Fisiopatología de la enfermedad COVID-19 / Pathophysiology of COVID-19 / Fisiopatologia da doença COVID-19

La enfermedad por coronavirus es una infección respiratoria causada por el virus SARS-CoV 2, el cual genera una cascada de eventos sistémicos, afectando diferentes órganos y tejidos. El entendimiento de la fisiopatología del COVID-19 es indispensable no solo al momento de brindar tratamiento a los pacientes, sino que también para comprender las causas de las complicaciones que presentan un número importante de pacientes recuperados. El objetivo de este trabajo es presentar una revisión actualizada de los efectos de la infección en diferentes órganos y sistemas principales que sea de utilidad como material de referencia para profesionales y estudiantes de la salud. Para ello se realizó una búsqueda bibliográfica en los portales PubMED, Scielo, Google Scholar, Cochrane y Springer Link, así como en las bases de repositorios científicos pre-publicación bioRxiv ("bioarchives") y medRxiv ("med-archives") y sobre un total de cerca de 200 mil artículos, se seleccionaron 100 artículos para esta revisión en base a su relevancia o sugerencias de parte de profesionales especializados.

Coronavirus disease is a respiratory infection caused by the SARS-CoV-2 virus, which causes a cascade of systemic events, affecting various organs and tissues. Understanding the pathophysiology of COVID-19 is essential to treat patients and understand the causes of the complications in a significant number of recovered patients. This article presents a review of the effects of infection on various organs and systems that will be useful as reference material for healthcare professionals and medical students. To this end, a literature search was conducted in PubMED, Scielo, Google Scholar, Cochrane, and Springer Link portals, as well as in the pre-publication scientific repositories bioRxiv ("bioarchives") and medRxiv ("med-archives") databases. From about 200,000 papers, 100 articles were selected for this review based on their relevance or suggestions from experts in the field.

A doença coronavírus é uma infecção respiratória causada pelo vírus SARS-CoV-2, que gera uma cascata de eventos sistêmicos, afetando diferentes órgãos e tecidos. Compreender a fisiopatologia da COVID-19 é essencial não apenas no tratamento de pacientes, mas também para compreender as causas das complicações que um número significativo de pacientes recuperados apresenta. O objetivo deste trabalho é apresentar uma revisão atualizada dos efeitos da infecção em diferentes órgãos e principais sistemas que seja útil como material de referência para profissionais de saúde e estudantes. Para isso, foi realizada uma pesquisa bibliográfica nos portais PubMED, Scielo, Google Scholar, Cochrane e Springer Link, bem como nos repositórios científicos de pré-publicação bioRxiv ("bioarquivos") e medRxiv ("arquivos med"). Num total de cerca de 200 mil artigos, 100 artigos foram selecionados para esta revisão por sua relevância ou sugestões de profissionais especializados.

The role of alveolar type II cells in swine leptospirosis / O papel das células alveolares tipo II na leptospirose suína

This study aimed to investigate a possible relationship between alveolar type II cells and the inflammatory response to infection with Leptospira spp., and thus comprise a further element that can be involved in the pathogenesis of lung injury in naturally infected pigs. The study group consisted of 73 adult pigs that were extensively reared and slaughtered in Teresina, Piauí state, and Timon, Maranhão state, Brazil. The diagnosis of leptospirosis was made using the microscopic agglutination test (MAT) aided by immunohistochemistry and polymerase chain reaction. The MAT registered the occurrence of anti-Leptospira antibodies in 10.96% (8/73) of the pigs. Immunohistochemistry allowed for the visualization of the Leptospira spp. antigen in the lungs of 87.67% (64/73) of the pigs. There was hyperplasia of bronchus-associated lymphoid tissue and circulatory changes, such as congestion of alveolar septa, parenchymal hemorrhage and edema within the alveoli. Lung inflammation was more intense (p = 0.0312) in infected animals, which also showed increased thickening of the alveolar septa (p = 0.0006). Evaluation of alveolar type II (ATII) cells using an anti-TTF-1 (Thyroid Transcription Factor-1) antibody showed that there were more immunostained cells in the non-infected pigs (53.8%) than in the infected animals (46.2%) and that there was an inverse correlation between TTF-1 positive cells and the inflammatory infiltrate. There was no amplification of Leptospira DNA in the lung samples, but leptospiral DNA amplification was observed in the kidneys. The results of this study showed that a relationship exists between a decrease in alveolar type II cells and a leptospire infection. Thus, this work points to the importance of studying the ATII cells as a potential marker of the level of lung innate immune response during leptospirosis in pigs...

