Ventilación en posición prona en el manejo de pacientes con síndrome de dificultad respiratoria aguda / Prone ventilation in the management of patients with acute respiratory distress syndrome

INTRODUCCIÓN. El posicionamiento prono es una de las estrategias ventilatorias más estudiadas y difundidas de la medicina intensiva, forma parte del manejo de ventilación protectiva con impacto en disminución de la mortalidad en pacientes con síndrome de dificultad respiratoria aguda. OBJETIVO. Revisar la evidencia disponible acerca de ventilación en posición prona en pacientes con síndrome de dificultad respiratoria aguda, enfocada en el análisis fisiopatológico y clínico. MATERIALES Y MÉTODOS. Se realizó una revisión bibliográfica en la base de datos de buscadores académicos como PubMed, Google Scholar y Elsevier, en los idiomas español e inglés, en el período comprendido entre los años 1970-2020; se seleccionaron 16 publicaciones en texto completo: 3 metaanálisis, 10 estudios randomizado, 3 revisiones sistemáticas. CONCLUSIÓN. En base a la evidencia y percepción recopilada de la experiencia de los autores, la ventilación en posición prona es una estrategia de manejo de primera línea, fiable, que no requiere para su empleo equipamiento costoso ni complejo y ha demostrado mejoría en desenlaces relevantes en el tratamiento del paciente crítico respiratorio como disminución en la mortalidad y optimización de los parámetros ventilatorios y de oxigenación.

INTRODUCTION. Prone positioning is one of the most studied and widespread ventilatory strategies in intensive medicine, it is part of protective ventilation management with an impact on mortality reduction in patients with acute respiratory distress syndrome. OBJECTIVE. To review the available evidence about ventilation in the prone position in patients with acute respiratory distress syndrome, focused on the pathophysiological and clinical analysis. MATERIALS AND METHODS. A bibliographic review was carried out in the databases of academic search engines such as PubMed, Google Scholar and Elsevier, in the Spanish and English languages, in the period between the years 1970-2020, 16 full text publications were selected: 3 meta-analyses, 10 randomized studies, 3 systematic reviews. CONCLUSION. Based on the evidence and perception gathered from the authors' experience, prone ventilation is a reliable first-line management strategy that does not require costly or complex equipment for its use and has demonstrated improvements in relevant outcomes in the treatment of the critically ill respiratory patient, such as decreased mortality and optimization of ventilatory and oxygenation parameters.

Respuesta inmune disfuncional en pacientes con COVID-19. ¿Qué nos dice la evidencia? / Dysfunctional immune response in COVID-19 patients. What does the evidence tell us?

In December 2019 a novel coronavirus (SARS-CoV-2) was identified in Wuhan, China, and became rapidly the worst pandemic in 100 years. Coronaviruses are respiratory viruses that can cause diseases ranging from mild to fatal lower respiratory tract infections. In a fraction of the affected patients, coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2, can lead to acute respiratory distress syndrome (ARDS) and intensive care unit (ICU) admission, both associated with high mortality. To date, the existing evidence suggests a leading role of the immune system in the pathogenesis of severe COVID-19, including mechanisms associated with hyperinflammation, immune evasion, cytokine release syndrome, depletion of functional T cells, and ineffective humoral immunity. Here we discuss the current evidence regarding these findings.

El lado oculto de la hipoxemia / The dark side of hypoxemia

Acute respiratory distress syndrome (ARDS) is characterized by an increase in the intrapulmonary shunt (measured by the PaO2/FiO2 ratio) caused by bilateral alveolar-interstitial infiltrates which are not fully explained by fluid overload. However, there are some ARDS cases which present severe hypoxemia without clear lung infiltrates. An example of this, which has generated great controver- sy, is the infection caused by SARS-CoV-2. Understanding the pathophysiology of hypoxemia is absolutely crucial in order to establish the most appropriate therapeutic strategy for each patient. In the case of a severe hypoxemia (PaO/ FiO2 < 200 which represents a shunt greater than 30%) with a chest X-ray (or CT) without clear and extensive bilateral infiltrates, it is important to consider that the shunt can be caused due to vascular involvement. This shunt could be explained two ways: an increase in pulmonary vascular resistance (PVR), which generates a right-to-left shunt through the patent foramen ovale (PFO), or an alteration of the hypoxic pulmonary vasoconstriction reflex (HPV). The HPV reflex is activated in an attempt to redistribute the vascular flow to better ventilated areas. However, there are some situations (such as viral infections) that can alter this reflex and worsen the hypoxemia. The concomitant use of vasoactive drugs (such as inhaled nitric oxide) and vasopressors (such as dopa- mine or norepinephrine) has been proposed with the aim of reducing PVR and the flow through the PFO; or to redistribute the flow to better ventilated areas if an alteration of the RVP is suspected.

