Inflammatory lung injury in rabbits: effects of high-frequency oscillatory ventilation in the prone position.

OBJECTIVE: To compare the effects that prone and supine positioning during high-frequency oscillatory ventilation (HFOV) have on oxygenation and lung inflammation, histological injury, and oxidative stress in a rabbit model of acute lung injury (ALI). METHODS: Thirty male Norfolk white rabbits were induced to ALI by tracheal saline lavage (30 mL/kg, 38°C). The injury was induced during conventional mechanical ventilation, and ALI was considered confirmed when a PaO2/FiO2 ratio < 100 mmHg was reached. Rabbits were randomly divided into two groups: HFOV in the supine position (SP group, n = 15); and HFOV with prone positioning (PP group, n = 15). For HFOV, the mean airway pressure was initially set at 16 cmH2O. At 30, 60, and 90 min after the start of the HFOV protocol, the mean airway pressure was reduced to 14, 12, and 10 cmH2O, respectively. At 120 min, the animals were returned to or remained in the supine position for an extra 30 min. We evaluated oxygenation indices and histological lung injury scores, as well as TNF-α levels in BAL fluid and lung tissue. RESULTS: After ALI induction, all of the animals showed significant hypoxemia, decreased respiratory system compliance, decreased oxygenation, and increased mean airway pressure in comparison with the baseline values. There were no statistically significant differences between the two groups, at any of the time points evaluated, in terms of the PaO2 or oxygenation index. However, TNF-α levels in BAL fluid were significantly lower in the PP group than in the SP group, as were histological lung injury scores. CONCLUSIONS: Prone positioning appears to attenuate inflammatory and histological lung injury during HFOV in rabbits with ALI.

Predictors of Respiratory Improvement 1 Week after Ligation of Patent Ductus Arteriosus in Preterm Infants.

OBJECTIVE: To characterize preterm infants that demonstrates respiratory improvement 7 days after ligation of a patent ductus arteriosus (PDA). STUDY DESIGN: We performed a 2-phase study of preterm infants (birthweight <1500 g between 2010 and 2016). We first did a retrospective analysis using regression modeling of ligation population. We then performed a case-control study comparing a ligation group with infants matched by gestational age, postnatal age, and preligation respiratory condition (ventilator mode, mean airway pressure [MAP], and fraction of inspired oxygen [FiO2]). Respiratory improvement was defined as either extubation, downgrading of ventilatory mode, reduction in MAP >25%, or decrease in FiO2 >25%. RESULTS: Forty-five (42%) of 107 preterm infants (gestational age 25.5 ± 1.7 weeks) with ligation showed respiratory improvement at 7 days. Infants on high frequency ventilation (HFV) were more likely to have respiratory improvement (aOR 5.03, 95% CI [1.14-22.18]). In matched-control analysis of 89 pairs, there was no difference in respiratory improvement. Among infants on HFV, the ligation group had an increase in MAP during 3 days prior to ligation. For infants on conventional ventilation, the ligation group had higher MAP and FiO2 than the control group during the first 2-3 postoperative days. CONCLUSIONS: Among infants undergoing PDA ligation, those on HFV were more likely to have respiratory improvement in the first week, possibly because of the prevention of further respiratory deterioration. For infants on conventional ventilation, ligation was associated with higher respiratory support in the immediate postligation period without respiratory benefits at 7 days. As HFV was used as a rescue mode, our findings suggest that those with worse lung disease may achieve greater short term benefit from PDA ligation.

Ambient Noise Production by High-Frequency Neonatal Ventilators.

OBJECTIVE: To assess sound levels of 4 high-frequency neonatal ventilators to determine whether there is a safety benefit in using modern high-frequency ventilators compared with older models. STUDY DESIGN: We performed a bench study comparing noise production of the Sensormedics 3100A Oscillator, Bunnell Life Pulse Jet Ventilators Model 203 and Model 204, and Dräger VN500 in high-frequency mode. A wide range of ventilation settings was examined. All measurements were performed in triplicate using a high-fidelity sound meter, with data analyzed using ANOVA and regression analyses. RESULTS: The Dräger ventilator was quietest overall, with average sound levels of 49.8 ± 0.49 dB across all settings. The average noise from the Sensormedics was 53.6 ± 2.01 dB, for Bunnell Model 203 was 54.1 ± 1.09 dB, and for Bunnell Model 204 was 53.7 ± 1.45 dB. Adjustments made to frequency/rate and mean airway pressure/positive end-expiratory pressure had minimal effect on noise, and increasing amplitude/peak inspiratory pressure resulted in significantly more noise by all ventilators. At all settings, the Sensormedics and Bunnell ventilators were louder than the Dräger, and the difference became greater as amplitude/peak inspiratory pressure was increased. CONCLUSIONS: The Dräger VN500 in high-frequency mode produces significantly less noise that both the Sensormedics and Bunnell ventilators. These data suggest that using the Dräger VN500 as a high-frequency ventilator may reduce the potential for adverse outcomes created by ventilator noise.

