Smart Care™ versus respiratory physiotherapy-driven manual weaning for critically ill adult patients: a randomized controlled trial.

INTRODUCTION: A recent meta-analysis showed that weaning with SmartCare™ (Dräger, Lübeck, Germany) significantly decreased weaning time in critically ill patients. However, its utility compared with respiratory physiotherapist-protocolized weaning is still a matter of debate. We hypothesized that weaning with SmartCare™ would be as effective as respiratory physiotherapy-driven weaning in critically ill patients. METHODS: Adult critically ill patients mechanically ventilated for more than 24 hours in the adult intensive care unit of the Albert Einstein Hospital, São Paulo, Brazil, were randomly assigned to be weaned either by progressive discontinuation of pressure support ventilation (PSV) with SmartCare™. Demographic data, respiratory function parameters, level of PSV, tidal volume (VT), positive end-expiratory pressure (PEEP), inspired oxygen fraction (FIO2), peripheral oxygen saturation (SpO2), end-tidal carbon dioxide concentration (EtCO2) and airway occlusion pressure at 0.1 second (P0.1) were recorded at the beginning of the weaning process and before extubation. Mechanical ventilation time, weaning duration and rate of extubation failure were compared. RESULTS: Seventy patients were enrolled 35 in each group. There was no difference between the two groups concerning age, sex or diagnosis at study entry. There was no difference in maximal inspiratory pressure, maximal expiratory pressure, forced vital capacity or rapid shallow breathing index at the beginning of the weaning trial. PEEP, VT, FIO2, SpO2, respiratory rate, EtCO2 and P0.1 were similar between the two groups, but PSV was not (median: 8 vs. 10 cmH2O; p =0.007). When the patients were ready for extubation, PSV (8 vs. 5 cmH2O; p =0.015) and PEEP (8 vs. 5 cmH2O; p <0.001) were significantly higher in the respiratory physiotherapy-driven weaning group. Total duration of mechanical ventilation (3.5 [2.0-7.3] days vs. 4.1 [2.7-7.1] days; p =0.467) and extubation failure (2 vs. 2; p =1.00) were similar between the two groups. Weaning duration was shorter in the respiratory physiotherapy-driven weaning group (60 [50-80] minutes vs. 110 [80-130] minutes; p <0.001). CONCLUSION: A respiratory physiotherapy-driven weaning protocol can decrease weaning time compared with an automatic system, as it takes into account individual weaning difficulties. TRIAL REGISTRATION: Clinicaltrials.gov Identifier: NCT02122016 . Date of Registration: 27 August 2013.

How large is the lung recruitability in early acute respiratory distress syndrome: a prospective case series of patients monitored by computed tomography.

INTRODUCTION: The benefits of higher positive end expiratory pressure (PEEP) in patients with acute respiratory distress syndrome (ARDS) have been modest, but few studies have fully tested the "open-lung hypothesis". This hypothesis states that most of the collapsed lung tissue observed in ARDS can be reversed at an acceptable clinical cost, potentially resulting in better lung protection, but requiring more intensive maneuvers. The short-/middle-term efficacy of a maximum recruitment strategy (MRS) was recently described in a small physiological study. The present study extends those results, describing a case-series of non-selected patients with early, severe ARDS submitted to MRS and followed until hospital discharge or death. METHODS: MRS guided by thoracic computed tomography (CT) included two parts: a recruitment phase to calculate opening pressures (incremental steps under pressure-controlled ventilation up to maximum inspiratory pressures of 60 cmH2O, at constant driving-pressures of 15 cmH2O); and a PEEP titration phase (decremental PEEP steps from 25 to 10 cmH2O) used to estimate the minimum PEEP to keep lungs open. During all steps, we calculated the size of the non-aerated (-100 to +100 HU) compartment and the recruitability of the lungs (the percent mass of collapsed tissue re-aerated from baseline to maximum PEEP). RESULTS: A total of 51 severe ARDS patients, with a mean age of 50.7 years (84% primary ARDS) was studied. The opening plateau-pressure was 59.6 (±5.9 cmH2O), and the mean PEEP titrated after MRS was 24.6 (±2.9 cmH2O). Mean PaO2/FiO2 ratio increased from 125 (±43) to 300 (±103; P<0.0001) after MRS and was sustained above 300 throughout seven days. Non-aerated parenchyma decreased significantly from 53.6% (interquartile range (IQR): 42.5 to 62.4) to 12.7% (IQR: 4.9 to 24.2) (P<0.0001) after MRS. The potentially recruitable lung was estimated at 45% (IQR: 25 to 53). We did not observe major barotrauma or significant clinical complications associated with the maneuver. CONCLUSIONS: MRS could efficiently reverse hypoxemia and most of the collapsed lung tissue during the course of ARDS, compatible with a high lung recruitability in non-selected patients with early, severe ARDS. This strategy should be tested in a prospective randomized clinical trial.

Importância da tomografia computadorizada de tórax na avaliação de pacientes com síndrome do desconforto respiratório agudo / Importance of computed tomography scans of the chest in the evaluation of patients with acute respiratory distress syndrome

A tomografia computadorizada (TC) é uma excelente ferramenta diagnóstica de fundamental importância para o cuidado de pacientes graves nas unidades de terapia intensiva e que revolucionou o entendimento do comportamento pulmonar na lesão pulmonar aguda/síndrome do desconforto respiratório agudo (SDRA). O emprego da TC de tórax como ferramenta de ajuste da ventilação mecânica em pacientes com SDRA pode conferir maior proteção à ocorrência dos vários mecanismos de lesão induzida por ventilação mecânica e talvez até melhorar o desfecho clínico. O objetivo do presente artigo foi descrever a importância da TC de tórax na avaliação de pacientes com SDRA, com detalhamento dos mecanismos envolvidos no colapso pulmonar e na individualização da estratégia ventilatória por meio da estratégia de recrutamento máximo.