Un síndrome de distrés respiratorio agudo (SDRA) se caracteriza por un incremento del intrapulmonar (medido por el cociente PaO2/FiO2) causado por una afectación alveolo-intersticial bilateral no explicada por sobrecarga hídrica. Sin embargo, hay casos de SDRA que presentan una marcada hipoxemia sin claros infiltrados pulmonares. Un ejemplo de este caso, que ha generado gran controversia, es la infección por SARS-CoV-2. El entendimiento de la fisiopato- logía de la hipoxemia es absolutamente clave para establecer la estrategia terapéutica más adecuada en cada paciente. Ante una hipoxemia grave (PaO2/FiO2 < 200 que representa un superior al 30%) y con una radiografía de tórax (o con TAC) sin claros y extensos infiltrados bilaterales, el podría deberse a una afectación vascular. Esto podría explicarse por dos causas: un aumento de las resistencias vasculares pulmonares (RVP), que genera un derecha- izquierda a través del foramen oval permeable (FOP) o una alteración del reflejo de vasoconstricción pulmonar hipóxico (VPH). El reflejo de VPH se activa en un intento por redistribuir el flujo vascular hacia las zonas mejor ventiladas. Sin embargo, existen situaciones (como infecciones víricas) que pueden alterar dicho reflejo y agravar la hipoxemia. Se ha propuesto el uso concomitante de fármacos vasoactivos (como el óxido nítrico inhalado) y vasopresores (como do- pamina o noradrenalina) con el objetivo de disminuir las RVP y el flujo a través del FOP; o para redistribuir el flujo a zonas mejor ventiladas si se sospecha una alteración del RVP.

Efecto de la PEEP sobre el componente resistivo inspiratorio en pacientes con sindrome de distrés respiratorio agudo ventilados a bajo volumen corriente / Effect of PEEP on inspiratory resistance components in patients with acute respiratory distress syndrome ventilated at low tidal volume

RESUMEN Objetivo: Describir el comportamiento del componente resistivo ante el incremento de la presión positiva espiratoria final (PEEP) en pacientes con síndrome de distrés respiratorio agudo ventilados con una estrategia de ventilación protectora. Métodos: En modo controlada por volumen, a 6mL/Kg y flujo constante se realizaron oclusiones teleinspiratorias a PEEP 0, 5 10, 15 y 20cmH2O. Se obtuvieron valores de presión pico, inicial, plateau y se calculó resistencias máxima, mínima y diferencial. Las comparaciones se realizaron mediante test de ANOVA para muestras relacionadas con corrección post hoc de Bonferroni. Se consideró significativo una p < 0,05. Resultados: La resistencia máxima más elevada se observó en los niveles de PEEP más bajos. Los valores de PEEP 10 y 15cmH2O tuvieron diferencias significativas con PEEP 5 y 0cmH2O, mientras que PEEP 20cmH2O únicamente con PEEP 0cmH2O (p < 0,05). La resistencia mínima tuvo la misma conducta que la resistencia máxima. A partir de PEEP 10cmH2O todos tuvieron diferencias significativas con PEEP 0 y 5cmH2O (p < 0,05). La resistencia diferencial se expresó de manera opuesta a la resistencia máxima y mínima. El único nivel de PEEP que experimentó diferencias significativas con PEEP 0 y 5cmH2O fue PEEP 20cmH2O. También hubo diferencias entre PEEP 15 y PEEP 5cmH2O (p < 0,05). Conclusiones: Durante ventilación protectora en pacientes com síndrome de distrés respiratorio agudo, la resistencia máxima del sistema respiratorio tiene un comportamiento decreciente con la PEEP y refleja la respuesta que tiene la resistencia mínima. Mientras que la resistencia diferencial mantiene su conducta creciente con los valores de PEEP.

