Tidal lung hysteresis to interpret PEEP-induced changes in compliance in ARDS patients.

BACKGROUND: In ARDS, the PEEP level associated with the best respiratory system compliance is often selected; however, intra-tidal recruitment can increase compliance, falsely suggesting improvement in baseline mechanics. Tidal lung hysteresis increases with intra-tidal recruitment and can help interpreting changes in compliance. This study aims to assess tidal recruitment in ARDS patients and to test a combined approach, based on tidal hysteresis and compliance, to interpret decremental PEEP trials. METHODS: A decremental PEEP trial was performed in 38 COVID-19 moderate to severe ARDS patients. At each step, we performed a low-flow inflation-deflation manoeuvre between PEEP and a constant plateau pressure, to measure tidal hysteresis and compliance. RESULTS: According to changes of tidal hysteresis, three typical patterns were observed: 10 (26%) patients showed consistently high tidal-recruitment, 12 (32%) consistently low tidal-recruitment and 16 (42%) displayed a biphasic pattern moving from low to high tidal-recruitment below a certain PEEP. Compliance increased after 82% of PEEP step decreases and this was associated to a large increase of tidal hysteresis in 44% of cases. Agreement between best compliance and combined approaches was accordingly poor (K = 0.024). The combined approach suggested to increase PEEP in high tidal-recruiters, mainly to keep PEEP constant in biphasic pattern and to decrease PEEP in low tidal-recruiters. PEEP based on the combined approach was associated with lower tidal hysteresis (92.7 ± 20.9 vs. 204.7 ± 110.0 mL; p < 0.001) and lower dissipated energy per breath (0.1 ± 0.1 vs. 0.4 ± 0.2 J; p < 0.001) compared to the best compliance approach. Tidal hysteresis ≥ 100 mL was highly predictive of tidal recruitment at next PEEP step reduction (AUC 0.97; p < 0.001). CONCLUSIONS: Assessment of tidal hysteresis improves the interpretation of decremental PEEP trials and may help limiting tidal recruitment and energy dissipated into the respiratory system during mechanical ventilation of ARDS patients.

Performance of helmet CPAP using different configurations: Turbine-driven ventilators vs Venturi devices.

BACKGROUND: Traditionally, Venturi-based flow generators have been preferred over mechanical ventilators to provide continuous positive airway pressure (CPAP) through the helmet (h-CPAP). Recently, modern turbine-driven ventilators (TDVs) showed to be safe and effective in delivering h-CPAP. We aimed to compare the pressure stability during h-CPAP delivered by Venturi devices and TDVs and assess the impact of High Efficiency Particulate Air (HEPA) filters on their performance. METHODS: We performed a bench study using an artificial lung simulator set in a restrictive respiratory condition, simulating two different levels of patient effort (high and low) with and without the interposition of the HEPA filter. We calculated the average of minimal (Pmin), maximal (Pmax) and mean (Pmean) airway pressure and the time product measured on the airway pressure curve (PTPinsp). We defined the pressure swing (Pswing) as Pmax - Pmin and pressure drop (Pdrop) as End Expiratory Pressure - Pmin. RESULTS: Pswing across CPAP levels varied widely among all the tested devices. During "low effort", no difference in Pswing and Pdrop was found between Venturi devices and TDVs; during high effort, Pswing (p<0.001) and Pdrop (p<0.001) were significantly higher in TDVs compared to Venturi devices, but the PTPinsp was lower (1.50 SD 0.54 vs 1.67 SD 0.55, p<0.001). HEPA filter addition almost doubled Pswing and PTPinsp (p<0.001) but left unaltered the differences among Venturi and TDVs systems in favor of the latter (p<0.001). CONCLUSIONS: TDVs performed better than Venturi systems in delivering a stable positive pressure level during h-CPAP in a bench setting.

