acute respiratory distress syndrome (ARDS) can be a devastating condition in children with cancer and alveolar recruitment maneuvers (ARMs) can theoretically improve oxygenation and survival. The study aimed to assess the feasibility of ARMs in critically ill children with cancer and ARDS. Methods: We retrospectively analyzed 31 maneuvers in a series of 12 patients (median age of 8.9 years) with solid tumors (n=4), lymphomas (n=2), acute lymphoblastic leukemia (n=2), and acute myeloid leukemia (n=4). Patients received positive end-expiratory pressure from 25 up to 40 cmH20, with a delta pressure of 15 cmH2O for 60 seconds. We assessed blood gases pre- and post-maneuvers, as well as ventilation parameters, vital signs, hemoglobin, clinical signs of pulmonary bleeding, and radiological signs of barotrauma. Pre- and post-values were compared by the Wilcoxon test. Results: Median platelet count was 53,200/mm3. Post-maneuvers, mean arterial pressure decreased more than 20% in two patients, and four needed an increase in vasoactive drugs. Hemoglobin levels remained stable 24 hours after ARMs, and signs of pneumothorax, pneumomediastinum, or subcutaneous emphysema were absent. Fraction of inspired oxygen decreased significantly after ARMs (FiO2; p=0.003). Oxygen partial pressure (PaO2)/FiO2 ratio increased significantly (p=0.0002), and the oxygenation index was reduced (p=0.01), but all these improvements were transient. Recruited patients' 28-day mortality was 58%. Conclusions: ARMs, although feasible in the context of thrombocytopenia, lead only to transient improvements, and can cause significant hemodynamic instability.

RESUMO Objetivo: A síndrome do desconforto respiratório agudo (SDRA) pode ser uma condição devastadora em crianças com câncer e as manobras de recrutamento alveolar (MRA) podem melhorar a oxigenação e a sobrevida. O objetivo foi avaliar a viabilidade das MRA em crianças gravemente doentes com câncer e SDRA. Métodos: Analisamos retrospectivamente 31 manobras em 12 pacientes (idade mediana de 8,9 anos), com tumores sólidos (n=4), linfomas (n=2) e leucemias linfoide (n=2) e mieloide agudas (n=4). Os pacientes receberam pressão expiratória final positiva de 25 a 40 cmH20, com delta de pressão de 15 cmH2O por 60 segundos. Gasometrias foram analisadas pré e pós-manobras, bem como os parâmetros de ventilação, sinais vitais, hemoglobina, sinais clínicos de sangramento pulmonar e sinais radiológicos de barotrauma. Valores foram comparados com o teste de Wilcoxon. Resultados: A contagem mediana de plaquetas era de 53.200/mm3. Após as manobras, em dois pacientes, a pressão arterial média declinou mais de 20%, e quatro necessitaram de aumento de drogas vasoativas. A hemoglobina permaneceu estável 24 horas após a MRA, sem sinais de pneumotórax, pneumomediastino ou enfisema subcutâneo. Houve diminuição significativa nas frações inspiradas de oxigênio (FiO2; p=0,003). A relação pressão arterial de oxigênio (PaO2)/FiO2 aumentou (p=0,002), e o índice de oxigenação caiu (p=0,01), mas essas melhoras foram transitórias. A mortalidade em 28 dias foi de 58%. Conclusões: As MRA, embora viáveis no contexto da trombocitopenia, levam apenas a melhorias transitórias e podem causar instabilidade hemodinâmica significativa.

Suporte ventilatório ao nascer e associação com doenças respiratórias aos seis anos: Coorte de Nascimentos de Pelotas, Rio Grande do Sul, Brasil, 2004 / Soporte ventilatorio en el período neonatal y enfermedades respiratorias en los seis primeros años de vida: Cohorte de Nacimientos de Pelotas, Rio Grande do Sul, Brasil, 2004 / Neonatal ventilatory support and respiratory diseases in children up to six years of age: the 2004 Pelotas (Brazil) Birth Cohort study

O objetivo do estudo foi avaliar a associação entre suporte ventilatório no período neonatal e doenças respiratórias até os seis anos de idade. Estudo de coorte de nascimentos de base populacional. A exposição principal foi o suporte ventilatório ao nascimento, definido como o uso de pressão contínua positiva nasal (CPAPn) e/ou ventilação mecânica (VM) por mais de três horas, desde o momento da hospitalização ao nascimento até os 28 dias. Os desfechos foram chiado no peito nos últimos 12 meses, diagnóstico médico de asma alguma vez na vida e episódio de pneumonia ocorrido até os seis anos de idade. Foram realizadas análises brutas e ajustadas para potenciais variáveis de confusão, usando regressão de Poisson. Foram analisadas 3.624 crianças. O uso de CPAPn e VM ou unicamente VM esteve associado com maior frequência de diagnóstico médico de asma, mesmo após ajuste para características maternas e das crianças (RP = 2,24; IC95%: 1,27-3,99). Os resultados do presente estudo alertam para as complicações respiratórias, em médio prazo, decorrentes do suporte ventilatório realizado no período neonatal.

