Estimación de Distensibilidad Dinámica Toraco-pulmonar en Modelos Neonatales de Ventilación Mecánica de Alta Frecuencia / Estimation of dynamic thoracopulmonary compliance in neonatal high-frequency mechanical ventilation models

Introducción. La ventilación de alta frecuencia (VAF) es utilizada en pacientes graves neonatales con un uso cercano al 10% del total de usuarios en ventilación mecánica (VM). Actualmente estos equipos miden volumen corriente de manera precisa, continua y rutinaria, sin embargo no hay estimaciones del comportamiento mecánico del sistema respiratorio del usuario, como lo es la distensibilidad toracopulmonar, durante el ciclo ventilatorio que sean reportadas por las pantallas de los equipos. Objetivo. Estimar distensibilidad dinámica toracopulmonar en modelos neonatales de VAF. Métodos. Estudio cuantitativo, observacional, descriptivo, y "wench work", donde se midió distensibilidad en VM convencional y volumen corriente (Vt) en VAF con equipo Acutronics Fabian® por 4 evaluadores independientes, en 5 tipos de pulmón de ensayo y bajo diferentes escenarios de parámetros de VAF con ajustes de presión media de la vía aérea (PMVA), amplitud, frecuencia respiratoria, tiempo inspiratorio, volumen garantizado, y tipo de circuito. Mediante suavización de regresiones locales por estimación mínima cuadrática (LOWESS) y análisis de regresión multivariada se obtuvieron los valores asociados a distensibilidad, con los que se construyeron ecuaciones de estimación de distensibilidad en VAF. Resultados. Se realizaron en total 46080 mediciones, con correlación intra e interevaluador > 0.99. La distensibilidad mediana (percentil 25; 75) de los 5 modelos pulmonares fue de 0.455 (0.3; 0.98). Se asociaron a distensibilidad, mediante modelos de regresión lineal múltiple de manera significativa, todas las variables evaluadas, salvo PMVA. Se establecieron asociaciones multivariantes crudas (R2=.311), de distensibilidad predicha por LOWESS (R2=.744) y distensibilidad predicha y variables independientes predichas por regresión lineal simple (R2=.973). Conclusiones. La distensibilidad en VAF esta determinada en pulmones de ensayos por los parámetros programados de: tipo de circuito, uso de volumen garantizado, tiempo inspiratorio, frecuencia respiratoria y amplitud, además del Vt medido. Se reporta ecuación explicativa de distensibilidad en VAF.

Background. Background: High frequency mechanical ventilation (HFV) is used in severe neonatal subjects nearly 10% of total mechanically ventilated (MV) users. Currently, this MV's mode allow to measure tidal volumen in an accurately, continuous and routinarie way in HFV, however there are non estimation to assess mechanical behavior of respiratory system during ventilatory cycle, like thoraco-pulmonary compliance, who be report in the equipment display. Objetive. To estimate thoraco-pulmonary compliance in artificial neonatal lung models in HFV. Methods. Quantitative, observational, descriptive, and wench work study, where distensibility was measured in conventional MV and tidal volume (TV) in HFV with Acutronics Fabian® equipment by 4 independent evaluators, in 5 types of test lung and under different scenarios of HFV parameters with adjustments of mean airway pressure (MAP), amplitude, respiratory rate, inspiratory time, guaranteed volume, and type of circuit. By smoothing local regressions by least quadratic estimation (LOWESS) and multivariate regression analysis, the values associated with distensibility were obtained, with this measures, equations for estimating compliance in VAF were constructed. Results. A total of 46080 measurements were made, with intra and inter-evaluator correlation coefficent > 0.99. The median compliance (25th percentile; 75) of the 5 lung models was 0.455 (0.3; 0.98). All variables evaluated, except MAP, were associated with compliance, by means of multiple linear regression models. Crude multivariate associations (R2 = .311), predicted compliance by LOWESS (R2 = .744) and predicted compliance and independent variables predicted by simple linear regression (R2 = .973) were established to estimate thoraco-pulmonary compliance. Conclusions. Compliance in VAF is determined in test lungs by the programmed parameters of: type of circuit, use of guaranteed volume, inspiratory time, respiratory frequency and amplitude, in addition to the measured Vt. An explanatory equation for distensibility in VAF is reported.