Inflammatory lung injury in rabbits: effects of high-frequency oscillatory ventilation in the prone position / Lesão inflamatória pulmonar em coelhos: efeitos da ventilação oscilatória de alta frequência em posição prona

ABSTRACT Objective: To compare the effects that prone and supine positioning during high-frequency oscillatory ventilation (HFOV) have on oxygenation and lung inflammation, histological injury, and oxidative stress in a rabbit model of acute lung injury (ALI). Methods: Thirty male Norfolk white rabbits were induced to ALI by tracheal saline lavage (30 mL/kg, 38°C). The injury was induced during conventional mechanical ventilation, and ALI was considered confirmed when a PaO2/FiO2 ratio < 100 mmHg was reached. Rabbits were randomly divided into two groups: HFOV in the supine position (SP group, n = 15); and HFOV with prone positioning (PP group, n = 15). For HFOV, the mean airway pressure was initially set at 16 cmH2O. At 30, 60, and 90 min after the start of the HFOV protocol, the mean airway pressure was reduced to 14, 12, and 10 cmH2O, respectively. At 120 min, the animals were returned to or remained in the supine position for an extra 30 min. We evaluated oxygenation indices and histological lung injury scores, as well as TNF-α levels in BAL fluid and lung tissue. Results: After ALI induction, all of the animals showed significant hypoxemia, decreased respiratory system compliance, decreased oxygenation, and increased mean airway pressure in comparison with the baseline values. There were no statistically significant differences between the two groups, at any of the time points evaluated, in terms of the PaO2 or oxygenation index. However, TNF-α levels in BAL fluid were significantly lower in the PP group than in the SP group, as were histological lung injury scores. Conclusions: Prone positioning appears to attenuate inflammatory and histological lung injury during HFOV in rabbits with ALI.

RESUMO Objetivo: Comparar os efeitos das posições prona e supina durante ventilação oscilatória de alta frequência (VOAF) sobre oxigenação e inflamação pulmonar, lesão histológica e estresse oxidativo em um modelo de lesão pulmonar aguda (LPA) em coelhos. Métodos: Trinta coelhos Norfolk machos brancos foram submetidos à LPA por meio de lavagem traqueal com salina (30 ml/kg, 38°C). A lesão foi induzida durante a ventilação mecânica convencional, e a LPA foi considerada confirmada na presença de relação PaO2/FiO2 < 100 mmHg. Os coelhos foram aleatoriamente divididos em dois grupos: VOAF em posição supina (grupo PS, n = 15); e VOAF em posição prona (grupo PP, n = 15). Para a VOAF, a pressão média das vias aéreas foi inicialmente estabelecida em 16 cmH2O. No 30º, 60º e 90º min após o início do protocolo de VOAF, a pressão média das vias aéreas foi reduzida para 14, 12 e 10 cmH2O, respectivamente. No 120º min, os animais foram recolocados ou permaneceram na posição supina por mais 30 min. Foram avaliados os índices de oxigenação e escores histológicos de lesão pulmonar, bem como os níveis de TNF-α em lavado broncoalveolar e tecido pulmonar. Resultados: Após a indução da LPA, todos os animais apresentaram hipoxemia significativa, diminuição da complacência do sistema respiratório, diminuição da oxigenação e aumento da pressão média das vias aéreas em comparação aos valores basais. Não houve diferenças estatisticamente significativas entre os dois grupos, em nenhum dos momentos avaliados, quanto a PaO2 e índice de oxigenação. Entretanto, os níveis de TNF-α no lavado broncoalveolar foram significativamente menores no grupo PP que no grupo PS, assim como os escores histológicos de lesão pulmonar. Conclusões: A posição prona parece atenuar a lesão pulmonar inflamatória e histológica durante a VOAF em coelhos com LPA.

Ventilación de alta frecuencia oscilatoria en pediatría / High frequency oscillatory ventilation in pediatrics

Mechanical ventilation (MV) is a usual therapy for the management of critically ill children. However its inappropriate use can produce lung injury. Today, the evidence recommends protective ventilation such as strategie low tidal volumes (VT) that minimize injury and thus, high frequency oscillatory ventilation (HFOV) would have a theoretical role. HFOV allows gas exchange using low tidal volumes (1 – 2 ml/kg) and supraphysiologic respiratory frequencies. In pediatrics it comprises 3 – 30 percent of mechanically ventilated patients, most of the time as a rescue therapy in refractory respiratory failure cases where conventional mechanical ventilation fails. Many aspects of HFVO in children remain unclear, theoretical benefits has no solid clinical basis, when is the best time to initiate (early vs rescue mode), which are the optimal settings, and how to monitor lung mechanics. This review examines HFVO theoretical bases, suggest recommendations for its use and considers the available evidence to understand the aspects that are still unclear.

