Negative Pressure Ventilation Research Articles

Negative pressure ventilation, an umbrella against ventilator induced lung injury.

Negative pressure ventilation, an umbrella against ventilator induced lung injury.

Technical Advances Targeting Multiday Preservation of Isolated Ex Vivo Lung Perfusion.

Indications for ex vivo lung perfusion (EVLP) have evolved from assessment of questionable donor lungs to treatment of some pathologies and the logistics. Yet up to 3 quarters of donor lungs remain discarded across the globe. Multiday preservation of discarded human lungs on EVLP platforms would improve donor lung utilization rates via application of sophisticated treatment modalities, which could eventually result in zero waitlist mortality. The purpose of this article is to summarize advances made on the technical aspects of the protocols in achieving a stable multiday preservation of isolated EVLP. Based on the evidence derived from large animal and/or human studies, the following advances have been considered important in achieving this goal: ability to reposition donor lungs during EVLP; perfusate adsorption/filtration modalities; perfusate enrichment with plasma and/or donor whole blood, nutrients, vitamins, and amino acids; low-flow, pulsatile, and subnormothermic perfusion; positive outflow pressure; injury specific personalized ventilation strategies; and negative pressure ventilation. Combination of some of these advances in an automatized EVLP device capable of managing perfusate biochemistry and ventilation would likely speed up the processes of achieving multiday preservation of isolated EVLP.

Ventilation retrofit design for existing primary and secondary school classrooms under epidemic conditions

In the context of regular epidemic prevention and control, most primary and secondary schools in developing countries are naturally ventilated. They are unable to use measures such as air filters equipped with centralized mechanical ventilation systems and demand-controlled ventilation. Therefore, the feasibility of using automatic control of negative pressure ventilation (NPV) in conjunction with CO2 concentration detectors to reduce the rate of infection in the classroom was investigated. Firstly, the CO2 concentration threshold calculation for epidemic prevention was carried out, and then the measured data of the classroom was fitted with the Computational Fluid Dynamics (CFD) simulation data to establish a simulation and analysis platform to comprehensively evaluate different NPV conditions. The results show that NPV can control the direction of airflow and CO2 concentration in the teaching room, which can significantly reduce the risk of infection, and that Upward Supply Upward Return NPV with automatic control of the CO2 concentration detector and the combination of windshields can protect the students from cross-infection. The study aims to optimize classroom ventilation strategies for epidemic proofing through low-cost building modifications, which could inform the retrofitting of hundreds of thousands of established primary and secondary schools in developing countries. Practical Application Ventilation systems controlled by environmental parameters have the advantages of low cost, high automation, and ease of operation. This system makes designing classrooms to combat airborne epidemics easier by implementing simple retrofitting measures for developing countries where natural ventilation is predominantly used and where most classrooms are not equipped with fresh air ducts. Tests of the top inlet and top return ventilation system proposed in this paper found that the classroom’s measured indoor carbon dioxide concentrations were reduced to below the theoretical limits.

Air change per hour improvement for positive and negative pressure mechanical ventilation facilities systems

Ventilation reduces indoor pollutants, and this issue has recently received attention. Most scholars adopt ventilation strategies to reduce energy consumption. While natural ventilation does not require ventilation facilities, it also brings many challenges, such as lack of external openings and insufficient air change per hour. Therefore, it is necessary to rely on mechanical ventilation to increase indoor air change per hour. However, mechanical ventilation comes with increased energy consumption, which poses a significant challenge to reducing energy usage at present.To improve energy usage, increase air changes per hour, and reduce the number of fans by half, we propose implementing positive and negative pressure ventilation indoors at the same airflow rate (3000 CMH). The research results showed that positive and negative pressure ventilation increased air changes per hour by 94 % and 62 %, respectively, while also reducing fan energy usage by 50 %. Through visualization, we also discovered the uneven distribution of indoor carbon dioxide levels. This breakthrough is of significant importance for current indoor mechanical ventilation systems and contributes greatly to future near-zero carbon emissions.

ExoventQ: A novel low-cost portable negative pressure ventilator design and implementation

ExoventQ: A novel low-cost portable negative pressure ventilator design and implementation

Negative-Pressure Ventilation in the Pediatric ICU.

