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1.
Intensive Care Med ; 46(12): 2314-2326, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33140181

RESUMO

Mechanical ventilation may have adverse effects on both the lung and the diaphragm. Injury to the lung is mediated by excessive mechanical stress and strain, whereas the diaphragm develops atrophy as a consequence of low respiratory effort and injury in case of excessive effort. The lung and diaphragm-protective mechanical ventilation approach aims to protect both organs simultaneously whenever possible. This review summarizes practical strategies for achieving lung and diaphragm-protective targets at the bedside, focusing on inspiratory and expiratory ventilator settings, monitoring of inspiratory effort or respiratory drive, management of dyssynchrony, and sedation considerations. A number of potential future adjunctive strategies including extracorporeal CO2 removal, partial neuromuscular blockade, and neuromuscular stimulation are also discussed. While clinical trials to confirm the benefit of these approaches are awaited, clinicians should become familiar with assessing and managing patients' respiratory effort, based on existing physiological principles. To protect the lung and the diaphragm, ventilation and sedation might be applied to avoid excessively weak or very strong respiratory efforts and patient-ventilator dysynchrony.

2.
Respir Care ; 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-33082218

RESUMO

BACKGROUND: The ratio of dead space to tidal volume (VD/VT) is a clinically relevant parameter in ARDS; it has been shown to predict mortality, and it determines the extent to which extracorporeal CO2 removal reduces tidal volume (VT) and driving pressure (ΔP). VD/VT can be estimated with volumetric capnography, but empirical formulas using demographic and physiological information have been proposed to estimate VD/VT without the need of additional equipment. It is unknown whether estimated and measured VD/VT produce similar estimates of the predicted effect of extracorporeal CO2 removal on ΔP. METHODS: We performed a secondary analysis of data from a previous clinical trial including subjects with ARDS in whom VD/VT and CO2 production (V̇CO2 ) were measured with volumetric capnography. The estimated ratio of dead space to tidal volume (VD,est/VT) was calculated using standard empiric formulas. Agreement between measured and estimated values was evaluated with Bland-Altman analysis. Agreement between the predicted change in ΔP with extracorporeal CO2 removal as computed using the measured ratio of alveolar dead space to tidal volume (VDalv/VT) or estimated VDalv/VT (VDalv,est/VT) was also evaluated. RESULTS: VD,est/VT was higher than measured VD/VT, and agreement between them was low (bias 0.05, limits of agreement -0.21 to 0.31). Differences between measured and estimated V̇CO2 accounted for 57% of the error in VD,est/VT. The predicted reduction in ΔP with extracorporeal CO2 removal computed using VDalv,est/VT was in reasonable agreement with the expected reduction using VDalv/VT (bias -0.7 cm H2O, limits of agreement -1.87 to 0.47 cm H2O). In multivariable regression, measured VD/VT was associated with mortality (odds ratio 1.9, 95% CI 1.2-3.1, P = .01), but VD,est/VT was not (odds ratio 1.2, 95% CI 0.8-1.8, P = .3). CONCLUSIONS: VD/VT and VD,est/VT showed low levels of agreement and cannot be used interchangeably in clinical practice. Nevertheless, the predicted decrease in ΔP due to extracorporeal CO2 removal was similar when computed from either estimated or measured VDalv/VT.

3.
Rev Fac Cien Med Univ Nac Cordoba ; 77(3): 208-210, 2020 08 21.
Artigo em Espanhol | MEDLINE | ID: mdl-32991115

RESUMO

Introduction: Idiopathic systemic capillary leak syndrome (ISCLS) or Clarkson's disease is unusual but potentially lethal, characterized by recurrent shock incidents and anasarca secondary to idiopathic increase of capillary permeability. In such a context, the use of venoarterial Extracorporeal Membrane Oxygenation (ECMO) as cardiorespiratory support is a rescue action that seeks hemodynamic stability generation until spontaneous disappearance of the capillary occurs with the objective of surpassing the complications of resorption phase. Case Report: A 42 year old patient presented ISCLS and required ECMO as hemodynamic support for 8 days. She remained 20 days in Intensive Care Unit and was given hospital release after 43 days. Conclusions: The use of ECMO in the reported case was a useful strategy in the ISCLS management as a bridge to recovery both in the leak stage and the fluid resorption phase. Notwithstanding its indication is limited to thoroughly selected patients and requires further debate between specialists about its risks and benefits.


