RESUMO
Lung physiology research advanced significantly over the last 100 years. Respiratory mechanics applied to animal models of lung disease extended the knowledge of the workings of respiratory system. In human research, a better understanding of respiratory mechanics has contributed to development of mechanical ventilators. In this review, we explore the use of respiratory mechanics in basic science to investigate asthma and chronic obstructive pulmonary disease (COPD). We also discuss the use of lung mechanics in clinical care and its role on the development of modern mechanical ventilators. Additionally, we analyse some bench-developed technologies that are not in widespread use in the present but can become part of the clinical arsenal in the future. Finally, we explore some of the difficult questions that intensive care doctors still face when managing respiratory failure. Bringing back these questions to bench can help to solve them. Interaction between basic and translational science and human subject investigation can be very rewarding, as in the conceptualization of "Lung Protective Ventilation" principles. We expect this interaction to expand further generating new treatments and managing strategies for patients with respiratory disease.
RESUMO
Las alteraciones de la relación entre la ventilación y el flujo sanguíneo (V/Q) en diversas regiones del pulmón alteran el aporte de oxígeno (O2) y remoción del dióxido de carbono (CO2) al organismo. Fisiológicamente existen diferencias regionales en la relación V/Q. Determinadas patologías pueden alterar esta relación, produciendo tres escenarios distintos: Cortocircuito (Shunt), Alteración V/Q y aumento del espacio muerto. Para evaluar estos escenarios y realizar una aproximación diagnostica son de utilidad el estudio de los gases arteriales y venosos, la diferencia alveolo arterial y la respuesta al suministrar O2
Alterations in the ventilation perfusion relationship (V/Q) in various lung regions alter the supply of oxygen (O2) and the removal of carbon dioxide (CO2) in the body. Physiologically, there are regional differences in the V/Q ratio. Certain pathologies can alter this relationship, producing three different scenarios: Shunt, V/Q mismach and dead space increased. To evaluate these scenarios and carry out a diagnostic approach, it is useful to study arterial and venous gasometry, the alveolar arterial difference and the response to oxygen supplying.
Assuntos
Humanos , Fenômenos Fisiológicos Respiratórios , Relação Ventilação-Perfusão/fisiologia , GasometriaRESUMO
BACKGROUND: Several studies have shown that exposure to air pollutants affects lung growth and development and can result in poor respiratory health in early life. METHODS: We included a subsample of 772 Mexican preschoolers whose mothers participated in a Prenatal Omega-3 fatty acid Supplements, GRowth, And Development birth cohort study with the aim to evaluate the impact of prenatal exposure to volatile organic compounds and nitrogen oxides on lung function measured by oscillation tests. The preschoolers were followed until 5 years of age. Anthropometric measurements and forced oscillation tests were performed at 36, 48, and 60 months of age. Information on sociodemographic and health characteristics was obtained during follow up. Prenatal exposure to volatile organic compounds and nitrogen oxides was evaluated using a land use regression models and the association between them was tested using a lineal regression and longitudinal linear mixed effect models adjusting for potential confounders. RESULTS: Overall, the mean (standard deviation) of the measurements of respiratory system resistance and respiratory system reactance at 6, 8, and 10 Hz during the follow-up period was 11.3 (2.4), 11.1 (2.4), 10.3 (2.2) and -5.2 (1.6), -4.8 (1.7), and -4.6 hPa s L-1 (1.6), respectively. We found a significantly positive association between respiratory resistance (ßRrs6 = 0.011; 95%CI: 0.001, 0.023) (P < .05) and prenatal exposure to nitrogen dioxide and a marginally negatively association between respiratory reactance (ßXrs6 = -11.40 95%CI: -25.26, 1.17 and ßXrs8 = -11.91 95%CI: -26.51, 1.43) (P = .07) and prenatal exposure to xylene. CONCLUSION: Prenatal exposure to air pollutants was significantly associated with the alteration of lung function measured by oscillation tests in these preschool children.