ABSTRACT Objective: To describe the behavior of inspiratory resistance components when positive end-expiratory pressure (PEEP) increases in patients with acute respiratory distress syndrome under a protective ventilation strategy. Methods: In volume-controlled mode, at 6mL/kg and constant flow, end-inspiratory occlusions were performed at 0, 5 10, 15 and 20cmH2O PEEP. Peak, initial and plateau pressure values were assessed, calculating the maximum, minimum and differential resistances. The results were compared by repeated measures analysis of variance (ANOVA) with post hoc Bonferroni correction, considering p < 0.05 significant. Results: The highest maximum resistance was observed at the lowest PEEP levels. The values for 10 and 15cmH2O PEEP significantly differed from those for 5 and 0cmH2O PEEP, whereas that for 20cmH2O PEEP only significantly differed from that for 0cmH2O PEEP (p < 0.05). The minimum resistance behaved similarly to the maximum resistance; the values for PEEP levels from 10cmH2O to 20cmH2O significantly differed from those for 0 and 5cmH2O PEEP (p < 0.05). Differential resistance showed the opposite variation to the maximum and minimum resistances. The only PEEP level that showed significant differences from 0 and 5cmH2O PEEP was 20cmH2O PEEP. Significant differences were also found between 15 and 5cmH2O PEEP (p < 0.05). Conclusions: During protective ventilation in patients with acute respiratory distress syndrome, the maximum resistance of the respiratory system decreases with PEEP, reflecting the minimum resistance response, whereas differential resistance increases with PEEP.

Síndrome do desconforto respiratório: influência do manejo sobre o estado hemodinâmico de recém-nascidos pré-termo ≤ 32 semanas nas primeiras 24 horas de vida / Respiratory distress syndrome: influence of management on the hemodynamic status of ≤ 32-week preterm infants in the first 24 hours of life

RESUMO Objetivo: Investigar a influência do manejo da síndrome do desconforto respiratório sobre parâmetros clínicos e ecocardiográficos de avaliação hemodinâmica em recém-nascidos ≤ 32 semanas. Métodos: Foram avaliados prospectivamente 33 recém-nascidos ≤ 32 semanas, submetidos à ventilação mecânica invasiva. A necessidade de surfactante exógeno e os parâmetros clínicos e ecocardiográficos nas primeiras 24 horas de vida foram detalhadas nesse grupo de pacientes. Resultados: O valor da pressão média de vias aéreas foi significativamente maior nos recém-nascidos que necessitaram de inotrópicos [10,8 (8,8 - 23) cmH2O versus 9 (6,2 - 12) cmH2O; p = 0,04]. Houve correlação negativa entre pressão média de vias aéreas e integral velocidade-tempo da artéria pulmonar (r = -0,39; p = 0,026), débito do ventrículo direito (r = -0,43; p = 0,017) e medidas da excursão do plano do anel tricúspide (r = -0,37; p = 0,036). Verificou-se correlação negativa entre o número de doses de surfactante exógeno e: débito de ventrículo direito (r = -0,39; p = 0,028) e a integral velocidade-tempo da artéria pulmonar (r = -0,35; p = 0,043). Conclusão: Nos recém-nascidos ≤ 32 semanas em ventilação mecânica invasiva, elevações de pressão média de vias aéreas e do número de doses de surfactante correlacionam-se com piora da função cardíaca precoce. Aparentemente, o manejo mais agressivo da síndrome do desconforto respiratório contribui para a instabilidade hemodinâmica desses pacientes.

ABSTRACT Objective: To investigate the influence of respiratory distress syndrome management on clinical and echocardiographic parameters used for hemodynamic evaluation in ≤ 32- week newborns. Methods: Thirty-three ≤ 32-week newborns were prospectively evaluated and subjected to invasive mechanical ventilation. The need for exogenous surfactant and clinical and echocardiographic parameters in the first 24 hours of life was detailed in this group of patients. Results: The mean airway pressure was significantly higher in newborn infants who required inotropes [10.8 (8.8 - 23) cmH2O versus 9 (6.2 - 12) cmH2O; p = 0.04]. A negative correlation was found between the mean airway pressure and velocity-time integral of the pulmonary artery (r = -0.39; p = 0.026), right ventricular output (r = -0.43; p = 0.017) and measurements of the tricuspid annular plane excursion (r = -0.37; p = 0.036). A negative correlation was found between the number of doses of exogenous surfactant and the right ventricular output (r = -0.39; p = 0.028) and pulmonary artery velocity-time integral (r = -0.35; p = 0.043). Conclusion: In ≤ 32-week newborns under invasive mechanical ventilation, increases in the mean airway pressure and number of surfactant doses are correlated with the worsening of early cardiac function. Therefore, more aggressive management of respiratory distress syndrome may contribute to the hemodynamic instability of these patients.

p38MAPK plays a pivotal role in the development of acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a life-threatening illness characterized by a complex pathophysiology, involving not only the respiratory system but also nonpulmonary distal organs. Although advances in the management of ARDS have led to a distinct improvement in ARDS-related mortality, ARDS is still a life-threatening respiratory condition with long-term consequences. A better understanding of the pathophysiology of this condition will allow us to create a personalized treatment strategy for improving clinical outcomes. In this article, we present a general overview p38 mitogen-activated protein kinase (p38MAPK) and recent advances in understanding its functions. We consider the potential of the pharmacological targeting of p38MAPK pathways to treat ARDS.

