Critical Care Ventilators Research Articles

In Vitro Comparison of Inspiration-Synchronized and Continuous Vibrating Mesh Nebulizer During Adult Invasive Mechanical Ventilation.

Background: Aerosol delivery may be enhanced by utilizing an inspiration-synchronized nebulization mode, where nebulization occurs only during inspiration. This study aimed to compare aerosol delivery of albuterol via a prototype of an inspiration-synchronized vibrating mesh nebulizer (VMN) versus continuous VMN during invasive mechanical ventilation. Methods: A critical care ventilator equipped with a heated-wire circuit to deliver adult parameters was attached to an endotracheal tube (ETT), a collection filter, and a test lung. The nebulizer was placed at the humidifier's inlet, inspiratory limb at the Y-piece, and between the Y-piece and ETT. Conventional VMNs producing standard size aerosol particles (Solo; Aerogen Ltd) were compared with prototype small-particle VMNs (Aerogen Pharma) in both inspiration-synchronization and continuous modes. In each run, 1 mL of albuterol (2.5 mg) was used (n = 5). The drug was eluted from the collection filter and assayed with UV spectrophotometry (276 nm). Results: The inhaled dose with inspiration-synchronization mode was 1.4 to 3.6 times that with the continuous mode, regardless of nebulizer positions (all p < 0.001). The small-particle VMN delivered an 8%-69% greater inhaled dose than the conventional VMN (Solo), regardless of the nebulizer placement or aerosol generation mode (all p < 0.001). The highest inhaled dose (50%-60%) with the inspiration-synchronized VMN was observed when it was placed at the ETT (all p < 0.001), whereas the continuous VMN performed better when positioned near the humidifier, with an inhaled dose of 21%-37% (p < 0.001). Conclusion: The inspiration-synchronized VMN delivered a greater inhaled dose than continuous VMN, irrespective of nebulizer placement. The prototype VMN producing smaller aerosol particles resulted in a greater inhaled dose than the conventional VMN (Solo), regardless of placement or aerosol generation modes. The inspiration-synchronized VMN achieved the highest delivery when placed close to the airway, whereas the continuous VMN delivered the most when positioned near the ventilator.

Association of PCSK9 inhibitors with mortality: insights from a retrospective cohort analysis.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors are effective in reducing cardiovascular events, but their impact on all-cause mortality and medical utilization compared to statins is unclear. This study investigated PCSK9 inhibitor use and its impact on mortality and medical utilization vs. statins, using TriNetX database data with up to 9 years of follow-up. This retrospective cohort study analysed TriNetX data spanning 1 July 2015, to 31 December 2023, including 79194 PCSK9 inhibitor users (alirocumab, evolocumab, inclisiran) and 5437513 statin users with hyperlipidaemia. The primary outcomes were all-cause mortality and medical utilization, including hospital inpatient services, emergency department visits, critical care, and mechanical ventilation. Propensity score matching showed that PCSK9 inhibitor use was associated with a 28.3% lower risk of all-cause mortality [adjusted hazard ratio (aHR) 0.717, 95% confidence interval (CI): 0.673-0.763] and significant reductions in medical utilization (hospital inpatient services usage: aHR 0.692, 95% CI: 0.664-0.721; emergency department services: aHR 0.756, 95% CI: 0.726-0.788; critical care services: aHR 0.619, 95% CI: 0.578-0.664; and mechanical ventilation: aHR 0.537, 95% CI: 0.484-0.596) compared to statins. These findings were consistent across various demographics and clinical subgroups. The sensitivity analyses supported the robustness of the findings. PCSK9 inhibitors significantly reduced all-cause mortality and medical utilization compared to statins, suggesting their important role in dyslipidaemia management, particularly for statin-naïve or intolerant patients. Further research, including randomized controlled trials, is needed to confirm these findings and explore the underlying mechanisms.

Reliability and Safety Testing of a Ventilator Remote Control System Against Communication Failures and Network Disruptions.