Síndrome do Desconforto Respiratório Agudo: definição / Acute Respiratory Distress Syndrome: definition

A definição da síndrome do desconforto respiratório agudo (SDRA), simplificada pela Conferência Americana e Europeia de Consenso em SDRA de 1998, inclui a presença de infiltrado pulmonar bilateral, relação pressão parcial arterial de oxigênio/fração inspirada de oxigênio < 200 mmHg e pressão capilar pulmonar < 18 mmHg ou ausência de sinais de insuficiência cardíaca esquerda. Atualmente, o entendimento mais complexo da SDRA inclui sua análise mais detalhada pela tomografia de tórax e por outros métodos de imagem. A utilização de marcadores genéticos e biomarcadores plasmáticos e no lavado broncoalveolar antecipará o diagnóstico e o prognóstico de SDRA. A introdução de sistemas automáticos de diagnóstico e a análise de fatores de risco e de fatores prognósticos associados à SDRA ajudarão no entendimento mais aprofundado da doença para seu melhor tratamento e diminuição de suas taxas de mortalidade.

The definition of acute respiratory distress syndrome (ARDS) was simplified at the 1998 American-European Consensus Conference of 1998 and now includes the following: bilateral pulmonary infiltrates; arterial oxygen tension/fraction of inspired oxygen < 200 mmHg; and pulmonary capillary wedge pressure < 18 mmHg or no signs of left heart failure. Recently, tomography and other imaging methods have allowed the chest to be analyzed in greater detail, thereby leading to a more complex understanding of ARDS. The use of genetic markers and biomarkers in plasma and bronchoalveolar lavage could lead to earlier ARDS diagnosis, thereby improving prognosis. The introduction of automatic diagnostic screening, together with the analysis of risk factors and prognostic factors associated with the syndrome, will deepen the understanding of ARDS, improving treatment and potentially reducing the associated mortality rates.

Reversibility of lung collapse and hypoxemia in early acute respiratory distress syndrome.

RATIONALE: The hypothesis that lung collapse is detrimental during the acute respiratory distress syndrome is still debatable. One of the difficulties is the lack of an efficient maneuver to minimize it. OBJECTIVES: To test if a bedside recruitment strategy, capable of reversing hypoxemia and collapse in > 95% of lung units, is clinically applicable in early acute respiratory distress syndrome. METHODS: Prospective assessment of a stepwise maximum-recruitment strategy using multislice computed tomography and continuous blood-gas hemodynamic monitoring. MEASUREMENTS AND MAIN RESULTS: Twenty-six patients received sequential increments in inspiratory airway pressures, in 5 cm H(2)O steps, until the detection of Pa(O(2)) + Pa(CO(2)) >or= 400 mm Hg. Whenever this primary target was not met, despite inspiratory pressures reaching 60 cm H(2)O, the maneuver was considered incomplete. If there was hemodynamic deterioration or barotrauma, the maneuver was to be interrupted. Late assessment of recruitment efficacy was performed by computed tomography (9 patients) or by online continuous monitoring in the intensive care unit (15 patients) up to 6 h. It was possible to open the lung and to keep the lung open in the majority (24/26) of patients, at the expense of transient hemodynamic effects and hypercapnia but without major clinical consequences. No barotrauma directly associated with the maneuver was detected. There was a strong and inverse relationship between arterial oxygenation and percentage of collapsed lung mass (R = - 0.91; p < 0.0001). CONCLUSIONS: It is often possible to reverse hypoxemia and fully recruit the lung in early acute respiratory distress syndrome. Due to transient side effects, the required maneuver still awaits further evaluation before routine clinical application.

Imbalances in regional lung ventilation: a validation study on electrical impedance tomography.

Imbalances in regional lung ventilation, with gravity-dependent collapse and overdistention of nondependent zones, are likely associated to ventilator-induced lung injury. Electric impedance tomography is a new imaging technique that is potentially capable of monitoring those imbalances. The aim of this study was to validate electrical impedance tomography measurements of ventilation distribution, by comparison with dynamic computerized tomography in a heterogeneous population of critically ill patients under mechanical ventilation. Multiple scans with both devices were collected during slow-inflation breaths. Six repeated breaths were monitored by impedance tomography, showing acceptable reproducibility. We observed acceptable agreement between both technologies in detecting right-left ventilation imbalances (bias = 0% and limits of agreement = -10 to +10%). Relative distribution of ventilation into regions or layers representing one-fourth of the thoracic section could also be assessed with good precision. Depending on electrode positioning, impedance tomography slightly overestimated ventilation imbalances along gravitational axis. Ventilation was gravitationally dependent in all patients, with some transient blockages in dependent regions synchronously detected by both scanning techniques. Among variables derived from computerized tomography, changes in absolute air content best explained the integral of impedance changes inside regions of interest (r(2) > or = 0.92). Impedance tomography can reliably assess ventilation distribution during mechanical ventilation.