Prevalence and factors associated with surfactant use in Brazilian Neonatal Intensive Care Units: A multilevel analysis / Prevalência e fatores associados ao uso de surfactante em unidades de Terapia Intensiva Neonatais brasileiras: análise multinível

Abstract The treatment with exogenous surfactant reduces mortality and the risk of complications in preterm newborns with Respiratory Distress Syndrome. Higher usage levels have been associated with individual and institutional factors. The study aimed to identify these factors associated with use of this technology in 16 public Brazilian Neonatal Units using logistic multilevel analysis. In a sample of 630 newborns the use at some time was 82.6%. Only 24.7% made use of this technology up to two hours after birth. An intraclass correlation of 0.30 showed that 30% of the variance in the use of exogenous surfactant could be assigned to the contextual level. In the final model, a greater severity score (SNAPPE-II) was associated with increased surfactant use (OR = 2.64), whereas being small for gestational age (SGA) (OR = 0.59) was associated with lower use of this technology. At the contextual level the number of beds in the unit >15 (OR = 5.86), units with higher complexity (OR = 1.73) or units with implemented Kangaroo Mother Care (OR = 2.91), especially units in Rio de Janeiro state (OR = 16.17) were associated with greater surfactant use. Although individual clinical features explained most of the variation in the use of this technology, factors linked to the institution were also of utmost importance.

Resumo O tratamento com surfactante exógeno reduz a mortalidade e o risco de complicações em recém-nascidos com Síndrome de Angústia Respiratória. Maiores níveis de utilização dessa tecnologia têm sido associados tanto a fatores individuais como institucionais. O estudo teve como objetivo identificar esses fatores em 16 unidades neonatais públicas brasileiras usando análise multinível. De 630 recém-nascidos, 82,6% usaram a tecnologia em algum momento. Apenas 24,7% fizeram uso até duas horas após o nascimento. Uma correlação intraclasse de 0,30 mostrou que 30% da variação no uso podem ser atribuídos ao nível contextual. No modelo final, um escore de gravidade maior (SNAPPE-II) foi associado com aumento do uso de surfactante (OR = 2,64), enquanto que ser pequeno para a idade gestacional (PIG) (OR = 0,59) foi associado a um menor uso dessa tecnologia. No nível contextual o número de leitos na unidade > 15 (OR = 5,86), as unidades com mais alta complexidade (OR = 1,73) ou unidades com Método Canguru implementado (OR = 2,91), especialmente unidades no estado do Rio de Janeiro (OR = 16,17), foram associados com uma maior utilização de surfactante. Embora características individuais tenham explicado a maior parte da variação no uso desta tecnologia, fatores ligados à instituição também foram de extrema importância.

Intercomunicación pulmón-riñón en el paciente crítico / Pulmonary-renal crosstalk in the critically ill patient

A pesar de los avances en el desarrollo de las terapias de reemplazo renal, la mortalidad de la falla renal aguda permanece elevada, especialmente, cuando se manifiesta simultáneamente con fallas orgánicas distantes, como es en el caso del síndrome de distrés respiratorio agudo. Se revisa la relación bidireccional deletérea entre pulmón y riñón, en el escenario de disfunción orgánica, la cual presenta aspectos clínicos relevantes de conocer. Se discuten los efectos renales del síndrome de distrés respiratorio agudo y del uso de la ventilación mecánica a presión positiva, siendo el daño inducido por este (ventilator induced lung injury) uno de los modelos utilizado frecuentemente para el estudio de la interacción pulmón-riñón. Se enfatiza el rol de la falla renal inducida por la ventilación mecánica (ventilator-induced kidney injury) en la patogenia de la falla renal aguda. Asimismo se analizan las repercusiones pulmonares de la falla renal aguda, reconociéndose que esta condición patológica induce un incremento en la permeabilidad vascular pulmonar, inflamación y alteración de los canales de sodio y agua del epitelio alveolar, entre otros efectos. Este modelo conceptual puede ser la base para el desarrollo de nuevas estrategias terapéuticas a utilizar en el paciente con síndrome de disfunción orgánica múltiple.