The need for remote ventilator control has been highlighted by the COVID-19 Public Health Emergency. Remote ventilator control from outside a patient's room can improve response time to patient needs, protect health care workers, and reduce personal protective equipment (PPE) consumption. Extending remote control to distant locations can expand the capabilities of frontline health care workers by delivering specialized clinical expertise to the point of care, which is much needed in diverse health care settings, such as tele-critical care and military medicine. However, the safety and effectiveness of remote ventilator control can be affected by many risk factors, including communication failures and network disruptions. Consensus safety requirements and test methods are needed to assess the resilience and safety of remote ventilator control under communication failures and network disruptions. We designed two test methods to assess the robustness, usability, and safety of a remote ventilator control prototype system jointly developed by Nihon Kohden OrangeMed, Inc. and DocBox, Inc. ("the NK-DocBox system") to control the operation of an NKV-550 critical care ventilator under communication failures and network disruptions. First, the robustness of the NKV-550 ventilator was tested using a remote-control application developed on OpenICE - an open-source medical device interoperability platform - to transmit customized high-frequency and erroneous remote-control commands that could be caused by communication failures in a real-world environment. The second method utilized a network emulator to create different types and severity of network quality of service (QoS) degradation, including bandwidth throttling, network delay and jitter, packet drop and reordering, and bit errors, in the NKV-DocBox system to quantitatively assess the impact on system usability and safety. The NKV-550 ventilator operated as expected when remote-control commands arrived as fast as once per second. It ignored erroneous commands attempting to adjust invalid ventilation parameters. When facing commands that set the ventilation mode and parameters to invalid values, it reset the ventilation mode or parameters to default values, the safety implication of which may merit further evaluation. When any network QoS attribute (except for packet reordering) started to degrade, the NK-DocBox System experienced interference to its remote-control function, such as delays in the transmission of ventilator data and remote-control commands within the system. When the network QoS was worse than 500 ms network delay, 100 ms network jitter, 1% data drop rate, 12Mbps minimal bandwidth, or 1e-6 bit error rate, the system became unsafe to use. For example, ventilator waveforms visualized on the remote-control application demonstrated freezes, out-of-synchronization, and moving backwards; and the connection between the ventilator and the remote-control application became unstable. The presented test methods confirmed the robustness of the NKV-550 ventilator against high-frequency and erroneous remote control, quantified the impact of network disruptions on the usability, reliability, and safety of the NK-DocBox system and identified the minimum network QoS requirements for it to function safely. These generalizable test methods can be customized to evaluate other remote ventilator control technologies and remote control of other types of medical devices against communication failures and network disruptions.

Electrical Impedance Tomography, Artificial Intelligence, and Variable Ventilation: Transforming Respiratory Monitoring and Treatment in Critical Care.

Electrical Impedance Tomography (EIT), combined with variable ventilation strategies and Artificial Intelligence (AI), is poised to revolutionize critical care by transitioning from reactive to predictive approaches. This integration aims to enhance patient outcomes through personalized interventions and real-time monitoring. this narrative review explores the principles and applications of EIT, variable ventilation, and AI in critical care. EIT impedance sensing creates dynamic images of internal physiology, aiding the management of conditions like Acute Respiratory Distress Syndrome (ARDS). Variable ventilation mimics natural breathing variability to improve lung function and minimize ventilator-induced lung injury. AI enhances EIT through advanced image reconstruction techniques, neural networks, and digital twin technology, offering more accurate diagnostics and tailored therapeutic interventions. the confluence of EIT, variable ventilation, and AI represents a significant advancement in critical care, enabling a predictive, personalized approach. EIT provides real-time insights into lung function, guiding precise ventilation adjustments and therapeutic interventions. AI integration enhances EIT diagnostic capabilities, facilitating the development of personalized treatment plans. This synergy fosters interdisciplinary collaborations and sets the stage for innovative research, ultimately improving patient outcomes and advancing the future of critical care.

Personalized music for cognitive and psychological symptom management during mechanical ventilation in critical care: A qualitative analysis.