Ventilação mecânica variável / Variable mechanical ventilation

RESUMO Objetivo: Revisar a literatura em relação à utilização da ventilação variável e aos principais desfechos relacionados à sua utilização. Métodos: Busca, seleção e análise de todos os artigos originais sobre ventilação variável, sem restrição quanto ao período de publicação e ao idioma, nas bases de dados eletrônicas LILACS, MEDLINE® e PubMed, encontrados por meio de busca pelos termos "variable ventilation" OR "noisy ventilation" OR "biologically variable ventilation". Resultados: Foram selecionados 36 artigos na busca. Após a análise, 24 artigos eram originais; destes 21 experimentais e 3 clínicos. Conclusão: Diversos estudos experimentais evidenciaram os efeitos benéficos de variadas estratégias ventilatórias variáveis sobre a função pulmonar em diferentes modelos de lesão pulmonar e em pulmões saudáveis. A ventilação variável parece ser uma estratégia viável para o aprimoramento da troca gasosa e mecânica respiratória, assim como para prevenção de lesão pulmonar associada à ventilação mecânica. Entretanto, estudos clínicos são necessários para investigar o potencial destas estratégias ventilatórias variáveis na melhora clínica dos pacientes submetidos à ventilação mecânica.

ABSTRACT Objective: To review the literature on the use of variable mechanical ventilation and the main outcomes of this technique. Methods: Search, selection, and analysis of all original articles on variable ventilation, without restriction on the period of publication and language, available in the electronic databases LILACS, MEDLINE®, and PubMed, by searching the terms "variable ventilation" OR "noisy ventilation" OR "biologically variable ventilation". Results: A total of 36 studies were selected. Of these, 24 were original studies, including 21 experimental studies and three clinical studies. Conclusion: Several experimental studies reported the beneficial effects of distinct variable ventilation strategies on lung function using different models of lung injury and healthy lungs. Variable ventilation seems to be a viable strategy for improving gas exchange and respiratory mechanics and preventing lung injury associated with mechanical ventilation. However, further clinical studies are necessary to assess the potential of variable ventilation strategies for the clinical improvement of patients undergoing mechanical ventilation.

Comparison of the curative effect of bi-level positive airway pressure and nasal continuous positive airway pressure in the treatment of neonatal respiratory distress syndrome / 中国基层医药

Objective To compare the clinical application effect of bi -level positive airway pressure ( BiPAP) and nasal continuous positive airway pressure ( CPAP) in the treatment of preterm infants with neonatal respiratory distress syndrome ( NRDS) .Methods 64 neonates with NRDS were divided into the BiPAP group ( n=35) and NCPAP group (n=29) according to the randomized controlled study method.The blood gas index before and after 2,12 hours of treatment,the total time for ventilation,length of stay,and the incidence rate of abdominal disten-sion,gastroesophageal reflux,bronchopulmonary dysplasia,intraventricular hemorrhage,ventilator-associated pneumo-nia in the two groups were compared.Results The levels of pH and PaO2 in the BiPAP group were higher than those in the NCPAP group in noninvasive respiratory support for 2,12h(t=2.391,2.556,2403,2.355,P=0.020,0.013, 0.019,0.022).The incidence rates of hypoxemia,apnea,re-intubation mechanical ventilation rate after 12h in the BiPAP group were lower than those in the NCPAP group(t=5.049,4.988,4.215,P=0.025,0.026,0.040).The length of stay and mechanical ventilation time in the BiPAP group were shorter than those in the NCPAP group( t=-2.096,-2.669,P=0.041,0.010).Conclusion Compared with NCPAP,early application of BiPAP can obviously reduce the invasive respiratory support rate of children with NRDS with intubation.It is worthy of promotion.

Clinical switching time of sequential mechanical ventilation on patients with chronic obstructive pulmonary disease with type Ⅱ respiratory failure / 中国基层医药

Objective To study clinical switching time of sequential mechanical ventilation on patients with chronic obstructive pulmonary disease with type Ⅱ respiratory failure.Methods The clinical data and laboratory data of 56 patients with chronic obstructive pulmonary disease combined with type Ⅱ respiratory failure,According to treatment intervention,56 cases were divided into the observation group and control group,each group with 28 cases,all adopted invasive mechanical ventilation patients,the control group adopted the trachea intubation and mechanical ventilation treatment;The observation group was the sequence through air treatment,The clinical effect of two groups was compared.Results The time of invasive mechanical ventilation in the observation group was (3.2 ± 0.9) d,the control group was (20.2 ± 1.6) d,the total length of hospital stay in the observation group was (13.6 ± 2.5) d,the control group was (27.6 ± 11.3) d,the cost in the observation group was (12 654.2 ± 1 654.7) yuan,the control group was (29 658.9 ± 3 654.2)yuan,the observation group was better than that of the control group,with statistical significance(P ＜ 0.05);The cure rates of the observation group was 89.29％,which was higher than 71.43％ of the control group (x2 =6.34,P ＜ 0.05).Conclusion Sequential mechanical ventilation in patients with chronic obstructive pulmonary disease with type Ⅱ respiratory failure of clinical switching time is the key factor for treatment,can achieve good treatment effect,reduce the incidence of pneumonia,which is worthy of clinical promotion and further study.

