Effect of intraoperative alveolar recruitment maneuver on intraoperative oxygenation and postoperative pulmonary function tests in patients undergoing robotic-assisted hysterectomy: a single-blind randomized study

Abstract Background Robotic-Assisted Hysterectomies (RAH) require Trendelenburg positioning and pneumoperitoneum, which further accentuate alteration in respiratory mechanics induced by general anesthesia. The role of Recruitment Maneuver (RM) as a lung-protective strategy during intraoperative surgical settings has not been much studied. We planned this study to evaluate the effect of RM on perioperative oxygenation and postoperative spirometry using PaO2/FiO2 and FEV1/FVC, respectively in patients undergoing RAH. Methods Sixty-six ASA I‒II female patients scheduled for elective RAH were randomized into group R (recruitment maneuver, n = 33) or group C (control, n = 33). Portable spirometry was done one day before surgery. Patients were induced with general anesthesia, and mechanical ventilation started with volume control mode, with Tidal Volume (TV) of 6-8 mL.kg−1, Respiratory Rate (RR) of 12 min, inspiratory-expiratory ratio (I: E ratio) of 1:2, FiO2 of 0.4, and Positive End-Expiratory Pressure (PEEP) of 5 cmH2O. Patients in group R received recruitment maneuvers of 30 cmH2O every 30 minutes following tracheal intubation. The primary objectives were comparison of oxygenation and ventilation between two groups intraoperatively and portable spirometry postoperatively. Postoperative pulmonary complications, like desaturation, pulmonary edema, pneumonia, were monitored. Results Patients who received RM had significantly higher PaO2 (mmHg) (203.2+-24.3 vs. 167.8+-27.3, p < 0.001) at T2 (30 min after the pneumoperitoneum). However, there was no significant difference in portable spirometry between the groups in the postoperative period (FVC, 1.40 ± 0.5 L vs. 1.32 ± 0.46 L, p= 0.55). Conclusion This study concluded that intraoperative recruitment did not prevent deterioration of postoperative spirometry values; however, it led to improved oxygenation intraoperatively.

Índice de respiración rápida superficial diafragmática como predictor weaning de la ventilación mecánica / Rate of rapid superficial diaphragmatic breathing as a weaning predictor of mechanical ventilation

El destete de la ventilación mecánica (VM) es un paso clave para los pacientes sometidos a VM invasiva en la unidad de cuidados intensivos (UCI). Entre las diversas herramientas destinadas a ayudar a predecir el fracaso sucesor del destete, encontramos el índice rápido de respiración superficial (RSBI por sus siglas en inglés), es decir, la relación entre la frecuencia respiratoria y el volumen corriente (Fr/Vt) medido durante una prueba de respiración espontánea (SBT por sus siglas en inglés). Objetivo: Describir el índice de respiración superficial diagramática como predictor Weaning de la ventilación mecánica. Materiales y métodos: Estudio de revisión, de tipo monográfico. Apoyado en artículos científicos, publicados en diferentes revistas indexzada en índices reconocidos. Resultado: Durante un SBT, el valor de RSBI parece ser paralelo a la evolución de la fatiga de los músculos respiratorios. Por lo tanto, se considera que el RSBI refleja la carga inspiratoria, siendo la disminución del volumen tidal junto con el aumento de frecuencia respiratoria indicativo de posible debilidad o fatiga de los músculos inspiratorios, u otros efectos fisiológicos. Conclusión: Entre los pacientes ventilados en la UCI, una alteración multifactorial del diafragma es común y puede resultar en falla del destete y prolongación de la VM invasiva; por lo tanto, evaluar la función del diafragma es un medio útil para evaluar la capacidad del paciente para tolerar la respiración espontánea(AU)

Weaning from mechanical ventilation (MV) is a key step for patients undergoing invasive MV in the intensive care unit (ICU). Among the various tools intended to help predict successor failure weaning, we found the rapid shallow breathing index (RSBI for its acronym in English), that is, the relationship between the respiratory rate and the volume current (Fr/Vt) measured during a spontaneous breathing test (SBT by its acronym in English). Objective: To describe the rate of shallow breathing Diagrammatic as a Weaning predictor of mechanical ventilation. Materials and methods: Review study, monographic type. supported by articles scientific, published in different magazines indexed in recognized indices. Result: During an SBT, the RSBI value appears to be parallel to the evolution of respiratory muscle fatigue. Therefore, it is considered that the RSBI reflects the inspiratory load, being the decrease in tidal volume together with the increased respiratory rate indicative of possible weakness or fatigue of the inspiratory muscles, or other physiological effects. Conclusion: Among the patients ventilated in the ICU, a multifactorial alteration of the diaphragm is common and can result in weaning failure and prolongation of invasive MV; by Therefore, assessing diaphragm function is a useful means of assessing the patient's ability to tolerate spontaneous breathing(AU)

Injuria pulmonar autoinducida por el paciente / Patient self-inflicted lung injury

La Injuria Pulmonar Autoinducida por el Paciente (p-SILI) es una entidad recientemente reconocida. Clásicamente, el daño producido por la ventilación mecánica (VM) se asoció al uso de presión positiva, y para disminuirlo se crearon distintas estrategias conocidas como parámetros de protección pulmonar. Sin embargo, es importante reconocer los potenciales efectos deletéreos de la ventilación espontánea dependientes de la injuria pulmonar previa que sufra el paciente y del esfuerzo que realice. En este artículo se explican los distintos mecanismos que pueden producir p-SILI y las estrategias descritas en la literatura para prevenirla (AU)

Patient self-inflicted lung injury (p-SILI) is a recently recognized disorder. Classically, damage produced by mechanical ventilation (MV) was associated with the use of positive pressure, and different strategies known as lung protection parameters were created to reduce it. Nevertheless, it is important to recognize the potential deleterious effects of the effort made during spontaneous breathing due to previous lung injury suffered by the patient. This article explains the different mechanisms that may produce p-SILI and the prevention strategies described in the literature. (AU)

Pulmonary complications and respiratory management in neurocritical care: a narrative review / 中华医学杂志(英文版)

Neurocritical care (NCC) is not only generally guided by principles of general intensive care, but also directed by specific goals and methods. This review summarizes the common pulmonary diseases and pathophysiology affecting NCC patients and the progress made in strategies of respiratory support in NCC. This review highlights the possible interactions and pathways that have been revealed between neurological injuries and respiratory diseases, including the catecholamine pathway, systemic inflammatory reactions, adrenergic hypersensitivity, and dopaminergic signaling. Pulmonary complications of neurocritical patients include pneumonia, neurological pulmonary edema, and respiratory distress. Specific aspects of respiratory management include prioritizing the protection of the brain, and the goal of respiratory management is to avoid inappropriate blood gas composition levels and intracranial hypertension. Compared with the traditional mode of protective mechanical ventilation with low tidal volume (Vt), high positive end-expiratory pressure (PEEP), and recruitment maneuvers, low PEEP might yield a potential benefit in closing and protecting the lung tissue. Multimodal neuromonitoring can ensure the safety of respiratory maneuvers in clinical and scientific practice. Future studies are required to develop guidelines for respiratory management in NCC.

