Lesão renal aguda em pacientes críticos em ventilação mecânica com pressão positiva / Lesión renal aguda en pacientes críticos en ventilación mecánica con presión positiva / Acute kidney injury in critically ill patients on positive pressure mechanical ventilation

Resumo Objetivo Avaliar o efeito do uso de ventilação mecânica com pressão positiva expiratória final (PEEP) na função renal dos pacientes internados em Unidade de Terapia Intensiva (UTI). Métodos Estudo de coorte retrospectivo, quantitativo, desenvolvido na UTI de um hospital público de Brasília, Distrito Federal. A amostra foi constituída de 52 prontuários de pacientes internados na UTI de novembro de 2016 a dezembro de 2018. A coleta dos dados foi realizada por meio de um questionário com dados demográficos, clínicos e laboratoriais. Os pacientes foram alocados em grupos: (1) PEEP ≤ 5 cmH2O, (2) PEEP > 5 cmH2O e < 10 cmH2O e (3) PEEP ≥ 10 cmH2O. Resultados A média de idade dos pacientes foi de 59 anos e 50% deles tinha mais de 63 anos. Constatou-se que 63,16% dos pacientes que estavam em ventilação mecânica com pressão positiva ao final da expiração ≥ 10 cmH2O evoluíram no estágio 1 (menor gravidade de lesão renal aguda (LRA)) e 21,5% no estágio 2 (moderada gravidade). Ainda assim, um pequeno percentual (5,8%) de pacientes evoluiu a óbito. Pacientes sem sucesso no desmame da ventilação mecânica apresentaram 10,24 vezes a chance de evoluir com LRA. Conclusão o emprego da ventilação mecânica pode determinar danos à função renal dos pacientes internados em unidade de terapia intensiva e que aqueles com maior necessidade de oferta de PEEP evoluíram com diferentes gravidades e persistência da LRA.

Resumen Objetivo Evaluar el efecto del uso de la ventilación mecánica con presión positiva espiratoria final (PEEP) en la función renal de los pacientes internados en Unidad de Cuidados Intensivos (UTI). Métodos Estudio de corte retrospectivo, cuantitativo, desarrollado en la UCI de un hospital público de Brasília, Distrito Federal. La amuestra estuvo constituida por 52 prontuarios de pacientes internados en la UCI de noviembre de 2016 a diciembre de 2018. La recolección de los datos se realizó por medio de un cuestionario con datos demográficos, clínicos y laboratoriales. Los pacientes fueron distribuidos en grupos: (1) PEEP ≤ 5 cmH2O, (2) PEEP > 5 cmH2O y < 10 cmH2O y (3) PEEP ≥ 10 cmH2O. Resultados El promedio de edad de los pacientes era de 59 años y el 50 % de ellos tenía más de 63 años. Se constató que el 63,16 % de los pacientes que estaban en ventilación mecánica con presión positiva al final de la expiración ≥ 10 cmH2O evolucionaron en la etapa 1 (menor gravedad de lesión renal aguda (LRA)) y 21,5 % en la etapa 2 (moderada gravedad). Aun así, un pequeño porcentaje (5,8 %) de pacientes falleció. Pacientes sin éxito en la descontinuación de la ventilación mecánica presentaron 10,24 veces la posibilidad de evolucionar con LRA. Conclusión el uso de la ventilación mecánica puede determinar daños a la función renal de los pacientes internados en una unidad de cuidados intensivos y que los que tengan una mayor necesidad de oferta de PEEP evolucionaron con distintas gravedades y persistencia de la LRA.

Abstract Objective To assess the effect of using mechanical ventilation with positive end-expiratory pressure (PEEP) on the renal function of patients admitted to the Intensive Care Unit (ICU). Methods This is a quantitative retrospective cohort study developed in the ICU of a public hospital in Brasília, Distrito Federal. The sample consisted of 52 medical records of patients admitted to the ICU from November 2016 to December 2018. Data collection was performed through a questionnaire with demographic, clinical and laboratory data. Patients were allocated in two groups: (1) PEEP ≤ 5 cmH2O, (2) PEEP > 5 cmH2O and < 10 cmH2O, and (3) PEEP ≥ 10 cmH2O. Results The mean age of patients was 59 years and 50% of them were over 63 years. It was found that 63.16% of patients who were on mechanical ventilation with positive end-expiratory pressure ≥ 10 cmH2O evolved in stage 1 (less severe acute kidney injury (AKI)) and 21.5% in stage 2 (moderate gravity). Even so, a small percentage (5.8%) of patients died. Patients who were unsuccessful in weaning from mechanical ventilation had a 10.24-fold chance of developing AKI. Conclusion mechanical ventilation use can cause damage to the renal function of patients hospitalized in the intensive care unit and that those with greater need to offer PEEP evolved with different severities and persistence of AKI.

