Electrical Impedance Tomography (EIT) is a groundbreaking, non-invasive, and radiation-free imaging technique for continuous, real-time ventilation monitoring. It also has an application in pulmonary perfusion monitoring. EIT quantifies ventilation and perfusion patterns across the lung from the measurement and processing of impedance changes in the thorax. It is a powerful tool for clinicians to visualize breath- by-breath changes in pulmonary function. An innovative application of EIT is its ability to assess pulmonary perfusion using the kinetic analysis of a hypertonic solution injection during a breath-hold. The solution generates an impedance change in the thorax as it circulates through the pulmonary vasculature. This indirect method allows for the estimation of perfusion patterns, contributing significantly to our understanding of pulmonary blood flow dynamics at the bedside. EIT is not just a tool for monitoring but also can be critical for the diagnosis of respiratory pathologies such as pneumothorax and bronchial intubation. It can help identify the etiology of ventilation/perfusion (V/Q) mismatch in patients receiving invasive mechanical ventilation, which is not possible with other diagnostic tools. Moreover, EIT can assist in the individual optimization of ventilator settings, such as Positive End-Expiratory Pressure (PEEP) titration and tidal volume improving oxygenation and lung health in critical care. In summary, EIT represents a paradigm shift in bedside pulmonary monitoring anddiagnostics. Its non-invasive nature and immediacy of data make EIT an indispensabletool in modern respiratory medicine. With its growing applications, EIT will be pivotalin advancing our understanding of and approach to respiratory care, particularly inintensive care settings

Background: Several nitric oxide (NO) generating devices have been developed to deliver NO between 1 part per million (ppm) and 80 ppm. Although inhalation of high-dose NO may exert antimicrobial effects, the feasibility and safety of producing high-dose (more than 100 ppm) NO remains to be established. In the current study, we designed, developed, and tested three high-dose NO generating devices. Methods: We constructed three NO generating devices: a double spark plug NO generator, a high-pressure single spark plug NO generator, and a gliding arc NO generator. The NO and NO2 concentrations were measured at different gas flows and under various atmospheric pressures. The double spark plug NO generator was designed to deliver gas through an oxygenator and mixing with pure oxygen. The high-pressure and gliding arc NO generators were used to deliver gas through a ventilator into artificial lungs to mimic delivering high-dose NO in the clinical settings. The energy consumption was measured and compared among the three NO generators. Results: The double spark plug NO generator produced 200 & PLUSMN; 2 ppm (mean & PLUSMN; SD) of NO at gas flow of 8 L/min (or 320 & PLUSMN; 3 ppm at gas flow of 5 L/min) with electrode gap of 3 mm. The nitrogen dioxide (NO2) levels were below 3.0 & PLUSMN; 0.1 ppm when mixing with various volumes of pure oxygen. The addition of a second generator increased the delivered NO from 80 (with one spark plug) to 200 ppm. With the high-pressure chamber, the NO concentration reached 407 & PLUSMN; 3 ppm with continuous air flow at 5 L/min when employing the 3 mm electrode gap under 2.0 atmospheric pressure (ATA). When compared to 1 ATA, NO production was increased 22% at 1.5 ATA and 34% at 2 ATA. The NO level was 180 & PLUSMN; 1 ppm when connecting the device to a ventilator with a constant inspiratory airflow of 15 L/min, and NO2 levels were below 1 (0.93 & PLUSMN; 0.02) ppm. The gliding arc NO generator produced up to 180 & PLUSMN; 4 ppm of NO when connecting the device to a ventilator, and the NO2 level was below 1 (0.91 & PLUSMN; 0.02) ppm in all testing conditions. The gliding arc device required more power (in watts) to generate the same concentrations of NO when compared to double spark plug or high-pressure NO generators. Conclusions: Our results demonstrated that it is feasible to enhance NO production (more than 100 ppm) while maintaining NO2 level relatively low (less than 3 ppm) with the three recently developed NO generating devices. Future studies might include these novel designs to deliver high doses of inhaled NO as an antimicrobial used to treat upper and lower respiratory tract infections.