El objetivo del estudio fue evaluar la asociación entre el soporte ventilatorio durante el período neonatal y las enfermedades respiratorias durante los seis primeros años de vida. Se trata de un estudio de cohorte de nacimiento con base poblacional. La exposición principal, soporte ventilatorio al nacimiento, fue definida como el uso de presión positiva nasal (CPAPn) y/o ventilación mecánica (VM) durante más de tres horas, desde la hospitalización al nacimiento, hasta los 28 días de vida. Los resultados analizados fueron: broncoespasmo en los últimos doce meses, diagnóstico médico de asma - realizado alguna vez en la vida- y episodio de neumonía ocurrido hasta los seis años de edad. Se realizaron análisis brutos y ajustados para potenciales variables de confusión, usando la regresión de Poisson. Fueron estudiados 3.624 niños. El uso de soporte ventilatorio estuvo asociado con una mayor frecuencia de diagnóstico médico de asma, incluso tras ajustar las características maternas y de los niños (RP = 2,24; IC95%: 1,27-3,99). Los resultados alertan sobre las complicaciones respiratorias a medio plazo tras el soporte ventilatorio realizado en el período neonatal.

The study's objective was to evaluate the association between neonatal ventilatory support and the subsequent occurrence of respiratory diseases in children up to six years of age. This was a population-based birth cohort study. The main exposure was ventilatory support at birth, defined as the use of nasal continuous positive airway pressure (NCPAP) and/or mechanical ventilation (MV) for more than three hours from the time of hospitalization at birth until the first 28 days of life. Outcomes were: chest wheezing in the twelve months prior to the follow-up interview, medical diagnosis of asthma any time in the child´s life, and occurrence of pneumonia up to six years of age. Crude and adjusted analyses for potential confounding variables were performed using Poisson regression. 3,624 children were analyzed. NCPAP plus MV or MV alone was associated with higher frequency of medical diagnosis of asthma, even after adjusting for maternal and child characteristics (PR = 2.24; 95%CI: 1.27-3.99). The results highlight medium-term respiratory complications associated with neonatal ventilatory support.

Avaliação da ventilação não-invasiva com dois níveis de pressão positiva nas vias aéreas após cirurgia cardíaca / Assessment of noninvasive ventilation with two levels of positive airway pressure in patients after cardiac surgery

INTRODUÇÃO: A aplicação de ventilação por dois níveis de pressão positiva (BiPAP®) associada à fisioterapia respiratória convencional (FRC) no pós-operatório (PO) imediato de cirurgia cardíaca pode contribuir para a diminuição das complicações pulmonares. OBJETIVO: Avaliar a segurança e a adesão da aplicação preventiva do BiPAP® associado a FRC no PO imediato de revascularização do miocárdio. MÉTODOS: Vinte e seis pacientes submetidos a revascularização do miocárdio foram aleatoriamente alocados. O Grupo Controle (GC) foi tratado com FRC, o Grupo BiPAP (GB) foi submetido a 30 minutos de BiPAP®, duas vezes ao dia, associado à FRC. A FRC foi realizada em ambos os grupos, duas vezes ao dia. Todos os pacientes foram avaliados quanto: capacidade vital, permeabilidade das vias aéreas, pressões respiratórias máximas, saturação de oxigênio, frequência cardíaca, frequência respiratória, volume minuto, volume corrente, pressões arteriais sistólica e diastólica. As avaliações foram realizadas durante a internação no pré-operatório, imediatamente após a extubação, e na 24ª e 48ª horas após extubação. RESULTADOS: No GC, 61,5 por cento dos pacientes tiveram algum grau de atelectasias, no GB, 54 por cento (P=0,691). A capacidade vital foi estatisticamente maior no GB no PO (P<0,015). Todos os outros parâmetros de ventilometria, gasometria, manovacuometria e hemodinâmicos foram semelhantes entre os grupos. CONCLUSÃO: A cirurgia de revascularização do miocárdio leva à degradação da função respiratória no PO, e a aplicação da ventilação com pressão positiva (BiPAP®) pode ser benéfica para reestabelecer a função pulmonar mais rapidamente, principalmente a capacidade vital, de forma segura, sendo bem aceita pelos paciente, devido ao maior conforto em relação à sensação de dor durante a execução da fisioterapia respiratória.

INTRODUCTION: The application of two levels of ventilation by positive pressure (BiPAP®) associated with conventional respiratory therapy (CRT) in postoperative periord of cardiac surgery may contribute to reduction of pulmonary complications. OBJECTIVES: To evaluate the safety and compliance of preventive application of BiPAP® CRT associated with immediate postoperative myocardial revascularization. METHODS: 26 patients undergoing coronary artery bypass grafting were randomly allocated in one of the groups. Patients of the Control Group (CG) were treated only with conventional respiratory therapy, compared to BiPAP group (BG) (in addition to conventional respiratory therapy the patients were subjected to 30 minutes of ventilation by two levels twice a day). The conventional respiratory therapy was held in both groups, twice a day. All patients were evaluated for vital capacity, airway permeability, maximal respiratory pressures, oxygen saturation, heart rate, respiratory frequency, Volume Minute, tidal volume, systolic and diastolic blood pressure. Evaluations were performed during hospitalization preoperatively, immediately after extubation, 24h and 48h after extubation. RESULTS: In CG 61.5 percent of patients had some degree of atelectasias, in comparison to 54 percent of BG (P=0.691). The vital capacity was higher in the GB postoperatively (P<0.015). All the other ventilometric, gasometric, hemodynamic and manometric parameters were similar between groups. CONCLUSION: Coronary artery bypass grafting leads to deterioration of respiratory function postoperatively, and the application of positive pressure ventilation (BiPAP®) may be beneficial to restore lung function more quickly, especially vital capacity, safely, and well accepted by patients due to greater comfort with the sensation of pain during the execution of respiratory therapy.