Invasive Mechanical Ventilation in COVID-19

Patients with severe COVID-19 pneumonia present with severe hypoxemic respiratory failure, typically meet the clinical criteria for acute respiratory distress syndrome (ARDS) and often require invasive mechanical ventilation. While peculiar pathophysiological aspects deserve discussion to better tailor the mechanical ventilation settings in these patients, most recommendations on the ventilatory management of these patients are derived from studies in patients with ARDS from causes other than COVID-19. Protective ventilation is recommended in most COVID-19 patients, tidal volume should be kept around 6 mL per kg of predicted body weight, positive end-expiratory pressure (PEEP) should be titrated individually considering that in many patients with COVID-19 improvement of oxygenation at higher PEEP is often accompanied by worsening of respiratory system compliance. Therefore, attention should be paid in limiting plateau and driving pressures to avoid excessive strain potentially resulting in ventilator-induced lung injury. Prone positioning has been used extensively in COVID-19 patients, but its impact on mortality is uncertain. Inhaled nitric oxide, extracorporeal CO2 removal (ECCO2R), and extracorporeal membrane oxygenation (ECMO) should be considered in selected patients as rescue measures. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.

Mechanical Ventilation in COVID

From the start of the pandemic, amid the frequency of cases with COVID-19 associated respiratory failure, mechanical ventilation has been the object of controversy. Reports associating its use with higher mortality, likely reflecting the severity of an unknown illness devastating the entire world, as well as the turmoil caused by the lack of sufficient equipment to supply the increasing demands in our hospitals, both were points of attention for media and public in general. However, from the clinical perspective, the need to apply different methods or to deviate from stablished guidelines to be able to adequately support these patients, was soon noticed. Multiple publications were guiding clinicians in the obscured territory of the unknown disease and to its variable impact on the respiratory system. This chapter aims to summarize the knowledge acquired throughout the pandemic, describing some of the elements of COVID-19 respiratory failure as well as its management with mechanical ventilation. The chapter recovers some of the increasing information appearing almost daily in the literature. We recognize that given the changing nature of the disease and the progressive knowledge of the same, some of the concepts covered in this chapter might be subject of some review or modification at the moment of the publication. We, the authors, have attempted to summarize the existing evidence and to maintain a basic conceptual approach to the management of COVID-19 respiratory failure. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.

Outcomes of tracheostomies performed in COVID-19 positive patients at Hospital Central del Estado Chihuahua, Mexico.

OBJECTIVE: Provide a description of clinical characteristics, associated factors and outcome of tracheostomies performed in COVID-19 patients. METHOD: Observational prospective study of 14 patients who underwent tracheostomy. 10 of them were diagnosed with COVID 19, confirmed with RT-PCR test of nasopharyngeal exudate and compatible tomographic findings. RESULTS: Of the 10 patients, five were discharged and five died. The average age of patients who died was 66.6 years; of those who were discharged, it was 60.4 years. Ventilatory parameters cut was taken as FiO2 ≤ 40% and PEEP ≤ 8; of the patients discharged, four met both criteria. On the other hand, of the patients who died, neither met both. Of the latter, an average of APACHE II of 16.4 and SOFA 7.4 were documented, while in discharged patients an average of 12.6 and 4.6 were observed, respectively. CONCLUSIONS: Tracheostomy performed in patients with specific criteria, such as low ventilatory parameters, age, or low score in severity scales, may have a better prognosis.

OBJETIVO: Realizar una descripción de las características clínicas, los factores asociados y el desenlace de las traqueostomías realizadas en pacientes con COVID-19. MÉTODO: Estudio retrospectivo observacional de 14 pacientes a quienes se realizó traqueostomía. Diez de ellos se encontraban diagnosticados con COVID-19, confirmada con prueba RT-PCR de exudado nasofaríngeo y hallazgos tomográficos compatibles. RESULTADOS: De los 10 pacientes, cinco fueron dados de alta y cinco fallecieron. La edad promedio de los pacientes que fallecieron fue de 66.6 años, y la de los que fueron dados de alta fue de 60.4 años. De los parámetros ventilatorios, se tomó como corte una FiO2 ≤ 40% y una PEEP ≤ 8; entre los pacientes dados de alta, cuatro cumplían con ambos criterios. En cambio, de los pacientes que fallecieron, ninguno los cumplió. En estos últimos se documentó un promedio de APACHE II de 16.4 y un SOFA de 7.4, mientras que en los pacientes dados de alta se observó un promedio de 12.6 y 4.6, respectivamente. CONCLUSIONES: La traqueostomía realizada en pacientes con criterios específicos, como parámetros ventilatorios bajos, edad o puntuación baja en las escalas de gravedad, pueden llegar a tener mejor pronóstico.