OBJECTIVES:. Experimental models suggest that prone position and positive end-expiratory pressure (PEEP) homogenize ventral–dorsal ventilation distribution and regional respiratory compliance. However, this response still needs confirmation on humans. Therefore, this study aimed to assess the changes in global and regional respiratory mechanics in supine and prone positions over a range of PEEP levels in acute respiratory distress syndrome (ARDS) patients. DESIGN:. A prospective cohort study. PATIENTS:. Twenty-two intubated patients with ARDS caused by COVID-19 pneumonia. INTERVENTIONS:. Electrical impedance tomography and esophageal manometry were applied during PEEP titrations from 20 cm H2O to 6 cm H2O in supine and prone positions. MEASUREMENTS:. Global respiratory system compliance (Crs), chest wall compliance, regional lung compliance, ventilation distribution in supine and prone positions. MAIN RESULTS:. Compared with supine position, the maximum level of Crs changed after prone position in 59% of ARDS patients (n = 13), of which the Crs decreased in 32% (n = 7) and increased in 27% (n = 6). To reach maximum Crs after pronation, PEEP was changed in 45% of the patients by at least 4 cm H2O. After pronation, the ventilation and compliance of the dorsal region did not consistently change in the entire sample of patients, increasing specifically in a subgroup of patients who showed a positive change in Crs when transitioning from supine to prone position. These combined changes in ventilation and compliance suggest dorsal recruitment postpronation. In addition, the subgroup with increased Crs postpronation demonstrated the most pronounced difference between dorsal and ventral ventilation distribution from supine to prone position (p = 0.01), indicating heterogeneous ventilation distribution in prone position. CONCLUSIONS:. Prone position modifies global respiratory compliance in most patients with ARDS. Only a subgroup of patients with a positive change in Crs postpronation presented a consistent improvement in dorsal ventilation and compliance. These data suggest that the response to pronation on global and regional mechanics can vary among ARDS patients, with some patients presenting more dorsal lung recruitment than others.

Background and Objectives Carbon monoxide (CO) poisoning is responsible for nearly 50,000 emergency department visits and 1200 deaths per year. Compared to oxygen, CO has a 250-fold higher affinity for hemoglobin (Hb), resulting in the displacement of oxygen from Hb and impaired oxygen delivery to tissues. Optimal treatment of CO-poisoned patients involves the administration of hyperbaric 100% oxygen to remove CO from Hb and to restore oxygen delivery. However, hyperbaric chambers are not widely available and this treatment requires transporting a CO-poisoned patient to a specialized center, which can result in delayed treatment. Visible light is known to dissociate CO from carboxyhemoglobin (COHb). In a previous study, we showed that a system composed of six photo-extracorporeal membrane oxygenation (ECMO) devices efficiently removes CO from a large animal with CO poisoning. In this study, we tested the hypothesis that the application of hyperbaric oxygen to the photo-ECMO device would further increase the rate of CO elimination. Study Design/Material and Methods We developed a hyperbaric photo-ECMO device and assessed the ability of the device to remove CO from CO-poisoned human blood. We combined four devices into a "hyperbaric photo-ECMO system" and compared its ability to remove CO to our previously described photo-ECMO system, which was composed of six devices ventilated with normobaric oxygen. Results Under normobaric conditions, an increase in oxygen concentration from 21% to 100% significantly increased CO elimination from CO-poisoned blood after a single pass through the device. Increased oxygen pressure within the photo-ECMO device was associated with higher exiting blood PO2 levels and increased CO elimination. The system of four hyperbaric photo-ECMO devices removed CO from 1 L of CO-poisoned blood as quickly as the original, normobaric photo-ECMO system composed of six devices. Conclusion This study demonstrates the feasibility and efficacy of using a hyperbaric photo-ECMO system to increase the rate of CO elimination from CO-poisoned blood. This technology could provide a simple portable emergency device and facilitate immediate treatment of CO-poisoned patients at or near the site of injury.