Recrutamento alveolar em pacientes no pós-operatório imediato de cirurgia cardíaca / Alveolar recruitment in patients in the immediate postoperative period of cardiac surgery

Complicações pulmonares no pós-operatório de cirurgia cardíaca são frequentes, destacando-se a atelectasia e a hipoxemia. As manobras de recrutamento alveolar contribuem significativamente para a prevenção e o tratamento destas complicações. Desta forma, este estudo buscou agrupar e atualizar os conhecimentos relacionados à utilização das manobras de recrutamento alveolar no pós-operatório imediato de cirurgia cardíaca. Observou-se a eficácia do recrutamento alveolar por meio de diferentes técnicas específicas e a necessidade do desenvolvimento de novas pesquisas.

Lung complications during postoperative period of cardiac surgery are frequently, highlighting atelectasis and hypoxemia. Alveolar recruitment maneuvers have an important role in the prevention and treatment of these complications. Thus, this study reviewed and updated the alveolar recruitment maneuvers performance in the immediate postoperative period of cardiac surgery. We noted the efficacy of alveolar recruitment through different specific techniques and the need for development of new studies.

Pressão expiratória positiva na via aérea por máscara facial na hemodinâmica de pós-operatórios cardíacos / Expiratory positive airway pressure in postoperative cardiac hemodynamics

FUNDAMENTOS: A pressão expiratória positiva na via aérea por máscara facial (EPAP) é utilizada no pós-operatório de cirurgias cardíacas, entretanto, seus efeitos hemodinâmicos não foram claramente estudados. OBJETIVO: Avaliar as alterações hemodinâmicas causadas pela EPAP em pacientes pós-cirurgia cardíaca monitorados por cateter de Swan-Ganz. MÉTODOS: Foram incluídos no estudo, pacientes no primeiro ou segundo pós-operatório de cirurgia cardíaca, estáveis hemodinamicamente e com cateter de Swan-Ganz. Eles foram avaliados em repouso e após o uso de 10 cmH2O de EPAP, de forma randomizada. As variáveis estudadas foram: saturação de oxigênio, frequências cardíaca e respiratória, pressões arteriais médias sistêmica e pulmonar (PAM e PAMP), pressões venosa central (PVC) e de oclusão da atéria pulmonar (POAP), débito e índice cardíacos, e resistências vasculares sistêmica e pulmonar. Os pacientes foram divididos em subgrupos (com fração de ejeção <; 50 por cento ou > 50 por cento) e os dados foram comparados por teste t e ANOVA. RESULTADOS: Vinte e oito pacientes foram estudados (22 homens, idade média 68 ± 11 anos). Comparando o período de repouso versus EPAP, as alterações observadas foram: POAP (11,9 ± 3,8 para 17,1 ± 4,9 mmHg, p < 0,001); PVC (8,7 ± 4,1 para 10,9 ± 4,3 mmHg, p = 0,014); PAMP (21,5 ± 4,2 para 26,5 ± 5,8 mmHg, p < 0,001); PAM (76 ± 10 para 80 ± 10 mmHg, p = 0,035). As demais variáveis não mostraram diferenças significativas. CONCLUSÃO: A EPAP foi bem tolerada nos pacientes e as alterações hemodinâmicas encontradas mostraram aumento nas medidas de pressão de enchimento ventricular direito e esquerdo, assim como, na pressão arterial média.

BACKGROND: Expiratory positive airway pressure (EPAP) is used in after cardiac surgeries. However, its hemodynamic effects have not been clearly studied. OBJECTIVE: To evaluate the hemodynamic changes caused by EPAP in patients after cardiac surgery monitored by Swan-Ganz. METHODS: Patients at the first or second cardiac surgery postoperative period hemodynamically stable with a Swan-Ganz catheter were included in the study. They were assessed at rest and after using 10 cmH2O EPAP at random. The variables studied were: oxygen saturation, heart rate and respiratory rate, mean artery pressures and pulmonary artery mean pressures (MAP and PAMP), central venous pressure (CVP) and pulmonary capillary wedge pressure (PAOP), cardiac output and index, and systemic and pulmonary vascular resistances. Patients were divided into subgroups (with ejection fraction <; 50 percent or > 50 percent) and data were compared by t test and ANOVA. RESULTS: Twenty-eight patients were studied (22 men, aged 68 ± 11 years). Comparing the period of rest versus EPAP, the changes observed were: PAOP (11.9 ± 3.8 to 17.1 ± 4.9 mmHg, p < 0.001), PVC (8.7 ± 4.1 to 10.9 ± 4.3 mmHg, p = 0.014), PAMP (21.5 ± 4.2 to 26.5 ± 5.8 mmHg, p < 0.001), MAP (76 ± 10 for 80 ± 10 mmHg, p = 0.035). The other variables showed no significant differences. CONCLUSION: EPAP was well tolerated by patients and the hemodynamic changes found showed an increase in pressure measurements of right and left ventricular filling, as well as mean arterial pressure.