Influência da ventilação assistida e dos ajustes do ventilador mecânico sobre o volume corrente e as pressões alveolares na síndrome do desconforto respiratório agudo: um estudo de bancada / Influences of assisted breathing and mechanical ventilator settings on tidal volume and alveolar pressures in acute respiratory distress syndrome: a bench study

RESUMO Objetivo: Avaliar a influência dos esforços musculares respiratórios e do ajuste da frequência respiratória no ventilador sobre o volume corrente e as pressões de distensão alveolar ao final da inspiração e expiração com ventilação sob os modos controle por volume e controle por pressão na síndrome do desconforto respiratório agudo. Métodos: Utilizou-se um simulador mecânico de pulmão (ASL 5000™) conectado a cinco tipos de ventiladores utilizados em unidade de terapia intensiva, em um modelo de síndrome do desconforto respiratório agudo. Os esforços musculares respiratórios (pressão muscular) foram configurados de três formas distintas: sem esforço (pressão muscular: 0cmH2O), apenas esforços inspiratórios (pressão muscular: - 5cmH2O, tempo inspiratório neural de 0,6 segundos) e esforços musculares inspiratórios e expiratórios (pressão muscular:-5/+5cmH2O). Foram configuradas ventilação sob os modos controle por volume e ventilação com controle por pressão para oferecer um volume corrente de 420mL e pressão positiva expiratória final de 10cmH2O. Avaliaram-se o volume corrente fornecido aos pulmões, as pressões alveolares no final da inspiração e as pressões alveolares no final da expiração. Resultados: Quando disparado pelo paciente simulado, o volume corrente mediano foi 27mL menor do que o volume corrente ajustado (variação-63 a +79mL), e ocorreu uma variação nas pressões alveolares com mediana de 25,4cmH2O (faixa de 20,5 a 30cmH2O). Nos cenários simulados com esforço muscular tanto inspiratório quanto expiratório e com frequência respiratória mandatória inferior à dos esforços do paciente simulado, o volume corrente mediano foi maior com ventilação controlada. Conclusão: O ajuste do esforço muscular respiratório e da frequência respiratória no ventilador em um valor acima da frequência respiratória do paciente nos modos de ventilação assistida/controlada gerou maiores variações no volume corrente e nas pressões pulmonares, enquanto o modo controlado não mostrou variações nesses desfechos.

ABSTRACT Objective: To evaluate the influences of respiratory muscle efforts and respiratory rate setting in the ventilator on tidal volume and alveolar distending pressures at end inspiration and expiration in volume-controlled ventilation and pressure-controlled ventilation modes in acute respiratory distress syndrome. Methods: An active test lung (ASL 5000™) connected to five intensive care unit ventilators was used in a model of acute respiratory distress syndrome. Respiratory muscle efforts (muscle pressure) were configured in three different ways: no effort (muscle pressure: 0cmH2O); inspiratory efforts only (muscle pressure:-5cmH2O, neural inspiratory time of 0.6s); and both inspiratory and expiratory muscle efforts (muscle pressure:-5/+5cmH2O). Volume-controlled and pressure-controlled ventilation modes were set to deliver a target tidal volume of 420mL and positive end-expiratory pressure of 10cmH2O. The tidal volume delivered to the lungs, alveolar pressures at the end of inspiration, and alveolar pressures at end expiration were evaluated. Results: When triggered by the simulated patient, the median tidal volume was 27mL lower than the set tidal volume (range-63 to +79mL), and there was variation in alveolar pressures with a median of 25.4cmH2O (range 20.5 to 30cmH2O). In the simulated scenarios with both spontaneous inspiratory and expiratory muscle efforts and with a mandatory respiratory rate lower than the simulated patient's efforts, the median tidal volume was higher than controlled breathing. Conclusion: Adjusting respiratory muscle effort and pulmonary ventilator respiratory rate to a value above the patient's respiratory rate in assisted/controlled modes generated large variations in tidal volume and pulmonary pressures, while the controlled mode showed no variations in these outcomes.

Equations for calculating ideal body weight in patients on mechanical ventilation in adult intensive care units in Latin America: exploratory review / Ecuaciones para calcular el peso ideal en pacientes con ventilación mecánica en unidades de cuidado intensivo adulto en Latinoamérica: revisión exploratoria

Abstract Introduction Ideal body weight calculation is used in critical medicine for drug dosing and setting ventilation parameters. However, the suggested and used equations were designed on the basis of anthropometric variables that do not represent the Latin American population. Objective To map and present the current evidence on the equations used to calculate ideal weight in patients on mechanical ventilation in intensive care units in Latin America. Material and Methods Exploratory review using the Joanna Briggs Institute method conceived by Arskey / O'Malley. A search was performed in the BVS, LILLACS, REDALYC, Ovid, Google Scholar and Scielo databases using keywords and MeSH terms in Spanish, English, and Portuguese, with no time limitation. The results are presented in descriptive tables. Results Overall, 1126 studies were identified and 1120 were excluded; 6 studies were reviewed and 3 additional studies were identified through a manual search. The studies were published in Chile, Brazil, Mexico, Ecuador, and Peru. In 89%, the ARDS Network equation was used to calculate tidal volume. Acute respiratory distress syndrome was the most reported pathology (33%). Conclusions Adult intensive care units in Latin America use the equation suggested by the ARDS Network, which was designed in a population with different anthropometric characteristics.