Heterogeneity of Ventilation/Perfusion Mismatch at Different Levels of PEEP and in Mechanical Phenotypes of COVID-19 ARDS.

BACKGROUND: COVID-19-related ARDS is characterized by severe hypoxemia with initially preserved lung compliance and impaired ventilation/perfusion (V̇/Q̇) matching. PEEP can increase end-expiratory lung volume, but its effect on V̇/Q̇ mismatch in COVID-19-related ARDS is not clear. METHODS: We enrolled intubated and mechanically ventilated subjects with COVID-19 ARDS and used the automatic lung parameter estimator (ALPE) to measure V̇/Q̇. Respiratory mechanics measurements, shunt, and V̇/Q̇ mismatch (low V̇/Q̇ and high V̇/Q̇) were collected at 3 PEEP levels (clinical PEEP = intermediate PEEP, low PEEP [clinical - 50%], and high PEEP [clinical + 50%]). A mixed-effect model was used to evaluate the impact of PEEP on V̇/Q̇. We also investigated if PEEP might have a different effect on V̇/Q̇ mismatch in 2 different respiratory mechanics phenotypes, that is, high elastance/low compliance (phenotype H) and low elastance/high compliance (phenotype L). RESULTS: Seventeen subjects with COVID-related ARDS age 66 [60-71] y with a PaO2 /FIO2 of 141 ± 74 mm Hg were studied at low PEEP = 5.6 ± 2.2 cm H2O, intermediate PEEP = 10.6 ± 3.8 cm H2O, and high PEEP = 15 ± 5 cm H2O. Shunt, low V̇/Q̇, high V̇/Q̇, and alveolar dead space were not significantly influenced, on average, by PEEP. Respiratory system compliance decreased significantly when increasing PEEP without significant variation of PaO2 /FIO2 (P = .26). In the 2 phenotypes, PEEP had opposite effects on shunt, with a decrease in the phenotype L and an increase in phenotype H (P = .048). CONCLUSIONS: In subjects with COVID-related ARDS placed on invasive mechanical ventilation for > 48 h, PEEP had a heterogeneous effect on V̇/Q̇ mismatch and, on average, higher levels were not able to reduce shunt. The subject's compliance could influence the effect of PEEP on V̇/Q̇ mismatch since an increased shunt was observed in subjects with lower compliance, whereas the opposite occurred in those with higher compliance.

Efficacy of proning in acute respiratory distress syndrome on extracorporeal membrane oxygenation.

Objectives: Proning patients with acute respiratory distress syndrome (ARDS) has been associated with increased survival, although few data exist evaluating the safety and feasibility of proning patients with ARDS on extracorporeal membrane oxygenation (ECMO). Methods: A single-institution retrospective review of all patients with ARDS placed on ECMO between March 1 and May 31, 2020, was performed. All proning events were evaluated for complications, as well as change in compliance, sweep, oxygenation, and flow. The primary outcome of this study was the rate major morbidity associated with proning while on ECMO. Results: In total, 30 patients were placed on ECMO for ARDS, with 12 patients (40%) proned while on ECMO. A total of 83 proning episodes occurred, with a median of 7 per patient (interquartile range, 3-9). No ECMO cannula-associated bleeding, cannula displacement, or endotracheal tune dislodgements occurred (0%). Oropharyngeal bleeding occurred twice (50%). Four patients were proned with chest tubes in place, and none had complications (0%). Lung compliance improved after proning in 70 events (84%), from a mean of 15.4 mL/mm Hg preproning to 20.6 mL/mm Hg postproning (P < .0001). Sweep requirement decreased in 36 events (43%). Oxygenation improved in 63 events (76%), from a mean partial pressure of oxygen of 86 preproning to 103 postproning (P < .0001). Mean ECMO flow was unchanged. Conclusions: Proning in patients with ARDS on ECMO is safe with an associated improvement in lung mechanics. With careful planning and coordination, these data support the practice of appropriately proning patients with severe ARDS, even if they are on ECMO.