Electronic cigarettes (e-cigarettes) have been used widely as an alternative to conventional cigarettes and have become particularly popular among young adults. A growing body of evidence has shown that e-cigarettes are associated with acute lung injury and adverse effects in multiple other organs. Previous studies showed that high emissions of aldehydes (formaldehyde and acetaldehyde) in aerosols were associated with increased usage of the same e-cigarette coils. However, the impact on lung function of using aged coils has not been reported. We investigated the relationship between coil age and acute lung injury in mice exposed to experimental vaping for 1 h (2 puffs/min, 100 ml/puff). The e-liquid contains propylene glycol and vegetable glycerin (50:50, vol) only. The concentrations of formaldehyde and acetaldehyde in the vaping aerosols increased with age of the nichrome coils starting at 1200 puffs. Mice exposed to e-cigarette aerosols produced from 1800, but not 0 or 900, puff-aged coils caused acute lung injury, increased lung wet/dry weight ratio, and induced lung inflammation (IL-6, TNF-α, IL-1β, MIP-2). Exposure to vaping aerosols from 1800 puff-aged coils decreased heart rate, respiratory rate, and oxygen saturation in mice compared to mice exposed to air or aerosols from new coils. In conclusion, we observed that the concentration of aldehydes (formaldehyde and acetaldehyde) increased with repeated and prolonged usage of e-cigarette coils. Exposure to high levels of aldehyde in vaping aerosol was associated with acute lung injury in mice. These findings show significant risk of lung injury associated with prolonged use of e-cigarette devices.

INTRODUCTION: The prone position and protective lung ventilation are the only interventions to improve survival in Acute Respiratory Distress Syndrome (ARDS) patients. Due to early reports during the COVID-pandemic showing dramatic improvements in oxygenation, the use of prone position has been broadly adopted in intubated patients around the globe. However, it remains unclear on whether titration of ventilation should be reassessed when the patient is repositioned. Therefore, the objective of this study was to characterize the response of respiratory mechanics in supine and prone positions during a decremental end-expiratory positive pressure trial in COVID-19 related ARDS patients. METHODS: This is a retrospective analysis of patients with COVID-19 related ARDS under invasive mechanical ventilation in supine and prone positions. The study was approved by the Investigational Review Board at the Massachusetts General Hospital and by the Ethics and Research Committee at Heart Institute (InCor) from the University of São Paulo. Prone position was recommended based on hypoxia, measured as PaO2/FIO2 ratio (< 150 mmHg). Patients were sedated, and under volume-controlled ventilation (5-6 mL/Kg PBW). Airway pressure, flow, esophageal pressure and electrical impedance tomography (EIT) were recorded. A decremental PEEP trial was performed on supine and prone position. RESULTS: We included 10 patients with COVID-19 related ARDS. Median age was 62 years (range, 35-72), 5 patients (50%) were female, and BMI was 35 (range, 27-46). After 24 hours of intubation, median PaO2/FIO2 was 174 mmHg (IQR, 166-192), PEEP was 10 cmH2O (IQR, 10-14.5), and static compliance of respiratory system (CRS) was 28.5 mL/cmH2O (IQR, 24.2-35.7). The time interval between intubation and the supine-prone assessment was 7 days (IQR, 5-10). During the supine/prone assessment, a variety of CRS responses were observed among patients (Figure 1). Overall, the highest CRS was 44 mL/cmH2O (IQR, 29-57) in supine and 52 mL/cmH2O (IQR, 39-67) in prone position. At the highest CRS, from supine to prone position: lung compliance (CL) increased by 15 mL/cmH2O (IQR, 13-31), suggesting lung recruitment, and chest wall compliance (CCW) was reduced by 28 ml/cmH2O (IQR, 14-48) indicating external compression of the chest;and end-expiratory transpulmonary pressure (PLend-exp) increased from-3.4 cmH2O (IQR,-4.6 to-2.5) to 0.4 cmH2O (IQR, 0.1-3.0) suggesting decreased pleural pressure. CONCLUSION: Patients with COVID-19 related ARDS assessed in supine and prone positions revels a variety response to prone position on CRS during decremental PEEP trial, suggesting the necessity to reassess the PEEP when the patient is repositioned. (Table Presented).