Negative-pressure ventilation (NPV) is a form of noninvasive ventilation that has been recently utilized in pediatric acute respiratory failure. Negative-pressure ventilators apply negative pressure onto the chest wall via a cuirass to recruit areas of atelectasis. Continuous negative extrathoracic pressure, the most common mode, is similar to CPAP, where negative pressure is maintained at a constant level throughout the respiratory cycle while patients initiate their own breaths and continue to breathe spontaneously throughout. Control mode, which is similar to bi-level positive airway pressure, alternates negative pressure with positive pressure and controls both phases of breathing at a mandatory frequency set higher than the patient's spontaneous frequency. Supplemental oxygen is provided through a nasal cannula or face mask due of the lack of NPV devices' interface with the mouth or nose. NPV can improve preload to the heart and cardiac output (CO) in patients with restrictive right-ventricular physiology requiring CO augmentation and those with Fontan physiology. The purpose of this article is to review the physiological principles of spontaneous and NPV, examine the evidence supporting the use of NPV, give practical and meaningful guidance on its clinical application in the pediatric ICU, and summarize areas for future studies on its uses.

Effects of Negative Pressure Ventilation on Lung Volume and Airflow in Drug-Induced Sleep Endoscopy

Effects of Negative Pressure Ventilation on Lung Volume and Airflow in Drug-Induced Sleep Endoscopy

Quantifying Ventilation Design, Room Layout, and Occupant Activity Parameters during Aerosol-Generating Medical Procedures in Hospitals

The risk of airborne disease transmission in hospital rooms during aerosol-generating medical procedures is known to be influenced by the size of the room, air ventilation rate, input-to-output flow ratio, vent surface area, and vent location. However, quantitative recommendations for each ventilation design parameter are scarce. Moreover, room layout and occupant activity parameters, such as furniture locations and healthcare worker movement, are often omitted from studies on airborne disease transmission in hospital settings. As a result, the development of policies and technologies aimed at mitigating airborne disease transmission in hospitals has been limited. To address this shortfall, this study is aimed at first characterizing existing ventilation, room layout, and occupancy parameters in hospital rooms where aerosol generation medical procedures (AGMPs) occur and then testing the hypotheses that ventilation, room layout, and occupancy parameters vary significantly between hospital rooms and, in some cases, with time. Information on AGMPs was collected via a survey circulated to healthcare workers within British Columbia’s Interior Health Authority (IHA), while hospital room and ventilation system information was collected by reviewing drawing packages of 37 IHA hospital rooms. The survey results indicate that AGMPs commonly occur in trauma, ICU, or general ward rooms with positive or negative pressure ventilation systems. Statistical tests, with room type (trauma, ICU, or general), room pressure (positive or negative), and/or time as independent variables, show that variables relating to ventilation (number of supply vents, supply and exhaust vent location, ventilation rate, and supply and exhaust area) and room layout (congestion score, room volume, light area, and number of lights) vary with room type but not with room pressure. Occupant activity variables (number of workers, number of moving workers, and speed score) also vary with room type, although to differing extent with room pressure and time. The survey and drawing review data presented in this study can help guide systematic comparisons of mitigative technologies as well as parametric investigations on how room layout, ventilation, and operational parameters influence airborne disease spread. This is a crucial first step in achieving quantitative and clinically relevant recommendations for mitigating airborne disease transmission in healthcare settings.

A Comparative Study of Ex-Vivo Murine Pulmonary Mechanics Under Positive- and Negative-Pressure Ventilation

Increased ventilator use during the COVID-19 pandemic resurrected persistent questions regarding mechanical ventilation including the difference between physiological and artificial breathing induced by ventilators (i.e., positive- versus negative-pressure ventilation, PPV vs NPV). To address this controversy, we compare murine specimens subjected to PPV and NPV in ex vivo quasi-static loading and quantify pulmonary mechanics via measures of quasi-static and dynamic compliances, transpulmonary pressure, and energetics when varying inflation frequency and volume. Each investigated mechanical parameter yields instance(s) of significant variability between ventilation modes. Most notably, inflation compliance, percent relaxation, and peak pressure are found to be consistently dependent on the ventilation mode. Maximum inflation volume and frequency note varied dependencies contingent on the ventilation mode. Contradictory to limited previous clinical investigations of oxygenation and end-inspiratory measures, the mechanics-focused comprehensive findings presented here indicate lung properties are dependent on loading mode, and importantly, these dependencies differ between smaller versus larger mammalian species despite identical custom-designed PPV/NPV ventilator usage. Results indicate that past contradictory findings regarding ventilation mode comparisons in the field may be linked to the chosen animal model. Understanding the differing fundamental mechanics between PPV and NPV may provide insights for improving ventilation strategies and design to prevent associated lung injuries.

