Mechanical Power

Acute respiratory distress syndrome (ARDS) is characterized by pathological pulmonary edema caused by direct or indirect damage to the alveolar-capillary membrane. Its management relies on etiological treatment, invasive mechanical ventilation, and the use of sedatives and neuromuscular blockers, depending on the patient's condition. Improvements in patient care have led to an improved prognosis. However, in-hospital mortality remains high (between 35% and 45%). Notably, morbidity among surviving patients is very high and is largely dominated by neuropsychological sequelae. Attention and executive function disorders, confusion, disorientation, or memory impairment are thus found in 70 to 100% of patients following ARDS. These disorders are still present in 46 to 80% of surviving patients one year after ARDS and in 20% of them five years later. Although essential to treatment, mechanical ventilation carries a risk of significant complications. Beyond the risk of infection and complications related to sedation and neuromuscular blockade, the use of mechanical ventilation is associated with a risk of ventilator-induced lung injury (VILI). The use of so-called protective ventilation reduces the risk of VILI and improves patient outcomes. However, analysis of relevant physiological parameters shows that the risk of VILI may still exist even when ventilator settings comply with recommendations and the concept of protective ventilation. Driving pressure (which represents Strain) is a good marker of VILI; it represents the distension of the lung with each breath relative to the initial lung volume. Values above 14 cmH₂O are associated with high mortality in patients with ARDS. Inspiratory transpulmonary pressure represents Stress-that is, the pressure that distends the alveoli at the end of inspiration-and is also associated with the risk of VILI. Finally, mechanical power represents the amount of energy delivered to the lung by the ventilator and has been validated as a marker of VILI. The advantage of mechanical power over the other indices described is that it incorporates all components that can lead to VILI. Among the various sources of neurological damage during ARDS, inflammatory processes appear to play a major role. Numerous inflammatory mediators (TNF-α, IL-6, IL-8, IL-1β) are secreted during ARDS, and animal studies have demonstrated a link between inflammation and hippocampal damage. Furthermore, cerebral ischemic lesions, exacerbated by systemic inflammation and endothelial activation leading to coagulation activation with thrombus formation, may also contribute to the development of cognitive impairments. In addition to the inflammatory processes associated with ARDS, mechanical ventilation itself may have a significant impact on neuroinflammatory damage. Recently, the term "ventilator-associated brain injury" (VABI) has been proposed to describe these secondary neurological lesions induced by mechanical ventilation. Studies in mouse and pig models have demonstrated a relationship between the dose and duration of VILI, apoptosis, neuroinflammation, and neuronal damage. An animal study in mice also showed an association between the duration of mechanical ventilation and the onset of cognitive impairments. During brain injury, proteins and neurotransmitters are released and serve as biomarkers of brain damage. Elevated plasma levels of S100B protein indicate astrocyte damage caused by traumatic, anoxic-ischemic, or inflammatory mechanisms. It correlates with neurological prognosis following cardiac arrest, in ischemic or hemorrhagic strokes, in neurodegenerative diseases, and in patients with traumatic brain injury. Clinical studies have shown a negative correlation between elevated S100B protein levels, the MoCA (Montreal Cognitive Assessment) score, and the MMSE (Mini-mental state evaluation ) in patients with OSA (Obstructive Sleep Apnea) or COPD (chronic obstructive pulmonary disease), respectively, indicating an association between this protein and cognitive impairment. The investigators therefore hypothesize that mechanical ventilation associated with high mechanical power is linked to a significant risk of brain injury, reflected by elevated serum S100B protein levels and the presence of neurocognitive disorders long after ARDS.