Time constant to determine PEEP levels in mechanically ventilated COVID-19 ARDS: a feasibility study.

BACKGROUND: We hypothesized that the measured expiratory time constant (TauE) could be a bedside parameter for the evaluation of positive end-expiratory pressure (PEEP) settings in mechanically ventilated COVID-19 patients during pressure-controlled ventilation (PCV). METHODS: A prospective study was conducted including consecutively admitted adults (n = 16) with COVID-19-related ARDS requiring mechanical ventilation. A PEEP titration using PCV with a fixed driving pressure of 14 cmH2O was performed and TauE recorded at each PEEP level (0 to 18 cmH2O) in prone (n = 29) or supine (n = 24) positions. The PEEP setting with the highest TauE (TauEMAX) was considered to represent the best tradeoff between recruitment and overdistention. RESULTS: Two groups of patterns were observed in the TauE plots: recruitable (R) (75%) and nonrecruitable (NR) (25%). In the R group, the optimal PEEP and PEEP ranges were 8 ± 3 cmH2O and 6-10 cmH2O for the prone position and 9 ± 3 cmH2O and 7-12 cmH2O for the supine position. In the NR group, the optimal PEEP and PEEP ranges were 4 ± 4 cmH2O and 1-8 cmH2O for the prone position and 5 ± 3 cmH2O and 1-7 cmH2O for the supine position, respectively. The R group showed significantly higher optimal PEEP (p < 0.004) and PEEP ranges (p < 0.001) than the NR group. Forty-five percent of measurements resulted in the most optimal PEEP being significantly different between the positions (p < 0.01). Moderate positive correlation has been found between TauE vs CRS at all PEEP levels (r2 = 0.43, p < 0.001). CONCLUSIONS: TauE may be a novel method to assess PEEP levels. There was wide variation in patient responses to PEEP, which indicates the need for personalized evaluation.

Association of Positive End-Expiratory Pressure and Lung Recruitment Selection Strategies with Mortality in Acute Respiratory Distress Syndrome: A Systematic Review and Network Meta-analysis.

Rationale: The most beneficial positive end-expiratory pressure (PEEP) selection strategy in patients with acute respiratory distress syndrome (ARDS) is unknown, and current practice is variable. Objectives: To compare the relative effects of different PEEP selection strategies on mortality in adults with moderate to severe ARDS. Methods: We conducted a network meta-analysis using a Bayesian framework. Certainty of evidence was evaluated using grading of recommendations assessment, development and evaluation methodology. Measurements and Main Results: We included 18 randomized trials (4,646 participants). Compared with a lower PEEP strategy, the posterior probability of mortality benefit from a higher PEEP without lung recruitment maneuver (LRM) strategy was 99% (risk ratio [RR], 0.77; 95% credible interval [CrI], 0.60-0.96, high certainty), the posterior probability of benefit of the esophageal pressure-guided strategy was 87% (RR, 0.77; 95% CrI, 0.48-1.22, moderate certainty), the posterior probability of benefit of a higher PEEP with brief LRM strategy was 96% (RR, 0.83; 95% CrI, 0.67-1.02, moderate certainty), and the posterior probability of increased mortality from a higher PEEP with prolonged LRM strategy was 77% (RR, 1.06; 95% CrI, 0.89-1.22, low certainty). Compared with a higher PEEP without LRM strategy, the posterior probability of increased mortality from a higher PEEP with prolonged LRM strategy was 99% (RR, 1.37; 95% CrI, 1.04-1.81, moderate certainty). Conclusions: In patients with moderate to severe ARDS, higher PEEP without LRM is associated with a lower risk of death than lower PEEP. A higher PEEP with prolonged LRM strategy is associated with increased risk of death when compared with higher PEEP without LRM.