La ventilación mecánica (VM) constituye un apoyo frecuente en el manejo de niños críticamente enfermos, quienes pueden requerirla por diferentes etiologías, entre ellas el síndrome de dificultad respiratoria aguda (SDRA). Sabemos que a pesar de ser un soporte vital, su uso inapropiado puede producir daño inducido por ventilación mecánica (DIVM). En la actualidad, la evidencia recomienda las estrategias de “ventilación protectora”, bajos volúmenes corrientes, que minimicen este daño y es ahí donde la ventilación de alta frecuencia oscilatoria (VAFO) tendría un rol teórico. La VAFO permite el intercambio gaseoso usando pequeños volúmenes corrientes (VT) 1-2 ml /kg y frecuencias respiratorias supra fisiológicas, con la consiguiente disminución del riesgo de atelectrauma, manteniendo el “pulmón abierto” y en la zona de seguridad de la curva presión-volumen. Su uso en pediatría oscila entre el 3 y el 30 por ciento de los pacientes ventilados, la mayoría de las veces como terapia de rescate frente a la falla de la ventilación convencional (VMC) en insuficiencia respiratoria refractaria. Muchos aspectos de la VAFO en pediatría no han sido totalmente esclarecidos; su efecto protector teórico permanece aún sin bases sólidas en el escenario clínico, quienes se benefician de su uso, cuál es el mejor momento para iniciarla (temprana o rescate), cuales son los valores óptimos del oscilador y como monitorear la mecánica pulmonar en VAFO. La presente revisión pretende repasar los conceptos teóricos de la VAFO, formular recomendaciones para su uso y considerar la evidencia disponible que nos permitan dilucidar las interrogantes antes mencionadas.

High-frequency oscillatory ventilation in children: a 10-year experience.

OBJECTIVES: The aim of the study was to describe the experience with high-frequency oscillatory ventilation (HFOV) in a Portuguese Pediatric Critical Care Unit, and to evaluate whether HFOV allowed improvement in oxygenation and ventilation. METHODS: This was a retrospective observational cohort study of children ventilated by HFOV between January, 2002 and December, 2011. The following parameters were recorded: demographic and clinical data, and blood gases and ventilatory parameters during the first 48 hours of HFOV. RESULTS: 80 children were included, with a median age of 1.5 months (min: one week; max: 36 months). Pneumonia (n=50; 62.5%) and bronchiolitis (n=18; 22.5%) were the main diagnoses. Approximately 40% (n=32) of the patients developed acute respiratory distress syndrome (ARDS). Conventional mechanical ventilation was used in 68 (85%) of patients prior to HFOV. All patients who started HFOV had hypoxemia, and 56 (70%) also presented persistent hypercapnia. Two hours after starting HFOV, a significant improvement in SatO2/FiO2 ratio (128±0.63 vs. 163±0.72; p<0.001) that was sustained up to 24 hours of HFOV and a decrease in FiO2 were observed. Since the beginning of HFOV, the mean PCO2 significantly decreased (87±33 vs. 66±25; p<0.001), and the pH significantly improved (7.21±0.17 vs. 7.32±0.15; p<0.001). Overall survival was 83.8%. CONCLUSIONS: HFOV enabled an improvement in hypercapnia and oxygenation. It is a safe option for the treatment of ARDS and severe small airway diseases.

Ventilação oscilatória de alta frequência em crianças: uma experiência de 10 anos / High-frequency oscillatory ventilation in children: a 10-year experience

OBJETIVOS: O objetivo do estudo foi descrever a experiência com ventilação oscilatória de frequência (VOAF) em uma unidade portuguesa de Cuidados Intensivos Neonatais e Pediátricos e avaliar se a VOAF permitiu uma melhoria na oxigenação e na ventilação. MÉTODOS: Estudo de coorte retrospectivo observacional em crianças submetidas À ventilação com VOAF entre janeiro de 2002 e dezembro de 2011. Os seguintes parâmetros foram registrados: dados demográficos e clínicos; gases sanguíneos; e parâmetros ventilatórios durante as primeiras 48 horas de VOAF. RESULTADOS: O estudo incluiu 80crianças com uma idade média de 1,5 mês (mínima: uma semana; máxima: 36 meses). Pneumonia (n = 50; 62,5%) e bronquiolite (n = 18; 22,5%) foram os principais diagnósticos. Cerca de 40% (n = 32) dos pacientes desenvolveram a síndrome da angústia respiratória aguda (SARA). A ventilação mecânica convencional foi utilizada em 68 (85%) pacientes antes da VOAF. Todos os pacientes que começaram a VOAF tiveram hipoxemia, e 56 (70%) também apresentaram hipercapnia persistente. Duas horas após o início da VOAF, foi observada uma melhoria significativa na proporção SatO2/FiO2 (128 ± 0,63 em comparação a 163 ± 0,72; p < 0,001), que foi mantida durante as 24 horas de VOAF, e uma redução da FiO2. Desde o início da VOAF, a PCO2 média teve uma queda significativa (87 ± 33 em comparação a 66 ± 25; p < 0,001) e o pH aumentou significativamente (7,21 ± 0,17 em comparação a 7,32 ± 0,15; p < 0,001). A sobrevida geral foi de 83,8%. CONCLUSÕES: A VOAF permitiu uma melhoria na hipercapnia e na oxigenação. Trata-se de uma opção segura no tratamento da SARA e de doenças graves das pequenas vias aéreas.