Setenta e três suínos adultos de criação extensiva, abatidos em Teresina, no estado do Piauí e Timon, no estado do Maranhão, constituíram o grupo de estudo. O diagnóstico da leptospirose foi realizado utilizando a técnica de soroaglutinação microscópica (MAT), auxiliada por imunoistoquímica e reação em cadeia pela polimerase. A SAM registrou a ocorrência de anticorpos anti-leptospiras em 10,96% (8/73) dos suínos. A imunoistoquímica permitiu a visualização de antígenos de Leptospira spp. em pulmões de 87,67% (64/73) dos suínos. Havia hiperplasia do tecido linfoide associado ao brônquio e alterações circulatórias como, congestão do septo alveolar, hemorragia parenquimatosa e edema no interior de alvéolos. Os focos de inflamações pulmonares eram mais numerosos (p=0,0312) nos animais infectados, bem como o espessamento do septo alveolar (p=0,0006). A quantificação de células alveolares tipo II marcadas pelo anticorpo anti-TTF-1 (Thyroid Transcription Factor-1) mostrou que existia mais células imunocoradas em suínos não infectados (53,8%) comparados aos infectados (46,2%) e uma correlação inversa em relação ao infiltrado inflamatório. Não houve amplificação de DNA de Leptospira spp. em amostras de tecido pulmonar, no entanto DNA leptospiral foi observado em rim. Os resultados deste estudo mostraram que existe uma relação entre a diminuição das células alveolares tipo II e a infecção por leptospiras. Dessa forma, este trabalho aponta para a importância do estudo dessas células, como um provável marcador da modulação da resposta imune inata do pulmão na leptospirose em suínos...

Immunohistochemical and morphometric evaluation of COX 1 and COX-2 in the remodeled lung in idiopathic pulmonary fibrosis and systemic sclerosis / Avaliacao imuno-histoquimica e morfometrica de COX-1 e COX-2 no remodelamento pulmonar na fibrose pulmonar idiopatica e na esclerose sistemica

OBJECTIVE: To study the expression of COX-1 and COX-2 in the remodeled lung in systemic sclerosis (SSc) and idiopathic pulmonary fibrosis (IPF) patients, correlating that expression with patient survival. METHODS: We examined open lung biopsy specimens from 24 SSc patients and 30 IPF patients, using normal lung tissue as a control. The histological patterns included fibrotic nonspecific interstitial pneumonia (NSIP) in SSc patients and usual interstitial pneumonia (UIP) in IPF patients. We used immunohistochemistry and histomorphometry to evaluate the expression of COX-1 and COX-2 in alveolar septa, vessels, and bronchioles. We then correlated that expression with pulmonary function test results and evaluated its impact on patient survival. RESULTS: The expression of COX-1 and COX-2 in alveolar septa was significantly higher in IPF-UIP and SSc-NSIP lung tissue than in the control tissue. No difference was found between IPF-UIP and SSc-NSIP tissue regarding COX-1 and COX-2 expression. Multivariate analysis based on the Cox regression model showed that the factors associated with a low risk of death were younger age, high DLCO/alveolar volume, IPF, and high COX-1 expression in alveolar septa, whereas those associated with a high risk of death were advanced age, low DLCO/alveolar volume, SSc (with NSIP), and low COX-1 expression in alveolar septa. CONCLUSIONS: Our findings suggest that strategies aimed at preventing low COX-1 synthesis will have a greater impact on SSc, whereas those aimed at preventing high COX-2 synthesis will have a greater impact on IPF. However, prospective randomized clinical trials are needed in order to confirm that. .

