Predictors of VILI risk: driving pressure, 4DPRR and mechanical power ratio-an experimental study.

Background: Ventilator-induced lung injury (VILI) is one of the side effects of mechanical ventilation during ARDS; a prerequisite for averting it is the quantification of its risk factors associated with a given ventilatory setting. Many clinical variables have been proposed as predictors of VILI, of which driving pressure is the most widely used. In this study, we compared the performance of driving pressure, four times the driving pressure added to respiratory rate (4DPRR) and mechanical power ratio.

Rethinking ARDS classification: oxygenation impairment fails to predict VILI risk.

Purpose: The selection and intensity of respiratory support for ARDS are guided by PaO/FiO. However, ventilator-induced lung injury (VILI) is linked to respiratory mechanics and ventilator settings. We explored whether the VILI risk is related to ARDS severity based on oxygenation.

Impact of Fluid Balance on the Development of Lung Injury.

Rationale: The pathophysiological relationship between fluid administration, fluid balance, and mechanical ventilation in the development of lung injury is unclear.

Objectives: To quantify the relative contribution of mechanical power and fluid balance in the development of lung injury.

Methods: Thirty-nine healthy female pigs, divided into four groups, were ventilated for 48 hours with high (~18J/min) or low (~6J/min) mechanical power; and high (~4L) or low (~1L) targeted fluid balance.

Mechanical power ratio threshold for ventilator-induced lung injury.

Rationale: Mechanical power (MP) is a summary variable incorporating all causes of ventilator-induced-lung-injury (VILI). We expressed MP as the ratio between observed and normal expected values (MP).

Objective: To define a threshold value of MP leading to the development of VILI.

Determinants of acute kidney injury during high-power mechanical ventilation: secondary analysis from experimental data.

Background: The individual components of mechanical ventilation may have distinct effects on kidney perfusion and on the risk of developing acute kidney injury; we aimed to explore ventilatory predictors of acute kidney failure and the hemodynamic changes consequent to experimental high-power mechanical ventilation.

Methods: Secondary analysis of two animal studies focused on the outcomes of different mechanical power settings, including 78 pigs mechanically ventilated with high mechanical power for 48 h. The animals were categorized in four groups in accordance with the RIFLE criteria for acute kidney injury (AKI), using the end-experimental creatinine: (1) NO AKI: no increase in creatinine; (2) RIFLE 1-Risk: increase of creatinine of > 50%; (3) RIFLE 2-Injury: two-fold increase of creatinine; (4) RIFLE 3-Failure: three-fold increase of creatinine; RESULTS: The main ventilatory parameter associated with AKI was the positive end-expiratory pressure (PEEP) component of mechanical power.

High- versus Low-Flow Extracorporeal Respiratory Support in Experimental Hypoxemic Acute Lung Injury.

In the EOLIA (ECMO to Rescue Lung Injury in Severe ARDS) trial, oxygenation was similar between intervention and conventional groups, whereas [Formula: see text]e was reduced in the intervention group. Comparable reductions in ventilation intensity are theoretically possible with low-flow extracorporeal CO removal (ECCOR), provided oxygenation remains acceptable. To compare the effects of ECCOR and extracorporeal membrane oxygenation (ECMO) on gas exchange, respiratory mechanics, and hemodynamics in animal models of pulmonary (intratracheal hydrochloric acid) and extrapulmonary (intravenous oleic acid) lung injury.

Ventilatory ratio, dead space, and venous admixture in patients with acute respiratory distress syndrome.

Background: Ventilatory ratio (VR) has been proposed as an alternative approach to estimate physiological dead space. However, the absolute value of VR, at constant dead space, might be affected by venous admixture and CO volume expired per minute (VCO).

Methods: This was a retrospective, observational study of mechanically ventilated patients with acute respiratory distress syndrome (ARDS) in the UK and Italy.

Energy dissipation during expiration and ventilator-induced lung injury: an experimental animal study.