OBJECTIVES: The aim of the study was to describe the experience with high-frequency oscillatory ventilation (HFOV) in a Portuguese Pediatric Critical Care Unit, and to evaluate whether HFOV allowed improvement in oxygenation and ventilation. METHODS: This was a retrospective observational cohort study of children ventilated by HFOV between January, 2002 and December, 2011. The following parameters were recorded: demographic and clinical data, and blood gases and ventilatory parameters during the first 48 hours of HFOV. RESULTS: 80 children were included, with a median age of 1.5 months (min: one week; max: 36 months). Pneumonia (n = 50; 62.5%) and bronchiolitis (n = 18; 22.5%) were the main diagnoses. Approximately 40% (n = 32) of the patients developed acute respiratory distress syndrome (ARDS). Conventional mechanical ventilation was used in 68 (85%) of patients prior to HFOV. All patients who started HFOV had hypoxemia, and 56 (70%) also presented persistent hypercapnia. Two hours after starting HFOV, a significant improvement in SatO2/FiO2 ratio (128 ± 0.63 vs. 163 ± 0.72; p < 0.001) that was sustained up to 24 hours of HFOV and a decrease in FiO2 were observed. Since the beginning of HFOV, the mean PCO2 significantly decreased (87 ± 33 vs. 66 ± 25; p < 0.001), and the pH significantly improved (7.21 ± 0.17 vs. 7.32 ± 0.15; p < 0.001). Overall survival was 83.8%. CONCLUSIONS:HFOV enabled an improvement in hypercapnia and oxygenation. It is a safe option for the treatment of ARDS and severe small airway diseases.

Ventilación de alta frecuencia: una opción terapéutica del Síndrome de Distrés Respiratorio del Adulto / High-frequency ventilation: a therapeutic option of adult respiratory distress syndrome

El síndrome de Distrés Respiratorio del Adulto es una de las enfermedades nosológicas de mayor gravedad en los pacientes ingresados en las unidades de cuidados intensivos. Se realiza una revisión del uso de la ventilación de alta frecuencia como una opción terapéutica para estos pacientes. Desde hace aproximadamente una década se están utilizando diferentes estrategias ventilatorias en el tratamiento del distrés, como el uso de la presión positiva al final de la espiración y las maniobras de reclutamiento alveolar. La ventilación de alta frecuencia surge como alternativa en el tratamiento de aquellos pacientes donde la ventilación mecánica convencional ha fallado; es una modalidad de ventilación donde se aplican bajo volúmenes tidales y altas frecuencias respiratorias, para lo cual es necesario la utilización de un tipo especial de máquina de ventilación capaz de garantizar altas frecuencias respiratorias. Actualmente la más utilizada es la ventilación oscilatoria de alta frecuencia, sus ventajas principales son requerir menos volumen tidal, niveles de presión. Se puede combinar con técnicas de ventilación prona para lograr mayor efectividad, la mortalidad es menor y se produce menos lesión asociada a la ventilación mecánica. Las complicaciones más frecuentes son el neumotórax, el incremento de los niveles de presión venosa central y de oclusión de la arteria pulmonar con ligera disminución del gasto cardíaco (AU)

Adult respiratory distress syndrome is one of the nosologic diseases most seriousness in patients admitted at intensive care units. A review on the use of high-frequency ventilation as a therapeutic option for these patients was conducted. For approximately one decade different ventilatory strategies are using in the treatment of distress, as the use of positive pressure to the end of the expiration and the maneuvers of alveolar recruitment. High-frequency ventilation arises as alternative in the treatment of those patients where conventional mechanical ventilation has failed; it is a ventilation mode where low tidal volumes and high respiratory frequencies are applied, for which is necessary the use of a special type of ventilation machine able to guarantee high respiratory frequencies. Nowadays the most used is the oscillatory ventilation of high frequency, its main advantages are to require less tidal volume, levels of pressure. It may combine with prone ventilation technique to achieve bigger effectiveness, mortality is smaller and less associated lesion to the mechanical ventilation takes place. The most frequent complications are the pneumothorax, the increment of central venous pressure and occlusion levels of the pulmonary artery with slight decrease of heart output (AU)