OBJETIVO: Estudar a expressão de COX-1 e COX-2 em áreas pulmonares remodeladas em pacientes com esclerose sistêmica (ES) ou fibrose pulmonar idiopática (FPI) e correlacioná-la com a sobrevida desses pacientes. MÉTODOS: Examinamos espécimes de biópsia pulmonar a céu aberto de 24 pacientes com ES e de 30 pacientes com FPI, utilizando-se tecido pulmonar normal como controle. Os padrões histológicos incluíram pneumonia intersticial não específica (PINE) fibrótica em pacientes com ES e pneumonia intersticial usual (PIU) nos pacientes com FPI. Imuno-histoquímica e histomorfometria foram usadas para avaliar a expressão celular de COX-1 e COX-2 em septos alveolares, vasos e bronquíolos, sua correlação com provas de função pulmonar e seu impacto na sobrevida. RESULTADOS: A expressão de COX-1 e COX-2 em septos alveolares foi significativamente maior em FPI-PIU e ES-PINE do que no tecido controle. Não houve diferença entre FPI-PIU e ES-PINE quanto à expressão de COX-1 e COX-2. A análise multivariada baseada no modelo de regressão de Cox mostrou que os fatores associados a baixo risco de morte foram ter idade menor, valores elevados de DLCO/volume alveolar, FPI, e alta expressão de COX-1 em septos alveolares, ao passo que os fatores associados a alto risco de morte foram ter idade maior, valores baixos de DLCO/volume alveolar, ES (com PINE) e baixa expressão de COX-1 em septos alveolares. CONCLUSÕES: Nossos resultados sugerem que estratégias de prevenção de baixa síntese de COX-1 terão maior impacto sobre a ES, ao passo que as de prevenção de alta síntese de COX-2 terão maior impacto sobre a FPI. Porém, são necessários ensaios clínicos randomizados prospectivos para confirmar essa hipótese. .

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.

Mechanical ventilation and volutrauma: study in vivo of a healthy pig model

Mechanical ventilation is essential in intensive care units. However, it may itself induce lung injury. Current studies are based on rodents, using exceptionally large tidal volumes for very short periods, often after a "priming" pulmonary insult. Our study deepens a clinically relevant large animal model, closely resembling human physiology and the ventilator setting used in clinic settings. Our aim was to evaluate the pathophysiological mechanisms involved in alveolo/capillary barrier damage due to mechanical stress in healthy subjects. We randomly divided 18 pigs (sedated with medetomidine/tiletamine-zolazepam and anesthetised with thiopental sodium) into three groups (n=6): two were mechanically ventilated (tidal volume of 8 or 20 ml/kg), the third breathed spontaneously for 4 hours, then animals were sacrificed (thiopental overdose). We analyzed every 30' hemogasanalysis and the main circulatory and respiratory parameters. Matrix gelatinase expression was evaluated on bronchoalveolar lavage fluid after surgery and before euthanasia. On autoptic samples we performed zymographic analysis of lung, kidney and liver tissues and histological examination of lung. Results evidenced that high Vt evoked profound alterations of lung mechanics and structure, although low Vt strategy was not devoid of side effects, too. Unexpectedly, also animals that were spontaneously breathing showed a worsening of the respiratory functions.

Análises histopatológica e morfométrica no diagnóstico da "nova" displasia broncopulmonar e comparação clinicopatológica com a forma clássica da doença / Histopathological and morphometric analysis in the diagnosis of "new" broncopulmonar dysplasia and clinical and pathological comparison with the classic form of the disease