Assuntos
Síndrome de Vazamento Capilar , Oxigenação por Membrana Extracorpórea , Adulto , Síndrome de Vazamento Capilar/terapia , Feminino , Humanos , Unidades de Terapia Intensiva
4.
Respir Care ; 2020 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-32843513

RESUMO

BACKGROUND: The unifying goal of lung-protective ventilation strategies in ARDS is to minimize the strain and stress applied by mechanical ventilation to the lung to reduce ventilator-induced lung injury (VILI). The relative contributions of the magnitude and frequency of mechanical stress and the end-expiratory pressure to the development of VILI is unknown. Consequently, it is uncertain whether the risk of VILI is best quantified in terms of tidal volume (VT), driving pressure (ΔP), or mechanical power. METHODS: The correlation between differences in VT, ΔP, and mechanical power and the magnitude of mortality benefit in trials of lung-protective ventilation strategies in adult subjects with ARDS was assessed by meta-regression. Modified mechanical power was computed including PEEP (Powerelastic), excluding PEEP (Powerdynamic), and using ΔP (Powerdriving). The primary analysis incorporated all included trials. A secondary subgroup analysis was restricted to trials of lower versus higher PEEP strategies. RESULTS: We included 9 trials involving 4,731 subjects in the analysis. Odds ratios for moderation derived from meta-regression showed that variations in VT, ΔP, and Powerdynamic were associated with increased mortality with odds ratios of 1.24 (95% CI 1.03-1.49), 1.31 (95% CI 1.03-1.66), and 1.37 (95% CI 1.05-1.78), respectively. In trials comparing higher versus lower PEEP strategies, Powerelastic was increased in the higher PEEP arm (24 ± 1.7 vs 20 ± 1.5 J/min, respectively), whereas the other parameters were not affected on average by a higher PEEP ventilation strategy. CONCLUSIONS: In trials of lung-protective ventilation strategies, VT, ΔP, Powerelastic, Powerdynamic, and Powerdriving exhibited similar moderation of treatment effect on mortality. In this study, modified mechanical power did not add important information on the risk of death from VILI in comparison to VT or ΔP.

7.
Crit Care Explor ; 2(5): e0118, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32671348

RESUMO

Objectives: To design and test a ventilator circuit that can be used for ventilation of two or more patients with a single ventilator, while allowing individualization of tidal volume, fractional concentration of oxygen, and positive end-expiratory pressure to each patient, irrespective of the other patient's respiratory system mechanics. Design: Description and proof of concept studies. Settings: Respiratory therapy laboratory. Subjects: Ventilation of mechanical test lungs. Interventions: Following a previously advocated design, we used components readily available in our hospital to assemble two "bag-in-a-box" breathing circuits. Each patient circuit consisted of a flexible bag in a rigid container connected via one-way valve to a test lung, along with an inline positive end-expiratory pressure valve, connected to the ventilator's expiratory limb. Compressed gas fills the bags during "patient" exhalation. During inspiration, gas from the ventilator, in pressure control mode, enters the containers and displaces gas from the bags to the test lungs. We varied tidal volume, "respiratory system" compliance, and positive end-expiratory pressure in one lung and observed the effect on the tidal volume of the other. Measurements and Main Results: We were able to obtain different tidal volume, dynamic driving pressure, and positive end-expiratory pressure in the two lungs under widely different compliances in both lungs. Complete obstruction, or disconnection at the circuit connection to one test lung, had minimal effect (< 5% on average) on the ventilation to the co-ventilated lung. Conclusions: A secondary circuit "bag-in-the-box" system enables individualized ventilation of two lungs overcoming many of the concerns of ventilating more than one patient with a single ventilator.