Cost-effective and power-efficient portable turbine-based emergency ventilator.

Ventilators have always been common in medical scenarios but are very expensive to procure or develop. One of the main reasons for these is the components that are being used are expensive and require precise instrumentation, research, and development. This paper attempts to mitigate that problem by proposing a novel way to rapidly develop a portable ventilator that uses common 3D printing technology and off-the-shelf components. This turbine and valve-based ventilator feature most of the modes that are commonly used by healthcare professionals. A unique servo-based pressure release mechanism has been designed that makes the system around 36 times more efficient than solenoid-based systems. Reliability and efficiency have been increased further through the use of a novel positive end-expiratory pressure (PEEP) valve that does not contain any electromechanical component. Effective algorithms such as feed-forward and proportional-integral-derivative (PID) controllers were used alongside the unique 'Sensor data filtration methodology'. The system also provides an interactive graphical user interface (GUI) via an android application that can be installed on any readily found tabs while the firmware manages the breathing detection algorithm using a flow meter and pressure sensor. This modular and portable ventilator also features a replaceable battery and holds the ability to run on solar power. This energy-efficient low-noise system can run for 5 to 6 h at a stretch without needing to be connected to the main's supply.

Positive End-Expiratory Pressure Setting in COVID-19-Related Acute Respiratory Distress Syndrome: Comparison Between Electrical Impedance Tomography, PEEP/FiO2 Tables, and Transpulmonary Pressure.

Introduction: The best way to titrate the positive end-expiratory pressure (PEEP) in patients suffering from acute respiratory distress syndrome is still matter of debate. Electrical impedance tomography (EIT) is a non-invasive technique that could guide PEEP setting based on an optimized ventilation homogeneity. Methods: For this study, we enrolled the patients with 2019 coronavirus disease (COVID-19)-related acute respiratory distress syndrome (ARDS), who required mechanical ventilation and were admitted to the ICU in March 2021. Patients were monitored by an esophageal catheter and a 32-electrode EIT device. Within 48 h after the start of mechanical ventilation, different levels of PEEP were applied based upon PEEP/FiO2 tables, positive end-expiratory transpulmonary (PL)/ FiO2 table, and EIT. Respiratory mechanics variables were recorded. Results: Seventeen patients were enrolled. PEEP values derived from EIT (PEEPEIT) were different from those based upon other techniques and has poor in-between agreement. The PEEPEIT was associated with lower plateau pressure, mechanical power, transpulmonary pressures, and with a higher static compliance (Crs) and homogeneity of ventilation. Conclusion: Personalized PEEP setting derived from EIT may help to achieve a more homogenous distribution of ventilation. Whether this approach may translate in outcome improvement remains to be investigated.

A Bench Comparison of the Effect of High-Flow Oxygen Devices on Work of Breathing.