Resumen Introducción El cálculo del peso ideal se utiliza en medicina crítica para dosificación de medicaciones y programación de parámetros ventilatorios; sin embargo, las ecuaciones sugeridas y usadas fueron diseñadas con variables antropométricas que no representan la población latinoamericana. Objetivo Mapear y presentar la evidencia actual de las ecuaciones utilizadas para calcular el peso ideal en pacientes con ventilación mecánica en unidades de cuidado intensivo de Latinoamérica. Material y métodos Revisión exploratoria con el método del Instituto Joanna Briggs concebido por Arskey y O'Malley. Se realizó una búsqueda en las bases de datos BVS, LILACS, Redalyc, Ovid, Google Scholar y SciELO con el uso de palabras clave y términos MeSH en idiomas español, inglés y portugués, sin límites de tiempo. Los resultados se presentan de forma descriptiva. Resultados Se identificaron 1.126 estudios, se excluyeron 1.120, se revisaron seis y se encontraron tres adicionales mediante búsqueda manual. Los estudios fueron publicados en Chile, Brasil, México, Ecuador y Perú. En el 89 % se usó la ecuación del ARDS Network para calcular volumen corriente. El síndrome de dificultad respiratoria aguda fue la patología más informada (33 %). Conclusiones En las unidades de cuidado intensivo adulto de Latinoamérica se usa la ecuación sugerida por el ARDS Network diseñada en población con características antropométricas diferentes.

Prospects and developments in the technologies of high frequency oscillatory ventilation / 生物医学工程学杂志

The high frequency oscillatory ventilation (HFOV) is characterized with low tidal volume and low mean airway pressure, and can well support the breathing of the patients with respiratory diseases. Since the HFOV was proposed, it has been widely concerned by medical and scientific researchers. About the HFOV, this paper discussed its current research status and prospected its future development in technologies. The research status of ventilation model, mechanisms and ventilation mode were introduced in detail. In the next years, the technologies in developing HFOV will be focused on: to develop the branched high-order nonlinear or volume-depended resistance-inertance-compliance (RIC) ventilation model, to fully understand the mechanisms of HFOV and to achieve the noninvasive HFOV. The development in technologies of HFOV will be beneficial to the patients with respiratory diseases who failed with conventional mechanical ventilation as one of considerable ventilation methods.

Efeitos da PEEP na ventilação controlada a volume sobre parâmetros hemodinâmicos em suínos submetidos ao pneumoperitônio associado ao cefalodeclive / Effects of PEEP on hemodynamic variables in pigs submitted to volume-controlled ventilation under pneumoperitoneum associated to cephalodeclive

Videolaparoscopic procedures have gained prominence due to their low invasiveness, causing less surgical trauma and better post-surgical recovery. However, the increase in intra-abdominal pressure due to the institution of pneumoperitoneum can alter the patient's homeostasis. Therefore, volume-controlled ventilation, associated with positive end-expiratory pressure (PEEP), improves arterial oxygenation and prevents pulmonary collapse, but it can lead to important hemodynamic changes. The aim of this study was to evaluate, comparatively, the effects of positive end expiratorypressure (PEEP) on hemodynamic variables of pigs submitted to volume-controlled ventilation, during pneumoperitoneum and maintained in head-down tilt and determine which PEEP value promotes greater stability on hemodynamic variables. Twenty-four pigs were used, between 55 and 65-day-old, weighing between 15 and 25 kg, randomly divided into 3 distinct groups differentiated by positive end-expiratory pressure: PEEP 0 (volume-controlled ventilation and PEEP of 0 cmH2O), PEEP 5 (volume-controlled ventilation and PEEP of 5 cmH2O) and PEEP 10 (volume-controlled ventilation and PEEP of 10 cmH2O). Volume-controlled ventilation was adjusted to 8 mL/kg of tidal volume and a respiratory rate of 25 movements per min. Anesthesia was maintained with continuous infusion of propofol (0.2 mg/kg/min) and midazolam (1 mg/kg/h). Pneumoperitoneum was performed with carbon dioxide (CO2), keeping the intraabdominal pressure at 15 mmHg and the animals were positioned on a 30° head-down tilt. The evaluations of hemodynamic variables started 30 min after induction of anesthesia (M0), followed by measurements at 15-min intervals (from M15 to M90), completing a total of 7 evaluations. The variables of interest were collected over 90 min and submitted to analysis of variance followed by Tukey's post-hoc test, with P < 0.05. The PEEP 10 group had higher values of CVP and mCPP, while the PEEP 5 group, mPAP and PVR were higher. The PEEP 0 group, on the other hand, had higher means of CI. Regarding the moments, there were differences in HR, SAP, DAP, MAP, CO, IC and TPR. According to the literature, important hemodynamic effects due to pneumoperitoneum are reported, which can be caused by the pressure used in abdominal insufflation, CO2 accumulation, duration of the surgical procedure, hydration status and patient positioning. Mechanical ventilation associated with PEEP can also cause an increase in intrathoracic pressure and, therefore, reduce cardiac output. Cardiovascular changes are proportional to the PEEP used. Central venous pressure (PVC) measure the patient's preload, and intrathoracic pressure can interfere with this parameter. The peak pressure values in the PEEP 10 group were higher than the other groups, demonstrating that the increase in intrathoracic pressure results in higher PVC values. Regarding PAPm and PCPm, these variables can be influenced according to the PEEP values and the patient's position. In relation to CI, the increase in PEEP may reflect on intrathoracic pressure, resulting in greater compression of the heart, with a consequent reduction in cardiac output and cardiac index. Therefore, it is concluded that the PEEP effects of 0 cmH2O and 5 cmH2O on hemodynamics are discrete, under the proposed conditions.(AU)

Quantitative analysis of breathing patterns based on wearable systems / 生物医学工程学杂志

Breathing pattern parameters refer to the characteristic pattern parameters of respiratory movements, including the breathing amplitude and cycle, chest and abdomen contribution, coordination, etc. It is of great importance to analyze the breathing pattern parameters quantificationally when exploring the pathophysiological variations of breathing and providing instructions on pulmonary rehabilitation training. Our study provided detailed method to quantify breathing pattern parameters including respiratory rate, inspiratory time, expiratory time, inspiratory time proportion, tidal volume, chest respiratory contribution ratio, thoracoabdominal phase difference and peak inspiratory flow. We also brought in "respiratory signal quality index" to deal with the quality evaluation and quantification analysis of long-term thoracic-abdominal respiratory movement signal recorded, and proposed the way of analyzing the variance of breathing pattern parameters. On this basis, we collected chest and abdomen respiratory movement signals in 23 chronic obstructive pulmonary disease (COPD) patients and 22 normal pulmonary function subjects under spontaneous state in a 15 minute-interval using portable cardio-pulmonary monitoring system. We then quantified subjects' breathing pattern parameters and variability. The results showed great difference between the COPD patients and the controls in terms of respiratory rate, inspiratory time, expiratory time, thoracoabdominal phase difference and peak inspiratory flow. COPD patients also showed greater variance of breathing pattern parameters than the controls, and unsynchronized thoracic-abdominal movements were even observed among several patients. Therefore, the quantification and analyzing method of breathing pattern parameters based on the portable cardiopulmonary parameters monitoring system might assist the diagnosis and assessment of respiratory system diseases and hopefully provide new parameters and indexes for monitoring the physical status of patients with cardiopulmonary disease.