Caracterização do comprometimento pulmonar associado à COVID-19 em pacientes com necessidade de ventilação mecânica / Characterization of pulmonary impairment associated with COVID-19 in patients requiring mechanical ventilation

RESUMO Objetivo: Detectar precocemente a instabilidade respiratória e hemodinâmica para caracterizar o comprometimento pulmonar em pacientes com COVID-19 grave. Métodos: Analisamos retrospectivamente os dados colhidos de pacientes com COVID-19 que apresentaram insuficiência respiratória aguda com necessidade de intubação e ventilação mecânica. Utilizamos a avaliação da termodiluição transpulmonar por meio do dispositivo PiCCO™. Foram coletados os dados demográficos, respiratórios, hemodinâmicos e ecocardiográficos dentro das primeiras 48 horas após a admissão. Para resumir os dados, utilizamos estatística descritiva. Resultados: Entre 22 de março e 7 de abril de 2020, foram admitidos 23 pacientes com COVID-19 grave. Foram monitorados com o dispositivo PiCCO™ 12 (22,6%) deles. Quando da admissão, o volume diastólico final global indexado era normal (média de 738,8mL ± 209,2) e, na hora 48, encontrava-se moderadamente aumentado (879mL ± 179), enquanto o índice cardíaco se achava abaixo do normal (2,84 ± 0,65). Todos os pacientes revelaram a presença de água extravascular pulmonar acima de 8mL/kg na admissão (17,9 ± 8,9). Não identificamos qualquer evidência de origem cardiogênica. Conclusão: No caso de pneumonia grave por COVID-19, o quadro hemodinâmico e respiratório é compatível com edema pulmonar sem evidência de origem cardiogênica, o que favorece o diagnóstico de síndrome do desconforto respiratório agudo.

ABSTRACT Objective: To detect early respiratory and hemodynamic instability to characterize pulmonary impairment in patients with severe COVID-19. Methods: We retrospectively analyzed data collected from COVID-19 patients suffering from acute respiratory failure requiring intubation and mechanical ventilation. We used transpulmonary thermodilution assessment with a PiCCO™ device. We collected demographic, respiratory, hemodynamic and echocardiographic data within the first 48 hours after admission. Descriptive statistics were used to summarize the data. Results: Fifty-three patients with severe COVID-19 were admitted between March 22nd and April 7th. Twelve of them (22.6%) were monitored with a PiCCO™ device. Upon admission, the global-end diastolic volume indexed was normal (mean 738.8mL ± 209.2) and moderately increased at H48 (879mL ± 179), and the cardiac index was subnormal (2.84 ± 0.65). All patients showed extravascular lung water over 8mL/kg on admission (17.9 ± 8.9). We did not identify any argument for cardiogenic failure. Conclusion: In the case of severe COVID-19 pneumonia, hemodynamic and respiratory presentation is consistent with pulmonary edema without evidence of cardiogenic origin, favoring the diagnosis of acute respiratory distress syndrome.

Evaluation of Respiratory Dynamics in an Asymmetric Lung Compliance Model / 대한구급학회지