BACKGROUND: Oxygen therapy via high-flow nasal cannula (HFNC) has been extensively used during the COVID-19 pandemic. The number of devices has also increased. We conducted this study to answer the following questions: Do HFNC devices differ from the original device for work of breathing (WOB) and generated PEEP? METHODS: Seven devices were tested on ASL 5000 lung model. Compliance was set to 40 mL/cm H2O and resistance to 10 cm H2O/L/s. The devices were connected to a manikin head via a nasal cannula with FIO2 set at 0.21. The measurements were performed at baseline (manikin head free of nasal cannula) and then with the cannula and the device attached with oxygen flow set at 20, 40, and 60 L/min. WOB and PEEP were assessed at 3 simulated inspiratory efforts (-5, -10, -15 cm H2O muscular pressure) and at 2 breathing frequencies (20 and 30 breaths/min). Data were expressed as median (first-third quartiles) and compared with nonparametric tests to the Optiflow device taken as reference. RESULTS: Baseline WOB and PEEP were comparable between devices. Over all the conditions tested, WOB was 4.2 (1.0-9.4) J/min with the reference device, and the relative variations from it were 0, -3 (2-4), 1 (0-1), -2 (1-2), -1 (1-2), and -1 (1-2)% with Airvo 2, G5, HM80, T60, V500, and V60 Plus devices, respectively, (P < .05 Kruskal-Wallis test). PEEP was 0.9 (0.3-1.5) cm H2O with Optiflow, and the relative differences were -28 (22-33), -41 (38-46), -30 (26-36), -31 (28-34), -37 (32-42), and -24 (21-34)% with Airvo 2, G5, HM80, T60, V500, and V60 Plus devices, respectively, (P < .05 Kruskal-Wallis test). CONCLUSIONS: WOB was marginally higher and PEEP marginally lower with devices as compared to the reference device.

High efficiency particulate air filters and heat & moisture exchanger filters increase positive end-expiratory pressure in helmet continuous positive airway pressure: A bench-top study.

BACKGROUND: Helmet continuous positive airway pressure (CPAP) has been widely used during the COVID-19 pandemic. Specific filters (i.e. High Efficiency Particulate Air filter: HEPA; Heat & Moisture Exchanger Filter: HMEF) were used to prevent Sars-CoV2 environmental dispersion and were connected to the CPAP helmet. However, HEPA and HMEF filters may act as resistors to expiratory gas flow and increase the levels of pressure within the hood. METHODS: In a bench-top study, we investigated the levels of airway pressure generated by different HEPA and HMEF filters connected to the CPAP helmet in the absence of a Positive End Expiratory Pressure (PEEP) valve and with two levels of PEEP (5 and 10 cmH2O). All steps were performed using 3 increasing levels of gas flow (60, 80, 100 L/min). RESULTS: The use of 8 different commercially available filters significantly increased the pressure within the hood of the CPAP helmet with or without the use of PEEP valves. On average, the increase of pressure above the set PEEP ranged from 3 cmH2O to 10 cmH2O across gas flow rates of 60 to 100 L/min. The measure of airway pressure was highly correlated between the laboratory pressure transducer and the Helmet manometer. Bias with 95% Confidence Interval of Bias between the devices was 0.7 (-2.06; 0.66) cmH2O. CONCLUSIONS: The use of HEPA and HMEF filters placed before the PEEP valve at the expiratory port of the CPAP helmet significantly increase the levels of airway pressure compared to the set level of PEEP. The manometer can detect accurately the airway pressure in the presence of HEPA and HMEF filters in the helmet CPAP and its use should considered.

Understanding dead space in giraffes, and its application to critically ill COVID-19 patients

Giraffes have long been a subject of study for scientists due to the physiological anomaly their anatomical design can present. The study of the species helps aid in understanding of clinically relevant processes. The long trachea of a giraffe presents the dilemma of exaggerated dead space;however, this physiological problem is surmounted by a narrow trachea when compared to mammals of similar size, thus decreasing potential dead space. As COVID-19 patients in the hospital and ICU can develop COVID-19 associated acute respiratory distress syndrome, limiting excess dead space in COVID-19 patients is favorable. Removing additional tubing for a patient with an endotracheal tube in a ventilator circuit could help lower the patient's PaCO2 and raise their pH.

Treatment of COVID-19 Acute Respiratory Distress Syndrome With a Tabletop Noninvasive Ventilation Device in a Respiratory Intermediate Care Unit.