The amount of energy delivered to the respiratory system is recognized as a cause of ventilator-induced lung injury (VILI). How energy dissipation within the lung parenchyma causes damage is still a matter of debate. Expiratory flow control has been proposed as a strategy to reduce the energy dissipated into the respiratory system during expiration and, possibly, VILI.

Mechanical power thresholds during mechanical ventilation: An experimental study.

The extent of ventilator-induced lung injury may be related to the intensity of mechanical ventilation--expressed as mechanical power. In the present study, we investigated whether there is a safe threshold, below which lung damage is absent. Three groups of six healthy pigs (29.

Lung Ultrasound and Electrical Impedance Tomography During Ventilator-Induced Lung Injury.

Objectives: Lung damage during mechanical ventilation involves lung volume and alveolar water content, and lung ultrasound (LUS) and electrical impedance tomography changes are related to these variables. We investigated whether these techniques may detect any signal modification during the development of ventilator-induced lung injury (VILI).

Design: Experimental animal study.

Mechanisms of oxygenation responses to proning and recruitment in COVID-19 pneumonia.

Purpose: This study aimed at investigating the mechanisms underlying the oxygenation response to proning and recruitment maneuvers in coronavirus disease 2019 (COVID-19) pneumonia.

Methods: Twenty-five patients with COVID-19 pneumonia, at variable times since admission (from 1 to 3 weeks), underwent computed tomography (CT) lung scans, gas-exchange and lung-mechanics measurement in supine and prone positions at 5 cmHO and during recruiting maneuver (supine, 35 cmHO). Within the non-aerated tissue, we differentiated the atelectatic and consolidated tissue (recruitable and non-recruitable at 35 cmHO of airway pressure).

Computed tomographic assessment of lung aeration at different positive end-expiratory pressures in a porcine model of intra-abdominal hypertension and lung injury.

Background: Intra-abdominal hypertension (IAH) is common in critically ill patients and is associated with increased morbidity and mortality. High positive end-expiratory pressures (PEEP) can reverse lung volume and oxygenation decline caused by IAH, but its impact on alveolar overdistension is less clear. We aimed to find a PEEP range that would be high enough to reduce atelectasis, while low enough to minimize alveolar overdistention in the presence of IAH and lung injury.

Using Artificial Intelligence for Automatic Segmentation of CT Lung Images in Acute Respiratory Distress Syndrome.

Knowledge of gas volume, tissue mass and recruitability measured by the quantitative CT scan analysis (CT-qa) is important when setting the mechanical ventilation in acute respiratory distress syndrome (ARDS). Yet, the manual segmentation of the lung requires a considerable workload. Our goal was to provide an automatic, clinically applicable and reliable lung segmentation procedure.

Role of Fluid and Sodium Retention in Experimental Ventilator-Induced Lung Injury.

Ventilator-induced lung injury (VILI) via respiratory mechanics is deeply interwoven with hemodynamic, kidney and fluid/electrolyte changes. We aimed to assess the role of positive fluid balance in the framework of ventilation-induced lung injury. analysis of seventy-eight pigs invasively ventilated for 48 h with mechanical power ranging from 18 to 137 J/min and divided into two groups: high vs.

Role of total lung stress on the progression of early COVID-19 pneumonia.

Purpose: We investigated if the stress applied to the lung during non-invasive respiratory support may contribute to the coronavirus disease 2019 (COVID-19) progression.

Methods: Single-center, prospective, cohort study of 140 consecutive COVID-19 pneumonia patients treated in high-dependency unit with continuous positive airway pressure (n = 131) or non-invasive ventilation (n = 9). We measured quantitative lung computed tomography, esophageal pressure swings and total lung stress.

Comparison of pulmonary function in isoflurane anaesthetized ventilated sheep () following administration of intravenous xylazine versus medetomidine.

