Ventilator-induced Lung Injury Vortex in Patients With SARS-CoV-2

Study Overview
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Brief Summary
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The concept of Ventilator-induced Lung Injury Vortex (VILI vortex) has recently been proposed as a progressive lung injury mechanism in which the alveolar stress/strain increases as the ventilable lung shrinks (1). This positive feedback inexorably leads to the acceleration of lung damage, with potentially irreversible results. Little is known about the clinical aspects of this condition. Understanding its behavior could contribute to changing its potential devastating impact. The objective of this study is to evaluate the incidence of VILI vortex in patients with acute respiratory syndrome (ARDS) secondary to COVID-19, to establish a connection between this phenomenon and mortality, and to identify the factors that have an impact on its development.

Detailed Description
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Mechanical ventilation is an essential tool for the treatment of patients with acute respiratory distress syndrome (ARDS). However, as with other strategies, it is not free of complications. Inadequate ventilation may have a negative impact on pulmonary and systemic hemodynamics, and it could both cause structural damage to pulmonary parenchyma and activate inflammation (2). This process is known as ventilator-induced lung injury (VILI) and may promote the development of multiple organ failure and, eventually, death. VILI results from the interaction between the mechanical load applied to the ventilable lung and its capacity to tolerate it. Factors such as tidal volume (Vt), driving pressure (ΔP), inspiratory flow rate (VI), respiratory rate (RR), excessive inspiratory effort, high levels of FiO2 and, in some cases, PEEP, have been involved in damage mechanism. In that sense, the concept of mechanical power (MP) tries to encompass most of these factors within a measurable unit (3). Furthermore, the decrease in ventilable lung volume (baby lung concept), the heterogeneous lung compromise in ARDS), and the presence of cofactors that have a negative impact on the lung (fluid overload, presence of sepsis or shock) could increase its susceptibility to damage (4-5). Due to the fact that the mechanical conditions of the lung change dynamically with the progression of the disease, the ventilatory strategy needs constant adjustments in order to maintain a balance between the load and the size of the ventilable lung (concept of ergonomic ventilation). In fact, a protective ventilatory strategy of low tidal volume (Vt: 6 ml/kg/PBW) and limited plateau pressure (PPlat <30 cmH2O) may cause damage if the functional residual capacity (FRC) decreases significantly, thus making a lower number of alveoli (including capillaries) withstand a higher mechanical load per unit. The concept of VILI vortex has recently been proposed as a progressive lung injury mechanism in which the alveolar stress/strain increases as the ventilable lung shrinks. This positive feedback inexorably leads to the acceleration of lung damage, with potentially irreversible results (1). Little is known about the clinical aspects of this condition. Understanding its behavior could contribute to changing its potential devastating impact. The objective of this study is to evaluate the incidence of VILI vortex in patients with ARDS secondary to COVID-19, to establish a connection between this phenomenon and mortality, and to identify the factors that have an impact on its development.

Official Title
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Ventilator-induced Lung Injury Vortex in Patients With SARS-CoV-2

Conditions
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ARDS, Mechanical Ventilation Complication, Ventilator-Induced Lung Injury

Intervention / Treatment
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* Diagnostic Test: CT scan


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: ARDS - Exclusion Criteria: Patients with do-not-resuscitate (DNR) orders and pregnant women. Cardiac arrest before ICU admission. Extra corporeal membrane oxygenation (ECMO) requirement within the first 24 h of ICU admission and chronic obstructive pulmonary disease with gold class 3 or 4, or home oxygen therapy

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| VILI VORTEX and No VILI VORTEX<br>Measurement of pulmonary pressures and volumes in the same patient | Diagnostic Test: CT scan<br>* Mechanical variables and PaO2/FiO2 were registered daily for 14 days or until initiating assisted ventilation. These data were obtained in passive mechanical conditions. Ventilator-induced lung injury vortex was defined as a progressive increase in driving pressure (ΔP) as Vt remained constant or even decreased. Refractory hypoxemia was defined as PaO2/FiO2 <100 despite the optimization of mechanical ventilation and prone positioning.<br>* Other names: Transpulmonary pressures (TP) will be measured;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Participants Who Survived and Died | The number of patients who died and survived was compared between patients with SARS-CoV-2 who progressed with VILI VORTEX and without VILI VORTEX) | 90 days | 
| Number of Patients With and Without Refractory Hypoxemia | The number of patients that evolved with refractory hypoxemia was compared between the patients with SARS-CoV-2 that evolved with VILI VORTEX and without VILI VORTEX) Refractory hypoxemia was defined as PaO2/FiO2 <100 despite the optimization of mechanical ventilation and prone positioning. | 90 days | 
| Number of Patients With Complications | The following variables and complications were also observed during the period of analysis: incidence of pneumonia associated with mechanical ventilation, need for noradrenaline over 0.1 γ/kg/min for more than 24 h, positive blood cultures, accumulated fluid balance, dialysis treatment, clinical and/or echocardiographic evidence of heart failure, lactate ≥2 mmol/L in at least two consecutive samples, presence of persistent fever (≥38º at least once a day for three consecutive days), and the highest value of ferritin, D-dimer, C-reactive protein, troponin I and LDH obtained during the first 14 days of invasive mechanical ventilation. VILI vortex patients had positive blood cultures, moderate to severe shock, persistent fever and fluid balance was considerably more positive. | 90 days |