INTRODUÇÃO: A displasia broncopulmonar (DBP) continua sendo a principal complicação nos recém-nascidos (RN) prematuros. Com o uso de surfactante exógeno e da prevenção de doenças respiratórias no período neonatal a incidência de DBP clássica vem diminuindo, porém uma nova forma de DBP tem surgido, mais branda e associada aos desenvolvimentos pulmonar alveolar e vascular incompletos. Do ponto de vista anatomopatológico a DBP clássica é caracterizada por processos de lesão e reparação, e os achados da "nova" DBP são de hipoplasia alveolar com nenhuma fibrose. OBJETIVOS: Demonstrar as alterações histopatológicas e morfométricas em pulmões de prematuros que foram a óbito, com quadro clínico compatível com "nova" DBP, comparando-as com um grupo controle (sem DBP) e com a forma clássica da doença, além de correlacionar os três grupos com o tempo de uso de oxigênio entre outros fatores de risco da DBP. MATERIAL E MÉTODOS: A população foi composta por 59 amostras de pulmões de prematuros com idade gestacional (IG) menor que 34 semanas e submetidos à oxigenioterapia. Fatores de risco para DBP foram coletados por meio da revisão de prontuários. Amostras pulmonares foram separadas em dois grupos, o com DBP clássica e o sem DBP clássica. O segundo grupo foi então submetido à análise morfométrica para contagem do número de alvéolos, medidas as áreas e os perímetros dos alvéolos. Após esta análise a população estudada ficou dividida em grupo com DBP clássica; com "nova" DBP (casos com mais de sete dias de oxigenioterapia); e grupo controle ou sem DBP clássica ou "nova" (casos com menos de sete dias de oxigenioterapia). RESULTADOS: o primeiro grupo apresentava inflamação e fibrose septal evidentes. Já os segundo e terceiro grupos apresentavam alterações histopatológicas mínimas, sendo então necessária a análise morfométrica para separá-los. O grupo com "nova" DBP apresentou número de alvéolos, sua área e perímetro diminuídos (p < 0,005) quando comparados...

INTRODUCTION: The bronchopulmonary dysplasia (BPD) remains as a major complication in premature infants. The incidence of classic BPD has decreased due to the use of exogenous surfactant and prevention of respiratory diseases in the neonatal period. However, a new and milder form of BPD has appeared, which is associated with incomplete vascular and pulmonary alveolar development. Anatomopathologically, classic BPD is characterized by lesion and repair processeses and "new" BPD findings are alveolar hypoplasia with no fibrosis. OBJECTIVES: To demonstrate the morphometric and histopathological alterations in the lungs of deceased premature infants with clinical course consistent with the new BPD by comparing these changes with a control group (without BPD) and with its classic form. Furthermore, to correlate the three groups with the duration of oxygen therapy and other risk factors. METHODS: The population comprised 59 lungs samples from premature infants of gestational age lower than 34 weeks and that had undergone oxygen therapy. The risk factors for BPD were collected from the review of clinical records. The lungs samples were separated into 2 groups: 1 - with classic BPD and 2 - without classic BPD. Group 2 underwent morphometric analysis for alveoli counting and measurement of alveolar area and perimeter. Subsequently, the studied population was divided into: 1 - with classic BPD, 2 - with new BPD (cases with more than 7 days of oxygen therapy) and 3 - control group or without classic or new BPD (cases with less than 7 days of oxygen therapy). RESULTS: Group 1 (classic BPD) had inflammation and evident septal fibrosis. Groups 2 and 3 (new BPD and control) showed minimal histopathological alterations requiring morphometric analysis to separate them. Group 2 (new BPD) showed reduced number of alveoli, area and perimeter when compared with group 3 (control), p < 0,005. There was no statistically significant difference among the 3 groups...