Alpha receptor agonists (alpha-agonists) are useful sedative and analgesic agents in sheep, but have adverse pulmonary effects, which are reportedly similar between different alpha-agonists. This randomized crossover study compared pulmonary function after intravenous administration of an alpha-agonist, either xylazine or an equipotent dose of medetomidine in 34 female sheep anaesthetized twice. Pulmonary function was assessed using spirometry, volumetric capnography, arterial blood gas analysis 1 min prior to, and 5 and 10 min after administration of the allocated alpha 2 agonist drug.

The impact of ventilation-perfusion inequality in COVID-19: a computational model.

COVID-19 infection may lead to acute respiratory distress syndrome (CARDS) where severe gas exchange derangements may be associated, at least in the early stages, only with minor pulmonary infiltrates. This may suggest that the shunt associated to the gasless lung parenchyma is not sufficient to explain CARDS hypoxemia. We designed an algorithm (VentQ), based on the same conceptual grounds described by J.

Physiological and quantitative CT-scan characterization of COVID-19 and typical ARDS: a matched cohort study.

Purpose: To investigate whether COVID-19-ARDS differs from all-cause ARDS.

Methods: Thirty-two consecutive, mechanically ventilated COVID-19-ARDS patients were compared to two historical ARDS sub-populations 1:1 matched for PaO/FiO or for compliance of the respiratory system. Gas exchange, hemodynamics and respiratory mechanics were recorded at 5 and 15 cmHO PEEP.

Mobilizing Carbon Dioxide Stores. An Experimental Study.

Understanding the physiology of CO stores mobilization is a prerequisite for intermittent extracorporeal CO removal (ECCOR) in patients with chronic hypercapnia. To describe the dynamics of CO stores. Fifteen pigs (61.

Does Iso-mechanical Power Lead to Iso-lung Damage?: An Experimental Study in a Porcine Model.

Background: Excessive tidal volume, respiratory rate, and positive end-expiratory pressure (PEEP) are all potential causes of ventilator-induced lung injury, and all contribute to a single variable: the mechanical power. The authors aimed to determine whether high tidal volume or high respiratory rate or high PEEP at iso-mechanical power produce similar or different ventilator-induced lung injury.

Methods: Three ventilatory strategies-high tidal volume (twice baseline functional residual capacity), high respiratory rate (40 bpm), and high PEEP (25 cm H2O)-were each applied at two levels of mechanical power (15 and 30 J/min) for 48 h in six groups of seven healthy female piglets (weight: 24.

Positive End-expiratory Pressure and Mechanical Power.

Background: Positive end-expiratory pressure is usually considered protective against ventilation-induced lung injury by reducing atelectrauma and improving lung homogeneity. However, positive end-expiratory pressure, together with tidal volume, gas flow, and respiratory rate, contributes to the mechanical power required to ventilate the lung. This study aimed at investigating the effects of increasing mechanical power by selectively modifying its positive end-expiratory pressure component.

High-frequency oscillatory ventilation guided by transpulmonary pressure in acute respiratory syndrome: an experimental study in pigs.

Background: Recent clinical studies have not shown an overall benefit of high-frequency oscillatory ventilation (HFOV), possibly due to injurious or non-individualized HFOV settings. We compared conventional HFOV (HFOV) settings with HFOV settings based on mean transpulmonary pressures (P) in an animal model of experimental acute respiratory distress syndrome (ARDS).

Methods: ARDS was induced in eight pigs by intrabronchial installation of hydrochloric acid (0.

Reclassifying Acute Respiratory Distress Syndrome.

Rationale: The ratio of Pa to Fi (P/F) defines acute respiratory distress syndrome (ARDS) severity and suggests appropriate therapies.

Objectives: We investigated 1) whether a 150-mm-Hg P/F threshold within the range of moderate ARDS (100-200 mm Hg) would define two subgroups that were more homogeneous; and 2) which criteria led the clinicians to apply extracorporeal membrane oxygenation (ECMO) in severe ARDS.

Methods: At the 150-mm-Hg P/F threshold, moderate patients were split into mild-moderate (n = 50) and moderate-severe (n = 55) groups.