Objective: To study the outcomes of noninvasive ventilation (NIV) administered through a tabletop device for coronavirus disease 2019 acute respiratory distress syndrome in the respiratory intermediate care unit (RIMCU) at a tertiary care hospital in India. Patients and Methods: We retrospectively studied a cohort of hospitalized patients deteriorating despite low-flow oxygen support who received protocolized management with positive airway pressure using a tabletop NIV device in the RIMCU as a step-up rescue therapy from July 30, 2020 to November 14, 2020. Treatment was commenced on the continuous positive airway pressure mode up to a pressure of 10 cm of H2O, and if required, inspiratory pressures were added using the bilevel positive air pressure mode. Success was defined as weaning from NIV and stepping down to the ward, and failure was defined as escalation to the intensive care unit, the need for intubation, or death. Results: In total, 246 patients were treated in the RIMCU during the study period. Of these, 168 received respiratory support via a tabletop NIV device as a step-up rescue therapy. Their mean age was 54 years, and 83% were men. Diabetes mellitus (78%) and hypertension (44%) were the commonest comorbidities. Treatment was successful with tabletop NIV in 77% (129/168) of the patients; of them, 41% (69/168) received treatment with continuous positive airway pressure alone and 36% (60/168) received additional increased inspiratory pressure via the bilevel positive air pressure mode. Conclusion: Respiratory support using the tabletop NIV device was an effective and economical treatment for coronavirus disease 2019 acute respiratory distress syndrome. Further studies are required to assess the appropriate time of initiation for maximal benefits and judicious utilization of resources.

Thoracic Computed Tomography to Assess ARDS and COVID-19 Lungs.

This review was designed to discuss the role of thoracic-computed tomography (CT) in the evaluation and treatment of patients with ARDS and COVID-19 lung disease. Non-aerated lungs characterize the ARDS lungs, compared to normal lungs in the lowermost lung regions, compressive atelectasis. Heterogenous ARDS lungs have a tomographic vertical gradient characterized by progressively more aerated lung tissues from the gravity-dependent to gravity-independent lungs levels. The application of positive pressure ventilation to these heterogeneous ARDS lungs provides some areas of high shear stress, others of tidal hyperdistension or tidal recruitment that increases the chances of appearance and perpetuation of ventilator-induced lung injury. Other than helping to the correct diagnosis of ARDS, thoracic-computed tomography can help to the adjustments of PEEP, ideal tidal volume, and a better choice of patient position during invasive mechanical ventilation. Thoracic tomography can also help detect possible intra-thoracic complications and in the follow-up of the ARDS patients' evolution during their hospital stay. In COVID-19 patients, thoracic-computed tomography was the most sensitive imaging technique for diagnosing pulmonary involvement. The most common finding is diffuse pulmonary infiltrates, ranging from ground-glass opacities to parenchymal consolidations, especially in the lower portions of the lungs' periphery. Tomographic lung volume loss was associated with an increased risk for oxygenation support and patient intubation and the use of invasive mechanical ventilation. Pulmonary dual-energy angio-tomography in COVID-19 patients showed a significant number of pulmonary ischemic areas even in the absence of visible pulmonary arterial thrombosis, which may reflect micro-thrombosis associated with COVID-19 pneumonia. A greater thoracic tomography severity score in ARDS was independently related to poor outcomes.

Effects of Prone Positioning on Respiratory Mechanics and Oxygenation in Critically Ill Patients With COVID-19 Requiring Venovenous Extracorporeal Membrane Oxygenation.