Short-term effects of positive expiratory airway pressure in patients being weaned from mechanical ventilation

OBJECTIVE: To investigate the feasibility and the cardiorespiratory effects of using positive expiratory airway pressure, a physiotherapeutic tool, in comparison with a T-tube, to wean patients from mechanical ventilation. METHODS/DESIGN: A prospective, randomized, cross-over study. SETTING: Two intensive care units. PATIENTS AND INTERVENTIONS: We evaluated forty patients who met weaning criteria and had been mechanically-ventilated for more than 48 hours, mean age 59 years, including 23 males. All patients were submitted to the T-tube and Expiratory Positive Airway Pressure devices, at 7 cm H2O, during a 30-minute period. Cardiorespiratory variables including work of breathing, respiratory rate (rr), peripheral oxygen saturation (SpO2), heart rate (hr), systolic, diastolic and mean arterial pressures (SAP, DAP, MAP) were measured in the first and thirtieth minutes. The condition was analyzed as an entire sample set (n=40) and was also divided into subconditions: chronic obstructive pulmonary disease (n=14) and non-chronic obstructive pulmonary disease (non- chronic obstructive pulmonary disease) (n=26) categories. Comparisons were made using a t-test and Analysis of Variance. The level of significance was p < 0.05. RESULTS: Our data showed an increase in work of breathing in the first and thirtieth minutes in the EPAP condition (0.86+ 0.43 and 1.02+1.3) as compared with the T-tube condition (0.25+0.26 and 0.26+0.35) (p<0.05), verified by the flow-sensor monitor (values in J/L). No statistical differences were observed when comparing the Expiratory Positive Airway Pressure and T-tube conditions with regard to cardiorespiratory measurements. The same result was observed for both chronic obstructive pulmonary disease and non- chronic obstructive pulmonary disease subconditions. CONCLUSIONS: Our study demonstrated that, in weaning patients from mechanical ventilation, the use of a fixed level of Expiratory Positive Airway Pressure caused ...

Generador de flujo con presión binivelada (BiPAP) a través de traqueostomía / Flow generator with double level pressure (BiPAP) through tracheostomy

Background: The Chilean Program of Noninvasive Home Ventilation started using flow generating equipment with differential pressure at 2 levels (BiPAP) through tracheostomies for prolonged mechanical ventilation (PMV). Objective: Describe the experience of this ventilatory support, reporting selection criteria, procedure and technological requirements. Method: Descriptive-transversal study that includes 20 patients treated at Hospital Josefina Martinez, other pediatric hospitals and at home, for 12 months since June 2006. The clinical features, ventilation support, technical characteristics, follow-up and complications were reported. Results: The mean age was 3.5 years-old (range 3 months - 17 years). The duration of PMV ranged between 1 month to 5 years. Six patients (30 percent) are at home and 14 (70 percent) are hospitalized. In 14 patients (70 percent), the need of PMV was due to neuromuscular diseases. There was no mortality related to the use of Bipap through tracheostomy; only 4 patients had minor complications. Conclusions: This report suggests that the use of BiPAP through tracheostomy in patients with selection criteria is an applicable PVM method. However, comparative systematic trials are necessary to define costs, benefits and risks of this type of ventilation.

Introducción: El Programa Chileno de Ventilación No Invasiva en domicilio (AVNI) extendió su cobertura utilizando generadores de flujo con presión bi-nivelada (BiPAP) en niños con ventilación mecánica prolongada (VMP) y traqueostomía (TQT). Objetivo: Reportar la experiencia de esta estrategia describiendo criterios de selección, modalidades de uso y tecnologías complementarias. Pacientes y Métodos: Estudio descriptivo, transversal y prospectivo durante un año desde Junio 2006, en 20 pacientes manejados en el Hospital Josefina Martínez, otros centros de la red asistencial del Ministerio de Salud y en domicilio. Se registraron las características clínicas, modos ventilatorios, evolución y complicaciones. Resultados: La mediana de edad fue de 3,5 años (rango 3 meses a 17 a±os). La duración de la VMP fue lm a 5a, 6 pacientes (30 por ciento) se encuentran en domicilio y 14 (70 por ciento) hospitalizados. La principal causa para VMP fue enfermedad neuromuscular (14, 70 por ciento). No hubo mortalidad y 4 pacientes tuvieron complicaciones menores. Conclusión: El BiPAP a través de TQT, usado con criterios estrictos de selección, es un método de VMP que puede ser factible. Se requieren estudios comparativos para definir costos, beneficios y riesgos de estos equipos comparándolos con ventiladores licenciados para soporte vital.