Assuntos
Poluentes Atmosféricos/toxicidade , Exposição Ambiental/efeitos adversos , Pulmão/efeitos dos fármacos , Óxidos de Nitrogênio/toxicidade , Efeitos Tardios da Exposição Pré-Natal , Compostos Orgânicos Voláteis/toxicidade , Poluentes Atmosféricos/análise , Pré-Escolar , Estudos de Coortes , Exposição Ambiental/análise , Feminino , Humanos , Pulmão/fisiologia , Masculino , Troca Materno-Fetal , Óxidos de Nitrogênio/análise , Gravidez , Testes de Função Respiratória , Compostos Orgânicos Voláteis/análiseRESUMO
Introduction: Breathing produces a phenomenon of cyclic deformation throughout life. Biomechanically, deformation of the lung is measured as strain. Regional strain recently started to be recognised as a tool in the study of lung pathophysiology, but regional lung strain has not been studied in healthy subjects breathing spontaneously without voluntary or pharmacological control of ventilation. Our aim is to generate three-dimensional (3D) regional strain and heterogeneity maps of healthy rat lungs and describe their changes over time. Methods: Micro-CT and image-based biomechanical analysis by finite element approach were carried out in six anaesthetised rats under spontaneous breathing in two different states, at the beginning of the experiment and after 3 hours of observation. 3D regional strain maps were constructed and divided into 10 isovolumetric region-of-interest (ROI) in three directions (apex to base, dorsal to ventral and costal to mediastinal), allowing to regionally analyse the volumetric strain, the strain progression and the strain heterogeneity. To describe in depth these parameters, and systematise their report, we defined regional strain heterogeneity index [1+strain SD ROI(x)]/[1+strain mean ROI(x)] and regional strain progression index [ROI(x)-mean of final strain/ROI(x)-mean of initial strain]. Results: We were able to generate 3D regional strain maps of the lung in subjects without respiratory support, showing significant differences among the three analysed axes. We observed a significantly lower regional volumetric strain in the apex sector compared with the base, with no significant anatomical systematic differences in the other directions. This heterogeneity could not be identified with physiological or standard CT methods. There was no progression of the analysed regional volumetric strain when the two time-points were compared. Discussion: It is possible to map the regional volumetric strain in the lung for healthy subjects during spontaneous breathing. Regional strain heterogeneity and changes over time can be measured using a CT image-based numerical analysis applying a finite element approach. These results support that healthy lung might have significant regional strain and its spatial distribution is highly heterogeneous. This protocol for CT image acquisition and analysis could be a useful tool for helping to understand the mechanobiology of the lung in many diseases.
Assuntos
Imageamento Tridimensional , Pulmão/diagnóstico por imagem , Respiração , Animais , Fenômenos Biomecânicos , Estudos de Viabilidade , Pulmão/fisiologia , Modelos Animais , Ratos , Ratos Sprague-Dawley , Microtomografia por Raio-XRESUMO
ABSTRACT Objective: To evaluate the impact of lipoabdominoplasty on diaphragmatic mobility (DM) and lung function in healthy women. Methods: This was a prospective cohort study using high-resolution ultrasound and forced spirometry to assess DM and lung function, respectively, prior to lipoabdominoplasty, as well as on postoperative day (POD) 10 and POD 30. DM was measured under two conditions: during tidal volume breathing and during a VC maneuver. Results: The sample consisted of 20 women, with a mean age of 39.85 ± 7.52 years and a mean body mass index of 26.21 ± 2.0 kg/m2. Comparing the preoperative and postoperative periods, we found that DM and lung function values were significantly lower after lipoabdominoplasty, the mean DM on POD 10 being 17% and 15% lower during tidal volume breathing and during the VC maneuver, respectively, in comparison with the preoperative mean (p = 0.009 and p < 0.001, respectively). In addition, FEV1, FVC, and PEF were significantly lower on POD 10 than in the preoperative period (p = 0.046, p = 0.002, and p < 0.001, respectively), returning to preoperative values by POD 30. Conclusions: Lipoabdominoplasty appears to have negative short-term repercussions for DM and lung function in healthy women. However, lung function and DM are both apparently restored to preoperative conditions by POD 30. (ClinicalTrials.gov identifier: NCT02762526 [http://www.clinicaltrials.gov/])