[Evaluation of alveolar basement membrane function in the diabetes mellitus patients]

The thickening of alveolar basement membrane is found in autopsies, along with microvascular pathologies, in type 1 and 2 diabetes mellitus [DM]. To detect the function and permeability of alveolar basement membrane carbon monoxide diffusion capacity [DLCO] can be used. The aim of this study was to determine alveolar basement membrane damage using this method. In this descriptive and analytical study, fifty five women and 15 men, nonsmoking, type 2 DM cases, without any lung and / or heart disease who had neither anemia nor renal failure and no respiratory symptoms, made up the patients group. They were compared with 55 female and 15 male healthy cases who had the same characteristics as the diabetes cases. For all of the cases who had normal spirometry, DLCO were measured by single- breath method. Data were analyzed using t-student test. The amounts of measured DLCO in the patients with diabetes and in the control group were 9.65 +/- 2.4 and 9.1 +/- 1.79 milimlo/min/kilopascal, respectively [P>0.05]. Also, there was no significant relationship between the volume corrected transfer factor in the patients and the control group. DLCO was not reduced in patients with diabetes without complication who had no clinical respiratory symptoms. We can use DLCO as indicator of microangiopathy in diabetic patients

Variáveis capnográficas pré e pós-tromboendarterectomias pulmonares / Pre and post-pulmonary thromboendarterectomies campnographic variables

Este relato de dois casos com os resultados da fração tardia de espaço morto (fDlate), fração do espaço morto alveolar end-tidal (AVDSf), gradiente artério-alveolar de CO2 [P(a-et)CO2] e slope da fase 3 do espirograma, submetidos à tromboendarterectomia pulmonar por tromboembolismo pulmonar (TEP). O TEP foi diagnosticado pela cintilografia pulmonar, tomografia helicoidal computadorizada e por arteriografia pulmonar. O cálculo da fDlate, AVDSf e P(a-et)CO2 baseou-se na capnografia volumétrica associada à gasometria arterial. A fDlate préoperatória do primeiro paciente foi de 0,16 (cutoff de 0,12) e a AVDSf = 0,30 (cutoff de 0,15). Já a fDlate do segundo paciente resultou falso-negativa (0,01), embora a AVDSf resultasse positiva (0,28). A fDlate pós-operatória do primeiro paciente foi de -0,04 e a AVDSf de 0,16; a fDlate do segundo paciente foi de 0,07 e a AVDSf = 0,28. A associação destas variáveis com os exames por imagem reforça a importância deste método como ferramenta diagnóstica não-invasiva no diagnóstico de TEP.

In these case report, the results of late dead space fraction (fDlate), end-tidal alveolar dead space fraction (AVDSf), arterial-alveolar gradient CO2 [P(a-et)CO2], and slope phase 3 of spirogram of two patients who underwent thromboendarterectomy for pulmonary embolism (PE) are shown. PE was diagnosed by pulmonary scintigraphy, helical tomography, and pulmonary angiography. The calculation of fDlate, AVDSf and P(a-et)CO2 was based on volumetric capnography associated with arterial blood gas analysis. The pre-operative fDlate of the first patient was 0.16 (cutoff 0.12) and AVDSf was 0.30 (cutoff 0.15). However, the fDlate of the second patient was false-negative (0.01) but, the AVDSf was positive (0.28). Postoperative fDlate of the first patient was -0.04 and AVDSf was 0.16; for the second patient, the values were 0.07 and 0.28, respectively. The association of these capnographic variables with image exams reinforces the importance of this noninvasive diagnosis method.