BACKGROUND: Unilateral lung hyperinflation develops in lungs with asymmetric compliance, which can lead to vital instability. The aim of this study was to investigate the respiratory dynamics and the effect of airway diameter on the distribution of tidal volume during mechanical ventilation in a lung model with asymmetric compliance. METHODS: Three groups of lung models were designed to simulate lungs with a symmetric and asymmetric compliance. The lung model was composed of two test lungs, lung1 and lung2. The static compliance of lung1 in C15, C60, and C120 groups was manipulated to be 15, 60, and 120 ml/cmH₂O, respectively. Meanwhile, the static compliance of lung2 was fixed at 60 ml/cmH₂O. Respiratory variables were measured above (proximal measurement) and below (distal measurement) the model trachea. The lung model was mechanically ventilated, and the airway internal diameter (ID) was changed from 3 to 8 mm in 1-mm increments. RESULTS: The mean ± standard deviation ratio of volumes distributed to each lung (VL1/VL2) in airway ID 3, 4, 5, 6, 7, and 8 were in order, 0.10 ± 0.05, 0.11 ± 0.03, 0.12 ± 0.02, 0.12 ± 0.02, 0.12 ± 0.02, and 0.12 ± 0.02 in the C15 group; 1.05 ± 0.16, 1.01 ± 0.09, 1.00 ± 0.07, 0.97 ± 0.09, 0.96 ± 0.06, and 0.97 ± 0.08 in the C60 group; and 1.46 ± 0.18, 3.06 ± 0.41, 3.72 ± 0.37, 3.78 ± 0.47, 3.77 ± 0.45, and 3.78 ± 0.60 in the C120 group. The positive end-expiratory pressure (PEEP) of lung1 was significantly increased at airway ID 3 mm (1.65 cmH₂O) in the C15 group; at ID 3, 4, and 5 mm (2.21, 1.06, and 0.95 cmH₂O) in the C60 group; and ID 3, 4, and 5 mm (2.92, 1.84, and 1.41 cmH₂O) in the C120 group, compared to ID 8 mm (P < 0.05). CONCLUSIONS: In the C15 and C120 groups, the tidal volume was unevenly distributed to both lungs in a positive relationship with lung compliance. In the C120 group, the uneven distribution of tidal volume was improved when the airway ID was equal to or less than 4 mm, but a significant increase of PEEP was observed.

Is It Essential to Consider Respiratory Dynamics? / 대한구급학회지

No abstract available.

Evaluation of Respiratory Dynamics in an Asymmetric Lung Compliance Model / 대한중환자의학회지

BACKGROUND: Unilateral lung hyperinflation develops in lungs with asymmetric compliance, which can lead to vital instability. The aim of this study was to investigate the respiratory dynamics and the effect of airway diameter on the distribution of tidal volume during mechanical ventilation in a lung model with asymmetric compliance. METHODS: Three groups of lung models were designed to simulate lungs with a symmetric and asymmetric compliance. The lung model was composed of two test lungs, lung1 and lung2. The static compliance of lung1 in C15, C60, and C120 groups was manipulated to be 15, 60, and 120 ml/cmH₂O, respectively. Meanwhile, the static compliance of lung2 was fixed at 60 ml/cmH₂O. Respiratory variables were measured above (proximal measurement) and below (distal measurement) the model trachea. The lung model was mechanically ventilated, and the airway internal diameter (ID) was changed from 3 to 8 mm in 1-mm increments. RESULTS: The mean ± standard deviation ratio of volumes distributed to each lung (VL1/VL2) in airway ID 3, 4, 5, 6, 7, and 8 were in order, 0.10 ± 0.05, 0.11 ± 0.03, 0.12 ± 0.02, 0.12 ± 0.02, 0.12 ± 0.02, and 0.12 ± 0.02 in the C15 group; 1.05 ± 0.16, 1.01 ± 0.09, 1.00 ± 0.07, 0.97 ± 0.09, 0.96 ± 0.06, and 0.97 ± 0.08 in the C60 group; and 1.46 ± 0.18, 3.06 ± 0.41, 3.72 ± 0.37, 3.78 ± 0.47, 3.77 ± 0.45, and 3.78 ± 0.60 in the C120 group. The positive end-expiratory pressure (PEEP) of lung1 was significantly increased at airway ID 3 mm (1.65 cmH₂O) in the C15 group; at ID 3, 4, and 5 mm (2.21, 1.06, and 0.95 cmH₂O) in the C60 group; and ID 3, 4, and 5 mm (2.92, 1.84, and 1.41 cmH₂O) in the C120 group, compared to ID 8 mm (P < 0.05). CONCLUSIONS: In the C15 and C120 groups, the tidal volume was unevenly distributed to both lungs in a positive relationship with lung compliance. In the C120 group, the uneven distribution of tidal volume was improved when the airway ID was equal to or less than 4 mm, but a significant increase of PEEP was observed.

Is It Essential to Consider Respiratory Dynamics? / 대한중환자의학회지

No abstract available.