Ajustes da pressão positiva expiratória final ideal na síndrome do desconforto respiratório agudo na posição prona / Best positive end expiratory pressure settlement in acute respiratory discomfort syndrome and prone position

JUSTIFICATIVA E OBJETIVOS: A posição em decúbito ventral (posição prona) aplicada em pacientes com síndrome do desconforto respiratório agudo (SDRA), tem demonstrado melhora da oxigenação em mais de 70 por cento dos casos. Uma vez que essa posição promove uma série de alterações pulmonares, inclusive na mecânica pulmonar, abre-se a hipótese da necessidade de otimizar os parâmetros ventilatórios após a instalação deste novo decúbito, principalmente do valor da pressão positiva expiratória final (PEEP). O objetivo deste estudo foi avaliar a influência da posição prona no cálculo da PEEP ideal, titulada pela melhor complacência pulmonar e comparar as alterações pulmonares de mecânica, de oxigenação e de ventilação nas posições supina e prona. MÉTODO: Estudo prospectivo realizado no Serviço de Terapia Intensiva da Irmandade Santa Casa de Misericórdia de São Paulo. Foram comparadas três fases. Fase 1: na posição supina, após o cálculo de PEEP ideal. Fase 2: após duas horas o decúbito do paciente era modificado para prona, após cálculo da PEEP. O paciente era mantido por seis horas neste decúbito. Fase 3: após este período, era colocado na posição supina, realizando-se novo cálculo da PEEP e nova coleta gasométrica, após duas horas. Foi comparada a fase 1 versus fase 2, fase 2 versus fase 3 e fase 3 versus fase 1. RESULTADOS: Não foram encontradas diferenças nos valores de PEEP ideal nas três fases do estudo: fase 1 = 14 ± 4,43, fase 2 = 14,73 ± 4,77 e fase 3 = 13,65 ± 4,92. CONCLUSÕES: Não houve diferença de PEEP ideal quando na posição prona ou supina. Portanto, de acordo com este estudo não há necessidade de se readequar a PEEP a cada mudança de decúbito.

BACKGROUND AND OBJECTIVES: In acute respiratory discomfort syndrome (ARDS) patients, prone position improves oxygenation in more than 70 percent of the cases. It is well known that prone position promotes a lot of pulmonary changes, including pulmonary mechanics, so we hypothesized that there is the necessity to optimize the ventilatory parameters after the patient is placed in prone position, especially the positive end expiratory pressure (PEEP) values. The objective of this study valued the influence of the prone position at the calculation of the ideal PEEP, given a title by the best pulmonary complaisance and he compared the pulmonary alterations of mechanics, of oxygenation and of ventilation in the positions supine and prone. METHODS: Prospective study, taken place in the Irmandade Santa Casa de Misericórdia de São Paulo Intensive Care Service. Three fases have been compared. Fase 1: in supine position, after the best PEEP calculation. Fase 2: two hours after the patient was placed in prone position and the best PEEP was calculated. The patient was kept for 6 hours in this position. Fase 3: after this time, patient was placed in supine again and after two hours, a new best PEEP calculation and arterial gas analysis was done. And then fase1 versus fase 2, fase 2 versus fase 3, fase 3 versus fase1 were compared. RESULTS: There were no differences in the PEEP values found in all study fases: fase 1 = 14 ± 4.43; fase 2 = 14.73 ± 4.77 and fase 3 = 13.65 ± 4.92. CONCLUSIONS: There were no differences in best PEEP values between prone and supine position. Therefore, there is no need to recalculate the PEEP value after each position change.

Utilization of the lower inflection point of the pressure-volume curve results in protective conventional ventilation comparable to high frequency oscillatory ventilation in an animal model of acute respiratory distress syndrome

INTRODUCTION: Studies comparing high frequency oscillatory and conventional ventilation in acute respiratory distress syndrome have used low values of positive end-expiratory pressure and identified a need for better recruitment and pulmonary stability with high frequency. OBJECTIVE: To compare conventional and high frequency ventilation using the lower inflection point of the pressure-volume curve as the determinant of positive end-expiratory pressure to obtain similar levels of recruitment and alveolar stability. METHODS: After lung lavage of adult rabbits and lower inflection point determination, two groups were randomized: conventional (positive end-expiratory pressure = lower inflection point; tidal volume=6 ml/kg) and high frequency ventilation (mean airway pressures= lower inflection point +4 cmH2O). Blood gas and hemodynamic data were recorded over 4 h. After sacrifice, protein analysis from lung lavage and histologic evaluation were performed. RESULTS: The oxygenation parameters, protein and histological data were similar, except for the fact that significantly more normal alveoli were observed upon protective ventilation. High frequency ventilation led to lower PaCO2 levels. DISCUSSION: Determination of the lower inflection point of the pressure-volume curve is important for setting the minimum end expiratory pressure needed to keep the airways opened. This is useful when comparing different strategies to treat severe respiratory insufficiency, optimizing conventional ventilation, improving oxygenation and reducing lung injury. CONCLUSIONS: Utilization of the lower inflection point of the pressure-volume curve in the ventilation strategies considered in this study resulted in comparable efficacy with regards to oxygenation and hemodynamics, a high PaCO2 level and a lower pH. In addition, a greater number of normal alveoli were found after protective conventional ventilation in an animal model of acute respiratory distress syndrome.