Ventilación de alta frecuencia: una opción terapéutica del síndrome de distrés respiratorio del adulto: [revisión] / High-frequency ventilation: a therapeutic option of adult respiratory distress syndrome: [review]

El síndrome de Distrés Respiratorio del Adulto es una de las enfermedades nosológicas de mayor gravedad en los pacientes ingresados en las unidades de cuidados intensivos. Se realiza una revisión del uso de la ventilación de alta frecuencia como una opción terapéutica para estos pacientes. Desde hace aproximadamente una década se están utilizando diferentes estrategias ventilatorias en el tratamiento del distrés, como el uso de la presión positiva al final de la espiración y las maniobras de reclutamiento alveolar. La ventilación de alta frecuencia surge como alternativa en el tratamiento de aquellos pacientes donde la ventilación mecánica convencional ha fallado; es una modalidad de ventilación donde se aplican bajo volúmenes tidales y altas frecuencias respiratorias, para lo cual es necesario la utilización de un tipo especial de máquina de ventilación capaz de garantizar altas frecuencias respiratorias. Actualmente la más utilizada es la ventilación oscilatoria de alta frecuencia, sus ventajas principales son requerir menos volumen tidal, niveles de presión. Se puede combinar con técnicas de ventilación prona para lograr mayor efectividad, la mortalidad es menor y se produce menos lesión asociada a la ventilación mecánica. Las complicaciones más frecuentes son el neumotórax, el incremento de los niveles de presión venosa central y de oclusión de la arteria pulmonar con ligera disminución del gasto cardíaco.

Adult respiratory distress syndrome is one of the nosologic diseases most seriousness in patients admitted at intensive care units. A review on the use of high-frequency ventilation as a therapeutic option for these patients was conducted. For approximately one decade different ventilatory strategies are using in the treatment of distress, as the use of positive pressure to the end of the expiration and the maneuvers of alveolar recruitment. High-frequency ventilation arises as alternative in the treatment of those patients where conventional mechanical ventilation has failed; it is a ventilation mode where low tidal volumes and high respiratory frequencies are applied, for which is necessary the use of a special type of ventilation machine able to guarantee high respiratory frequencies. Nowadays the most used is the oscillatory ventilation of high frequency, its main advantages are to require less tidal volume, levels of pressure. It may combine with prone ventilation technique to achieve bigger effectiveness, mortality is smaller and less associated lesion to the mechanical ventilation takes place. The most frequent complications are the pneumothorax, the increment of central venous pressure and occlusion levels of the pulmonary artery with slight decrease of heart output.

Neurodesarrollo de primeros neonatos cubanos ventilados con alta frecuencia / Neurodevelopment of the first high frequency ventilated Cuban neonates

INTRODUCCIÓN. El objetivo de este estudio fue describir el neurodesarrollo en los primeros 2 años de vida de los primeros recién nacidos (RN) cubanos que recibieron ventilación de alta frecuencia (VAF) en la modalidad oscilatoria. MÉTODOS. Se realizó un estudio descriptivo y longitudinal de 19 RN tratados con VAF y se relacionó la evaluación final del neurodesarrollo con algunas variables perinatales y del modo de ventilación. Se utilizaron medidas descriptivas, tales como valores absolutos y porcentajes. RESULTADOS. Hubo un 21 por ciento de neonatos con alteraciones del neurodesarrollo. La evolución fue normal en todos los menores de 2000 g de peso al nacer y en el 40 por ciento del grupo de 2500 g y más. Hubo alteraciones en el 13 por ciento de los neonatos pretérmino y en el 50 por ciento de los nacidos a término. Existió un ligero predominio de normalidad en el sexo masculino (82 por ciento frente al 75 por ciento). Hubo un solo paciente con Apgar bajo sostenido, de los 4 que presentaron secuelas. La evolución del neurodesarrollo fue normal en el 89 por ciento de los ventilados con alta frecuencia por 48 h o más; se detectaron alteraciones en el 30 por ciento de los que la recibieron por menos de 48 h. Casi todos los neonatos fueron ventilados por más de 96 h, incluidos los que presentaron secuelas. CONCLUSIONES. La quinta parte de los RN sometidos a VAF presentaron secuelas del neurodesarrollo en los primeros 2 años de vida, con predominio de las moderadas. Esta modalidad de ventilación en sí misma no estuvo asociada a una mayor incidencia de secuelas, las que fueron más frecuentes en los neonatos de mayor peso y mayor edad gestacional. A menor tiempo en alta frecuencia y mayor tiempo total en ventiloterapia, mayor fue la incidencia de las alteraciones del neurodesarrollo(AU)