El espacio muerto (VD/VT) como predictor de éxito en la extubación de pacientes postquirúrgicos de cirugía cardiovascular pediátrica / Dead space (VD/VT) as a predictor of successful extubation of patients after pediatric cardiovascular surgery

Introducción: La ventilación mecánica (VM) forma parte de la recuperación postoperatoria (PO) de niños con cirugía de cardiopatía congénita, pero su uso no está exento de riesgos. El fracaso de extubación (FE) se ha asociado con internaciones prolongadas, aumento de complicaciones y mortalidad. El objetivo es determinar un valor de Vd/Vt predictor de extubación exitosa (EE). Material y métodos: estudio de cohorte prospectivo y observacional realizado del 1 de Enero al 31 de Diciembre de 2016 en niños menores de 6 meses cursando PO de cirugía cardiovascular con circulación extracorpórea (CEC) con requerimientos de VM por más de 48 horas. En los mismo se analizó el éxito o fracaso de extubación. Previo a la extubación se registraron valores de mecánica respiratoria; Vd/Vt, CO2 espiratoria final, Vt/kg, etc. Otras variables registradas: edad, sexo, peso, requerimiento de VM antes de la cirugía, fisiología de ventrículo único, duración de VM, complicaciones, duración de la internación y mortalidad. Las variables continuas se describieron como mediana y rango intercuartilo (25-75) y se compararon con prueba de Wilcoxon, las categóricas como proporciones o porcentajes y se analizaron con chi2 . Se efectuó un análisis bivariado con diferentes puntos de corte de Vd/Vt pre extubación para realizar un análisis de sensibilidad del valor predictivo de EE. Resultados: Se evaluó Vd/Vt en 67 pacientes, tres se eliminaron por parálisis cordal (1) y parálisis del diafragma (2). Mediana de edad 23 días (10-55), peso 3.2 Kg (2.89- 3.88), días de VM 5 (3-7), días de internación 15 (2- 128), mortalidad 7,8%. Se extubaron con éxito 76% de los pacientes (50/64). Las características demográficas de los pacientes, la mecánica respiratoria, gases de sangre arterial y EtCO2 no tuvieron asociación significativa con EE. Un Vd/Vt pre extubación < 0,53 se asoció con EE. Conclusión: En la población estudiada un valor de Vd/Vt <0,53 se asoció con EE. Los pacientes con ventrículo único presentaron mayor FE.(AU)

Introduction: Mechanical ventilation (MV) is part of postoperative (PO) recovery of children with congenital heart disease surgery, but is not without risks. Extubation failure (EF) has been associated with prolonged hospital stays and increased complication and mortality rates. The goal is to determine the value of Vd/Vt as a predictor of successful extubation (SE). Material and methods: A prospective and observational cohort study was conducted from January 1 to December 31, 2016, in children under 6 months of age undergoing cardiovascular surgery with extracorporeal circulation (ECC) and requiring MV for more than 48 hours. Intubation success or failure was evaluated. Prior to extubation, respiratory mechanics values, such as Vd/Vt, final expiratory CO2, and Vt/kg, were recorded. Other variables, including age, sex, weight, VM requirement before surgery, single ventricle physiology, VM duration, complications, length of hospital stay, and mortality were also recorded. Continuous variables were described as median and interquartile range (25-75) and compared with the Wilcoxon test. Categorical variables were described as proportions or percentages and analyzed with chi2. Bivariate analysis was performed with different pre-extubation Vd/Vt cut-off points to analyze the sensitivity of the predictive value for SE. Results: Vd/Vt was evaluated in 67 patients; three were excluded because of vocal fold (1) and diaphragm paralysis (2). Median age was 23 days (10-55), weight 3.2 Kg (2.89- 3.88), days on MV 5 (3-7), length of hospital stay 15 (2- 128), and mortality rate 7.8%. Overall, 76% of patients (50/64) were successfully extubated. Patient demographics, respiratory mechanics, arterial blood gases, and EtCO2 were not significantly associated with SE. A pre-extubation Vd/ Vt < 0.53 was associated with SE. Conclusion: In this series of patients, a Vd/Vt value of <0.53 was associated with SE. EF was increased in patients with a single ventricle (AU)

Características y resultados de los pacientes infectados con nCoV19 con requerimiento de ventilación mecánica invasiva en la Argentina / Characteristics and outcomes of patients infected with nCoV19 requiring invasive mechanical ventilation in Argentina

RESUMEN Objetivo: El coronavirus ha emergido este año como causa de neumonía viral. Una de las principales características es su rápida transmisión y su potencial severidad. El objetivo de este estudio de serie de casos es describir las características clínicas de los pacientes con confirmación de enfermedad por coronavirus (COVID-19) admitidos en diferentes unidades de cuidados intensivos de la Argentina con requerimiento de ventilación mecánica. Métodos: Estudio de serie de casos, descriptivo-prospectivo, multicéntrico realizado entre el 01 de abril y el 08 de mayo de 2020. Se incluyeron los datos de los pacientes mayores a 18 años, que ingresaron a la unidad de cuidados intensivos con requerimiento de ventilación mecánica por falla respiratoria aguda con diagnóstico positivo de COVID-19 Resultados: Se registraron las variables de 47 pacientes de 31 unidades cuidados intensivos, 78.7% hombres de una mediana de edad de 61 años, con un SAPS II de 43, un índice de Charlson de 3. El modo ventilatorio inicial fue volume control - continuous mandatory ventilation con volumen corriente menor a 8mL/kg en el 100% de los casos, con una mediana de presión positiva al final de la espiración de 10,5cmH2O. A la fecha de cierre del estudio, 29 pacientes fallecieron, 8 alcanzaron el alta, y 10 pacientes continúan internados al cierre del estudio. El SAPS II fue mayor entre los fallecidos (p = 0.046). El índice de Charlson se asoció con mayor mortalidad (OR = 2,27 IC95% 1,13 - 4,55; p = 0,02). Conclusión: Los pacientes con COVID-19 y ventilación mecánica de esta serie presentan variables clínicas similares a las descriptas a la fecha en otros reportes internacionales. Nuestros hallazgos proporcionan datos que permitirían de alguna manera predecir los resultados.