Atelectasis Induced by Thoracotomy Causes Lung Injury during Mechanical Ventilation in Endotoxemic Rats

Atelectasis can impair arterial oxygenation and decrease lung compliance. However, the effects of atelectasis on endotoxemic lungs during ventilation have not been well studied. We hypothesized that ventilation at low volumes below functional residual capacity (FRC) would accentuate lung injury in lipopolysaccharide (LPS)-pretreated rats. LPS-pretreated rats were ventilated with room air at 85 breaths/min for 2 hr at a tidal volume of 10 mL/kg with or without thoracotomy. Positive end-expiratory pressure (PEEP) was applied to restore FRC in the thoracotomy group. While LPS or thoracotomy alone did not cause significant injury, the combination of endotoxemia and thoracotomy caused significant hypoxemia and hypercapnia. The injury was observed along with a marked accumulation of inflammatory cells in the interstitium of the lungs, predominantly comprising neutrophils and mononuclear cells. Immunohistochemistry showed increased inducible nitric oxide synthase (iNOS) expression in mononuclear cells accumulated in the interstitium in the injury group. Pretreatment with PEEP or an iNOS inhibitor (1400 W) attenuated hypoxemia, hypercapnia, and the accumulation of inflammatory cells in the lung. In conclusion, the data suggest that atelectasis induced by thoracotomy causes lung injury during mechanical ventilation in endotoxemic rats through iNOS expression.

Conventional mechanical ventilation Vs. noninvasive positive pressure ventilation in COPD patients

In patients with COPD and mild to moderate hypercapnic ARF, the addition of NPPV to medical treatment has been proven to be effective in relieving dyspnea, improving vital signs and gas exchange, preventing endotracheal intubation and improving hospital survival. For this reason we compared the response to conventional ventilation delivered via ETI vs. NPPV delivered via face mask in COPD patients with ARF failing to sustain the initial improvement with conventional medical therapy in the emergency ward and meeting predetermined criteria for mechanical ventilation. We evaluated 72 consecutive patients. 18 were already intubated and 14 improved with standard medical therapy. The condition of 40 patients initially improved with medical therapy, and they stayed in the medical ward, but their improvement was not maintained over time and<24h. They met predetermined criteria for ventilatory support and were admitted to receive mechanical ventilation. 18 patients were randomized to NPPV and 22 patients to [ETMV] conventional ventilation. There were no differences between the two group before institution of mechanical ventilation, except in SAPS II, Albumin and GCS were significantly different [0.006, 0.05, 0.003] respectively. Patients randomized to NPPV, had a trend toward a lower rate of ventilator associated pneumonia [2vs.7] severe sepsis [lvs.7] and septic shock [lvs.3]. NPPV had decreased duration of ventilation, ICU stay, and post ICU hospital stay. [12.5vs.7.8 and 13.2 vs. 8.83 and 7.27vs.4.5] respectively [SD]. The ETMV group had a trend toward requiring permanent oxygen supplementation and open tracheastomy in comparison with NPPV group [8vs.0 and 5vs.2] respectively [%]. After failure of medical treatment in acute exacerbation of COPD patients NPPV is comparable to invasive mechanical ventilation. The reasons for improved outcome are not clear, but it is possible that a reduction in duration of ventilation, ICU stay, mortality rate and serious complications may play an important role, Improvement in PH and a decrease in PCO[2] after 2h of use benefited from NPPV. There are no clear clinical predictors to identify which patients with COPD RF would benefit from NPPV. A score based on SAPS II and serum albumin level is predictive of outcome in COPD patients. A high percentage of patients with the primary diagnosis of COPD successfully treated with NPPV

Ventilación mecánica prolongada con BiPAP a través de traqueostomía / Long-term noninvasive ventilation via tracheostomy

No existen reportes que describan el uso de equipos generadores de flujo con presión diferencial en 2 niveles (BiPAP) a través de traqueostomía para entregar ventilación mecánica prolongada (VMP) en niños. Este documento describe los criterios de selección, modalidad de uso y requerimientos tecnológicos como guía para implementar esta estrategia ventilatoria.

Daño pulmonar inducido por ventilación mecánica y estrategia ventilatoria convencional protectora / Pulmonary damage produced by mechanical ventilation and conventional protective ventilatory strategy