Health Risk Assessment and Covid-19 Infection Rate by Using Bacterial Aerosol in Healthcare Workers in a Tertiary Care Hospital in Thailand During SARS-CoV-2 Pandemic

Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a worldwide transmission and healthcare worker is the risk group. Therefore, the infection rate and health risk assessment from exposure to airborne transmission for healthcare workers were performed. Methods: This cross-sectional study was carried out on 106 healthcare workers at four selected service areas in Songklanagarind Hospital, Thailand, from February to September 2021. The N6 impactor was used with simultaneous measurement of temperature, relative humidity, and wind speed. The general characteristics of subjects and hospitals were collected by questionnaire and presented by descriptive statistics. Results: Most of the participants were female and they worked more than 8 hours per day. The bacteria concentration was highest in the Pediatric Outpatient Department (1837.46±177.52 cfu/m3). The lowest chronic daily intake and hazard quotient with no threshold (4.86±3.81, 95%CI: 3.59, 6.13) were at Covid-19 Intensive Care Unit - due to negative pressure ventilation in this room was effective in reducing the airborne concentration of the pathogens. Overall, the hospital’s hazard index with no threshold (30.87±35.25, 95%CI: 23.91, 37.83) was higher than 1.0, indicating that bacterial bioaerosol may affect healthcare workers’ health. The highest confirmed Covid-19 case was at Acute Respiratory Infection Clinic (19.29±10.67 cases/week). The probability of infection by SARS-CoV-2 in healthcare workers was high at Acute Respiratory Infection Clinic (1.0) and Covid-19 Intensive Care Unit (0.998±0.002, 95%CI: 0.998, 0.999). Conclusion: Therefore, inhalation reference concentration for hospitals should be as low as possible and appropriate ventilation systems should be implemented with adherence to standards to protect healthcare workers.

Adjuvant Transthoracic Negative-Pressure Ventilation in Nonintubated Thoracoscopic Surgery.

To minimize the risks of barotrauma during nonintubated thoracoscopic-surgery under spontaneous ventilation, we investigated an adjuvant transthoracic negative-pressure ventilation (NPV) method in patients operated on due to severe emphysema or interstitial lung disease. In this retrospective study, NPV was employed for temporary low oxygen saturation and to achieve end-operative lung re-expansion during nonintubated lung volume reduction surgery (LVRS) for severe emphysema (30 patients, LVRS group) and in the nonintubated wedge resection of undetermined interstitial lung disease (30 patients, wedge-group). The results were compared following 1:1 propensity score matching with equivalent control groups undergoing the same procedures under spontaneous ventilation, with adjuvant positive-pressure ventilation (PPV) performed on-demand through the laryngeal mask. The primary outcomes were changes (preoperative-postoperative value) in the arterial oxygen tension/fraction of the inspired oxygen ratio (ΔPO2/FiO2;) and ΔPaCO2, and lung expansion completeness on a 24 h postoperative chest radiograph (CXR-score, 2: full or 1: incomplete). Intergroup comparisons (NPV vs. PPV) showed no differences in demographic and pulmonary function. NPV could be accomplished in all instances with no conversion to general anesthesia with intubation. In the LVRS group, NPV improved ΔPO2/FiO2 (9.3 ± 16 vs. 25.3 ± 30.5, p = 0.027) and ΔPaCO2 (-2.2 ± 3.15 mmHg vs. 0.03 ± 0.18 mmHg, p = 0.008) with no difference in the CXR score, whereas in the wedge group, both ΔPO2/FiO2 (3.1 ± 8.2 vs. 9.9 ± 13.8, p = 0.035) and the CXR score (1.9 ± 0.3 vs. 1.6 ± 0.5, p = 0.04) were better in the NPV subgroup. There was no mortality and no intergroup difference in morbidity. In this retrospective study, NITS with adjuvant transthoracic NPV resulted in better 24 h oxygenation measures than PPV in both the LVRS and wedge groups, and in better lung expansion according to the CXR score in the wedge group.

Reply to: Julius Comroe Is Right: Positive and Negative Pressure Ventilation Are The Same.

"Reply to: Julius Comroe Is Right: Positive and Negative Pressure Ventilation Are The Same." American Journal of Respiratory and Critical Care Medicine, 0(ja), pp.