Abstract Objective: A novel coronavirus emerged this year as a cause of viral pneumonia. The main characteristics of the virus are rapid transmission, high contagion capacity and potential severity. The objective of this case series study is to describe the clinical characteristics of patients with confirmed coronavirus disease (COVID-19) admitted to different intensive care units in Argentina for mechanical ventilation. Methods: A descriptive, prospective, multicenter case series study was conducted between April 1 and May 8, 2020. Data from patients older than 18 years who were admitted to the intensive care unit for mechanical ventilation for acute respiratory failure with a positive diagnosis of COVID-19 were included. Results: The variables for 47 patients from 31 intensive care units were recorded: 78.7% were men (median age of 61 years), with a SAPS II score of 43 and a Charlson index score of 3. The initial ventilatory mode was volume control - continuous mandatory ventilation with a tidal volume less than 8mL/kg in 100% of cases, with a median positive end-expiratory pressure of 10.5cmH2O. At the end of the study, 29 patients died, 8 were discharged, and 10 remained hospitalized. The SAPS II score was higher among patients who died (p = 0.046). Charlson comorbidity index was associated with higher mortality (OR = 2.27, 95% CI 1.13 - 4.55, p = 0.02). Conclusion: Patients with COVID-19 and on mechanical ventilation in this series presented clinical variables similar to those described to date in other international reports. Our findings provide data that may predict outcomes.

Parâmetros hemodinâmicos e ventilatórios em coelhos anestesiados com isoflurano, submetidos à ventilação controlada à pressão com ou sem PEEP / Hemodynamic and ventilatory parameters in rabbits anesthetized with isoflurane submitted to pressure controlled ventilation with or without PEEP

Foi comparada a ventilação controlada à pressão com ou sem pressão positiva expiratória final (PEEP), em coelhos, distribuídos em três grupos, denominados GP (grupo ventilação ciclada à pressão), GPP (grupo ventilação ciclada à pressão com PEEP) e GE (grupo ventilação espontânea - grupo controle). Os animais foram anestesiados com isoflurano, em circuito com reinalação de gases, durante duas horas. As médias de pressão arterial média (PAM) e pressão arterial sistólica (PAS) permaneceram discretamente abaixo dos valores normais em todos os grupos. Houve diminuição significativa da PAM e da PAS no grupo submetido à PEEP (GPP) ao longo do tempo. A pressão parcial de dióxido de carbono arterial (PaCO2) foi maior no GPP quando comparado aos outros grupos no último momento, gerando acidemia respiratória após uma hora de procedimento. A concentração de dióxido de carbono ao final da expiração (ETCO2) apresentou médias discretamente elevadas no grupo não tratado com PEEP (GP) e no grupo controle, enquanto o GPP apresentou maiores médias, possivelmente, relacionadas à diminuição do volume corrente neste grupo. Com base nesses resultados, foi possível concluir que a utilização da PEEP levou à acidemia, que se agravou ao longo do tempo anestésico. Ademais, a anestesia prolongada com isoflurano promove depressão cardiorrespiratória, independentemente do modo ventilatório empregado.(AU)

Pressure controlled ventilation with or without positive end-expiratory pressure (PEEP) was compared in rabbits, which were divided into three groups denominated GP (pressure cycled ventilation group), GPP (pressure cycled ventilation with PEEP group) and GE (spontaneous ventilation group - control group). The animals were anesthetized with isoflurane in a gas rebreathing circuit for two hours. The means of mean arterial pressure (MAP) and systolic blood pressure (SBP) remained slightly below normal values ​​in all groups. There was a significant decrease in MAP and SBP in the group submitted to PEEP (GPP) over time. The partial pressure of arterial carbon dioxide (PaCO2) was higher in GPP when compared to the other groups, inducing respiratory acidosis after one hour. The end-expired carbon dioxide concentration (ETCO2) presented slightly elevated means in the GP, while the GPP presented higher means, possibly related to the decrease in tidal volume in this group. Based on these results it was concluded that the use of PEEP led to acidemia that worsened over anesthetic time. In addition, prolonged isoflurane anesthesia promotes cardiorespiratory depression, regardless the ventilatory mode employed.(AU)

Capacidade pulmonar e funcional no pós-operatório de mulheres submetidas à mastectomia: série de casos / Pulmonary and functional capacity in the post-surgery of women submitted to mastectomy: preliminary results

Mulheres submetidas à cirurgia de mastectomia podem apresentar algumas complicações, dentre elas, alterações respiratórias e prejuízo funcional. O objetivo deste estudo foi avaliar a cinemática da parede torácica e a capacidade funcional no pós-operatório de pacientes mastectomizadas sem tratamento neoadjuvante e adjuvante associados. Foram avaliadas 4 mulheres no grupo mastectomia (GM) e 4 mulheres no grupo controle (GC). Todas as participantes foram submetidas aos procedimentos de avaliação antropométrica, função pulmonar, força muscular respiratória, cinemática da parede torácica e capacidade funcional. O GM também foi submetido à avaliação de inspeção e palpação torácica. Os dados foram analisados por meio de estatística descritiva. Foi observado que o GM apresentou menor variação de volume corrente da parede torácica, com delta de variação de 22,03% a menos que o GC, sendo a maior redução de volume corrente evidenciada no compartimento de caixa torácica pulmonar, com redução de 41,57% em relação ao GC. O GM não apresentou alterações de função pulmonar, força muscular respiratória e capacidade funcional, apresentando valores de normalidade nessas avaliações. Portanto, mulheres submetidas ao procedimento cirúrgico de mastectomia, sem tratamento neoadjuvante e adjuvante associados, não apresentaram comprometimento da função pulmonar, da força muscular respiratória e da capacidade funcional, contudo foi verificado redução do volume pulmonar na região do procedimento cirúrgico.