Postoperative pulmonary complications (PPCs) are an important cause of morbidity and mortality after major surgery and are frequently observed in cardiac surgery patients undergoing cardiopulmonary bypass (CPB). These complications are associated with prolonged mechanical ventilation, longer intensive care unit and hospital stays, increased healthcare costs, and higher mortality (1,2). Intraoperative lung-protective ventilation strategies have traditionally focused on individual parameters such as low tidal volume, positive end-expiratory pressure (PEEP), plateau pressure, and driving pressure. However, the effects of these parameters on postoperative pulmonary outcomes in cardiac surgery patients remain unclear. In particular, PEEP- and driving pressure-guided approaches are controversial in terms of feasibility and safety in patients undergoing CPB, who may be hemodynamically vulnerable. Mechanical power is a comprehensive parameter that reflects the total energy delivered to the respiratory system per unit of time by integrating ventilatory variables such as tidal volume, airway pressures, respiratory rate, and flow. Therefore, mechanical power may provide a more comprehensive assessment of the mechanical load applied to the lungs compared with individual ventilatory parameters. Previous studies have reported that higher mechanical power values may be associated with lung injury, postoperative pulmonary complications, and mortality (3). The aim of this study is to evaluate the effect of monitoring mechanical power during perioperative mechanical ventilation on postoperative pulmonary complications in patients undergoing cardiac surgery with cardiopulmonary bypass. The study hypothesis is that a mechanical power-based ventilation approach may reduce the incidence of PPCs compared with strategies based on conventional ventilation parameters.

The goal of this randomized controlled clinical trial is to compare the pulmonary protective effects of two different positive end-expiratory pressure (PEEP) titrating methods in patients with non-injured lungs undergoing laparoscopic gynecological surgery. Despite dynamic pulmonary compliance (Cdyn) guided lung protective ventilation has several proven advantages, the investigators hypothesize that optimizing intraoperative mechanical ventilation using electrical impedance tomography (EIT) may further improve patient outcomes, enhance postoperative recovery, shorten in-hospital stay and reduce healthcare related costs. The main questions aim to answer are: * May EIT-guided PEEP titration reduce the mechanical power of ventilation and improve oxygenation more significantly than the Cdyn-guided method? * What effect might a decrease in mechanical power of ventilation have on postoperative pulmonary complications? Participants will: * Receive an EIT-guided or a Cdyn-guided PEEP titration procedure during laparoscopic gynecological surgery. * Be assessed for mechanical power of ventilation, oxygenation, atelectasis and postoperative pulmonary complications during and 2 days after surgery. * Be followed-up for mortality until the 28th postoperative day.

The goal of this clinical trial is to compare two different types of perioperative mechanical ventilation (MV), specifically Protective Mechanical Ventilation (PMV) and MV with the lowest possible Driving Pressure (ΔP), in relation to the appearance of postoperative pulmonary complications (PPCs) in adult patients who are operated and have higher risk of PPCs. The main questions it aims to answer are: * Is MV with lower ΔP better than conventional PMV in preventing PPCs in patients with higher risk for PPCs? * Does MV with lower ΔP decrease hospital stay, Intensive Care Unit (ICU) need and mortality? * Does MV with lower ΔP suit better than PMV to lung characteristics and needs intraoperatively? Researchers will compare MV with the lowest possible Driving Pressure (ΔP) to Protective Mechanical Ventilation (PMV) to see if any of this is more protective than the other concerning PPCs. All participants will receive perioperative MV. Half of them will receive conventional Protective Mechanical Ventilation (PMV). This will include well known generally protective settings for mechanical ventilation of patients, concerning volumes, pressures, respiratory rate, inspiratory gases and ventilation maneuvers. The rest of participants will be ventilated with the lowest possible Driving Pressure (ΔP). This will be similar to PMV in the chosen volumes, respiratory rate, inspiratory gases and ventilation maneuvers. However, the pressure inside lung at the end of expiration, eg Positive End Expiratory Pressure (PEEP), will be not be preset for every patient. Initially, the investigators will perform a maneuver that will quantify each individual's lung characteristics and mechanics. According to this, the investigators will find the exact PEEP that seems to suit each patients lungs most, and use this perioperatively, trying to provide lungs the best conditions every time. After the completion of the operation, all the patients will be screened for PPCs, via arterial blood testing and chest X ray, and the results will be statistically analyzed trying to find if any of the forementioned strategies of mechanical ventilation surpasses the other concerning PPCs appearance. PPCs include atelectasis, respiratory failure, bronchospasm, pleural effusion, pneumonia, aspiration and pneumothorax. Furthermore hospital stay, ICU need and mortality will be noted. Finally, measurements of perioperative lung pressures, volumes and derived variables will be noted and compared statistically as well.

