RESUMO
INTRODUCTION: The benefits of prone position ventilation are well demonstrated in the severe forms of acute respiratory distress syndrome, but not in the milder forms. We investigated the effects of prone position on arterial blood gases, lung inflammation, and histology in an experimental mild acute lung injury (ALI) model. METHODS: ALI was induced in Wistar rats by intraperitoneal Escherichia coli lipopolysaccharide (LPS, 5 mg/kg). After 24 h, the animals with PaO2/FIO2 between 200 and 300 mmHg were randomized into 2 groups: prone position (n = 6) and supine position (n = 6). Both groups were compared with a control group (n = 5) that was ventilated in the supine position. All of the groups were ventilated for 1 h with volume-controlled ventilation mode (tidal volume = 6 ml/kg, respiratory rate = 80 breaths/min, positive end-expiratory pressure = 5 cmH2O, inspired oxygen fraction = 1) RESULTS: Significantly higher lung injury scores were observed in the LPS-supine group compared to the LPS-prone and control groups (0.32 ± 0.03; 0.17 ± 0.03 and 0.13 ± 0.04, respectively) (p < 0.001), mainly due to a higher neutrophil infiltration level in the interstitial space and more proteinaceous debris that filled the airspaces. Similar differences were observed when the gravity-dependent lung regions and non-dependent lung regions were analyzed separately (p < 0.05). The BAL neutrophil content was also higher in the LPS-supine group compared to the LPS-prone and control groups (p < 0.05). There were no significant differences in the wet/dry ratio and gas exchange levels. CONCLUSIONS: In this experimental extrapulmonary mild ALI model, prone position ventilation for 1 h, when compared with supine position ventilation, was associated with lower lung inflammation and injury.
Assuntos
Lesão Pulmonar Aguda/prevenção & controle , Lipopolissacarídeos , Pulmão/patologia , Pneumonia/prevenção & controle , Respiração com Pressão Positiva/métodos , Decúbito Ventral , Lesão Pulmonar Induzida por Ventilação Mecânica/prevenção & controle , Lesão Pulmonar Aguda/sangue , Lesão Pulmonar Aguda/induzido quimicamente , Lesão Pulmonar Aguda/patologia , Animais , Modelos Animais de Doenças , Injeções Intraperitoneais , Pulmão/fisiopatologia , Masculino , Infiltração de Neutrófilos , Pneumonia/sangue , Pneumonia/induzido quimicamente , Pneumonia/patologia , Respiração com Pressão Positiva/efeitos adversos , Ratos Wistar , Taxa Respiratória , Decúbito Dorsal , Volume de Ventilação Pulmonar , Lesão Pulmonar Induzida por Ventilação Mecânica/sangue , Lesão Pulmonar Induzida por Ventilação Mecânica/induzido quimicamente , Lesão Pulmonar Induzida por Ventilação Mecânica/patologiaRESUMO
Recent data suggest that deep hypothermia has protective effects on experimental induced lung injury. It is not well known if these effects persist with mild hypothermia. The authors hypothesized that mild hypothermia may attenuate lung injury and decrease local and systemic proinflammatory cytokines in a rat model of injurious mechanical ventilation (MV). Twelve Sprague-Dawley male adult rats were anesthetized, intubated, and randomly allocated to normothermia group (37°C) (NT) or mild hypothermia group (34°C) (MH). After 2 hours of deleterious MV (peak inspiratory pressure [PIP] 40 cm H(2)O, zero end-expiratory pressure [ZEEP], and inspiratory fraction of oxygen [Fio(2)] 100%), arterial blood gases, lung gravimetry, and histological study were obtained. Protein content, interleukin (IL)-1ß, and tumor necrosis factor (TNF)-α were measured in plasma and bronchoalveolar lavage (BAL) fluid. Subjects that underwent MH had a significant lower wet-to-dry lung weight ratio (8.32 ± 0.28 vs. 10.8 ± 0.49, P = .01), IL-1ß plasma concentration (0.6 ± 0.6 vs. 10.27 ± 2.80 pg/mL, P = .0048) and PaCO(2). There were no differences in terms of PaO(2), histological injury, or BAL protein content. In this model of injurious mechanical ventilation, subjects treated with mild hypothermia had less lung edema and lower plasma IL-1ß. Some of known beneficial effects of deep hypothermia can be obtained with mild hypothermia.
Assuntos
Edema/terapia , Hipotermia Induzida , Interleucina-1beta/sangue , Lesão Pulmonar Induzida por Ventilação Mecânica/terapia , Animais , Gasometria , Permeabilidade Capilar , Masculino , Ratos , Ratos Sprague-Dawley , Respiração Artificial/efeitos adversos , Lesão Pulmonar Induzida por Ventilação Mecânica/sangueRESUMO
OBJECTIVE: To evaluate plasma levels of interleukin (IL)-1beta, IL-6, IL-8, IL-10, and tumor necrosis factor (TNF)-alpha in newborn infants immediately before and after 2 hours of mechanical ventilation. STUDY DESIGN: Term and late preterm neonates with no history of mechanical ventilation and/or ventilatory support were studied prospectively. Exclusion criteria were congenital malformations, congenital infections, use of nitric oxide, resuscitation with positive-pressure ventilation, and any procedure in the delivery room or neonatal intensive care unit that resulted in tracheal intubation. Blood samples for IL-1beta, IL-6, IL-8, IL-10, and TNF-alpha levels were collected before intubation and mechanical ventilation and 2 hours later. RESULTS: Nineteen newborn infants with gestational age 35.8 +/- 1.9 weeks and birth weight 2280 +/- 370 g were included. Pro-inflammatory cytokines increased: IL-8 (2.5-fold), IL-1beta (7.5-fold), and TNF-alpha (10-fold), and the anti-inflammatory cytokine IL-10 decreased by 90%. Although median IL-6 levels were similar between before and after ventilation, IL-6 increased in 89.4% of infants. CONCLUSIONS: A short period of mechanical ventilation promotes an imbalance of plasma levels of pro-inflammatory and anti-inflammatory cytokines. The systemic alteration of cytokines in response to mechanical ventilation may lead to ventilator-induced lung injury.