Efeitos de técnicas respiratórias no clearance mucociliar, força e fluxo expiratório no pós-operatório de revascularização do miocárdio / Effects of respiratory techniques in the mucociliary clearance, strength and expiratory flow in the post-operative myocardial revascularization

Introdução: Técnicas respiratórias são fundamentais no pós-operatório de cirurgia cardíaca a fim de reduzir complicações pós-operatórias. Objetivos: Comparar duas técnicas de fisioterapia respiratória no clearance mucociliar, força muscular respiratória e obstrução de vias aéreas após cirurgia cardíaca. Métodos: Foram avaliados 32 pacientes submetidos à cirurgia de revascularização do miocárdio, alocados para o grupo respiração por pressão positiva intermitente ou para o grupo exercício de respiração profunda. As avaliações foram compostas de: força muscular respiratória (pressão expiratória máxima e da pressão inspiratória máxima), pico de fluxo respiratório e clearance mucociliar (através do teste do tempo de transito da sacarina, expresso em minutos); e realizadas em três momentos: pré-operatório e pós-operatório antes e após a aplicação das técnicas. Resultados: Na análise do transporte mucociliar, força muscular respiratória e pico de fluxo expiratório, a comparação entre os momentos antes e após a aplicação das técnicas não apresentaram diferenças significativas (transporte mucociliar: p = 0,3844, Pimáx p = 0,2244; Pemáx p = 0,4968; Peak flow p = 0,8383). Nas análises individuais de cada grupo, puderam ser observadas diferenças significativas nas variáveis de força muscular respiratória e pico de fluxo expiratório (p<0.0001). Conclusão: Não foram observadas diferenças significativas entre as técnicas, porém foram eficientes no clearance mucociliar, força muscular e pico de fluxo expiratório quando avaliadas separadamente.

Introduction: Respiratory techniques are fundamental in the postoperative period of cardiac surgery in order to reduce postoperative complications. Objectives: The aim of this study was to compare two techniques of respiratory physiotherapy in mucociliary clearance, respiratory muscle strength and airway obstruction after cardiac surgery. Methods: Thirty-two patients undergoing coronary artery bypass grafting were assigned to the intermittent positive pressure group or to the deep breathing exercise group. The evaluations were composed of: respiratory muscle strength (maximal expiratory pressure and maximal inspiratory pressure), peak respiratory flow and mucociliary clearance (through the saccharine transit time test, expressed in minutes); And performed in three moments: preoperative and postoperative before and after the application of the techniques. Results: In the analysis of mucociliary transport, respiratory muscle strength and peak expiratory flow, the comparison between the moments before and after the application of the techniques did not present significant differences (mucociliary transport: p = 0.3844, Pimax p = 0.2244; = 0.4968; Peak flow p = 0.8383). In the individual analyzes of each group, significant differences were observed in the variables of respiratory muscle strength and peak expiratory flow (p <0.0001). Conclusion: There were no significant differences between the techniques, but were efficient in mucociliary clearance, muscle strength and peak expiratory flow when evaluated separately.

Avaliação da força muscular respiratória emindivíduos com síndrome de down / Evaluation of respiratory muscle strength in individuals havingDown syndrome

Em consequência das alterações musculares, decorrentes do quadro de hipotonia generalizada, encontradas nos indivíduoscom síndrome de Down (SD), esses desenvolvem também alterações na força muscular respiratória (FMR). Assim, oobjetivo do estudo foi avaliar a FMR de indivíduos com SD. Trata-se de um estudo do tipo transversal, realizado na Associaçãode Pais e Amigos dos Excepcionais (APAE) de município do interior de São Paulo. Foram avaliados 20 voluntários,divididos em dois grupos, sendo 10 indivíduos não sindrômicos e 10 indivíduos com diagnóstico de SD, com idade entre18 e 35 anos, de ambos os gêneros. A avaliação da FMR foi realizada com um manovacuômetro analógico, por meio dasmedidas da pressão inspiratória máxima (PIMáx) e da pressão expiratória máxima (PEMáx). Para a análise estatística, foiutilizado o programa Bioestat versão 5.3. A normalidade dos dados foi verificada pelo teste de Shapiro-Wilk. Logo após,foram utilizados testes de comparação para duas amostras independentes (teste t de Student e Mann-Whitney), adotandonível de significância de 5%. Na comparação entre os grupos estudados, pode-se constatar diferença significativa daPIMáx (p= 0,0011) e da PEMáx (p= 0,0002), sendo que menores valores de FMR foram obtidos no grupo de indivíduos comSD (PIMáx: -109±49,49 x -29,50±9,07) e (PEMáx: 127±44,06 x 45,50±10,11). Portanto, indivíduos com SD apresentamredução da FMR. Acredita-se que estes indivíduos se beneficiariam de um programa de reabilitação, incluindo fisioterapiarespiratória, minimizando assim, possíveis complicações respiratórias.