Patients experience high symptom burden during critical care hospitalization and mechanical ventilation. Medications are of limited effectiveness and are associated with increased morbidity such as delirium and long-term cognitive and psychological impairments. Music-based interventions have been used for pain and anxiety management in critical care but remain understudied in terms of music selection and range of symptoms. This study aimed to describe the ways in which a diverse sample of critically ill adults used personalized music listening and their perceptions of the effects of music listening on symptom experience after critical injury. Semi-structured interviews (N = 14) of adult patients, families and friends who were provided with personalized music in an urban, academic, neurotrauma intensive care unit were collected and analyzed with grounded theory methodology. Open coding of transcripts, field notes and memos was performed using Atlas.ti.9.1. Recruitment and data collection were deemed complete once thematic saturation was achieved. We identified 6 uses of personalized music listening in critical care: 1) Restoring consciousness; 2) Maintaining cognition; 3) Humanizing the hospital experience; 4) Providing a source of connection; 5) Improving psychological wellbeing; and 6) Resolving the problems of silence. Patients used music to address psychological experiences of loneliness, fear, confusion, and loss of control. Personalized music helped patients maintain their identity and process their trauma. Additional benefits of music included experiencing pleasure, hope, resilience, and feelings of normalcy. Patients disliked being sedated and used music to wake up. Findings also highlighted the problem of the lack of meaningful stimulation in critical care. Critically injured adults used personalized music to achieve psychological and cognitive homeostasis during critical care hospitalization. These results can inform future studies designed to explore the use of music-based interventions to prevent and treat the cognitive and emotional morbidity of critical care.

Guideline-informed reinforcement learning for mechanical ventilation in critical care

Reinforcement Learning (RL) has recently found many applications in the healthcare domain thanks to its natural fit to clinical decision-making and ability to learn optimal decisions from observational data. A key challenge in adopting RL-based solution in clinical practice, however, is the inclusion of existing knowledge in learning a suitable solution. Existing knowledge from e.g. medical guidelines may improve the safety of solutions, produce a better balance between short- and long-term outcomes for patients and increase trust and adoption by clinicians. We present a framework for including knowledge available from medical guidelines in RL. The framework includes components for enforcing safety constraints and an approach that alters the learning signal to better balance short- and long-term outcomes based on these guidelines. We evaluate the framework by extending an existing RL-based mechanical ventilation (MV) approach with clinically established ventilation guidelines. Results from off-policy policy evaluation indicate that our approach has the potential to decrease 90-day mortality while ensuring lung protective ventilation. This framework provides an important stepping stone towards implementations of RL in clinical practice and opens up several avenues for further research.

Arrangement of residence before hospital discharge for children on home-invasive mechanical ventilation.

Children on long-term home mechanical ventilation are a growing population due to clinical and technological advances and the benefit for the child's quality of life. Invasive home ventilation is one of the most complex therapies offered in the home setting, requiring adequate home environment and appropriate equipment and supplies before discharge.The transition from hospital to home represents a vulnerable period that can be facilitated with an established transition plan with multidisciplinary team involvement. Readiness for home care is achieved when the patient is stable and has been transitioned from a critical care ventilator to a home mechanical ventilator. In parallel, comprehensive competency-based training regarding the knowledge and skills needed to help families use the equipment confidently and safely. Before discharge, families should be counseled on an adequate home environment to ensure a safe transition. The residence arrangement may include physical space modifications, verifying electrical installation, or moving to another home. Durable medical equipment and supplies must be ordered, and community healthcare support arranged. Parents should receive practical advice on setting up the equipment at home and on preventive measures to minimize complications related to tracheostomy and ventilator dependence, including regular maintenance and replacement of necessary equipment.Given the overall impact of invasive ventilation on home life, a structured home care action package is essential to alleviate the burdens involved.