RESUMO Objetivo: Avaliar o impacto da lipoabdominoplastia na mobilidade diafragmática (MD) e na função pulmonar de mulheres saudáveis. Métodos: Estudo prospectivo de coorte com ultrassonografia de alta resolução e espirometria forçada para a avaliação da MD e da função pulmonar, respectivamente, antes da lipoabdominoplastia, no 10º dia do pós-operatório e no 30º dia do pós-operatório. A MD foi medida durante a respiração em volume corrente e durante uma manobra de CV. Resultados: A amostra foi composta por 20 mulheres, com média de idade de 39,85 ± 7,52 anos e média de índice de massa corporal de 26,21 ± 2,0 kg/m2. Ao compararmos os períodos pré e pós-operatório, observamos que a MD e a função pulmonar foram significativamente menores após a lipoabdominoplastia; a média de MD no 10º dia do pós-operatório foi 17% menor durante a respiração em volume corrente e 15% menor durante a manobra de CV do que a média pré-operatória (p = 0,009 e p < 0,001, respectivamente). Além disso, o VEF1, a CVF e o PFE foram significativamente menores no 10º dia do pós-operatório que no pré-operatório (p = 0,046, p = 0,002 e p < 0,001, respectivamente), retornando aos valores pré-operatórios até o 30º dia do pós-operatório. Conclusões: A lipoabdominoplastia parece ter repercussões negativas em curto prazo na MD e função pulmonar de mulheres saudáveis. No entanto, tanto a função pulmonar como a MD aparentemente retornam ao estado pré-operatório até o 30º dia do pós-operatório. (ClinicalTrials.gov identifier: NCT02762526 [http://www.clinicaltrials.gov/])
Assuntos
Humanos , Feminino , Adulto , Pessoa de Meia-Idade , Diafragma/fisiologia , Lipoabdominoplastia , Pulmão/fisiologia , Período Pós-Operatório , Espirometria , Medição da Dor , Diafragma/diagnóstico por imagem , Estudos Prospectivos , Ultrassonografia , Dispneia/fisiopatologia , Período Pré-OperatórioRESUMO
Abstract Objective: To compare the effects of extended- versus short-time noninvasive positive pressure ventilation on pulmonary function, tissue perfusion, and clinical outcomes in the early postoperative period following coronary artery bypass surgery in patients with preserved left ventricular function. Methods: Patients were randomized into two groups according to noninvasive positive pressure ventilation intensity: short-time noninvasive positive pressure ventilation n=20 (S-NPPV) and extended-time noninvasive positive pressure ventilation n=21 (E-NPPV). S-NPPV was applied for 60 minutes during immediate postoperative period and 10 minutes, twice daily, from postoperative days 1-5. E-NPPV was performed for at least six hours during immediate postoperative period and 60 minutes, twice daily, from postoperative days 1-5. As a primary outcome, tissue perfusion was determined by central venous oxygen saturation and blood lactate level measured after anesthetic induction, immediately after extubation and following noninvasive positive pressure ventilation protocols. As a secondary outcome, pulmonary function tests were performed preoperatively and in the postoperative days 1, 3, and 5; clinical outcomes were recorded. Results: Significant drop in blood lactate levels and an improvement in central venous oxygen saturation values in the E-NPPV group were observed when compared with S-NPPV group after study protocol (P<0.01). The E-NPPV group presented higher preservation of postoperative pulmonary function as well as lower incidence of respiratory events and shorter postoperative hospital stay (P<0.05). Conclusion: Prophylactic E-NPPV administered in the early postoperative period of coronary artery bypass surgery resulted in greater improvements in tissue perfusion, pulmonary function and clinical outcomes than S-NPPV, in patients with preserved left ventricular function. Trial Registration: Brazilian Registry of Clinical trial - RBR7sqj78 - http://www.ensaiosclinicos.gov.br
Assuntos
Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Idoso , Ponte de Artéria Coronária/métodos , Respiração com Pressão Positiva/métodos , Ventilação não Invasiva/métodos , Pneumopatias/prevenção & controle , Oxigênio/sangue , Complicações Pós-Operatórias/prevenção & controle , Complicações Pós-Operatórias/sangue , Fatores de Tempo , Capacidade Vital , Volume Expiratório Forçado , Ponte de Artéria Coronária/efeitos adversos , Fatores de Risco , Análise de Variância , Resultado do Tratamento , Estatísticas não Paramétricas , Ácido Láctico/sangue , Tempo de Internação , Pneumopatias/etiologia , Pneumopatias/sangueRESUMO
Understanding regional deformation in the lung has long attracted the medical community, as parenchymal deformation plays a key role in respiratory physiology. Recent advances in image registration make it possible to noninvasively study regional deformation, showing that volumetric deformation in healthy lungs follows complex spatial patterns not necessarily shared by all subjects, and that deformation can be highly anisotropic. In this work, we systematically study the regional deformation in the lungs of eleven human subjects by means of in vivo image-based biomechanical analysis. Regional deformation is quantified in terms of 3D maps of the invariants of the right stretch tensor, which are related to regional changes in length, surface and volume. Based on the histograms of individual lungs, we show that log-normal distributions adequately represent the frequency distribution of deformation invariants in the lung, which naturally motivates the normalization of the invariant fields in terms of the log-normal score. Normalized maps of deformation invariants allow for a direct intersubject comparison, as they display spatial patterns of deformation in a range that is common to all subjects. For the population studied, we find that lungs in supine position display a marked gradient along the gravitational direction not only for volumetric but also for length and surface regional deformation, highlighting the role of gravity in the regional deformation of normal lungs under spontaneous breathing.