Despite advances in the development of renal replacement therapy, mortality of acute renal failure remains high, especially when occurring simultaneously with distant organic failure as it is in the case of the acute respiratory distress syndrome. In this update, birideccional deleterious relationship between lung and kidney on the setting of organ dysfunction is reviewed, which presents important clinical aspects of knowing. Specifically, the renal effects of acute respiratory distress syndrome and the use of positive-pressure mechanical ventilation are discussed, being ventilator induced lung injury one of the most common models for studying the lung-kidney crosstalk. The role of renal failure induced by mechanical ventilation (ventilator-induced kidney injury) in the pathogenesis of acute renal failure is emphasized. We also analyze the impact of the acute renal failure in the lung, recognizing an increase in pulmonary vascular permeability, inflammation, and alteration of sodium and water channels in the alveolar epithelial. This conceptual model can be the basis for the development of new therapeutic strategies to use in patients with multiple organ dysfunction syndrome.

Predisposición genética y síndrome de distrés respiratorio agudo pediátrico: nuevas herramientas de estudio genético / Genetic predisposition and Pediatric Acute Respiratory Distress Syndrome: New tools for genetic study

El síndrome de distrés respiratorio agudo (SDRA) es la forma más grave de falla respiratoria. Teóricamente, cualquier noxa pulmonar aguda puede resultar en un SDRA, pero solo un pequeño porcentaje de individuos desarrolla la enfermedad. Sobre este fundamento, factores genéticos han sido implicados en el riesgo de desarrollar SDRA. Basado en la fisiopatología de esta enfermedad, múltiples genes candidatos han sido evaluados como potenciales modificadores, tanto en pacientes como en modelos animales de SDRA. Datos experimentales y estudios clínicos recientes sugieren que variantes de genes implicados en procesos clave de daño tisular, celular y molecular pulmonar pueden influir en la predisposición y el pronóstico del SDRA. Sin embargo, la patogénesis del SDRA pediátrico es compleja y, en consecuencia, es posible anticipar que muchos genes pueden contribuir a ella. Variantes genéticas, tales como polimorfismos de nucleótido simple y variantes del número de copias, están probablemente asociadas con la predisposición al SDRA en niños con lesión pulmonar primaria. El estudio de asociación del genoma completo (GWAS, del inglés Genome-Wide Association Study) puede examinar estas variantes sin sesgos y ayudar a identificar nuevos genes fundamentales y vías patogénicas clave para futuros análisis. Esta aproximación también puede tener implicancias clínicas diagnósticas y terapéuticas, como predecir el riesgo del paciente o desarrollar un enfoque terapéutico personalizado para este grave síndrome.

Acute respiratory distress syndrome (ARDS) is the most severe form of respiratory failure. Theoretically, any acute lung condition can lead to ARDS, but only a small percentage of individuals actually develop the disease. On this basis, genetic factors have been implicated in the risk of developing ARDS. Based on the pathophysiology of this disease, many candidate genes have been evaluated as potential modifiers in patient, as well as in animal models, of ARDS. Recent experimental data and clinical studies suggest that variations of genes involved in key processes of tissue, cellular and molecular lung damage may influence susceptibility and prognosis of ARDS. However, the pathogenesis of pediatric ARDS is complex, and therefore, it can be expected that many genes might contribute. Genetic variations such as single nucleotide polymorphisms and copy-number variations are likely associated with susceptibility to ARDS in children with primary lung injury. Genome-wide association (GWA) studies can objectively examine these variations, and help identify important new genes and pathogenetic pathways for future analysis. This approach might also have diagnostic and therapeutic implications, such as predicting patient risk or developing a personalized therapeutic approach to this serious syndrome.

Clinical utility of early amplitude integrated EEG in monitoring term newborns at risk of neurological injury / Utilidade clínica de um monitoramento por EEG de amplitude integrada precoce em recém-nascidos a termo com risco de lesão neurológica

OBJECTIVE: to test the clinical utility of an early amplitude-integrated electroencephalography (aEEG) to predict short-term neurological outcome in term newborns at risk of neurology injury. METHODS: this was a prospective, descriptive study. The inclusion criteria were neonatal encephalopathy, neurologic disturbances, and severe respiratory distress syndrome. Sensitivity, specificity, positive and negative predictive values, and likelihood ratio (LR) were calculated. Clinical and demographic data were analyzed. Neurological outcome was defined as the sum of clinical, electroimaging, and neuroimaging findings. RESULTS: ten of the 21 monitored infants (48%) presented altered short-term neurologic outcome. The aEEG had 90% sensitivity, 82% specificity, 82% positive predictive value, and 90% negative predictive value. The positive LR was 4.95, and the negative LR was 0.12. In three of 12 (25%) encephalopathic infants, the aEEG allowed for a better definition of the severity of their condition. Seizures were detected in eight infants (38%), all subclinical at baseline, and none had a normal aEEG background pattern. The status of three infants (43%) evolved and required two or more drugs for treatment. CONCLUSIONS: in infants with encephalopathy or other severe illness, aEEG disturbances occur frequently. aEEG provided a better classification of the severity of encephalopathy, detected early subclinical seizures, and allowed for monitoring of the response to treatment. aEEG was a useful tool at the neonatal intensive care unit for predicting poor short-term neurological outcomes for all sick newborn. .