Development of a non-invasive ventilator for emergency and beyond

The SARS-CoV-2 pandemic led to the development and implementation of emergency ventilators owing to the shortage of ventilators globally. Using invasive ventilators for patient intubation has medical experts concerned about increasing mortality. Early intervention with oxygen and respiratory therapy reduces the need for intubation, increases survival rates, and reduces the stress of critical care ventilators in hospitals. This study explores the capabilities of an easy-to-build and accessible non-invasive ventilator during an emergency and the practical implementation of the ventilator beyond the scope of the emergency. The proposed system consists of a high-pressure turbine integrated with a microcontroller and pressure and flow sensors assembled in a portable design. The non-invasive pressure support system is tested with a single-chamber high-precision lung simulator capable of simulating multiple lung diseases. The system is operated in a spontaneous pressure support mode as a Bi-level Ventilator for varying degrees of pressure level and lung conditions. The proposed study implements two most commonly adapted non-invasive patient circuits, i.e., single passive limb leak circuit and single limb active circuit. Both circuits are tested with and without leakage compensation. Two clinically accepted ventilation modes, i.e., pressure support and volume-assured pressure support ventilation, are presented. The results demonstrate the feasibility of using this type of device for non-invasive respiratory support and highlight the need for further testing to assess its safety and effectiveness in various clinical settings.

Association Between Hypertension and Diabetes Control and COVID-19 Severity: National Patient-Centered Clinical Research Network, United States, March 2020 to February 2022.

Background Hypertension and diabetes are associated with increased COVID-19 severity. The association between level of control of these conditions and COVID-19 severity is less well understood. Methods and Results This retrospective cohort study identified adults with COVID-19, March 2020 to February 2022, in 43 US health systems in the National Patient-Centered Clinical Research Network. Hypertension control was categorized as blood pressure (BP) <130/80, 130 to 139/80 to 89, 140 to 159/90 to 99, or ≥160/100 mm Hg, and diabetes control as glycated hemoglobin <7%, 7% to <9%, ≥9%. Adjusted, pooled logistic regression assessed associations between hypertension and diabetes control and severe COVID-19 outcomes. Among 1 494 837 adults with COVID-19, 43% had hypertension and 12% had diabetes. Among patients with hypertension, the highest baseline BP was associated with greater odds of hospitalization (adjusted odds ratio [aOR], 1.30 [95% CI, 1.23-1.37] for BP ≥160/100 versus BP <130/80), critical care (aOR, 1.30 [95% CI, 1.21-1.40]), and mechanical ventilation (aOR, 1.32 [95% CI, 1.17-1.50]) but not mortality (aOR, 1.08 [95% CI, 0.98-1.12]). Among patients with diabetes, the highest glycated hemoglobin was associated with greater odds of hospitalization (aOR, 1.61 [95% CI, 1.47-1.76] for glycated hemoglobin ≥9% versus <7%), critical care (aOR, 1.42 [95% CI, 1.31-1.54]), mechanical ventilation (aOR, 1.12 [95% CI, 1.02-1.23]), and mortality (aOR, 1.18 [95% CI, 1.09-1.27]). Black and Hispanic adults were more likely than White adults to experience severe COVID-19 outcomes, independent of comorbidity score and control of hypertension or diabetes. Conclusions Among 1.5 million patients with COVID-19, higher BP and glycated hemoglobin were associated with more severe COVID-19 outcomes. Findings suggest that adults with poorest control of hypertension or diabetes might benefit from efforts to prevent and initiate early treatment of COVID-19.

Ventilator Training through International Telesimulation in Sierra Leone.

The coronavirus disease (COVID-19) pandemic resulted in an increased need for medical professionals with expertise in managing patients with acute hypoxemic respiratory failure, overwhelming the existing critical care workforce in many low-resource countries. To address this need in Sierra Leone, we developed, piloted, and evaluated a synchronous simulation-based tele-education workshop for healthcare providers on the fundamental principles of intensive care unit (ICU) management of the COVID-19 patient in a low-resource setting. Thirteen 2-day virtual workshops were implemented between April and July 2020 with frontline Sierra Leone physicians and nurses for potential ICU patients in hospitals throughout Sierra Leone. Although all training sessions took place at the 34 Military Hospital (a national COVID-19 center) in Freetown, participants were drawn from hospitals in each of the provinces of Sierra Leone. The workshops included synchronous tele-education-directed medical simulation didactic sessions about COVID-19, hypoxemia management, and hands-on simulation training about mechanical ventilation. Measures included pre and postworkshop knowledge tests, simulation checklists, and a posttest survey. Test results were analyzed with a paired sample t test; Likert-scale survey responses were reported using descriptive statistics; and open-ended responses were analyzed using thematic analysis. Seventy-five participants enrolled in the program. On average, participants showed 20.8% improvement (a score difference of 4.00 out of a maximum total score of 20) in scores between pre and postworkshop knowledge tests (P = 0.004). Participants reported satisfaction with training (96%; n = 73), achieved 100% of simulation checklist objectives, and increased confidence with ventilator skills (96%; n = 73). Themes from the participants' feedback included increased readiness to train colleagues on critical care ventilators at their hospitals, the need for longer and more frequent training, and a need to have access to critical care ventilators at their hospitals. This synchronous tele-education-directed medical simulation workshop implemented through partnerships between U.S. physicians and Sierra Leone healthcare providers was a feasible, acceptable, and effective means of providing training about COVID-19, hypoxemia management, and mechanical ventilation. Future ICU ventilator training opportunities may consider increasing the length of training beyond 2 days to allow more time for the hands-on simulation scenarios using the ICU ventilator and assessing knowledge application in long-term follow-up.