8.
J Intensive Care Soc ; 21(2): 119-123, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32489407

RESUMO

Rationale: Acute hypoxemic respiratory failure is a condition that comprises a wide array of entities. Obtaining a histological lung sample might help reach a diagnosis and direct an appropriate treatment in a select group of patients. Objective: To describe our experience in the use of cryobiopsy for the diagnosis of acute hypoxemic respiratory failure of undetermined origin. Methods: Retrospective analysis of case series of patients with acute hypoxemic respiratory failure who underwent lung cryobiopsy at the Intensive Care Unit of the Hospital Italiano de Buenos Aires, Argentina. Results: Cryobiopsy yielded a histological diagnosis in all patients (n = 10, 100%). This led to either a change in therapy or continuation of a specific treatment in eight of these patients. Cryobiopsy was found to be contributive in all the patients who did not meet Berlin criteria for acute respiratory distress syndrome. No major complications were associated with the procedure. Conclusions: Cryobiopsy is a safe procedure with a high diagnostic yield in a selected group of patients.

9.
Am J Respir Crit Care Med ; 202(7): 950-961, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-32516052

RESUMO

Mechanical ventilation can cause acute diaphragm atrophy and injury, and this is associated with poor clinical outcomes. Although the importance and impact of lung-protective ventilation is widely appreciated and well established, the concept of diaphragm-protective ventilation has recently emerged as a potential complementary therapeutic strategy. This Perspective, developed from discussions at a meeting of international experts convened by PLUG (the Pleural Pressure Working Group) of the European Society of Intensive Care Medicine, outlines a conceptual framework for an integrated lung- and diaphragm-protective approach to mechanical ventilation on the basis of growing evidence about mechanisms of injury. We propose targets for diaphragm protection based on respiratory effort and patient-ventilator synchrony. The potential for conflict between diaphragm protection and lung protection under certain conditions is discussed; we emphasize that when conflicts arise, lung protection must be prioritized over diaphragm protection. Monitoring respiratory effort is essential to concomitantly protect both the diaphragm and the lung during mechanical ventilation. To implement lung- and diaphragm-protective ventilation, new approaches to monitoring, to setting the ventilator, and to titrating sedation will be required. Adjunctive interventions, including extracorporeal life support techniques, phrenic nerve stimulation, and clinical decision-support systems, may also play an important role in selected patients in the future. Evaluating the clinical impact of this new paradigm will be challenging, owing to the complexity of the intervention. The concept of lung- and diaphragm-protective ventilation presents a new opportunity to potentially improve clinical outcomes for critically ill patients.


Assuntos
Diafragma/lesões , Atrofia Muscular/prevenção & controle , Respiração Artificial/métodos , Lesão Pulmonar Induzida por Ventilação Mecânica/prevenção & controle , Consenso , Cuidados Críticos , Sistemas de Apoio a Decisões Clínicas , Terapia por Estimulação Elétrica , Oxigenação por Membrana Extracorpórea , Humanos , Atrofia Muscular/etiologia , Nervo Frênico , Respiração Artificial/efeitos adversos , Lesão Pulmonar Induzida por Ventilação Mecânica/etiologia
10.
Curr Opin Crit Care ; 26(1): 35-40, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31738233