OBJETIVO: testar a utilidade clínica do aEEG precoce em recém-nascidos a termo com risco delesão neurológica, para prever resultados neurológicos de curto prazo. MÉTODOS: estudo prospectivo e descritivo. Os critérios de inclusão foram encefalopatia neonatal, distúrbios neurológicos e bebês com SARA grave. Sensibilidade, especificidade, valor preditivo positivo e negativo e razão de verossimilhança foram calculados. Dados clínicos edemográficos foram analisados. O resultado neurológico foi definido como a soma de conclusões clínicas, de eletro e de neuroimagem. RESULTADOS: dentre os 21 neonatos monitorados, dez (48%) apresentaram resultado neurológico de curto prazo alterado. O aEEG apresentou sensibilidade de 90%, especificidade de 82%, valor preditivo positivo de 82% e valor preditivo negativo de 90%. A VR positiva foi de 4,95, e a RV negativa de 0,12. Em três dos 12 (25%) neonatos com encefalopatia foi possível definir melhora gravidade de sua condição pelo aEEG. Foram detectadas convulsões em oito neonatos (38%), todas subclínicas no início do estudo, e nenhum apresentou um padrão histórico normal no aEEG. O estado de três neonatos (43%) evoluiu e exigiu dois ou mais medicamentos para tratamento. CONCLUSÕES: em neonatos com encefalopatia ou outra doença grave, os distúrbios no aEEGocorrem com mais frequência. O aEEG forneceu uma classificação melhor da gravidade da encefalopatia, detectou convulsões subclínicas precoces e permitiu que fosse feito o monitoramento da resposta ao tratamento. O aEEG é uma ferramenta útil para prever resultados neurológicos de curto prazo em todos os bebês doentes na UTIN. .

Síndrome de dificultad respiratoria agudo: revisión de causas, patogénesis y tratamiento / Acute respiratory distress syndrome: a review of causes, pathogenesis and treatment

El Síndrome de Dificultad Respiratrio Agudo (SDRA) es una patología pulmonar aguda, rápidamente progresiva, provocada por múltiples causas y con una alta morbimortalidad. Se caracteriza por una inflamación del conjunto alveolo-capilar resultando en una alteración de su permeabilidad y acumulación del material proteico de tipo exudativo dentro del alveolo por lo cual la capacidad de intercambio gaseoso entre el aire inspirado y la circulación sanguínea se ve comprometida. A pesar de constantes esfuerzos en afán de mejorar el tratamiento farmacológico, hasta la fecha no se ha logrado un resultado satisfactorio y el goal-standard del tratamiento sigue focalizado en el mantenimiento de un óptimo balance hídrico conjuntamente a una ventilación mecánica caracterizada por bajos volúmenes Tidales o Corrientes, una alta frecuencia respiratoria, baja presión Plateau, alto nivel de Presión Positiva Teleespiratoria PEEP (Positive End Expiratory Pressure) y todo esto para mantener valores adecuados de intercambio gaseoso sin provocar un baro y/o volutrauma.

Saturación de oxígeno en el período posnatal inmediato en neonatos nacidos por parto vaginal e intervención cesárea / Oxigen saturation during the inmediate postnatal period in newborns obtained by vaginal delivery or by cesarean section