The Impact of Various High-Flow Nasal Cannula Devices on Transnasal Aerosol Delivery.

Aerosol delivery via high-flow nasal cannula (HFNC) has gained popularity due to the increased use of the modality for treating hypoxemic and hypercapnic respiratory failure. Various HFNC devices are available in the United States; however, the effectiveness of aerosol delivery via HFNC devices remains unclear. Thus, this study aimed to investigate the impact of various commercially available devices on transnasal aerosol delivery. This was a bench study that used a 2-chamber lung model, in which one chamber was connected to an adult manikin with anatomically correct upper-airway proportions. The other chamber was connected to a critical care ventilator used to simulate spontaneous breathing. A size large nasal cannula was placed at the nasal opening of the manikin. Five different HFNC devices (Hamilton-C1, OptiFlow, Airvo2, V60 Plus, and Vapotherm) were compared. Four flow settings were used on each device, with a vibrating mesh nebulizer placed at the humidifier. Salbutamol (2.5 mg/3 mL) was used during the experiments to quantify inhaled drug doses. A collection filter was placed between the manikin's trachea and the lung model. The drug was eluted from the filter and assayed with ultraviolet spectrophotometry (276 nm). Among the 5 HFNC devices, OptiFlow had the highest inhaled dose at 10 L/min (mean ± SD 18.2% ± 1.2%). At 20 L/min, the Hamilton-C1 (mean ± SD 13.5% ± 0.4%) performed marginally better than the OptiFlow (mean ± SD 12.6% ± 1.9%) and Airvo2 (mean ± SD 12.8% ± 1%). At high flow settings (40-60 L/min), the inhaled dose of Hamilton-C1 was 2-3 times that of the Airvo2 and V60 Plus. When compared with the other devices, the mean inhaled dose with the Vapotherm was lower (0.9-2.5%). In all devices, the inhaled dose decreased as the flow increased. Transnasal aerosol delivery was significantly impacted by the types of HFNC devices and flow settings. Nominal doses might need to be adjusted if changing HFNC devices or flow is not an option.

Exploring clinicians' beliefs and practices regarding Non-Invasive Ventilation devices: An international survey study