INTRODUCTION: The objective of present study was to describe the neurodevelopment during the first 2 years of life of the first Cuban newborns underwent high frequency ventilation (HFV) in oscillatory modality. METHODS: A longitudinal and descriptive study was conducted in 19 newborns treated with HFV and the final assessment of neurodevelopment was related to some perinatal variables and to the ventilation type. RESULTS: There were neonates (21 percent) presenting with neurodevelopment alterations. Course was normal in all those weighing less than 2000 g at birth, and in the 40 percent of the series weighing 2500 or more. There were alterations in the 13 percent of pre-term neonates and in the 50 percent of at-term births, as well as a slight predominance of normality in male sex (82 percent versus 75 percent). There was only one patient with a low and a sustained Apgar score from the 4 with sequelae. Neurodevelopment course was normal in 89 percent of those underwent to high frequency ventilation during 8 hours or more; in 30 percent we found alterations from those underwent to ventilation during less than 48 hours. Almost all the neonates underwent to ventilation during more than 96 hours, including those presenting sequelae. CONCLUSIONS: The fifth part of newborns underwent high frequency ventilation had neurodevelopment sequelae during the first 2 years of life with a predominance of the moderate ones. This ventilation modality by itself was not associated with a higher sequelae incidence, which were more frequent in neonates with higher weight and gestational age. With less time in high frequency and a total higher time in ventilation therapy, greater was the incidence of neurodevelopment alterations(AU)

Neurodesarrollo de primeros neonatos cubanos ventilados con alta frecuencia / Neurodevelopment of the first high frequency ventilated Cuban neonates

INTRODUCCIÓN. El objetivo de este estudio fue describir el neurodesarrollo en los primeros 2 años de vida de los primeros recién nacidos (RN) cubanos que recibieron ventilación de alta frecuencia (VAF) en la modalidad oscilatoria. MÉTODOS. Se realizó un estudio descriptivo y longitudinal de 19 RN tratados con VAF y se relacionó la evaluación final del neurodesarrollo con algunas variables perinatales y del modo de ventilación. Se utilizaron medidas descriptivas, tales como valores absolutos y porcentajes. RESULTADOS. Hubo un 21 por ciento de neonatos con alteraciones del neurodesarrollo. La evolución fue normal en todos los menores de 2000 g de peso al nacer y en el 40 por ciento del grupo de 2500 g y más. Hubo alteraciones en el 13 por ciento de los neonatos pretérmino y en el 50 por ciento de los nacidos a término. Existió un ligero predominio de normalidad en el sexo masculino (82 por ciento frente al 75 por ciento). Hubo un solo paciente con Apgar bajo sostenido, de los 4 que presentaron secuelas. La evolución del neurodesarrollo fue normal en el 89 por ciento de los ventilados con alta frecuencia por 48 h o más; se detectaron alteraciones en el 30 por ciento de los que la recibieron por menos de 48 h. Casi todos los neonatos fueron ventilados por más de 96 h, incluidos los que presentaron secuelas. CONCLUSIONES. La quinta parte de los RN sometidos a VAF presentaron secuelas del neurodesarrollo en los primeros 2 años de vida, con predominio de las moderadas. Esta modalidad de ventilación en sí misma no estuvo asociada a una mayor incidencia de secuelas, las que fueron más frecuentes en los neonatos de mayor peso y mayor edad gestacional. A menor tiempo en alta frecuencia y mayor tiempo total en ventiloterapia, mayor fue la incidencia de las alteraciones del neurodesarrollo

INTRODUCTION: The objective of present study was to describe the neurodevelopment during the first 2 years of life of the first Cuban newborns underwent high frequency ventilation (HFV) in oscillatory modality. METHODS: A longitudinal and descriptive study was conducted in 19 newborns treated with HFV and the final assessment of neurodevelopment was related to some perinatal variables and to the ventilation type. RESULTS: There were neonates (21 percent) presenting with neurodevelopment alterations. Course was normal in all those weighing less than 2000 g at birth, and in the 40 percent of the series weighing 2500 or more. There were alterations in the 13 percent of pre-term neonates and in the 50 percent of at-term births, as well as a slight predominance of normality in male sex (82 percent versus 75 percent). There was only one patient with a low and a sustained Apgar score from the 4 with sequelae. Neurodevelopment course was normal in 89 percent of those underwent to high frequency ventilation during 8 hours or more; in 30 percent we found alterations from those underwent to ventilation during less than 48 hours. Almost all the neonates underwent to ventilation during more than 96 hours, including those presenting sequelae. CONCLUSIONS: The fifth part of newborns underwent high frequency ventilation had neurodevelopment sequelae during the first 2 years of life with a predominance of the moderate ones. This ventilation modality by itself was not associated with a higher sequelae incidence, which were more frequent in neonates with higher weight and gestational age. With less time in high frequency and a total higher time in ventilation therapy, greater was the incidence of neurodevelopment alterations

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.

Pulmonary morphofunctional effects of mechanical ventilation with high inspiratory air flow.