Women submitted to a mastectomy surgery may present some complications, among them, respiratory changes and functional impairment. The purpose of this study was to evaluate the chest wall kinematics and functional capacity in the postoperative period of mastectomized patients without associated adjuvant and neoadjuvant treatment. A total of four (4) women in the mastectomy group (MG) and four (4) in the control group (CG) were evaluated. All participants were submitted to the procedures of anthropometric evaluation, pulmonary function, respiratory muscle strength, chest wall kinematics and functional capacity. Patients in MG were also submitted to an inspection and palpation evaluation of the chest and breasts. Database was analyzed using descriptive statistics. It was observed that the MG presented a smaller variation of tidal volume of the chest wall, with a variation delta of 22.03% less than CG, with the largest reduction in tidal volume evidenced in the pulmonary chest cavity compartment, with a reduction of 41.57% when compared to CG. The MG did not present alterations of pulmonary function, respiratory muscle strength and functional capacity, presenting values of normality in these evaluations. Therefore, women submitted to the surgical procedure of mastectomy without associated neoadjuvant and adjuvant treatment did not present any impairment of pulmonary function, respiratory muscle strength and functional capacity. However, a reduction could be observed in the pulmonary volume in the region of the surgical procedure.

Uso y titulación de presión soporte en Argentina: estudio transversal de tipo encuesta online / Titration and characteristics of pressure-support ventilation use in Argentina: an online cross-sectional survey study

RESUMEN Objetivo: Identificar las prácticas habituales de uso y titulación del modo presión soporte (PC-CSV - pressure control continuous spontaneous ventilation) en pacientes bajo ventilación mecánica y analizar las formas de reconocimiento de sobreasistencia y subasistencia. Secundariamente, comparar las respuestas según profesión en relación al diagnóstico de sobreasistencia y subasistencia. Métodos: Se realizó una encuesta online utilizando la herramienta Survey Monkey. Se incluyeron a médicos, enfermeros y kinesiólogos de Argentina que tuvieran acceso al uso de PC-CSV en su práctica habitual. Resultados: Se recolectaron 509 encuestas desde octubre a diciembre 2018. El 74,1% de ellas correspondió a kinesiólogos. Un 77,6% refirió utilizar PC-CSV para iniciar la fase de soporte parcial. Un 43,8% selecciona el valor de presión de soporte inspiratorio basándose en volumen corriente. El principal objetivo de la selección de PEEP fue disminuir el trabajo respiratorio. El volumen corriente alto fue la variable primordial de detección de sobreasistencia, mientras que el uso de músculos accesorios fue la más elegida para subasistencia. Se observaron diferencias entre médicos y kinesiólogos en relación a las formas de detección de sobreasistencia. Conclusión: El modo más utilizado para la fase de soporte parcial es PC-CSV. La variable más elegida para titular la presión de soporte inspiratorio es volumen corriente y el principal objetivo de la PEEP es disminuir el trabajo respiratorio. La sobreasistencia es detectada prioritariamente por un volumen corriente elevado, mientras que la subasistencia mediante el uso de músculos accesorios. Se halló diferencias entre profesiones en relación a los criterios de detección de sobreasistencia.

ABSTRACT Objective: To identify common practices related to the use and titration of pressure-support ventilation (PC-CSV - pressure control-continuous spontaneous ventilation) in patients under mechanical ventilation and to analyze diagnostic criteria for over-assistance and under-assistance. The secondary objective was to compare the responses provided by physician, physiotherapists and nurses related to diagnostic criteria for over-assistance and under-assistance. Methods: An online survey was conducted using the Survey Monkey tool. Physicians, nurses and physiotherapists from Argentina with access to PC-CSV in their usual clinical practice were included. Results: A total of 509 surveys were collected from October to December 2018. Of these, 74.1% were completed by physiotherapists. A total of 77.6% reported using PC-CSV to initiate the partial ventilatory support phase, and 43.8% of respondents select inspiratory pressure support level based on tidal volume. The main objective for selecting positive end-expiratory pressure (PEEP) level was to decrease the work of breathing. High tidal volume was the primary variable for detecting over-assistance, while the use of accessory respiratory muscles was the most commonly chosen for under-assistance. Discrepancies were observed between physicians and physiotherapists in relation to the diagnostic criteria for over-assistance. Conclusion: The most commonly used mode to initiate the partial ventilatory support phase was PC-CSV. The most frequently selected variable to guide the titration of inspiratory pressure support level was tidal volume, and the main objective of PEEP was to decrease the work of breathing. Over-assistance was detected primarily by high tidal volume, while under-assistance by accessory respiratory muscles activation. Discrepancies were observed among professions in relation to the diagnostic criteria for over-assistance, but not for under-assistance.

Protective mechanical ventilation in suspected influenza infection

Abstract INTRODUCTION: Patients with acute respiratory failure due to influenza require ventilatory support. However, mechanical ventilation itself can exacerbate lung damage and increase mortality. METHODS: The aim of this study was to describe a feasible and protective ventilation protocol, with limitation of the tidal volume to ≤6 mL/kg of the predicted weight and a driving pressure ≤15 cmH2O after application of the alveolar recruitment maneuver and PEEP titration. RESULTS: Initial improvement in oxygenation and respiratory mechanics were observed in the four cases submitted to the proposed protocol. CONCLUSIONS: Our results indicate that the mechanical ventilation strategy applied could be optimized.