Introduction Non-invasive ventilation (NIV) has a significant role in supporting patients with respiratory failure with the goal of avoiding mechanical ventilation. Traditionally, NIV has been applied using dedicated NIV-specific devices but over the last decade, newer generation critical care ventilators have updated their capabilities to include NIV options with improved synchrony and leak compensation. No recent trials have compared the efficacy of new generation critical care ventilators to NIV ventilators. The purpose of this study was to evaluate clinicians attitudes and perceptions toward the use of NIV between the dedicated NIV and critical care ventilators. Methods An online survey of clinicians with seven questions regarding their thoughts and experience in using NIV in acute care settings was posted online and promoted through emails and social media. The survey was anonymous and an exemption of consent was obtained from the Institutional Review Board. Analysis of variants (ANOVA) was done for the total responses in each question, followed by multivariate analysis of variants (MANOVA) for responses per occupation. Results 514 responses from 54 countries were recorded. 151 from North America, 109 from South America, 125 from Europe, 97 from Asia, 21 from Africa, and 11 from Australia. 218 responders were physicians, 218 were respiratory therapists, 28 were nurses, and 50 were reported as other professionals (engineers, biomedical technicians). 346 (67.3%) reported using both types of ventilators for NIV, 91 (17.7%) use only NIV -specific devices, and 77 (15%) only use critical care ventilators (P 0.097), responses per occupation (P &lt; 0.001). 290 (56.4%) have automatic synchronization software on either of their ventilators, 113 (22%) do not, while 111 (21.6%) are unsure if they do (P 0.22), with significant variation by occupation (P 0.008). Regarding synchrony, 233 (45.3%) said NIV ventilators are better, and 165 (32.1%) said critical care ventilators are better, while 116 (22.5%) said both are similar (P 0.59) with significant variation by occupation (P 0.04). Regarding leak compensation, 241 (46.9%) said NIV ventilators are better, and 146 (284%) said critical care ventilators are better, while 127 (24.7%) said both are similar (P 0.6) without significant variation by occupation (P 0.07). Regarding the general opinion of superiority, 273 (53.1%) said NIV ventilators are better, 131 (25.5%) said critical care ventilators are better, and 110 (21.4%) said both are similar (P 0.42) without significant variation by occupation (P 0.098). Conclusion Despite the lack of evidence, there is wide variability in opinion with no clear consensus regarding the clinicians’ attitude towards which ventilators are superior to use during NIV, especially according to surveyed occupation.

Prone ventilation in Critical care: Decade since PROSEVA

No abstract available

Novel design of inspiratory flow generation and gas mixing for critical care ventilators suitable for rapid production and mass casualty incidents

Scarcity of medical resources inspired many teams worldwide to design ventilators utilizing different approaches during the recent COVID-19 pandemic. Although it can be relatively easy to design a simple ventilator in a laboratory, a large scale production of reliable emergency ventilators which meet international standards for critical care ventilators is challenging and time consuming. The aim of this study is to propose a novel and easily manufacturable principle of gas mixing and inspiratory flow generation for mechanical lung ventilators. Two fast ON/OFF valves, one for air and one for oxygen, are used to control the inspiratory flow generation using pulse width modulation. Short gas flow pulses are smoothed by low-pass acoustic filters and do not propagate further into the patient circuit. At the same time, the appropriate pulse width modulation of both ON/OFF valves controls the oxygen fraction in the generated gas mixture. Tests focused on the accuracy of the delivered oxygen fractions and tidal volumes have proved compliance with the international standards for critical care ventilators. The concept of a simple construction using two fast ON/OFF valves may be used for designing mechanical lung ventilators and thus suitable for their rapid production during pandemics.

Mechanical ventilator flow and pressure sensors: Does location matter?