PULM6: Exploratory In Vivo Testing Of A Non-Invasive Ventilation Assist Device

Background: Mechanical ventilation is normally accomplished by positive pressure, either invasively through an endotracheal tube, or non-invasively through a mask or nasal prongs. Positive pressure ventilation (PPV) is associated with ventilator induced lung injury (VILI), especially in infants. Negative pressure ventilation (NPV) is more physiologic and preferentially opens posterior areas of the sick lung refractory to opening with positive pressure ventilation alone. However, NPV is not widely used due to the cumbersome negative air pressure chambers requiring torso and neck seals. Methods: We have developed a more practical device for achieving NPV. The Torso Expander consists of flexible tubes attached to a base layer which adheres to the torso with a silicone skin adhesive. Positive air pressure applied to the tubes causes elongation of the tubes and a distending pressure on the torso. The distending pressure may be static or cycled on and off (Torso Assist Ventilation - TAV) at a manual rate, or synchronized to the patient’s respiration (spontaneous or ventilator induced). The Torso Expander, sized for infants, was tested acutely in 5 piglets (3.1+/- 0.2 kg) during normal physiologic states as well as simulated ARDS by saline lavage surfactant washout, and simulated neuromuscular dysfunction by rocuronium paralysis, in order to study the biomechanics and potential clinical applications with various testing modes. Results: In the ARDS model, when static inflation (up to 400 mmHg) was added to the synchronized intermittent mandatory ventilation (SIMV) for a period of 17 min, intra-abdominal pressure was reduced by 1.0-1.5 cm-water per 100 mmHg inflation pressure, average tidal volume (TV) was increased by 5ml, and average respiratory rate was decreased by 27/min compared to the baseline SIMV. Gastric pressure, which may be measured less invasively in clinical use, correlated linearly (r2 > 0.94) with intra-abdominal pressure. TAV, synchronized with spontaneous and ventilator breaths, was demonstrated, resulting in increases in TV. During static and TAV support oxygenation improved (PaO2/FiO2 increased from 69 to 222 mmHg on average after the interventions). TAV alone was able to support a TV of 5 ml/kg with the animal paralyzed. Discussion: Exploratory studies demonstrated the beneficial effects of this novel non-invasive method of NPV. Additional studies are underway to further quantify these observations and test the technology in adults. This technology may reduce the time on PPV, or avoid PPV in some cases.

The Autumn Ghost. How the Battle Against a Polio Epidemic Revolutionized Modern Medical Care

The Autumn Ghost. How the Battle Against a Polio Epidemic Revolutionized Modern Medical Care

0487 The effect of negative pressure ventilation on airflow in obstructive sleep apnea subjects undergoing drug induced sleep endoscopy

Abstract Introduction Drug induced sleep endoscopy (DISE) is used to visually characterize pharyngeal airway collapse in obstructive sleep apnea (OSA) to help determine appropriate patients for OSA surgery. The procedure has grown in complexity with the addition of airflow recording and continuous positive airway pressure (CPAP) titration to obtain additional measures of airway collapsibility. Lung volume can also influence airway collapse in OSA but is not evaluated as part of routine DISE. The purpose of this study is to characterize the relationship between changes in lung volume and upper airway collapse during DISE to gain further insight into factors contributing to airway collapse and their potential roles in influencing surgical decision making. Methods This study is an ongoing IRB approved prospective clinical trial assessing the effects of negative pressure ventilation on airway collapse during DISE. Enrolled patients first undergo DISE evaluation per clinical routine including a CPAP titration. CPAP is then held at a level where patients exhibit stable flow limitation. A negative pressure ventilator shell is placed over the torso of the body and negative pressures of up to -25cmH2O are applied to expand the chest and increase lung volume. Changes to nasal airflow and tidal volume are evaluated. The negative pressure ventilator is then released and changes to airflow back to baseline are recorded. Results Between 6/30/2022 and 11/30/2022, 5 patients completed the study. There were 4 men and 1 woman with an average age of 60 years, BMI of 26.67kg/m2, and apnea-hypopnea index (AHI) of 44.44 events/hr. Average peak inspiratory flow increased from 8.38L/min to 13.78L/min and average tidal volumes increased from 155mL to 269mL on negative pressure ventilation. Conclusion Increases in lung volume from negative pressure ventilation during DISE can improve airflow and tidal volume suggesting that changes in lung volume can influence the severity of upper airway collapse. Further study to better characterize this relationship can help add additional diagnostic information regarding airway collapse characteristics to provide better informed surgical decisions and develop new interventions. Support (if any) Supported by the National Center for Advancing Translational Sciences (NCATS) of the National Institutes of Health (NIH) under Award Numbers UL1TR002378 and KL2TR002381