RESUMO

PURPOSE OF REVIEW: Diaphragm weakness can impact survival and increases comorbidities in ventilated patients. Mechanical ventilation is linked to diaphragm dysfunction through several mechanisms of injury, referred to as myotrauma. By monitoring diaphragm activity and titrating ventilator settings, the critical care clinician can have a direct impact on diaphragm injury. RECENT FINDINGS: Both the absence of diaphragm activity and excessive inspiratory effort can result in diaphragm muscle weakness, and recent evidence demonstrates that a moderate level of diaphragm activity during mechanical ventilation improves ICU outcome. This supports the hypothesis that by avoiding ventilator overassistance and underassistance, the clinician can implement a diaphragm-protective ventilation strategy. Furthermore, eccentric diaphragm contractions and end-expiratory shortening could impact diaphragm strength as well. This review describes these potential targets for diaphragm protective ventilation. SUMMARY: A ventilator strategy that results in appropriate levels of diaphragm activity has the potential to be diaphragm-protective and improve clinical outcome. Monitoring respiratory effort during mechanical ventilation is becoming increasingly important.


Assuntos
Diafragma , Respiração Artificial , Diafragma/fisiopatologia , Humanos , Debilidade Muscular/etiologia , Debilidade Muscular/prevenção & controle , Respiração , Respiração Artificial/efeitos adversos , Ventiladores Mecânicos
11.
Respir Care ; 65(1): 11-20, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31615922

RESUMO

BACKGROUND: The difference between Bohr and Enghoff dead space are not well described in ARDS patients. We aimed to analyze the effect of PEEP on the Bohr and Enghoff dead spaces in a model of ARDS. METHODS: 10 pigs submitted to randomized PEEP steps of 0, 5, 10, 15, 20, 25 and 30 cm H2O were evaluated with the use of lung ultrasound images, alveolar-arterial oxygen difference (P(A-a)O2 ), transpulmonary mechanics, and volumetric capnography at each PEEP step. RESULTS: At PEEP ≥ 15 cm H2O, atelectasis and P(A-a)O2 progressively decreased while end-inspiratory transpulmonary pressure (PL), end-expiratory PL, and driving PL increased (all P < .001). Bohr dead space (VDBohr /VT), airway dead space (VDaw /VT), and alveolar dead space (VDalv /VTalv ) reached their highest values at PEEP 30 cm H2O (0.69 ± 0.10, 0.53 ± 0.13 and 0.35 ± 0.06, respectively). At PEEP <15 cm H2O, the increases in atelectasis and P(A-a)O2 were associated with negative end-expiratory PL and highest driving PL. VDBohr /VT and VDaw /VT showed the lowest values at PEEP 0 cm H2O (0.51 ± 0.08 and 0.32 ± 0.08, respectively), whereas VDalv /VTalv increased to 0.27 ± 0.05. Enghoff dead space and its derived VDalv /VTalv showed high values at low PEEPs (0.86 ± 0.02 and 0.79 ± 0.04, respectively) and at high PEEPs (0.84 ± 0.04 and 0.65 ± 0.12), with the lowest values at 15 cm H2O (0.77 ± 0.05 and 0.61 ± 0.11, respectively; all P < .001). CONCLUSIONS: Bohr dead space was associated with lung stress, whereas Enghoff dead space was partially affected by the shunt effect.


Assuntos
Respiração com Pressão Positiva/métodos , Espaço Morto Respiratório , /terapia , Animais , Capnografia , Pulmão , Modelos Teóricos , Atelectasia Pulmonar , Suínos , Volume de Ventilação Pulmonar
12.
Medicina (B Aires) ; 79(6): 506-508, 2019.
Artigo em Espanhol | MEDLINE | ID: mdl-31829954

RESUMO

The arteriovenous extracorporeal membrane is used in patients with hemodynamic and respiratory failure, unresponsive to conventional treatment. It provides transitory hemodynamic support, oxygenation and removal of CO2, allowing pulmonary rest. Moreover it offers the possibility of ultraprotective ventilation and avoids generation of VILI (Ventilation-Induced Lung Injury). It is not frequently used in patients with hemodynamic failure secondary to obstructive shock due to mediastinal compromise. We present the case of a patient with obstructive shock, mediastinal mass of lymphoproliferative origin that was treated with extracorporeal arteriovenous circulation membrane.