Characteristics of pulmonary function in infants and young children with pertussis-like coughing / 中国当代儿科杂志

OBJECTIVE@#To study the characteristics of pulmonary function in children with pertussis-like coughing caused by different pathogen infections.@*METHODS@#The data on etiology and tidal breathing pulmonary function were collected from 95 hospitalized infants and young children with pertussis-like coughing. The tidal breathing pulmonary function was compared between these children and 67 healthy children. According to the type of pathogen, the children with pertussis-like coughing were classified to 6 groups: pertussis (n=17), viral infection (n=23), tuberculosis infection (n=6), Mycoplasma infection (n=9), other bacterial infection (n=8), and unknown pathogen (n=32).@*RESULTS@#Among the 95 children with pertussis-like coughing, 15 (16%) had mild obstructive ventilatory dysfunction, 30 (32%) had moderate obstructive ventilatory dysfunction, and 22 (23%) had severe obstructive ventilatory dysfunction. Compared with the normal control group, the children with pertussis-like coughing had significant reductions in inspiratory-to-expiratory time ratio, ratio of time to peak tidal expiratory flow to total expiratory time (tPF%tE), and ratio of volume to peak tidal expiratory flow to total expiratory volume (vPF%vE) (P<0.05). The tuberculosis infection and Mycoplasma infection groups had a significantly lower tidal volume than the normal control group (P<0.05). All pathogen infection groups except the tuberculosis infection group had significantly lower tPF%tE and vPF%vE than the normal control group (P<0.05). The pertussis group had significantly lower tPF%tE and vPF%vE than the other infection groups (P<0.05).@*CONCLUSIONS@#Most of children with pertussis-like coughing have abnormal pulmonary functions. The children with Bordetella pertussis infection have the most severe pulmonary function impairment. Tidal breathing pulmonary function test may provide a reference for pathogen analysis of children with pertussis-like coughing.

Comparison of pressure-controlled volume-guaranteed ventilation and volume-controlled ventilation in obese patients during gynecologic laparoscopic surgery in the Trendelenburg position / Comparação entre ventilação garantida por volume controlado por pressão e ventilação controlada por volume em pacientes obesos durante cirurgia laparoscópica ginecológica na posição de Trendelenburg

Abstract Background and objectives: The aim of this study was to investigate the efficacy of the pressure-controlled, volume-guaranteed (PCV-VG) and volume-controlled ventilation (VCV) modes for maintaining adequate airway pressures, lung compliance and oxygenation in obese patients undergoing laparoscopic hysterectomy in the Trendelenburg position. Methods: Patients (104) who underwent laparoscopic gynecologic surgery with a body mass index between 30 and 40 kg.m-2 were randomized to receive either VCV or PCV-VG ventilation. The tidal volume was set at 8 mL.kg-1, with an inspired oxygen concentration of 0.4 with a Positive End-Expiratory Pressure (PEEP) of 5 mmHg. The peak inspiratory pressure, mean inspiratory pressure, plateau pressure, driving pressure, dynamic compliance, respiratory rate, exhaled tidal volume, etCO2, arterial blood gas analysis, heart rate and mean arterial pressure at 5 minutes after induction of anesthesia in the and at 5, 30 and 60 minutes, respectively, after pneumoperitoneum in the Trendelenburg position were recorded. Results: The PCV-VG group had significantly decreased peak inspiratory pressure, mean inspiratory pressur, plateau pressure, driving pressure and increased dynamic compliance compared to the VCV group. Mean PaO2 levels were significantly higher in the PCV-VG group than in the VCV group at every time point after pneumoperitoneum in the Trendelenburg position. Conclusions: The PCV-VG mode of ventilation limited the peak inspiratory pressure, decreased the driving pressure and increased the dynamic compliance compared to VCV in obese patients undergoing laparoscopic hysterectomy. PCV-VG may be a preferable modality to prevent barotrauma during laparoscopic surgeries in obese patients.

Resumo Justificativa e objetivos: O objetivo deste estudo foi investigar a eficácia dos modos de ventilação garantida por volume controlado por pressão (PCV-VG) e ventilação controlada por volume (VCV) para manter pressões adequadas nas vias aéreas, complacência pulmonar e oxigenação em pacientes obesos submetidos à histerectomia laparoscópica na posição de Trendelenburg. Métodos: Cento e quatro pacientes submetidos à cirurgia ginecológica laparoscópica, com índice de massa corporal entre 30 e 40 kg.m-2, foram randomizados para receber ventilação com VCV ou PCV-VG. O volume corrente foi fixado em 8 mL.kg-1, com uma concentração inspirada de oxigênio de 0,4 e pressão positiva expiratória final (PEEP) de 5 mmHg. Registramos os seguintes parâmetros: pressão de pico inspiratório, pressão inspiratória média, pressão de platô, driving pressure, complacência dinâmica, frequência respiratória, volume corrente expirado, etCO2, gasometria arterial, frequência cardíaca e pressão arterial média aos 5, 30 e 60 minutos, respectivamente, após o pneumoperitônio na posição de Trendelenburg. Resultados: O grupo PCV-VG apresentou uma redução significativa da pressão de pico inspiratório, pressão inspiratória média, pressão de platô, driving pressure e aumento da complacência dinâmica comparado ao grupo VCV. Os níveis médios de PaO2 foram significativamente maiores no grupo PCV-VG do que no grupo VCV em todos os momentos após o pneumoperitônio na posição de Trendelenburg. Conclusões: O modo de ventilação PCV-VG limitou a pressão de pico inspiratório, diminuiu a driving pressure e aumentou a complacência dinâmica, comparado ao VCV em pacientes obesas submetidas à histerectomia laparoscópica. O PCV-VG pode ser uma modalidade preferida para prevenir o barotrauma durante cirurgias laparoscópicas em pacientes obesos.

Efecto de la PEEP sobre el componente resistivo inspiratorio en pacientes con sindrome de distrés respiratorio agudo ventilados a bajo volumen corriente / Effect of PEEP on inspiratory resistance components in patients with acute respiratory distress syndrome ventilated at low tidal volume

RESUMEN Objetivo: Describir el comportamiento del componente resistivo ante el incremento de la presión positiva espiratoria final (PEEP) en pacientes con síndrome de distrés respiratorio agudo ventilados con una estrategia de ventilación protectora. Métodos: En modo controlada por volumen, a 6mL/Kg y flujo constante se realizaron oclusiones teleinspiratorias a PEEP 0, 5 10, 15 y 20cmH2O. Se obtuvieron valores de presión pico, inicial, plateau y se calculó resistencias máxima, mínima y diferencial. Las comparaciones se realizaron mediante test de ANOVA para muestras relacionadas con corrección post hoc de Bonferroni. Se consideró significativo una p < 0,05. Resultados: La resistencia máxima más elevada se observó en los niveles de PEEP más bajos. Los valores de PEEP 10 y 15cmH2O tuvieron diferencias significativas con PEEP 5 y 0cmH2O, mientras que PEEP 20cmH2O únicamente con PEEP 0cmH2O (p < 0,05). La resistencia mínima tuvo la misma conducta que la resistencia máxima. A partir de PEEP 10cmH2O todos tuvieron diferencias significativas con PEEP 0 y 5cmH2O (p < 0,05). La resistencia diferencial se expresó de manera opuesta a la resistencia máxima y mínima. El único nivel de PEEP que experimentó diferencias significativas con PEEP 0 y 5cmH2O fue PEEP 20cmH2O. También hubo diferencias entre PEEP 15 y PEEP 5cmH2O (p < 0,05). Conclusiones: Durante ventilación protectora en pacientes com síndrome de distrés respiratorio agudo, la resistencia máxima del sistema respiratorio tiene un comportamiento decreciente con la PEEP y refleja la respuesta que tiene la resistencia mínima. Mientras que la resistencia diferencial mantiene su conducta creciente con los valores de PEEP.