(873) Batch Replacement of Cellular Perfusate Does Not Improve Outcomes in a Model of 24-Hour Negative Pressure Ventilation Ex-Situ Lung Perfusion with Transplantation

(873) Batch Replacement of Cellular Perfusate Does Not Improve Outcomes in a Model of 24-Hour Negative Pressure Ventilation Ex-Situ Lung Perfusion with Transplantation

Air filtration to prevent porcine reproductive and respiratory syndrome virus infection

This commentary reviews results obtained in France and North America with different air filtration systems to prevent porcine reproductive and respiratory syndrome virus (PRRSV) infection. Most systems installed in France use high-efficiency particulate air (HEPA) filters and positive-pressure ventilation systems, while those in North America initially used mainly negative-pressure ventilation systems and filters with minimum efficiency rating values of 14 to 16. Major reductions in PRRSV cases were observed in most studies where the latter were used. Installing HEPA filters resulted in an almost complete elimination of PRRSV cases. No cases were recorded in 95% of farms where they were used.

‘Iron lung’ as metaphor

Negative pressure ventilators (NPVs) were used from the 1930s to keep patients with chest paralysis alive and they remained in use during the first half of the twentieth century. At the time paralysis was most commonly associated with poliomyelitis (infantile paralysis).[1] The most frequently used ventilators in the UK were the Both type, which were made of plywood to make them more cost effective. Despite their materiality, these wooden ventilators were, and are still, more commonly known as ‘iron lungs’. By considering the uses of the metaphor ‘iron lung’ prior to the invention of the NPV, I will argue that ‘iron lung’ became eponymous as it connected the material reality of the NPV with imagined sensory experiences for publics in the UK, though often in ways that contradicted earlier metaphors of modernity and sound.

The Role of Interventional Radiology and Management of an Angiography Suite in the Treatment of COVID-19 Patients: Single-Center, 2-Year Experience.

Background and Objectives: Hospital angiography suites with negative-pressure ventilation facilities are challenging to equip. During the COVID-19 pandemic, we aimed to introduce interventional radiology procedures performed on COVID-19 patients and understand management of the angiography suite without a negative-pressure ventilation facility before and after the procedures to prevent the spread of infection. Materials and Methods: Between December 2020 and November 2022, 52 COVID-19 patients underwent interventional radiology procedures in an angiography suite, where no negative-pressure ventilation facility was installed. During the procedure, all staff members wore full personal protection equipment, and after the procedure for the COVID-19-positive patient was completed, the angiography suite was disinfected and entry to the angiography suite was prohibited for 1-3 h. In this angiography suite, procedures for COVID-19 patients and non-COVID-19 patients were performed. Results: A total of 61 interventional radiology procedures were performed in 52 patients with COVID-19. Of 52 patients, 21 underwent procedures under intubation and mechanical ventilation. All procedures were performed according to the guidelines set by the Infection Control Committee of our hospital. No major or minor complications were associated with the procedures. There were no cases of infection among staff members or other non-COVID-19 patients related to procedures on COVID-19 patients. Conclusions: Interventional radiology can play an important role in solving the complications of COVID-19 and the problems caused by patients' underlying diseases. In addition, if accurate guidelines are followed, both COVID-19 and non-COVID-19 patients can undergo procedures in an angiography room without negative-pressure ventilation while preventing infection.

Missed nursing care and related factors during Covid-19 pandemic: A study in southeast Iran

BackgroundWorldwide, Coronavirus Disease (COVID-19) is currently the most significant health issue.Nurses, as key members of the health care team, playa crucialrole in the recovery and treatment ofthesepatients.Qualityof nursing care determines the most desirable health outcomes. The present study aimed to determine missed nursingcareand relatedfactors inCOVID-19 patients. MethodsTwohundred and onenurses participated in this descriptive cross-sectional study. Questionnaires on missed nursing care for COVID-19 patients and its related factors were used to collect data. Data were collected from July 10 to September 10, 2020 and were analyzed using descriptive and analytical statistics (independent t-test, Mann Whitney, One-Way ANOVA and Kruskal Wallis test) by SPSS V.19. ResultsThe mean (SD) missed nursing care and its related factors were (22.99 ± 5.52), (64.84 ± 10.42) respectively, which means that cares weremissedat a low level. Most of the missed cares were related to placing suspected patientsin negative pressure ventilation room 12 (6 %).Physical fatigue was the most important factor contributing to missed care among 159 staff members (79.1 %). ConclusionRegular monitoring strategies canbe decreasedMNC. More studiesregarding the outcomesof missed nursing care are recommended.