Maniobras de reclutamiento alveolar / Alveolar recruitment maneuvers

Las fuentes de las maniobras de reclutamiento alveolar en anestesia han sido las terapéuticas del paciente crítico respiratorio, especialmente en el síndrome del distress respiratorio del adulto (SDRA). En esta revisión tratamos de definir las lesiones pulmonares generadas por la ventilación mecánica que puedan ser beneficiadas por las principales estrategias de reclutamiento propuestas, tanto en el paciente de cuidado intensivo respiratorio, como en el anestesiado. Las atelectasias son colapsos alveolares que ocurren en la mayoría de los pacientes bajo anestesia general en la parte más declive del pulmón, cuyos mecanismos de aparición son la compresión del tejido pulmonar, la absorción del aire alveolar y/o la insuficiente eficacia del surfactante. Los tipos de lesiones pulmonares más comunes originados por la ventilación mecánica son: barotrauma, volutrauma, atelectrauma y biotrauma. Las estrategias protectoras del pulmón se resumen en: hipercapnia permisiva, disminución de la fracción inspirada de oxígeno y pulmón abierto con utilización de PEEP a altos niveles. Existen estrategias facilitadoras del reclutamiento alveolar, algunas de las cuales son maniobras de reclutamiento en sí mismas (según los valores de presiones utilizados), como ser: aumento de los valores de PEEP, insuflación sostenida, utilización de suspiro, recurrir a los beneficios de la respiración espontánea, ventilación oscilatoria de alta frecuencia, ventilación con variabilidad biológica manteniendo volumen minuto constante, posición prona, ventilación diferencial, ventilación líquida parcial y óxido nítrico inhalado. Monitoreo del reclutamiento acino alveolar: oximetría (arteriales y saturometría de pulso), PaCO2, presión arterial, tomografía axial computarizada (TAC), TAC dinámica (aquella que se realiza durante la maniobra de reclutamiento). Los tipos de maniobras de reclutamiento alveolar de mayor trascendencia son: insuflación sostenida a altas presiones, incremento del volumen corr...

Mechanisms underlying gas exchange alterations in an experimental model of pulmonary embolism

The aim of the present study was to determine the ventilation/perfusion ratio that contributes to hypoxemia in pulmonary embolism by analyzing blood gases and volumetric capnography in a model of experimental acute pulmonary embolism. Pulmonary embolization with autologous blood clots was induced in seven pigs weighing 24.00 ± 0.6 kg, anesthetized and mechanically ventilated. Significant changes occurred from baseline to 20 min after embolization, such as reduction in oxygen partial pressures in arterial blood (from 87.71 ± 8.64 to 39.14 ± 6.77 mmHg) and alveolar air (from 92.97 ± 2.14 to 63.91 ± 8.27 mmHg). The effective alveolar ventilation exhibited a significant reduction (from 199.62 ± 42.01 to 84.34 ± 44.13) consistent with the fall in alveolar gas volume that effectively participated in gas exchange. The relation between the alveolar ventilation that effectively participated in gas exchange and cardiac output (V Aeff/Q ratio) also presented a significant reduction after embolization (from 0.96 ± 0.34 to 0.33 ± 0.17 fraction). The carbon dioxide partial pressure increased significantly in arterial blood (from 37.51 ± 1.71 to 60.76 ± 6.62 mmHg), but decreased significantly in exhaled air at the end of the respiratory cycle (from 35.57 ± 1.22 to 23.15 ± 8.24 mmHg). Exhaled air at the end of the respiratory cycle returned to baseline values 40 min after embolism. The arterial to alveolar carbon dioxide gradient increased significantly (from 1.94 ± 1.36 to 37.61 ± 12.79 mmHg), as also did the calculated alveolar (from 56.38 ± 22.47 to 178.09 ± 37.46 mL) and physiological (from 0.37 ± 0.05 to 0.75 ± 0.10 fraction) dead spaces. Based on our data, we conclude that the severe arterial hypoxemia observed in this experimental model may be attributed to the reduction of the V Aeff/Q ratio. We were also able to demonstrate that V Aeff/Q progressively improves after embolization, a fact attributed to the alveolar ventilation redistribution induced by hypocapnic bronchoconstriction.

Hemorragia alveolar difusa associada ao uso de propiltiouracil / Diffuse alveolar haemorrhage associated with propylthiouracil

Propiltiouracil pode causar um número de reações adversas, incluindo leucopenia, rash, febre e artrite; entretanto, complicações pulmonares são extremamente raras. Recentemente, o propiltiouracil tem sido descrito como causa de vasculite associada à presença de anticorpo anticitoplasma de neutrófilos (ANCA), resultando em hemorragia alveolar e síndrome pulmão-rim. Os autores apresentam o caso de uma mulher de 81 anos, que desenvolveu hemorragia alveolar e microhematúria,durante tratamento com propiltiouracil.

Pulmonary alveolar proteinosis: a report of seven patients from King Chulalongkorn Memorial Hospital.