Introduction Accurate measurements of ventilatory outputs are crucial during mechanical ventilation support. These measurements are achieved through sensors that monitor parameters such as flow/volumes and pressures. External and internal flow sensors are both commonly used in mechanical ventilation systems to measure the flow of air entering and leaving the patient’s lungs. The sensors could be located outside the ventilator (external or proximal) or inside the ventilator (internal or distal), each of which have their own respective advantages and disadvantages. There are differences in the way they function and the information they provide, which can affect their accuracy and usefulness in different clinical situations. A few clinical studies have compared the use of external to internal sensors in mechanical ventilation, showing mixed results. The intent of this study is to reexamine the differences between two critical care ventilators utilizing external sensors to two other ventilators utilizing internal sensors. Methods A bench study using a lung simulator was conducted. We constructed three passive, single compartment models: 1) compliance of 40 ml/cmH2O, resistance of 10 cmH2O, 2) compliance of 40 ml/cmH2O, resistance of 20 cmH2O, 3) compliance of 20 ml/cmH2O, resistance of 10 cmH2O. In each experiment we used two different modes of ventilation, volume controlled (tidal volume 400 ml, respiratory rate 20, PEEP 5 cmH2O, inspiratory time 0.7 seconds) and pressure controlled (inspiratory pressure 15 cmH2O, respiratory rate 20, PEEP 5cmH2O, inspiratory time 0.7 seconds). We compared the inspiratory flow, inspiratory tidal volume, peak inspiratory pressures and PEEP in four commercially available critical care ventilators. Two use external flow sensors: G5 (Hamilton Medical), Bellavista 1000e (Vyaire Medical), and two use internal flow sensors: Evita Infinity 500 (Drager), and PB 980 (Medtronic). We also compared these parameters to a mathematical model. Statistics to compare the parameters in all four ventilators were done with Kruskal Wallis test followed by post-hoc Dunn’s test. A t-test was used to compare the parameters between the ventilator-measured and simulator-measured parameters in each ventilator. A P value of &lt; 0.05 was considered significant. Results There were statistically significant differences (P &lt; 0.001) in all four measured parameters: inspiratory flow, tidal volume, PIP and PEEP between all four ventilators, and between the mathematical model and all four ventilators in both modes, in all three clinical scenarios. The post-hoc Dunn test showed significant differences between each ventilator, except for a few parameters in PIP and PEEP. but not in flow or volume. There were variable but significant differences between some of the four parameters measured from the ventilator compared to those measured from the simulator of all four ventilators in both modes. The two ventilators using external sensors had more accurate differences between the delivered and measured tidal volumes (P &lt; 0.001) and inspiratory flow (P &lt; 0.001), however, the other two ventilators with internal sensors had more accurate differences between the delivered and measured PIP (P &lt; 0.001) and PEEP (P &lt; 0.001) levels. Conclusions All four ventilators performed differently from each other and from the mathematical model. The two ventilators using external sensors had more accurate differences between the delivered and measured tidal volumes and inspiratory flow, the two ventilators with internal sensors had more accurate differences between the delivered and measured PIP and PEEP levels. Differences between the ventilators depends on multiple factors including location, type of sensor, and respiratory mechanics. Keywords Flow sensor, Pressure sensor, PIP, PEEP, Tidal volume, Flow

Editor's Choice Articles for February.

Editor's Choice Articles for February.

An AI based digital-twin for prioritising pneumonia patient treatment.

A digital-twin based three-tiered system is proposed to prioritise patients for urgent intensive care and ventilator support. The deep learning methods are used to build patient-specific digital-twins to identify and prioritise critical cases amongst severe pneumonia patients. The three-tiered strategy is proposed to generate severity indices to: (1) identify urgent cases, (2) assign critical care and mechanical ventilation, and (3) discontinue mechanical ventilation and critical care at the optimal time. The severity indices calculated in the present study are the probability of death and the probability of requiring mechanical ventilation. These enable the generation of patient prioritisation lists and facilitates the smooth flow of patients in and out of Intensive Therapy Units (ITUs). The proposed digital-twin is built on pre-trained deep learning models using data from more than 1895 pneumonia patients. The severity indices calculated in the present study are assessed using the standard benchmark of Area Under Receiving Operating Characteristic Curve (AUROC). The results indicate that the ITU and mechanical ventilation can be prioritised correctly to an AUROC value as high as 0.89. This model may be employed in its current form to COVID-19 patients, but transfer learning with COVID-19 patient data will improve the predictions. The digital-twin model developed and tested is available via accompanying Supplemental material.

Potential rebreathing of carbon dioxide during noninvasive ventilation provided by critical care ventilator

BackgroundCritical care ventilators are frequently used to provide noninvasive ventilation (NIV) support to critically ill patients. Questions remain regarding carbon dioxide (CO2) clearance while using a critical care ventilator and dual limb circuit with various patient interfaces. The purpose of this study is to determine the positive end expiratory pressure (PEEP) level required to effectively washout CO2 for full-face and oronasal masks when using a dual limb circuit.MethodThis randomized crossover trial was conducted at an academic medical center in the Midwest United States. After obtaining informed consent, eight healthy volunteers were placed on a 980 Puritan Bennett (Medtronic, Minneapolis, MN) ventilator operating in the NIV mode. All subjects performed 20 min of breathing on four levels of PEEP (0, 2, 4, and 5 cm H2O) and pressure support of 5 cm H2O. NIV settings were applied to four masks (two oronasal and two full-face masks) that were randomly selected with a 5-min washout period between each mask. The fraction of inspired carbon dioxide (FICO2) was sampled/monitored with a nasal cannula using a Capnostream 20p monitor (Medtronic, Minneapolis, MN) and reported as percentages. A Kruskal–Wallis test was used to reveal significant differences across PEEP levels. Pairwise comparisons of the groups were made using Mann–Whitney tests with a family-wise error correction.ResultsMedian (IQR) FICO2 was significantly lower 0.0% (0%–0.92%) at PEEP of 5 compared to 1.83% (0.66%–4.0%; p < 0.001) at PEEP of 0 or 1.0% (0.33%–2.66%; p = 0.002) at PEEP of 2. FICO2 was significantly lower 0.5% (0%–1.92%) at PEEP of 4 compared to PEEP of 0 (p = 0.001).ConclusionA PEEP level of at least 5 cm H2O associated with the reported leak was required to minimize the likelihood of CO2 rebreathing while using a critical care ventilator to provide NIV with a double limb circuit and full-face or oronasal masks.