Assuntos
Pulmão/anatomia & histologia , Pulmão/diagnóstico por imagem , Fenômenos Fisiológicos Respiratórios , Humanos , Imageamento Tridimensional , RespiraçãoRESUMO
Resumen: La monitorización respiratoria representa un importante rol en el cuidado del niño con falla respiratoria aguda. Por tanto, su apropiado uso y correcta interpretación (reconociendo qué señales y variables deben ser priorizadas) deberían ayudar a un mejor entendimiento de la fisiopatología de la enfermedad y de los efectos de las intervenciones terapéuticas. Asimismo, la monitorización del paciente ventilado permite, entre otras determinaciones, evaluar diversos parámetros de la mecánica respiratoria, conocer el estado de los diferentes componentes del sistema respiratorio y guiar los ajustes de la terapia ventilatoria. En esta actualización se describe la utilidad de diversas técnicas de monitorización respiratoria (incluyendo métodos convencionales y otros más recientes), se definen conceptos básicos de mecánica ventilatoria, su interpretación y cómo el adecuado análisis de la información puede ocasionar un impacto en el manejo clínico del paciente.
Abstract: Respiratory monitoring plays an important role in the care of children with acute respiratory failure. Therefore, its proper use and correct interpretation (recognizing which signals and variables should be prioritized) should help to a better understanding of the pathophysiology of the disease and the effects of therapeutic interventions. In addition, ventilated patient monitoring, among other determinations, allows to evaluate various parameters of respiratory mechanics, know the status of the different components of the respiratory system and guide the adjustments of ventilatory therapy. In this update, the usefulness of several techniques of respiratory monitoring including conventional respiratory monitoring and more recent methods are described. Moreover, basic concepts of mechanical ventilation, their interpretation and how the appropriate analysis of the information obtained can cause an impact on the clinical management of the patient are defined.
RESUMO
RATIONALE: Household air pollution (HAP) from solid fuel combustion is a major contributor to the global burden of disease, with considerable impact from respiratory infections in children. The impact of HAP on lung function is unknown. OBJECTIVES: The Childhood Exposure to Respirable Particulate Matter (CRECER) prospective cohort study followed Guatemalan children who participated in the Randomised Exposure Study of Pollution Indoors and Respiratory Effects (RESPIRE) trial of a chimney stove intervention to determine the effect of early childhood HAP exposure on growth of lung function. METHODS: RESPIRE households with pregnant women or infant children were randomised to receive a chimney stove at the beginning or at the end of the 18-month trial. During CRECER, a subset of these children, as well as children from households with newly installed stoves, were followed with spirometry beginning at age 5. Biomass smoke exposure was measured using personal carbon monoxide tubes. Two-stage regression models were employed to analyse associations with lung function growth. MEASUREMENTS AND MAIN RESULTS: Longitudinal peak expiratory flow (PEF) and FEV1 data were available for 443 and 437 children, respectively, aged 5-8 (mean follow-up 1.3â years). Decreases in PEF growth of 173â mL/min/year (95% CI -341 to -7) and FEV1 of 44â mL/year (95% CI -91 to 4) were observed with stove installation at 18â months compared with stove installation at birth in analyses adjusted for multiple covariates. No statistically significant associations were observed between personal HAP exposure and lung function. CONCLUSIONS: A significant decrease in PEF growth and a large non-significant decrease in FEV1 growth were observed with later stove installation. Additional studies including longer follow-up and cleaner stoves or fuels are needed.