Background: The prone position and lung protective ventilation are the only interventions to improve survival in ARDS patients. Due to early reports during the COVID-19 pandemic showing dramatic improvements in oxygenation, the use of prone position has been broadly adopted in intubated patients around the globe. However, it remains unclear whether titration of ventilation should be reassessed when the patient is repositioned. To our knowledge, respiratory compliance (CRS) comparisons during supine and prone positions have been described in patients only at predefined levels of PEEP. Therefore, the objective of this study was to characterize the response of respiratory mechanics in supine and prone positions during a decremental PEEP trial in COVID-19 related ARDS patients. Methods: We studied a cohort of patients with COVID-19 related ARDS undergoing invasive mechanical ventilation. The study was approved by the local IRBs. Patients were ventilated with a tidal volume of 5–6 mL/kg PBW. A decremental PEEP trial was performed. Airway pressures and flow were recorded in supine and prone positions to calculate CRS. Ventilation distribution was measured by electrical impedance tomography (EIT) in three gravitational regions (ROI). Results: We included 14 patients with COVID-19 related ARDS. The cohort’s median age was 65 y (IQR 59–69) with a BMI of 32.5 (IQR 28–35). After 24 h of intubation, median PaO2/FIO2 was 151 mm Hg (IQR 105–170) and PEEP was 10 cm H2O (IQR 10–14). Figure 1-A, B, and C illustrate, respectively, patients whose maximum CRS was reduced, similar, or increased after pronation at a certain level of PEEP. The PEEP to obtain the maximum CRS was lower in prone compared to supine position in 14/20 (70%) patients (Figure 1-D). Changes in CRS after pronation had symmetrical distribution (Figure 1-E). The maximum CRS was reached with higher ventilation distribution in the non-dependent zone in prone position (~35%). Conclusions: In a cohort of mechanically ventilated patients with severe COVID-19 related ARDS, a subset of patients demonstrated a marked improvement in lung mechanics after pronation, with a resultant best PEEP for the highest compliance being lower in prone versus supine. Ventilation distribution was shifted to dorsal-predominant from ventral-predominant in prone position and correlates with changes in CRS. These results suggest that PEEP titration would be prudent to perform after prone positioning.

Purpose of review Obesity prevalence is increasing in most countries in the world. In the United States, 42% of the population is obese (body mass index (BMI) > 30) and 9.2% is obese class III (BMI > 40). One of the greatest challenges in critically ill patients with obesity is the optimization of mechanical ventilation. The goal of this review is to describe respiratory physiologic changes in patients with obesity and discuss possible mechanical ventilation strategies to improve respiratory function. Recent findings Individualized mechanical ventilation based on respiratory physiology after a decremental positive end-expiratory pressure (PEEP) trial improves oxygenation and respiratory mechanics. In a recent study, mortality of patients with respiratory failure and obesity was reduced by about 50% when mechanical ventilation was associated with the use of esophageal manometry and electrical impedance tomography (EIT). Summary Obesity greatly alters the respiratory system mechanics causing atelectasis and prolonged duration of mechanical ventilation. At present, novel strategies to ventilate patients with obesity based on individual respiratory physiology showed to be superior to those based on standard universal tables of mechanical ventilation. Esophageal manometry and EIT are essential tools to systematically assess respiratory system mechanics, safely adjust relatively high levels of PEEP, and improve chances for successful weaning.

The accumulation of secretions in the airways of ventilator-dependent patients is a common problem, and if not detected and treated in due time, it greatly increases the risk of infections and asynchrony. Unfortunately, cardiogenic oscillation modifies the flow signal shape that can confuse clinical staff and modern lung ventilators. In this article, the authors use an artificial immune system algorithm in a pre-processed flow signal. The authors' approach was able to automatically detect the presence or absence of airway secretions, even if the sample contains the influence of cardiogenic oscillation. The training and validation of the algorithm was carried out using a database containing flow signals of 457 respiratory cycles, obtained from three patients in different ventilation modes. The algorithm trained with 60% of the base cycles, was able to achieve specificity and sensitivity above 0.96 in the classification of the remaining cycles of the base.

Airway secretion must be avoid-ed due to liquid The accumulation in ventilator-dependent patients. As this cause serious complications to the patient. In this work we use an artificial immune system algorithm able to detect secretion automatically only from the flow signal analysis. The training and validation of the algorithm was done from a database containing flow signals of 457 respiratory cycles, obtained from three patients in different ventilation modes. The algorithm trained with 60% of the base cycles, was able to achieve specificity and sensitivity above 0.98 in the classification of the remaining cycles of the base.