Venovenous extracorporeal membrane oxygenation (VV-ECMO) is a salvage treatment for severe acute respiratory distress syndrome (ARDS). With the large-scale implementation of VV-ECMO in critical care medicine departments in China, significant progress has been made in treating severe ARDS. However, the patient mortality rate remains high. The pathophysiological essence of ARDS is an imbalance between the body's oxygen supply and demand, causing tissue and cell hypoxia, organ dysfunction, and even death. The VV-ECMO treatment process still requires mechanical ventilation assistance. However, inappropriate mechanical ventilation settings can lead to ventilator-related lung injury (VILI). In recent years, mechanical power has gradually attracted everyone's attention and is considered the cause of VILI. The transpulmonary mechanical power is more accurate to the energy directly performed to the lung tissue. Transpulmonary mechanical energy has a specific value in judging the prognosis of mechanically ventilated patients, but its clinical significance in treating patients with VV-ECMO is unclear. This study aimed to explore the value of transpulmonary mechanical power in predicting the prognosis of patients with severe ARDS patients treated with VV-ECMO.

This exploratory study aims to investigate the effect of Electrical Impedance Tomography (EIT)-guided ventilator settings on mechanical power in patients with acute hypoxemic respiratory failure (AHRF), including both ARDS and non-ARDS conditions. Mechanical power, a key factor associated with ventilator-induced lung injury (VILI), will be measured before and after EIT-guided PEEP titration. The study will evaluate feasibility and changes in lung mechanics, gas exchange, and EIT parameters. A total of 17 patients requiring invasive mechanical ventilation will be enrolled at Siriraj Hospital, Mahidol University.

The primary objective is to evaluate the mechanical power as a predictor of weaning of mechanical ventilation in COPD patients hospitalized in the respiratory intensive care unit of Assiut University Hospital The secondary objective is to compare between mechanical power and diaphragmatic excursion (DE) assessed by ultrasound as a predictor of weaning in these patients. Also, to investigate the association between MP and DE and mortality in these patients

The primary objective is to evaluate the mechanical power as a predictor of weaning of mechanical ventilation in COPD patients hospitalized in the respiratory intensive care unit of Assiut University Hospital. The secondary objective is to compare between mechanical power and diaphragmatic excursion (DE) assessed by ultrasound as a predictor of weaning in these patients. Also, to investigate the association between MP and DE and mortality in these patients

This is a single-centre prospective observational study aimed to determine if Pocc (occlusion pressure at 100 msec), TCe ( Expiratory time constant ), Mechanical Stress power, Ventilatory ratio and C20/Cdyn would predict outcomes in patients with moderately severe ARDS (Acute respiratory distress syndrome), who are on mechanical ventilation

The aim of this study is to report the proportion of patients with acute hypoxemic respiratory failyre (AHRF) undergoing mechanical ventilation who exceed 17 J/min of mechanical power (MP) and the difference in terms of proinflammatory cytokine concentration in blood samples and bronchoalveolar lavage. The main questions it aims to answer are: 1. Which is the proportion of patients who exceed 17 J/min of mechanical power (MP) during the first 72 hours of mechanical ventilation? 2. Is there a difference in terms of cytokine concentration in patients undergoing mechanical power \>17 J/min compared to \<17 J/min? Patients will be divided into two groups based on respiratory mechanics measurements: low MP group (average MP \<17 J/min) and high MP group (average MP ≥17 J/min). The researchers will collect blood and BAL samples and perform cytokine assays.