Performance Characteristics of a Novel 3D-Printed Bubble Intermittent Mandatory Ventilator (B-IMV) for Adult Pulmonary Support.

The COVID-19 pandemic has brought attention to the need for developing effective respiratory support that can be rapidly implemented during critical surge capacity scenarios in healthcare settings. Lung support with bubble continuous positive airway pressure (B-CPAP) is a well-established therapeutic approach for supporting neonatal patients. However, the effectiveness of B-CPAP in larger pediatric and adult patients has not been addressed. Using similar principles of B-CPAP pressure generation, application of intermittent positive pressure inflations above CPAP could support gas exchange and high work of breathing levels in larger patients experiencing more severe forms of respiratory failure. This report describes the design and performance characteristics of the BubbleVent, a novel 3D-printed valve system that combined with commonly found tubes, hoses, and connectors can provide intermittent mandatory ventilation (IMV) suitable for adult mechanical ventilation without direct electrification. Testing of the BubbleVent was performed on a passive adult test lung model and compared with a critical care ventilator commonly used in tertiary care centers. The BubbleVent was shown to deliver stable PIP and PEEP levels, as well as timing control of breath delivery that was comparable with a critical care ventilator.

The Impact of High-Flow Nasal Cannula Device, Nebulizer Type, and Placement on Trans-Nasal Aerosol Drug Delivery.

Aerosol delivery via high-flow nasal cannula (HFNC) has been increasingly used in recent years. However, the effects of different HFNC devices, nebulizer types, and placement on aerosol deposition remain largely unknown. An adult manikin with anatomically correct upper airway was used with a collection filter placed between the manikin's trachea and a breathing simulator, composed of a dual-chamber model lung driven by a critical care ventilator. Three HFNC device configurations were compared, with vibrating mesh nebulizer and small-volume nebulizer placed at the humidifier (inlet for Optiflow and outlet for Airvo 2) and proximal to the nasal cannula at gas flows of 10, 20, 40 and 60 L/min, in quiet and distressed breathing patterns. Albuterol (2.5 mg) was nebulized for each condition (no. = 3). The drug was eluted from the collection filter and assayed with ultraviolet spectrophotometry (276 nm). At all settings, except when a nebulizer was placed proximal to the nasal cannula with the Optiflow and when the HFNC flow was set at 60 L/min, the vibrating mesh nebulizer generated a higher inhaled dose than did the small-volume nebulizer (all P < .05). With the exception of distressed breathing at an HFNC flow of 10 L/min, the inhaled dose with the vibrating mesh nebulizer placed at the humidifier was greater than with the vibrating mesh nebulizer placed proximal to the nasal cannula (all P < .05), Optiflow provided a higher inhaled dose than did Airvo 2 with either AirSpiral or 900PT501 circuits with the vibrating mesh nebulizer placed at the humidifier (all P < .05). During transnasal aerosol delivery, the vibrating mesh nebulizer generated a higher inhaled dose than did the small-volume nebulizer when the nebulizer was placed at the humidifier. With the vibrating mesh nebulizer placed at the humidifier and an HFNC flow > 10 L/min, the inhaled dose was higher than with the vibrating mesh nebulizer placed proximal to the nasal cannula, and the inhaled dose was higher with Optiflow than with Airvo 2.