As a result of muscle changes caused by the generalized hypotonia found in individuals with Down syndrome (DS), thesesubjects develop changes in respiratory muscle strength. The objective of the study was to assess respiratory muscle strength(RMS) of individuals having DS. Thus, the objective of the study was to evaluate the respiratory muscle strength (RMS) inindividuals with DS. It was cross-sectional study, conducted at the Association of Parents and Friends of Exceptional (APFE)of countryside of São Paulo. 20 volunteers were evaluated, divided into two groups, 10 non-syndromic individuals and10 individuals diagnosed with DS, aged between 18 and 35 years, of both genders. The evaluation of RMS was performedby an analog manometer through which were measured maximal inspiratory pressures (MIP) and maximum expiratorypressures (MEP). For data analysis, were used the BioEstat version 5.3. Data normality was verified by the Shapiro-Wilktest. After, comparison tests were used for two independent samples (Student’s t and Mann-Whitney tests), adopting asignificance level of 5%. When comparing both groups, we can find a significant difference in MIP (p= 0.0011) and MEP(p= 0.0002), and lower RMS values were obtained in the group of individuals with DS. SD (MIP: -109±49.49 x -29.50±9.07)and (MEP: 127±44.06 x 45.50±10.11) Therefore, individuals with Down syndrome have decreased RMS. It is believed thatthese individuals would benefit from a rehabilitation program, including physiotherapy, thus minimizing possible respiratorycomplications.

Auto-PEEP-like condition recognized by a sudden decrease in airway pressure during pressure controlled ventilation and low-flow anesthesia: A case report

During mechanical ventilation in the intensive care unit, auto-positive end-expiratory pressure (auto-PEEP) has been reported to occur in obstructive airway conditions aggravated by inappropriate ventilator settings. In this paper, we report a case of auto-PEEP-like problem during anesthesia, mainly caused by excessive sputum. After being positioned prone for spine surgery, the patient received pressure controlled ventilation at a low fresh gas flow rate. One hour after the start of surgery, sudden decreases in pressure and flow occurred. The typical maneuvers which could be performed by the anesthesiologists in the situations suggesting leakage within the breathing circuit consist of pressing the oxygen flush valve and manual hyperventilation for the initial evaluation. But from our experience in this case, we have learned that such maneuvers could cause unacceptable aggravation in the event of auto-PEEP. Also in this report, we discuss the difficulties in prediction based on the present knowledge of preoperative evaluation and the presumably best management policy regarding this type of auto-PEEP.

Importance of slow vital capacity in the detection of airway obstruction / Importância da capacidade vital lenta na detecção de obstrução das vias aéreas

OBJECTIVE: To investigate the presence of airway obstruction by determining the FEV1/FVC and FEV1/slow vital capacity (SVC) ratios. METHODS: This was a quantitative, retrospective cross-sectional study. The sample comprised 1,084 individuals who underwent spirometry and plethysmography in a central hospital in Lisbon, Portugal. The study sample was stratified into six groups, by pulmonary function. RESULTS: The analysis of the FEV1/FVC ratio revealed the presence of airway obstruction in 476 individuals (43.9%), compared with 566 individuals (52.2%) for the analysis of the FEV1/SVC ratio. In the airway obstruction, airway obstruction plus lung hyperinflation, and mixed pattern groups, the difference between SVC and FVC (SVC − FVC) was statistically superior to that in the normal pulmonary function, reduced FEF, and restrictive lung disease groups. The SVC − FVC parameter showed a significant negative correlation with FEV1 (in % of the predicted value) only in the airway obstruction plus lung hyperinflation group. CONCLUSIONS: The FEV1/SVC ratio detected the presence of airway obstruction in more individuals than did the FEV1/FVC ratio; that is, the FEV1/SVC ratio is more reliable than is the FEV1/FVC ratio in the detection of obstructive pulmonary disease. .