Application study of noninvasive positive pressure ventilation in patients with AECOPD following extubation at the pulmonary infection control window / 中国基层医药

Objective To assess whether AECOPD patients can breathe independently at the PIC window and thus whether NPPV was necessary after extubation.Methods We performed a prospective observational study, we used the spontaneous breathing trial (SBT)to assess whether each patient could breathe independently at the PIC window,then performed extubation.Patients who passed the SBT received oxygen therapy only,whereas those who failed received NPPV.However,if the former showed respiratory distress,they also received NPPV.The primary out-come variables were SBT pass/fail,the demand for NPPV and rate of reintubation within 72h following extubation. Results In all,23 patients were enrolled,15cases(65.2%)of which passed the SBT.Of these,12cases (80.0%) patients developed respiratory distress after extubation and required NPPV (one of whom required reintubation).Of the eight patients that failed,one received reintubation after NPPV.The reintubation rates within 72h following extuba-tion of SBT-pass(7.0%)and SBT-fail (13.0%)(χ2 =1.476,P>0.05)patients were comparable.Conclusion Most AECOPD patients can breathe independently at the PIC window,but nonetheless develop respiratory distress and thus require NPPV following extubation.

Epidemiologia, estratégias e evolução de pacientes submetidos à ventilação mecânica / Epidemiology, strategies and outcome of patients submitted to mechanical ventilation

JUSTIFICATIVA E OBJETIVOS: A epidemiologia e uso de estratégias ventilatórias variam amplamente entre pacientes submetidos à ventilação mecânica (VM). O objetivo deste estudo foi avaliar o perfil dos pacientes submetidos à VM em diferentes instituições, bem como as estratégias ventilatórias e complicações.MÉTODO: Estudo de coorte prospectivo de pacientes submetidos à VM por período maior de 24h em cinco unidades de terapia intensiva (UTI) de três cidades da região Oeste do estado do Paraná. Foram analisados dados clínico-demográficos,complicações durante o período de VM e desfechos clínicos. As estratégias ventilatórias, de desmame e tratamento clínico geral ficaram a critério de cada UTI. RESULTADOS: Foram avaliados 242 pacientes (idade mediana de 49 anos; 65,7% do sexo masculino), que ficaram em VM por um período mediano de 8 dias. A etiologia mais frequente foi trauma e clínico/cardiológico. O modo ventilatório mais utilizado foi assistido-controlado ciclado a volume. Traqueostomia foi realizada em 36,8%, no 8º dia de VM. Pneumonia associada à VM ocorreu em 35,1% dos pacientes. A mortalidade na UTI foi de 45,0%, sendo de 47,5% nos pacientes com síndrome do desconforto respiratório agudo. Houve grande variabilidade na utilização de estratégias e nos resultados entre as instituições e de acordo com a etiologia. CONCLUSÃO: As características clínicas e utilização de estratégias ventilatórias variam amplamente entre os pacientes com insuficiência respiratória e VM. O conhecimento da epidemiologia e das condutas clínicas utilizadas pode contribuir para redução de complicações e melhor evolução entre estes pacientes.

BACKGROUND AND OBJECTIVES: Epidemiology and ventilatory strategies vary widely among patients undergoin gmechanical ventilation (MV). The objective of this study was to evaluate the profile of patients submitted to MV in different institutions, as well as ventilation strategies and complications. METHOD: Prospective cohort study of patients undergoing MV for longer than 24 hours in five intensive care units (ICU) of three cities in Paraná state, southern Brazil. We analyzed clinical and demographic data, complications during mechanical ventilation and clinical outcomes. Ventilatory strategies, weaning and clinical management were kept according of each ICU. RESULTS: It was evaluated 242 patients (median age 49 years; 65.7% male) who remained on MV for a median of 8 days.The most frequent etiologies were trauma and clinical/cardiology. Most used ventilatory mode was assisted controlled cycled volume. Tracheostomy was performed in 36.8%, at 8th day of MV. Ventilator-associated pneumonia occurred in 35.1% of patients.The ICU mortality was 45.0% (being 47.5% in patients with acute respiratory distress syndrome. There was great variability in the use of strategies and outcomes between institutions as well as according to the etiology. CONCLUSION: Clinical features and use of ventilatory strategies varies widely among patients with respiratory failure and MV. Knowledge of the epidemiology and clinical procedures used may contribute to reducing complications and better outcomes among these patients.