Sólo muchos años después de la descripción inicial del Síndrome de Distress Respiratorio Agudo (SDRA), se reconoce a éste como una enfermedad profundamente heterogénea y con un volumen pulmonar pequeño, siendo este pulmón con escasa capacidad de aireación (baby lung), el que da cuenta del daño inducido por ventilación mecánica (DIVM). La evidencia disponible apunta a que la injuria mecánica es la principal responsable del DIVM, así como también, su amplificación biológica a distancia. La aplicación cíclica de presiones transpulmonares que excedan la capacidad de inflación pulmonar pueden dañar la barrera epitelio-alveolar, especialmente en ausencia de una PEEP adecuada para mantener abierta las unidades alveolares mecánicamente inestables. Mientras no se cuente con terapias que puedan interferir y modular eficientemente la cascada de eventos biológicos gatillados, la única herramienta disponible para limitar su desarrollo es la administración cautelosa de la ventilación mecánica. Este tratamiento juicioso resultará en una menor tensión (stress) y elongación (strain) del parénquima pulmonar, y un consecuente menor impacto biológico. Así entonces, el principal mensaje es que la forma en que ventilamos a nuestros pacientes es crucial para su pronóstico, tratando de minimizar el DIVM, el cual comienza al momento de ventilar al paciente. En la presente comunicación pretendemos revisar conceptos básicos, aspectos anátomo-funcionales de este fenómeno mecánico y sus consecuencias biológicas, y actualizar intervenciones clínicas que nos permitan atenuar el impacto del soporte ventilatorio.

Ventilación no invasiva en pacientes con exacerbacion de EPOC / Non invasive positive pressure ventilation in patients with COPD exacerbation

Se realizó un estudio prospectivo sobre la utilización de la ventilación mecánica no invasiva (VNI) en pacientes internados en Clínica Médica Neumonológica por exacerbación de la enfermedad pulmonar obstructiva crónica (EPOC), con el objetivo de evaluar la evolución, los cambios gasométricos, las comorbilidades y la mortalidad de los pacientes internados. Desde enero 2000 a enero 2003 ingresaron al estudio 39 pacientes, evaluados según normas internacionales en 54 internaciones, siendo clasificados como de grado grave y muy grave, dado que la medición del volumen espiratorio forzado en un segundo (VEF1) era del 26%. Veintinueve pacientes (74.4%) presentaron alguna comorbilidad. Como consecuencia de la aplicación de la VNI, el pH se incrementó entre la primera y tercera medición. El pH promedio inicial fue de 7.25 llegando a 7.33 a las 2 horas y a 7.39 al alta, en tanto que la pCO2 con promedio inicial de 83.8 mm Hg llegó a 67.8 mm Hg y 54.2 mm Hg en el mismo período. Treinta y cinco de los 39 pacientes fueron dados de alta con un período de internación promedio de 13.6 días. Cuatro pacientes (10.3%) fallecieron. Se concluye que con la aplicación de la VNI en pacientes con exacerbación de EPOC, el pH y la PaCO2 cambian significativamente en las muestras sucesivas, y que la adecuada capacitación del equipo de salud puede permitir el tratamiento de estos pacientes en áreas de menor complejidad. Deben ser tenidas en cuenta las posibles complicaciones que pueden sufrir los pacientes durante la internación, que pueden requerir la aplicación de ventilación invasiva.

This is a prospective study on the implementation of the non-invasive positive pressure ventilation (NPPV) to treat respiratory failure resulting from exacerbation of chronic obstructive pulmonary disease (COPD) in patients hospitalized in a Pneumological Unit. From January 2000 to January 2003, 39 patients were included during 54 different exacerbation events after being evaluated under international standards. They were classified as severe and very severe patients on the basis of their FEV1 values of 26%. Twenty nine patients presented co-morbidities. As a consequence of the NPPV treatment, the pH values increased between the first and last register as well as the pCO2 dropped in the same period. The initial mean pH values were 7.25 reaching mean values of 7.33 at 2 hours and 7.39 at the discharge; the corresponding pCO2 mean values were 83.8 mmHg, 67.8 mmHg and 54.2 mmHg. Thirty five patients out of 39 were discharged after a mean hospitalization length of 13.6 days. Four patients died. Apropriate training of health care staff in general facilities could allow the implementation of NPPV in addition to usual medical care to treat exacerbation of COPD. High morbidity situations could arise during hospitalization, so invasive ventilation must be necessary.

Daño pulmonar agudo asociado a ventilación mecánica / Ventilator associated acute lung injury

Mechanical ventilation plays a central role In the critical care setting; but its use is closely related with some life threatening complications as nosocomial pneumonia and low cardiac performance. One of the most severe complications is called ventilator-associated lung injury (VALI) and it includes: Barotrauma, volutrauma, atelectrauma, biotrauma and oxygen-mediated toxic effects and it is related with an inflammatory response secondary to the stretching and recruitment process of alveoli within mechanical ventilation. The use of some protective ventilatory strategies has lowered the mortality rate 10% approximately.

La importancia de la asistencia mecánica ventilatoria (AMV) en la Unidad de Cuidados Intensivos (UCI) es indiscutible; sin embargo, su uso está ligado con complicaciones como neumonía nosocomial y deterioro del rendimiento cardiaco, que en algunas ocasiones ponen en peligro la vida del enfermo. Una de las complicaciones más graves es el daño pulmonar asociado a la ventilación mecánica (DPVM). El DPVM se caracteriza por la presencia de edema pulmonar rico en proteínas. Se recomienda establecer cierto número de estrategias de protección pulmonar (EPP) para prevenir este tipo de lesión. Una vez instituidas, las EPP han demostrado una disminución de la mortalidad de aproximadamente 10%.