OBJECTIVE: Uncertainties about the numerous degrees of freedom in ventilator settings leave many unanswered questions about the biophysical determinants of lung injury. We investigated whether mechanical ventilation with high air flow could yield lung mechanical stress even in normal animals. DESIGN: Prospective, randomized, controlled experimental study. SETTING: University research laboratory. SUBJECTS: Thirty normal male Wistar rats (180-230 g). INTERVENTIONS: Rats were ventilated for 2 hrs with tidal volume of 10 mL/kg and either with normal inspiratory air flow (V') of 10 mL/s (F10) or high V' of 30 mL/s (F30). In the control group, animals did not undergo mechanical ventilation. Because high flow led to elevated respiratory rate (200 breaths/min) and airway peak inspiratory pressure (PIP,aw = 17 cm H2O), two additional groups were established to rule out the potential contribution of these variables: a) normal respiratory rate = 100 breaths/min and V' = 30 mL/sec; and b) PIP,aw = 17 cm H2O and V' = 10 mL/sec. MEASUREMENTS AND MAIN RESULTS: Lung mechanics and histology (light and electron microscopy), arterial blood gas analysis, and type III procollagen messenger RNA expression in lung tissue were analyzed. Ultrastructural microscopy was similar in control and F10 groups. High air flow led to increased lung plateau and peak pressures, hypoxemia, alveolar hyperinflation and collapse, pulmonary neutrophilic infiltration, and augmented type III procollagen messenger RNA expression compared with control rats. The reduction of respiratory rate did not modify the morphofunctional behavior observed in the presence of increased air flow. Even though the increase in peak pressure yielded mechanical and histologic changes, type III procollagen messenger RNA expression remained unaltered. CONCLUSIONS: Ventilation with high inspiratory air flow may lead to high tensile and shear stresses resulting in lung functional and morphologic compromise and elevation of type III procollagen messenger RNA expression.

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.

Ventilación de alta frecuencia oscilatoria en pacientes pediátricos / High-frequency oscillatory ventilation in pediatric patients

Introduction: High-frequency oscillatory ventilation (HFOV) uses small tidal volumes, often smaller than the anatomic dead space, with high respiratory rates (> 1 Hz). This therapeutic option has become more popular in our country in the last years. Study objectives: To review the clinical experience with HFOV in our Pediatric Intensive Care Unit and to describe the patient's characteristics, HFOV strategies and outcome. Patients: A prospective study included patients less than 16 years old with Acute Respiratory Distress Syndrome (ARDS) refractary to conventional mechanical ventilation (CMV). We compare two periods (1999-2001 and 2002-2004). Measurements and results: Forty-nine patients underwent onto 51 episodes of HFO ventilation, 80 percent presented with primary ARDS. Previous conventional ventilation was 47 hours long. The median value of the oxygenation index (OI) at the beginning of HFOV was 24. Mean airway pressure was initially set at 9 cmH2O above the value in conventional ventilation. All the patients presented a decrease of their OI and ventilation was improved during the first 48 hours of therapy. Median duration on HFOV was 102 hours. The most frequent side effect was transient hypotension (25 percent). In the second period we observed a decrease in hemodynamic complications and also an increase in HFO duration. The mortality rate was 33 percent (22 percent due to pulmonary cause). Conclusion: HFOV is an effective therapy for pediatric respiratory failure refractory to conventional mechanical ventilation.

Introducción: La ventilación de alta frecuencia oscilatoria (VAFO) es una modalidad que emplea pequeños volúmenes corrientes, habitualmente menores que el espacio muerto anatómico, con rápidas frecuencias respiratorias (> 1 Hz). Esta opción ha sido cada vez más frecuente de disponer en nuestro país en los últimos años. Objetivos: Revisar la experiencia clínica con el uso de VAFO en nuestra UCI y describir las características de los pacientes, estrategia de VAFO empleada y pronóstico. Pacientes: Un estudio prospectivo, no controlado, de series de casos incluyó pacientes menores de 16 años, con Síndrome de Distress Respiratorio Agudo (SDRA), frente a fracaso de Ventilación Mecánica Convencional (VMC). Se compararon dos períodos dentro del estudio (1999-2001 y 2002-2004). Resultados: 51 episodios de empleo de VAFO, en 49 pacientes cuyo diagnóstico fue SDRA de causa pulmonar en el 80 por ciento. La duración de la VMC previo a la VAFO fue de 47 horas. El índice de oxigenación al iniciarse la VAFO fue 24. La presión media de vía aérea fue fijada en 9 cm H2O sobre el valor en VMC. Se logró una significativa mejoría en la oxigenación y en la ventilación. La duración media de la VAFO fue de 102 horas. El efecto adverso más frecuente fue la hipotensión transitoria (25 por ciento). En el segundo período analizado hubo una disminución de las complicaciones hemodinámicas (p < 0,05), como también un incremento en la duración de la VAFO. Un 33 por ciento de los pacientes fallecieron, un 22 por ciento por causa pulmonar. Conclusión: La VAFO es una terapia eficaz de soporte ventilatorio ante fracaso de la VMC.