Assuntos
Oxigenação por Membrana Extracorpórea/métodos , Linfoma Difuso de Grandes Células B/complicações , Insuficiência Respiratória/terapia , Choque Cardiogênico/etiologia , Choque Cardiogênico/terapia , Adulto , Angiografia por Tomografia Computadorizada/métodos , Feminino , Hemodinâmica , Humanos , Linfoma Difuso de Grandes Células B/diagnóstico por imagem , Linfoma Difuso de Grandes Células B/patologia , Choque Cardiogênico/diagnóstico por imagem , Tomografia por Raios X/métodos , Resultado do Tratamento
13.
Medicina (B.Aires) ; 79(6): 506-508, dic. 2019. ilus
Artigo em Espanhol | LILACS-Express | LILACS | ID: biblio-1056760

RESUMO

La membrana de oxigenación extracorpórea arteriovenosa se utiliza cuando ocurre falla hemodinámica y respiratoria refractaria al tratamiento convencional; brinda soporte hemodinamico transitorio, oxigenacion y remocion de CO2, y permite reposo pulmonar. Asimismo ofrece la posibilidad de realizar ventilación ultraprotectiva y evitar la generación de VILI (Ventilation-Induced Lung Injury). No ha sido demostrada su utilización como una terapia frecuente en los casos con insuficiencia hemodinámica secundaria a shock obstructivo por afectación mediastínica. Presentamos el caso de un paciente con shock obstructivo por una masa mediastínica de origen linfoproliferativo tratada con membrana de circulación arteriovenosa extracorpórea.


The arteriovenous extracorporeal membrane is used in patients with hemodynamic and respiratory failure, unresponsive to conventional treatment. It provides transitory hemodynamic support, oxygenation and removal of CO2, allowing pulmonary rest. Moreover it offers the possibility of ultraprotective ventilation and avoids generation of VILI (Ventilation-Induced Lung Injury). It is not frequently used in patients with hemodynamic failure secondary to obstructive shock due to mediastinal compromise. We present the case of a patient with obstructive shock, mediastinal mass of lymphoproliferative origin that was treated with extracorporeal arteriovenous circulation membrane.

14.
J Crit Care ; 45: 231-238, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29754942

RESUMO

PURPOSE: To analyze the effects of positive end-expiratory pressure (PEEP) on Bohr's dead space (VDBohr/VT) in patients with acute respiratory distress syndrome (ARDS). MATERIAL AND METHODS: Fourteen ARDS patients under lung protective ventilation settings were submitted to 4 different levels of PEEP (0, 6, 10, 16 cmH2O). Respiratory mechanics, hemodynamics and volumetric capnography were recorded at each protocol step. RESULTS: Two groups of patients responded differently to PEEP when comparing baseline with 16-PEEP: those in which driving pressure increased > 15% (∆P˃15%, n = 7, p = .016) and those in which the change was ≤15% (∆P≤15%, n = 7, p = .700). VDBohr/VT was higher in ∆P≤15% than in ∆P≤15% patients at baseline ventilation [0.58 (0.49-0.60) vs 0.46 (0.43-0.46) p = .018], at 0-PEEP [0.50 (0.47-0.54) vs 0.41 (0.40-0.43) p = .012], at 6-PEEP [0.55 (0.49-0.57) vs 0.44 (0.42-0.45) p = .008], at 10-PEEP [0.59 (0.51-0.59) vs 0.45 (0.44-0.46) p = .006] and at 16-PEEP [0.61 (0.56-0.65) vs 0.47 (0.45-0.48) p = .001]. We found a good correlation between ∆P and VDBohr/VT only in the ∆P˃15% group (r = 0.74, p < .001). CONCLUSIONS: Increases in PEEP result in higher VDBohr/VT only when associated with an increase in driving pressure.


Assuntos
/fisiopatologia , Adulto , Idoso , Capnografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Respiração com Pressão Positiva , Espaço Morto Respiratório , /terapia
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