A Practical Protocol for Titrating "Optimal" PEEP in Acute Lung Injury: Recruitment Maneuver and PEEP Decrement

This study was conducted to evaluate the effectiveness and safety of a practical protocol for titrating positive end-expiratory pressure (PEEP) involving recruitment maneuver (RM) and decremental PEEP. Seventeen consecutive patients with acute lung injury who underwent PEEP titration were included in the analysis. After baseline ventilation, RM (continuous positive airway pressure, 35 cm H2O for 45 sec) was performed and PEEP was increased to 20 cmH2O or the highest PEEP guaranteeing the minimal tidal volume of 5 mL/kg. Then PEEP was decreased every 20 min in 2 cmH2O decrements. The "optimal" PEEP was defined as the lowest PEEP attainable without causing a significant drop (>10%) in PaO2. The "optimal PEEP" was 14.5 +/- 3.8 cmH2O. PaO2 /FI O2 ratio was 154.8 +/- 63.3 mmHg at baseline and improved to 290.0 +/- 96.4 mmHg at highest PEEP and 302.7 +/- 94.2 mmHg at "optimal PEEP", both significantly higher than baseline (p<0.05). Static compliance was significantly higher at "optimal" PEEP (27.2 +/- 10.4 mL/ cmH2O) compared to highest PEEP (22.3 +/- 7.7 mL/cmH2O) (p<0.05). Three patients experienced transient hypotension and one patient experienced atrial premature contractions. No patient had gross barotrauma. PEEP titration protocol involving RM and PEEP decrement was effective in improving oxygenation and was generally welltolerated.

Asistencia ventilatoria no invasiva con sistemas generadores de flujo en pediatría: experiencia 1996-1999 / Non invasive mechanical ventilation with a flow generator device in pediatric patients: experience 1996-1999

La presión nasal positiva es un sistema de ventilación no invasivo que se indica en pacientes con apnea obstructiva del sueño, insuficiencia respiratoria crónica, hipoventilación central y rara vez en insuficiencia respiratoria aguda. Desde 1996 a 1999 diez pacientes que ingresaron a la guardia respiratoria pediátrica de nuestro hospital fueron incluídos en un programa de ventilación mecánica no invasiva. Las edades de los pacientes fluctuaron entre 1,5 y 14 años (promedio = 7 años). Cinco pacientes (50 por ciento) por presentar insuficiencia respiratoria aguda, tres por insuficiencia respiratoria crónica y dos por apnea obstructiva del sueño. Los diagnósticos al ingreso fueron los siguientes: infección respiratoria aguda baja (n=4) parálisis cerebral (n=3) miopatía congénita (n=2) y tumor torácico (n=1). Se utilizó BIPAP en siete pacientes y CPAP en tres, administrándose oxígeno suplementario en nueve pacientes. Resultados: seis pacientes mejoraron y cuatro de ellos fueron enviados a sus hogares con ventilación mecánica no invasiva. Un paciente con mucopolisacaridosis murió y tres no mejoraron, por lo que fueron manejados con ventilación mecánica. La única complicación observada fue edema nasal, que se presentó en dos pacientes. Conclusión: La asistencia ventilatoria no invasiva puede usarse en algunos pacientes con insuficiencia respiratoria aguda, esta eventual indicación podría agregarse a las convencionales. La aplicación de criterios estrictos de selección (mayores de 12 meses con vía aérea estable, hipercapnia pero con pH > 7,25, sin falla orgánica múltiple, inestabilidad hemodinámica o compromiso aguda de conciencia) podría evitar la ventilación mecánica en estos pacientes

Non invasive ventilation.

Non-invasive ventilation refers to the technique of providing ventilatory support to a patient without an endo/orotracheal airway. It is a promising and rapidly upcoming new technique and is being used as first line therapy in a wide variety of conditions causing respiratory failure. The major indications for its use include respiratory failure due to a variety of causes (chest wall abnormalities, neuromuscular disease, COPD), weaning and stabilization of cardio-respiratory status before and after surgery. Patients who are candidates for this modality usually have a hypercapnic respiratory failure but are able to protect the airway and cooperate with treatment. The biggest advantage of the technique is its simplicity and avoidance of complications of intubation like trauma, infection and delayed complications like tracheal stenosis. Patient comfort is significantly improved and important functions like speech, swallowing and cough are preserved. Several purpose built ventilators are available for use including pressure preset and volume present machines, each of which have their own advantages and disadvantages in clinical practice. A range of patient interfaces is available. The initiation of non-invasive ventilation is much easier as compared to invasive ventilation and can be done for most patients in an intermediary care unit thereby cutting down treatment costs and saving precious intensive care beds. Titration of ventilatory parameters can usually be done using simple tests like oxymetry and blood gases. Several technique related problems like skin pressure sores, nasal symptoms and abdominal distension can be managed with simple measures. Non invasive ventilation has got a special and evolving role in management of COPD, both in acute exacerbations and chronic respiratory failure. In short, the advantages of this form of ventilation are numerous and physicians must familiarize themselves with this new technique, facilities for which should be available in all hospitals admitting patients with respiratory failure.