Gas Ventilation Research Articles

Mathematical Model for Automated Heat Flow Control of an Energy­Efficient Ventilation System

Purpose of research.In modern ventilation and air conditioning systems (VAC), one of the main components is an automatic control system (ACS) which performs various functions and also provides highly efficient operation in the range from shutdown functions to centralized regulation and control of climate parameters (temperature, humidity, monitoring concentrations of harmful substances, air speed). The goal is to study a mathematical model of heat flow control of a supply and exhaust ventilation system with a builtin integrated recuperative heat exchanger for the purpose of utilization of low-temperature heat of ventilation gases and emissions with the associated production of thermoelectricity.Methods.To achieve these goals, we used methods of mathematical simulation and computational model development. The automatic control of VAC is based on the principle of feedback – regulation of processes by obtaining information from external sensors based on mathematical simulation of physical processes occurring in the building or structure serviced.Results.An experimental supply and exhaust system with a plate heat exchanger-recuperator operates in a quasi-steady heat transfer mode. Exhaust air removed from the room is used as a heating medium. At the same time, the system is controlled using an independent scheme of connection to the heat supply system. The air heated in the room is considered as an incompressible gas, the heat exchange between the heating and heated heat transfer media is a steady­state process, the turbulence of the heating and heated flow of heat transfer media is isotropic. The result of the study is a mathematical model of heat flow control in the supply and exhaust ventilation system with a builtin integrated heat exchanger-recuperator. The optimal values of the heat energy consumed and the parameters of the ventilation system operation are obtained.Conclusion.A mathematical model of heat flow control in a supply and exhaust ventilation system with a builtin integrated heat exchanger-recuperator is proposed and investigated. The optimal values of the consumed heat energy and the parameters of the ventilation system operation are obtained.

Experimental study on propagation law of shock wave and airflow induced by coal and gas outburst in mine ventilation network

Coal and gas outburst seriously threatens the safety of underground coal mining. After the outburst, it will not only cause harm in the near-field outburst roadway but may also have a strong impact on the far-field ventilation network connected to the outburst roadway, expanding the impact of the disaster. In order to define the propagation law of shock wave and airflow induced by the outburst and its influence on the far-field ventilation network, the coal and gas outburst experimental system was used to carry out an experimental study under different air current and local resistance conditions in this paper. The results show that, under different air current states, the first overpressure peak increases with an increase of outburst pressure and decreases with an increase of propagation distance. Compared with the propagation characteristics in a windless roadway, the first overpressure peak and attenuation coefficient of shock wave propagating downwind are smaller, whereas opposite in upwind state. The local resistance enhances the impact and disturbance ahead of it and weakens that after it. When shock airflow propagates downwind, the increase of shock airflow velocity is approximately equal to the original airflow velocity in the roadway, whereas the airflow direction may reverse when the shock airflow propagates upwind. This paper provides some references to prevent the impact expansion of coal and gas outburst, which are of great significance for the optimization of ventilation network and emergency management.

Coal Mine Underground Gas Control Scheme and Ventilation System Optimization

Coal Mine Underground Gas Control Scheme and Ventilation System Optimization

Mammalian enteral ventilation ameliorates respiratory failure

Several aquatic organisms such as loaches have evolved unique intestinal breathing mechanisms to survive under extensive hypoxia. To date, it is highly controversial whether such capability can be adapted in mammalian species as another site for gas exchange. Here, we report the advent of the intestinal breathing phenomenon in mammalians by exploiting EVA (enteral ventilation via anus). Two different modes of EVA were investigated in an experimental model of respiratory failure: intra-rectal oxygen O2 gas ventilation (g-EVA) or liquid ventilation (l-EVA) with oxygenated perfluorocarbon. After induction of type 1 respiratory failure, we analyzed the effectiveness of g-EVA and I-EVA in mouse and pig, followed by preclinical safety analysis in rat. Both intra-rectal O2 gas and oxygenated liquid delivery were shown to provide vital rescue of experimental models of respiratory failure, improving survival, behavior, and systemic O2 level. A rodent and porcine model study confirmed the tolerable and repeatable features of an enema-like l-EVA procedure with no major signs of complications. EVA has proven effective in mammalians such that it oxygenated systemic circulation and ameliorated respiratory failure. Due to the proven safety of perfluorochemicals in clinics, EVA potentially provides an adjunctive means of oxygenation for patients under respiratory distress conditions. This work is funded by the Research Program on Emerging and Re-emerging Infectious Diseases, Research Projects on COVID-19 (JP20fk0108278, 20fk0108506h0001), from the Japan Agency for Medical Research and Development (AMED), to T.T.; Strategic Promotion for Practical Application of Innovative Medical Technology, Seeds A (A145), to T.T.; and KAKENHI 19K22657, to T.C.-Y. This research is partially supported by the AMED Translational Research Program; Strategic Promotion for Practical Application of Innovative Medical Technology (TR-SPRINT), to T.C.-Y.; and AMED JP18bm0704025h0001 (Program for Technological Innovation of Regenerative Medicine), to T.T.