[Intraoperative high frequency oscillatory ventilation in 2 children undergoing lung surgery]. / Uso intraoperatorio de ventilación de alta frecuencia oscilatoria en dos casos pediátricos de cirugía pulmonar.

Over the past 10 years, the application of high frequency oscillatory ventilation (HFOV) has been extended beyond the neonatal period. The technique is now used in various respiratory disease settings when conventional mechanical ventilation fails. Even though HFOV has become increasingly routine in some pediatric intensive care units, familiarity with it is still limited among anesthesiologists and surgeons and it is not often applied during surgery. We report our experience using HFOV during thoracic surgery on 2 pediatric patients, one aged 5 years and the other aged 1 month. The respective surgical procedures were to close a bronchopleural fistula and to obtain a lung biopsy in order to provide guidance for limiting therapeutic intervention. In both cases the procedure was performed without adverse effects and allowed medical interventions to be carried out. We conclude that it is possible to perform thoracic surgery in pediatric patients undergoing HFOV. This ventilation mode can be useful during surgery and teams that care for critically ill children should be familiar with the equipment.

Ventilación de alta frecuencia en neonatología: a quiénes y cómo ventilar / High frequency ventilation in neonatology: who should be ventilated and how

En Cuba, desde inicios del presente siglo, los recién nacidos comenzaron a ventilarse con un método de asistencia respiratoria aún relativamente novedoso, que se denomina ventilación de alta frecuencia. Es el objetivo fundamental de esta revisión precisar sus indicaciones, contraindicaciones, orientar como utilizarla y señalar algunas de sus complicaciones. La ventilación de alta frecuencia es ya una estrategia alternativa muy útil en la asistencia respiratoria neonatal(AU)

Ventilación de alta frecuencia en neonatología: a quiénes y cómo ventilar / High frequency ventilation in neonatology: who should be ventilated and how

En Cuba, desde inicios del presente siglo, los recién nacidos comenzaron a ventilarse con un método de asistencia respiratoria aún relativamente novedoso, que se denomina ventilación de alta frecuencia. Es el objetivo fundamental de esta revisión precisar sus indicaciones, contraindicaciones, orientar como utilizarla y señalar algunas de sus complicaciones. La ventilación de alta frecuencia es ya una estrategia alternativa muy útil en la asistencia respiratoria neonatal

Empleo de ventilación oscilatoria de alta frecuencia en el tratamiento del síndrome de distress respiratorio agudo en niños: descripción clínica y actualización de condiciones asociadas para una visión kinésica integral / Use of high frequency oscilltory ventilation in the treatment of the acute respiratory distress syndrome in children: clinical description and update of conditions associated for integral kinesic vision

Introducción: El síndrome de Distress Respiratorio Agudo (SDRA) presenta nuevas opciones terapéuticas en nuestra realidad, una de ella es la ventilación de alta frecuencia oscilatoria (VAFO), la cual es una modalidad que emplea pequeños volúmenes corrientes, con bajos cambios bifásicos de presión a frecuencias suprafisiológicas. Se presenta la experiencia en la instauración de la VAFO en el tratamiento del SDRA. Del mismo modo se revisa desde un aspecto teórico la asociación con el uso de decúbito prono (DP), como también la inmovilización prolongada y neuro-miopatía de paciente crítico, hallazgos frecuentes de observar en esta entidad clínica. Pacientes y Métodos: Se incluyeron los pacientes menores de 16 años que ingresaron con diagnóstico de Falla Respiratoria Hipoxémica Aguda (PaO2/FiO2<200) refractaria a Ventilación Mecánica Convencional. Un estudio clínico prospectivo investigó las características clínicas, parámetros ventilatorios empleados y la respuesta de indicadores de oxigenación. Resultados: Se presenta un total de 31 conexiones de VAFO en 29 pacientes, cuyo diagnóstico fue SDRA en el 90 por ciento. Tanto en los pacientes vivos y fallecidos hubo un descenso del índice de oxigenación (10) durante las primeras 48 horas, pero no se observó diferencia estadística entre ambos grupos. El 10 al momento de iniciarse la VAFO fue de 27. La PMVA fue fijada en promedio 10 cmH2O sobre el valor en VM convencional. La duración de la VAFO tuvo una mediana de 85 horas. En el 71 por ciento de los pacientes se asoció a DP. Hubo un 19 por ciento de barotrauma. Ocurrió un caso de neuro-miopatía de paciente crítico. Diez pacientes fallecieron (7 por causa pulmonar), dando una letalidad de 34 por ciento para este grupo. Conclusiones: Si se reúnen ciertas condiciones, la VAFO parece ser un modo efectivo de ventilación en falla respiratoria pediátrica. El kinesiológo debe estar atento a las manifestaciones de las condiciones asociadas con los diversos modos de tratamiento a los cuales es sometido el niño con falla respiratoria aguda