BACKGROUND: The effect of prone positioning (PP) on respiratory mechanics remains uncertain in patients with severe acute respiratory distress syndrome (ARDS) requiring venovenous extracorporeal membrane oxygenation (VV-ECMO). METHODS: We prospectively analyzed the effects of PP on respiratory mechanics from continuous data with over a thousand time points during 16-h PP sessions in patients with COVID-19 and ARDS under VV-ECMO conditions. The evolution of respiratory mechanical and oxygenation parameters during the PP sessions was evaluated by dividing each PP session into four time quartiles: first quartile: 0-4 h, second quartile: 4-8 h, third quartile: 8-12 h, and fourth quartile: 12-16 h. RESULTS: Overall, 38 PP sessions were performed in 10 patients, with 3 [2-5] PP sessions per patient. Seven (70%) patients were responders to at least one PP session. PP significantly increased the PaO2/FiO2 ratio by 14 ± 21% and compliance by 8 ± 15%, and significantly decreased the oxygenation index by 13 ± 18% and driving pressure by 8 ± 12%. The effects of PP on respiratory mechanics but not on oxygenation persisted after supine repositioning. PP-induced changes in different respiratory mechanical parameters and oxygenation started as early as the first-time quartile, without any difference in PP-induced changes among the different time quartiles. PP-induced changes in driving pressure (-14 ± 14 vs. -6 ± 10%, p = 0.04) and mechanical power (-11 ± 13 vs. -0.1 ± 12%, p = 0.02) were significantly higher in responders (increase in PaO2/FiO2 ratio > 20%) than in non-responder patients. CONCLUSIONS: In patients with COVID-19 and severe ARDS, PP under VV-ECMO conditions improved the respiratory mechanical and oxygenation parameters, and the effects of PP on respiratory mechanics persisted after supine repositioning.

Higher mortality of hospitalized haematologic patients with COVID-19 compared to non-haematologic is driven by thrombotic complications and development of ARDS: An age-matched cohorts study.

BACKGROUND AND OBJECTIVES: The characteristics of COVID-19 in haematologic patients compared to non-haematologic patients have seldom been analyzed. Our aim was to analyze whether there are differences in clinical characteristics and outcome of haematologic patients with COVID-19 as compared to non-haematologic. PATIENTS AND METHODS: Retrospective cohort study in 2 University hospitals of patients admitted with laboratory-confirmed COVID-19 included in the SEMICOVID19 database. The cohort with underlying haematologic disease was compared to a cohort of age and date-of-COVID-19-matched controls without haematologic disease (1:2). RESULTS: 71 cases and 142 controls were included from March-May 2020.Twenty (28.1%) had received recent chemotherapy. Twelve (16.9%) were stem cell transplant recipients (SCT). Eleven (15.5%) were neutropenic concurrently with COVID-19 diagnosis.Haematologic patients presented ARDS (58.5 vs 20.7%, p = 0.0001), thrombotic complications (15.7 vs 2.1%, p = 0.002), DIC (5.7 vs 0.0%, p = 0.011), heart failure (14.3 vs 4.9%, p = 0.029) and required ICU admission (15.5 vs 2.8%, p = 0.001), MV (14.1% vs 2.1%, p 0.001), steroid (64.8 vs 33.1%, p = 0.0001), tocilizumab (33.8 vs 8.5%, p = 0.0001) or anakinra treatment (9.9% vs 0%, p = 0.0001) more often. In-hospital mortality was significantly higher (38.0% vs 18.3%, p = 0.002). CONCLUSIONS: Our results suggest COVID-19 has worse outcomes in haematologic patients than in non-haematologic, independently of age, and that the development of ARDS and thrombotic complications drive the higher in-hospital mortality.

Design and Implementation of a Helmet-based, Noninvasive CPAP Devices for COVID-19

The world is passing a terrible time while lives are despairing due to coronavirus. In Covid-19, most of the patients suffer from low oxygen saturation. Different types of devices are used to increase the oxygen level. This paper discusses a helmet-based Continuous Positive Airway Pressure (CPAP) device's design and implementation. A blower generates positive pressure, while a pressure sensor adjusts the required pressure. A TFT display is used to monitor the data, and two rotary encoders are used to set the required value. Two Arduino boards are used as real-time and user interface controllers. The hardware simulations and PCB designs are done in the Proteus software. The mechanical body of the CPAP device was designed in Solidworks software. A helmet is connected to the CPAP, also designed in the Solidworks software. The oxygen mixed pressurized air goes through the pipe to the helmet. Finally, the cost of the device is also presented in this paper. © 2021 IEEE.