From 1983 to 2001, 7 patients with pulmonary alveolar proteinosis were admitted to the King Chulalongkorn Memorial Hospital. Presenting symptoms varied from asymptomatic (1 patient), progressive dyspnea on exertion (4 patients) to respiratory failure (2 patients). Other symptoms included dry cough and weight loss. Gradual onset of dyspnea could be observed by average time to hospital (7 months). Early worsening of dyspnea and high-grade fever suggested a possibility of superimposed infection. Chest radiographs revealed symmetrical infiltration without lobar predominance. 4 of 7 patients were misdiagnosed as pulmonary tuberculosis before diagnosis of PAP was made. Diagnosis was made by bronchoscopic examination with typical lavage fluid or pathological results; only one case need open lung biopsy. 6 of 7 patients required lung lavage to relieve dyspneic symptoms. Coinfection with Nocardia and Mycobacterium tuberculosis was found in one patient. Prognosis was good but recurrence was common.

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%.

Surfactant protein-A: new insights into an old protein--II.

Pulmonary surfactant is a lipoprotein substance that lines the lungs and helps reduce surface tension. Surfactant associated protein-A (SP-A) is the most abundant non-serum protein in pulmonary surfactant. This complex glycoprotein aids in the synthesis, secretion and recycling of surfactant phospholipids, and facilitates the reduction of surface tension by surfactant phospholipids. Recent evidence has highlighted the role of SP-A in the innate immune system present in the lung. SP-A may play a major role in defense against pathogens by interacting with both infectious agents and the immune system. Factors that affect fetal lung maturation, e.g. gestational age and hormones regulate SP-A gene expression. Mediators of immune function also regulate SP-A levels. A number of lung disorders, including infectious diseases and respiratory distress syndrome are associated with abnormal alveolar SP-A levels. SP-A can no longer be called a lung-specific protein, since it has recently been detected in other tissues. In most species, SP-A is encoded by a single gene, however in humans it is encoded by two, very similar genes. Models for the structure of the human SP-A protein molecule have been proposed, suggesting that the mature alveolar SP-A molecule is composed of both gene products. The study of SP-A may provide information helpful in understanding disease processes and formulating new treatment modalities.

Pulmonary aerosol clearance studies of persons exposed to air pollution from burning oil wells in Kuwait

The integrity of the pulmonary epithelial membrane can be altered by certain acute or chronic pulmonary conditions, such as cigarette smoking, inhalation of toxicants, alveolitis, adult respiratory distress syndrome and hyaline membrane diseases. Most of these conditions can cause an increase in the clearance rate of Tc-99m DTPA aerosols. The aim of this study was to evaluate the integrity of the pulmonary epithelial membrane by using Tc-99m DTPA aerosol clearance rates in persons who inhaled the smoke from the burning oil wells in Kuwait. Four groups of 60 smokers [S] and non-smokers [NS], viz, oil field workers, residents fully or partially exposed to the oil smoke and new arrivals in Kuwait who were not exposed to the oil smoke were studied. Placed in a sitting position, the subjects inhaled Tc-99m DTPA aerosol for two minutes. Using a [G. E.] gamma camera interfaced with a star computer, and with the subject in a posterior supine position for both lungs, dynamic images [30 sec/frame] were acquired over a thirty minute period. Activity time curves were then generated by fitting a monoexponential equation using the G. E. Starcam computer. The t[1/2] values were calculated from the fitted curve and these are given below in minutes: Oil Field workers [S] [NS] Continuous exposure [S] [NS] Partial exposure [S] [NS] Recent arrivals [S] [NS] 28.6+7-5.3 77.0+7-8.8 26.2+7-5.1 68.3 +/- 8.1 31.1 +/- 5.6 76.6+7-8.8 28.0+7-5.3 72.5+7-8.5 The clearance rate of Tc-99m DTPA aerosols in these subjects would seem to indicate that the inhalation of smoke produced by the burning oil wells in Kuwait did not alter the integrity of the pulmonary epithelial membrane