ABSTRACT Objective: To describe the behavior of inspiratory resistance components when positive end-expiratory pressure (PEEP) increases in patients with acute respiratory distress syndrome under a protective ventilation strategy. Methods: In volume-controlled mode, at 6mL/kg and constant flow, end-inspiratory occlusions were performed at 0, 5 10, 15 and 20cmH2O PEEP. Peak, initial and plateau pressure values were assessed, calculating the maximum, minimum and differential resistances. The results were compared by repeated measures analysis of variance (ANOVA) with post hoc Bonferroni correction, considering p < 0.05 significant. Results: The highest maximum resistance was observed at the lowest PEEP levels. The values for 10 and 15cmH2O PEEP significantly differed from those for 5 and 0cmH2O PEEP, whereas that for 20cmH2O PEEP only significantly differed from that for 0cmH2O PEEP (p < 0.05). The minimum resistance behaved similarly to the maximum resistance; the values for PEEP levels from 10cmH2O to 20cmH2O significantly differed from those for 0 and 5cmH2O PEEP (p < 0.05). Differential resistance showed the opposite variation to the maximum and minimum resistances. The only PEEP level that showed significant differences from 0 and 5cmH2O PEEP was 20cmH2O PEEP. Significant differences were also found between 15 and 5cmH2O PEEP (p < 0.05). Conclusions: During protective ventilation in patients with acute respiratory distress syndrome, the maximum resistance of the respiratory system decreases with PEEP, reflecting the minimum resistance response, whereas differential resistance increases with PEEP.

Respiratory evaluation through volumetric capnography among grade III obese and eutrophic individuals: a comparative study

ABSTRACT BACKGROUND: Excess trunk body fat in obese individuals influences respiratory physiological function. The aims of this study were to compare volumetric capnography findings (VCap) between severely obese patients and normal-weight subjects and to assess whether there is any association between neck circumference (NC), waist-hip ratio (WHR) and VCap among grade III obese individuals. DESIGN AND SETTING: Analytical observational case-matched cross-sectional study, University of Campinas. METHODS: This cross-sectional study compared VCap variables between 60 stage III obese patients and 60 normal-weight individuals. RESULTS: In comparison with the normal-weight group, obese patients presented higher alveolar minute volume (8.92 ± 4.94 versus 6.09 ± 2.2; P = < 0.0001), CO2 production (278 ± 91.0 versus 209 ± 60.23; P < 0.0001), expiratory tidal volume (807 ± 365 versus 624 ± 202; P = 0.005), CO2 production per breath (21.1 ± 9.7 versus 16.7 ± 6.16; P = 0.010) and peak expiratory flow (30.9 ± 11.9 versus 25.5 ± 9.13; P = 0.004). The end-expiratory CO2 (PetCO2) concentration (33.5 ± 4.88 versus 35.9 ± 3.79; P = 0.013) and the phase 3 slope were normalized according to expired tidal volume (0.02 ± 0.05 versus 0.03 ± 0.01; P = 0.049) were lower in the obese group. CONCLUSIONS: The greater the NC was, the larger were the alveolar minute volume, anatomical dead space, CO2 production per minute and per breath and expiratory volume; whereas the smaller were the phase 2 slope (P2Slp), phase 3 slope (P3Slp) and pressure drop in the mouth during inspiration.

Otimização de condições para teste de apneia em paciente hipoxêmico com morte encefálica / Optimization of conditions for apnea testing in a hypoxemic brain dead patient

RESUMO Relatamos o caso de um paciente que evoluiu com suspeita de morte encefálica associada à atelectasia e à hipoxemia moderada a grave, apesar de instituídos ventilação protetora, sistema de aspiração traqueal fechado, pressão positiva ao final da expiração moderada e manobra de recrutamento. Diante da não obtenção de pressão parcial de oxigênio adequada para o teste de apneia, optamos por pronar o paciente, utilizar pressão positiva expiratória final mais elevada, realizar nova manobra de recrutamento e ventilar com volume corrente mais elevado (8mL/kg), sem ultrapassar pressão de platô de 30cmH2O. O teste de apneia foi realizado em posição prona, com válvula de pressão positiva contínua nas vias aéreas acoplada em tubo T. O atraso no diagnóstico foi de 10 horas; a doação de órgãos não foi possível devido à parada circulatória. Este relato demonstra as dificuldades para obtenção de níveis de pressão parcial de oxigênio mais altos para a realização do teste de apneia. Os atrasos que isso pode acarretar ao diagnóstico de morte encefálica e ao processo de doação de órgãos são discutidos, além de potenciais estratégias de otimização da pressão parcial de oxigênio para realização do teste, conforme as recomendações atuais.

ABSTRACT We report the case of a patient in whom brain death was suspected and associated with atelectasis and moderate to severe hypoxemia even though the patient was subjected to protective ventilation, a closed tracheal suction system, positive end-expiratory pressure, and recruitment maneuvers. Faced with the failure to obtain an adequate partial pressure of oxygen for the apnea test, we elected to place the patient in a prone position, use higher positive end-expiratory pressure, perform a new recruitment maneuver, and ventilate with a higher tidal volume (8mL/kg) without exceeding the plateau pressure of 30cmH2O. The apnea test was performed with the patient in a prone position, with continuous positive airway pressure coupled with a T-piece. The delay in diagnosis was 10 hours, and organ donation was not possible due to circulatory arrest. This report demonstrates the difficulties in obtaining higher levels of the partial pressure of oxygen for the apnea test. The delays in the diagnosis of brain death and in the organ donation process are discussed, as well as potential strategies to optimize the partial pressure of oxygen to perform the apnea test according to the current recommendations.