OBJETIVO: Investigar a ocorrência de obstrução das vias aéreas por meio da relação VEF1/CVF e da relação VEF1/capacidade vital lenta (CVL). MÉTODOS: Estudo do tipo quantitativo, retrospectivo e transversal. A amostra foi constituída por 1.084 indivíduos que realizaram espirometria e pletismografia num hospital central da região de Lisboa, Portugal. A amostra foi estratificada em seis grupos funcionais respiratórios. RESULTADOS: A análise da relação VEF1/CVF revelou a presença de obstrução das vias aéreas em 476 indivíduos (43,9%), enquanto a relação VEF1/CVL detectou a presença dessa em 566 indivíduos (52,2%). A diferença entre a CVL e a CVF (CVL − CVF) nos grupos relativos à obstrução brônquica, à obstrução brônquica com hiperinsuflação pulmonar e à alteração ventilatória mista foi estatisticamente superior àquela encontrada nos grupos sem alteração ventilatória, com diminuição dos FEFs e com restrição pulmonar. O parâmetro CVL − CVF apresentou correlação negativa significativa com VEF1 em % do previsto apenas no grupo com obstrução brônquica com hiperinsuflação pulmonar. CONCLUSÕES: A relação VEF1/CVL detectou a presença de obstrução das vias aéreas em um número maior de indivíduos que a relação VEF1/CVF, ou seja, a relação VEF1/CVL é mais confiável na detecção de alterações ventilatórias obstrutivas. .

Ventilación mecánica en paciente con enfermedad pulmonar obstructiva crónica / Mechanical ventilation in patient with chronic obstructive pulmonary disease

La enfermedad pulmonar obstructiva crónica (EPOC) es un problema sanitario y económico mundial. En los pacientes que presentan exacerbación aguda y son hospitalizados, alrededor del 8 por ciento requieren soporte ventilatorio. La ventilación no invasiva es el tratamiento de primera línea en la falla respiratoria, no obstante, la ventilación mecánica invasiva también es requerida. Un buen entendimiento de la fisiopatología de la vía aérea y de la mecánica respiratoria es necesario para un mejor manejo de las exacerbaciones y la falla respiratoria. La hiperinsuflación dinámica a nivel pulmonar derivado de una limitación de los flujos espiratorios es un hecho cardinal. Por ello, es necesario una óptima programación del ventilador mecánico que privilegie el vaciamiento espiratorio de los pulmones, mejorar el intercambio gaseoso y minimizar el trabajo respiratorio del paciente. Esta revisión discute las alteraciones fisiopatológicas y mecánicas respiratorias en el paciente con EPOC exacerbado y las técnicas ventilatorias para optimizar el manejo de la falla respiratoria hipercápnica.

Chronic obstructive pulmonary disease (COPD) is a major global healthcare problem. The patients that present acute exacerbation and are hospitalized, about 8 percent needs support ventilator. The noninvasive ventilation is the treatment of the first line in the respiratory failure, nevertheless, the mechanical invasive ventilation also is needed. A good understanding of the airway pathophysiology and lung mechanics in COPD is necessary for a better manage of the acute exacerbations and respiratory failure. The dynamic hyperinflation derived from an expiratory airflow limitation is a cardinal fact. For management, is necessary an appropriate programming of the mechanical ventilator that favors the reducing the amount of air trapping of the lungs, to improve the gas exchange and to minimize the respiratory work of the patient. This review discusses the alterations pathophysiology and lung mechanics in the patient with acute exacerbation of COPD and ventilatory strategies.

Effects of upper airway obstruction on respiratory mechanics in a variable compliance model

BACKGROUND: Upper airway obstruction is caused by an intrinsic or extrinsic neck mass and vocal cord paralysis. A recognized hazard of prolonged endotracheal intubation is progressive airway occlusion resulting from deposition of secretions. If the obstruction persists, it may be life threatening condition. However, early diagnosis of partial airway obstruction is very difficult because patients are asymptomatic and do not have lesions with abnormal radiological characteristics. METHODS: In the test lung model, lung compliances were set to normal (25 ml/cmH2O; [control, C25 group]) and to levels seen in chronic obstructive pulmonary disease (40 ml/cmH2O; [C40 group]), and acute respiratory distress syndrome (20 ml/cmH2O; [C20 group] and 15 ml/cmH2O; [C15 group]). A ventilator (Drager Fabius GS, Germany) was attached to a test lung, and a series of endotracheal tubes (ETTs) ranging in size from 7.5 to 2.5 mm in inner diameter (ID) of the connector were used to simulate progressive occlusion. During the lung compliance and the connector size were changed, we measured some respiratory mechanics. RESULTS: Progressive ETT occlusion induced an increase in the peak inspiratory pressure. In the C40 group, the inspiratory pause pressure spontaneously increased on repeated ventilation. Auto- positive end-expiratory pressure (Auto-PEEP) was observed under the condition of high compliance and occlusion. Dynamic compliance decreased at an ID of 5.5 mm in all groups. Respiratory resistance was inversely proportional to the ID of the connector. CONCLUSIONS: The dynamic compliance and resistance were significantly changed. However the change of static compliance had little effect on respiratory mechanics.