El monitoreo de la saturación de oxígeno (SO²) ha sido propuesto como indicador a fin de guiar la concentración óptima de oxígeno a ser usada al comienzo de la reanimación neonatal. Para ello, se requiere precisar los valores normales de SO² en los minutos iniciales del nacimiento. Describir los cambios posnatales inmediatos de la SO² en neonatos a término sanos. En un estudio de diseño transversal se analizaron 60 niños, 30 nacidos por vía vaginal y 30 por cesárea. Un censor de oximetría de pulso fue colocado en la mano derecha dentro del primer minuto y se obtuvo un registro de SO² hasta los 30 minutos. La SO² aumentó progresivamente en los primeros 10 minutos de vida en todos los neonatos. Los niños nacidos por cesárea sostuvieron valores de SO² más bajos a lo largo de todo el lapso de las mediciones, con diferencias significativas hasta el minuto seis. La SO² promedio durante los primeros 10 minutos fue 6 por ciento más alta en los niños de parto vaginal que en los extraídos por cesárea. El tiempo promedio global para alcanzar una SO²>90 por ciento fue 8,4 minutos, pero este período fue significativamente más prolongado en los neonatos nacidos por cesárea (10,3 minutos) que en los niños obtenidos por vía vaginal (6,1 minutos; p<0,05). La transición hacia una SO² posnatal normal requiere un lapso mayor de 6 minutos luego del parto vaginal y de 10 minutos en el nacido por cesárea. Los valores posnatales inmediatos de SO² de los neonatos sanos son inferiores a los tolerados en las unidades neonatales, lo que debería considerarse cuando se seleccionan los objetivos de la SO² durante la reanimación.

Continuous measurement of oxygen saturation (SO²) has been proposed to guide optimum oxygen concentration during neonatal resuscitation. For this reason it is important to know the normal values of SO² immediately after birth. To describe changes in SO² during the first minutes after birth in healthy term infants. In a cross-sectional study, 60 infants were analyzed and stratified into two groups according to delivery route. A sensor was placed on the right hand and SO² was registered over the first 30 minutes of life. SO² showed a gradual rise over the first 10 minutes in all infants. Infants delivered by cesarean section had significantly lower SO² values in all measurements. On average, infants born by vaginal delivery had a 6% higher SO² than infants delivered by cesarean section. Mean time to reach an SO²>90% for the whole group was 8.4 minutes, but this time was longer after cesarean delivery (10.3 minutes) than after vaginal deliver(6.1 minutes; p<0,05). SO² raises gradually during the first minutes of life in healthy term newborn infants. The time required for SO² to reach 90% was 6 and 10 minutes after vaginal and cesarean delivery, respectively. SO² values immediately after birth are lower than those usually accepted in neonatal units. This should be considered when choosing SO2 targets for infants in the delivery room.

[Effect of neonatal position on oxygen saturation in Hospitalized premature infants with respiratory distress syndrome]

Rspiratory distress syndrome is one of the most important of mortality and morbidity in premature newborns. The aim of this study was to determine the effect of body position on oxygen saturation in hospitalized premature infants with respiratory distress syndrome [RDS]. In an interventional analytic study, 69 premature infants with RDS were evaluated. Patients had a mean gestational age [ +/- SD] of 31.4 [ +/- 2.41] weeks [range: 28-35 weeks] with a mean birth weight [ +/- SD] of 1446.6 [ +/- 218.90] gram [range: 850-2400 gram]. Infants were studied both supine and prone positions. Each posture was maintained for 3 hours. Oxygen saturation was monitored by trans-cutaneous paIsoxymeter and mean of oxygen saturation was measured for 3 hours. All patients were premature, oxygen pendent and had RDS. Mean [ +/- SD] of oxygen saturation during 3 hours in prone and supine positions were 92.54% [ +/- 2.24%] and 91.78% [ +/- 2.35%] respectively [p=0.001]. Also mean [ +/- SD] of oxygen saturation at the end of each 3-hours period prone and supine positions were 91.30% [ +/- 2.42%] and 90.30% [ +/- 3.15%] respectively [p=0.006]. These findings suggest that, in premature infants with RDS oxygen saturation was significantly higher in the prone compard with the supine posture

Determining the effect of touch on arterial blood oxygen saturation in neonates with respiratory distress syndrome

The use of complementary and alternative therapy is increasing and touch is one of them but several studies have indicated that premature neonates hospitalized in neonatal intensive care unit receive very little touch. The purpose of this research was to determine the effect of touch on arterial blood oxygen saturation in neonates with respiratory distress syndrome. This is a clinical trial with repeated measures that was performed on 37 neonates with respiratory distress syndrome. An information record form was used for data collection. The information record form was consisted of two parts: demographic information and a table for recording oxygen saturations. Oxygen saturation was measured by Nelkor pulse oxy meter. Information was collected in 3 sequential days. Arterial blood oxygen saturation was controlled 5 minutes before touch, then samples undergone 5 minutes touch and then in 5 and 15 minute intervals arterial blood oxygen saturation was controlled again. Data was analyzed using repeated measure ANOVA. Findings showed that in the first day, arterial blood oxygen saturation in 5 minutes before, and 5 and 15 minutes after touch were 95/67, 95/91, 96 respectively. In second day, arterial blood and oxygen saturation in 5 minutes before, and 5 and 15 minutes after touch were 95/72, 96/05, 96/08 respectively. In third day, arterial blood oxygen saturation in 5 minutes before, and 5 and 15 minutes after touch were 95/75, 96/16, 96/13 respectively. Arterial blood oxygen saturation in 5 and 15 minutes after touch were more than 5 minutes before touch in each 3 day [p<0.01]. But there was no significant difference between 5 and 15 minutes after touch. Data analysis also showed no significant difference comparing arterial blood oxygen saturation in the 3 days. Findings suggested that premature neonates physiologically responded to touch. Nurses working in NICUs must be educated about the importance of touch in providing care for these neonates. Findings showed that touch is useful for premature neonates and this fact can be a start point for other investigations