Assuntos
Poluição do Ar em Ambientes Fechados/efeitos adversos , Monóxido de Carbono/efeitos adversos , Culinária , Fluxo Expiratório Forçado , Material Particulado/efeitos adversos , Pneumonia/induzido quimicamente , Gestantes , População Rural , Fumaça/efeitos adversos , Madeira/efeitos adversos , Poluição do Ar em Ambientes Fechados/análise , Criança , Pré-Escolar , Guatemala/epidemiologia , Humanos , Incidência , Pico do Fluxo Expiratório , Pneumonia/mortalidade , Pneumonia/prevenção & controle , Estudos Prospectivos , População Rural/estatística & dados numéricos , Nações UnidasRESUMO
Respiratory monitoring plays an important role in the care of children with acute respiratory failure. Therefore, its proper use and correct interpretation (recognizing which signals and variables should be prioritized) should help to a better understanding of the pathophysiology of the disease and the effects of therapeutic interventions. In addition, ventilated patient monitoring, among other determinations, allows to evaluate various parameters of respiratory mechanics, know the status of the different components of the respiratory system and guide the adjustments of ventilatory therapy. In this update, the usefulness of several techniques of respiratory monitoring including conventional respiratory monitoring and more recent methods are described. Moreover, basic concepts of mechanical ventilation, their interpretation and how the appropriate analysis of the information obtained can cause an impact on the clinical management of the patient are defined.
RESUMO
Objetivos: avaliar e comparar a função pulmonar de pacientes submetidos à cirurgia de revascularização do miocárdio com e sem o uso de circulação extracorpórea. Métodos: a amostra foi composta por 40 pacientes submetidos à cirurgia de revascularização do miocárdio, classificados em dois grupos: com circulação extracorpórea (grupo CCEC ? 20 pacientes) ou sem circulação extracorpórea (grupo SCEC ? 20 pacientes). Registros espirométricos da capacidade vital forçada (CVF) e do volume expiratório forçado no primeiro segundo (VEF1) foram obtidos no período pré-operatório (considerado basal) e no primeiro, terceiro e quinto dias do período pós-operatório. Resultados: obser-vou-se que no geral os valores de CVF e VEF1 diminuíram no primeiro pós-operatório em relação ao basal (diferença média = 1,8±1,0, p<0,001 e 1,3±1,0, p<0,001, respectivamente), tendo recuperação parcial no terceiro e no quinto pós-operatórios, sem retornar aos valores iniciais (diferença média 1,2±1,1, p<0,001 e 0,9±0,9, p<0,001, respectivamente). Após controle para os valores basais, não foram observadas diferenças significativas entre os grupos CCEC e SCEC quanto à CVF e ao VEF1 no quinto dia pós-operatório. Conclusões: a cirurgia de revascularização do miocárdio associou-se a um decréscimo significante na função pulmonar em todos os pacientes, havendo recuperação parcial da CVF e do VEF1 no quinto pós-operatório para os dois grupos, porém sem retorno aos valores basais. Não se observou associação estatisticamente significativa entre realização de circulação extracorpórea e função pulmonar no quinto dia pós-operatório.
Aims: To evaluate and compare the pulmonary function of patients submitted to myocardial revascularization surgery, with and without the use of extracorporeal circulation. Methods: The sample comprised 40 patients submitted to myocardial revascularization surgery, classified into two groups, depending on whether extracorporeal circulation was used (wECC ? 20 patients) or not (nECC ? 20 patients). Spirometric recordings of forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1) were obtained during the preoperative period (considered baseline) and on the first, third and fifth days postoperatively. Results: In general, the values of FVC and FEV1 diminished on the first day postoperatively compared to the baseline (mean difference = 1.8±1.0, p<0.001 and 1.3±1.0, p<0.001, respectively), with partial recovery on the third and fifth day postoperatively, with no return to the initial values (mean difference = 1.2±1.1, p<0.001 and 0.9±0.9, p<0.001, respectively). After controlling for baseline values, no significant differences were observed between the wECC and nECC groups as to FVC and FEV1 on the 5th day postoperatively. Conclusions: Myocardial revascularization surgery was associated to a significant decrease in pulmonary function in all patients, with partial recovery of FVC and FEV1 on the fifth day postoperatively for all groups, with no return to baseline values. No statistically significant association was found between extracorporeal circulation and pulmonary function on the fifth day postoperatively.