Evaluación de una estrategia de reclutamiento alveolar progresivo y comparación de diferentes técnicas de titulación de Peep en pacientes con SDRA focal / Evaluation of a progressive alveolar recruitment strategy and comparison of different Peep titration techniques in patients with focal ARDS

En este trabajo nosotros diseñamos una estrategia de reclutamiento alveolar dirigida para el tratamiento de pacientes con SDRA focal, que utiliza a partir del aumento creciente de la PEEP, presiones de apertura alveolar que no superan los 40 cm H2O Paw meseta. Los objetivos del mismo son, evaluar en pacientes con SDRA focal la eficacia y seguridad de una estrategia de reclutamiento alveolar progresivo (ERAP); y Comparar la curva PEEP/Cst (CPC) con otros métodos de titulación de PEEP: índice de estrés (IS), saturación arterial de oxígeno (SaO2) y PTP. Se ingresaron pacientes mayores de 18 años de edad con diagnóstico de SDRA focal. En este estudio observamos que la ERAP fue efectiva para mejorar la Crs y el intercambio gaseoso en esta población de pacientes. La titulación de la PEEP a partir de la variación de la distensibilidad resultó concordante con el mejor IE y se encontró dentro del rango propuesto para las PTP. La mejor SaO2 se asoció a parámetros mecánicos que sugieren sobredistensión alveolar.

A Case of Severe Acute Exacerbation of Bronchial Asthma Treated with Low Minute Ventilation: A Case Report / 대한구급학회지

We report a case of severe status asthmaticus in a 3-year-old boy who required mechanical ventilatory support. He initially presented with rapidly progressing respiratory distress and spontaneous air leaks. Although he was intubated and received mechanical ventilation, dynamic hyperinflation and air leaks were aggravated. We applied the volume control mode, providing sufficient tidal volume (10 ml/kg), a reduced respiratory rate (25/minute), and a prolonged expiratory time (1.8 seconds) to overcome dynamic hyperinflation. After allowing full expiration of trapped air, his over-expanded lung volumes were decreased and the air leaks resolved. He made a complete recovery without sequelae. Dynamic hyperinflation in asthmatic patients occurs from incomplete exhalation throughout narrowed airways. Controlled hypoventilation or permissive hypercapnia is an important lung-protective ventilator strategy and is beneficial in reducing dynamic hyperinflation. We suggest a controlled hypoventilation strategy with a prolonged expiratory time for patients in severe status asthmaticus with dynamic hyperinflation.

Interaction between intra-abdominal pressure and positive-end expiratory pressure

OBJECTIVE: The aim of this study was to quantify the interaction between increased intra-abdominal pressure and Positive-End Expiratory Pressure. METHODS: In 30 mechanically ventilated ICU patients with a fixed tidal volume, respiratory system plateau and abdominal pressure were measured at a Positive-End Expiratory Pressure level of zero and 10 cm H2O. The measurements were repeated after placing a 5 kg weight on the patients' belly. RESULTS: After the addition of 5 kg to the patients' belly at zero Positive-End Expiratory Pressure, both intra-abdominal pressure (p<0.001) and plateau pressures (p=0.005) increased significantly. Increasing the Positive-End Expiratory Pressure levels from zero to 10 cm H2O without weight on the belly did not result in any increase in intra-abdominal pressure (p=0.165). However, plateau pressures increased significantly (p< 0.001). Increasing Positive-End Expiratory Pressure from zero to 10 cm H2O and adding 5 kg to the belly increased intra-abdominal pressure from 8.7 to 16.8 (p<0.001) and plateau pressure from 18.26 to 27.2 (p<0.001). Maintaining Positive-End Expiratory Pressure at 10 cm H2O and placing 5 kg on the belly increased intra-abdominal pressure from 12.3 +/- 1.7 to 16.8 +/- 1.7 (p<0.001) but did not increase plateau pressure (26.6+/-1.2 to 27.2 +/-1.1 -p=0.83). CONCLUSIONS: The addition of a 5kg weight onto the abdomen significantly increased both IAP and the airway plateau pressure, confirming that intra-abdominal hypertension elevates the plateau pressure. However, plateau pressure alone cannot be considered a good indicator for the detection of elevated intra-abdominal pressure in patients under mechanical ventilation using PEEP. In these patients, the intra-abdominal pressure must also be measured.