Distress respiratorio agudo en el embarazo / Acute respiratory distress syndrome in pregnancy

Aunque la ocurrencia de Síndrome de distress respiratorio agudo/daño pulmonar agudo (SDRA/DPA) durante el embarazo es infrecuente, su letalidad es elevada y ha sido reportado como un factor importante en la mortalidad materna. Las investigaciones realizadas al respecto han sido escasas en la literatura nacional e internacional. Nuestra experiencia en la atención a la paciente materna crítica por más de 20 años demuestra que el distress en el embarazo constituye una entidad sindrómica de alta incidencia en nuestra serie. Motivados en ello y considerando que resulta potencialmente prevenible y altamente letal decidimos realizar la presente revisión sobre un aspecto de la paciente materna grave, muy poco abordado y de gran interés si deseamos reducir los niveles de mortalidad materna

Síndrome do desconforto respiratório agudo / Acute respiratory distress syndrome

A síndrome do desconforto respiratório agudo (SDRA) compreende uma manifestação clínica severa, caracterizada por lesão pulmonar aguda, edema pulmonar não-cardiogênico, hipoxia refratária e diminuição da complacência pulmonar. O objetivo dos autores é revisar a literatura sobre os principais aspectos relacionados com a síndrome do desconforto respiratório agudo e com a lesão pulmonar aguda (LPA). Os autores revisaram artigos publicados em periódicos disponíveis na base de dados MEDLINE, compreendidos entre 1985 e 2002. As palavras-chaves utilizadas na busca foram: síncrome do desconforto respiratório agudo, lesão pulmonar aguda e choque pulmonar. Existem critérios diagnósticos definidos para síndrome do desconforto respiratório agudo e lesão pulmonar aguda (começo agudo, relação PaO2/FiO2 ≤ 200, infiltrados bilaterais na visão frontal da radiografia de tórax e pressão capilar pulmonar ≤ 18mmHg). A atividade endotelial é considerada o principal mecanismo no complexo de eventos patológicos que resultam na SDRA. O balanço entre fatores pró-inflamatórios e entiinflamatórios influencia na resposta inflamatória pulmonar. O objetivo da ventilação em pacientes com SDRA e LPA é manter a adequada troca gasosa e evitar a selão pulmonar induzida pelo ventilador. Ainda não há consenso quanto à melhor forma de definir os níveis de PEEP a serem empregados no tratamento da SDRA. Estudos nível II com baixas doses de corticosteróides na fase fibroproliferativa da SDRA têm demonstrado algum benefício, recebendo nível de recomendação C

Changes in dead space/tidal volume ratio and pulmonary mechanics after surfactant replacement therapy in respiratory distress syndrome of the newborn infants

This study was performed to elucidate the mechanism of improved oxygenation after surfactant replacement therapy in respiratory distress syndrome (RDS) of the newborn infants. In 26 newborns with RDS, end tidal-CO2 tension (PetCO2), arterial blood gas analysis and pulmonary function tests were measured at baseline, 30 min, 2 hr and 6 hr after surfactant administration. The changes in dead space/tidal volume ratio (VD/VT ratio=(PaCO2-PetCO2)/PaCO2), oxygenation index and arterial-alveolar partial pressure difference for oxygen ((A-a)DO2) were elucidated and correlated with pulmonary mechanics. Oxygenation index and (A-a)DO2 improved, and VD/VT ratio decreased progressively after surfactant administration, becoming significantly different from the baseline at 30 min and thereafter with administration of surfactant. Pulmonary mechanics did not change significantly during the observation period. VD/VT ratio showed close correlation with OI and (A-a)DO2, but not with pulmonary mechanics. These results suggest that decreased physiologic dead space resulting from the recruitment of atelectatic alveoli rather than improvement in pulmonary mechanics is primarily responsible for the improved oxygenation after surfactant therapy in the RDS of newborn.