Comparison of Auto-PEEP Levels Measured by End-expiratory Port Occlusion Method and Trapped Lung Volume / 대한구급학회지

BACKGROUND: There are several METHODS: for auto-PEEP measurement during mechanical ventilation. The end-expiratory port occlusion (EEPO) method is simple and easy. Theoretically, auto- PEEP level can be also calculated by using trapped lung volume and static compliance. However, the relationship between measured auto-PEEP by EEPO method and the calculated auto-PEEP has not been studied. The purpose of this study is to observe the relationship between the measured and the calculated auto-PEEP. METHODS: 15 patients with auto-PEEP during mechanical ventilation were included. Auto-PEEP was measured by EEPO method, and calculated by using a formula; trapped lung volume/static compliance. All of the patients were paralyzed during the study. If the measured auto-PEEP is higher than calculated auto-PEEP, this patient was included in `high group'; in the opposite case, `low group'. We compared respiratory mechanics between these two groups. RESULTS: Measured auto-PEEP was 9.60+/-2.82 cmH2O, and calculated auto-PEEP was 9.78+/-2.90 cmH2O. There was statistically significant relationship between measured and calculated auto-PEEP (r=0.81, p<0.01). There was no difference on respiratory mechanics between `high group' and `low group'. CONCLUSIONS: The auto-PEEP obtained by calculation with trapped lung volume and static compliance showed a good correlation with that of using EEPO method in the paralyzed patients.

Auto - peep: How to detect and how to prevent - A review

Auto-positive end expiratory pressure [auto-PEEP] is a physiologic event that is common to mechanically ventilated patients. Auto-PEEP is commonly found in acute severe asthma, chronic obstructive pulmonary disease, or patients receiving inverse ratio ventilation. Factors predisposing to auto-PEEP include a reduction in expiratory time by increasing the respiratory rate, tidal volume or expiratory time. Auto- PEEP predisposes the patient to increased work of breathing, barotraumas, hemodynamic instability and difficulty in triggering the ventilator. Failure to recognize the hemodynamic consequences of auto-PEEP may lead to inappropriate fluid restriction or unnecessary vasopressor therapy. Auto- PEEP can potentially interfere with weaning from mechanical ventilation. Many methods have been described to measure the Auto-PEEP. Although not apparent during normal ventilator operation, the auto-PEEP effect can be detected and quantified by a simple bedside maneuver: expiratory port occlusion at the end of the set exhalation period. The measurement of static and dynamic auto-PEEP differs and depends upon the heterogeneity of the airways. The work of breathing can be decreased by providing external PEEP to 75-80% of auto-PEEP in patients who are spontaneously breathing during mechanical ventilation but there is no evidence such external PEEP would be useful during controlled mechanical ventilation when there is no patient expiratory effort. Ventilator setting should aim for a prolonged expiratory time by reducing The respiratory rate rather than increasing inspiratory flow. Routine monitoring for auto-PEEP in patients receiving controlled ventilation is recommended

Measurement of Auto-PEEP / 결핵및호흡기질환

No abstract available.

Different PEEP Effects on Lung Volume According to Underlying Lung Disease in Patients with Auto-PEEP / 결핵및호흡기질환

BACKGROUND: The effect of PEEP(ed note: Define PEEP.) on the lung volume in patients with auto-PEEP during mechanical ventilation is not even. In patients with an expiratory limitation such as COPD, a PEEP of 85% from an auto-PEEP can be used with minimal increase in the lung volume. However, the application of PEEP to patients without an expiratory flow limitation can result in progressive lung. This study was carried out to evaluate the different PEEP effects on the lung volume according to the different pulmonary diseases. METHODS: Sixteen patients who presented with auto-PEEP during mechanical ventilation were enrolled in this study. These patients were divided into 3 groups: asthma, COPD and tuberculosis sequela (patients with severe cicatrical fibrosis as a result of previous tuberculosis and compensatory emphysema). A PEEP of 25, 50, 75 and 100% of the auto-PEEP was applied, and the lung volume increments were estimated using the trapped lung volume. RESULTS: In the asthma group, the trapped lung volume was not increased at a PEEP of 25 and 50% of the auto-PEEP. This group showed a significant lung volume increment from a 75% PEEP. In the COPD group, the lung volume was increased only at 100% PEEP. In the tuberculosis sequela group, the lung volume was increased progressively from low PEEP levels. However, a significant increment of the lung volume was noted only at 100% PEEP. CONCLUSION: The effects of the applied PEEP on the lung volume were different depending on the underlying lung pathology. The level of the applied PEEP >50% of the auto-PEEP might increase the trapped lung volume in patients with asthma.