Textbook of Ventilation, Fluids, Electrolytes and Blood Gases, 1st ed.

Textbook of Ventilation, Fluids, Electrolytes and Blood Gases, 1st ed.

D-Cystine di(m)ethyl ester reverses the deleterious effects of morphine on ventilation and arterial blood gas chemistry while promoting antinociception

We have identified thiolesters that reverse the negative effects of opioids on breathing without compromising antinociception. Here we report the effects of d-cystine diethyl ester (d-cystine diEE) or d-cystine dimethyl ester (d-cystine diME) on morphine-induced changes in ventilation, arterial-blood gas chemistry, A-a gradient (index of gas-exchange in the lungs) and antinociception in freely moving rats. Injection of morphine (10 mg/kg, IV) elicited negative effects on breathing (e.g., depression of tidal volume, minute ventilation, peak inspiratory flow, and inspiratory drive). Subsequent injection of d-cystine diEE (500 μmol/kg, IV) elicited an immediate and sustained reversal of these effects of morphine. Injection of morphine (10 mg/kg, IV) also elicited pronounced decreases in arterial blood pH, pO2 and sO2 accompanied by pronounced increases in pCO2 (all indicative of a decrease in ventilatory drive) and A-a gradient (mismatch in ventilation-perfusion in the lungs). These effects of morphine were reversed in an immediate and sustained fashion by d-cystine diME (500 μmol/kg, IV). Finally, the duration of morphine (5 and 10 mg/kg, IV) antinociception was augmented by d-cystine diEE. d-cystine diEE and d-cystine diME may be clinically useful agents that can effectively reverse the negative effects of morphine on breathing and gas-exchange in the lungs while promoting antinociception. Our study suggests that the d-cystine thiolesters are able to differentially modulate the intracellular signaling cascades that mediate morphine-induced ventilatory depression as opposed to those that mediate morphine-induced antinociception and sedation.

The Reign of the Ventilator: Acute Respiratory Distress Syndrome, COVID-19, and Technological Imperatives in Intensive Care.

In the early phase of the COVID-19 pandemic, a dispute arose as to whether the disease caused a typical or atypical version of acute respiratory distress syndrome (ARDS). This essay recounts the emergence of ARDS and places it in the context of the technological transformation of modern hospital care-particularly the emergence of intensive care after the 1952 Copenhagen polio epidemic. The polio epidemic seemed to show the value of manual positive-pressure ventilation, leading to the proliferation of mechanical ventilators and the expansion of intensive care units in the 1960s. This created the conditions of possibility for ARDS to be described and institutionalized within modern intensive care. Yet the centrality of the ventilator to descriptions and definitions of ARDS quickly made it difficult to conceive of the disorder outside the framework of mechanical ventilation and blood gas levels, or to acknowledge the degree to which the ventilator was a source of iatrogenic injury and complications. Moreover, the imperative to understand and treat ARDS with mechanical ventilation set the stage for the early confusion about whether patients with COVID-19 should receive mechanical ventilation. This history offers many crucial lessons about how new technologies can lead to new and valuable therapies but can also subtly shape and constrain medical thinking. Moreover, ventilators not only changed how respiratory disorders were conceived; they also brought new forms of respiratory illness into existence.

Development of an artificial placenta for support of premature infants: narrative review of the history, recent milestones, and future innovation.

Over 50 years ago, visionary researchers began work on an extracorporeal artificial placenta to support premature infants. Despite rudimentary technology and incomplete understanding of fetal physiology, these pioneering scientists laid the foundation for future work. The research was episodic, as medical advances improved outcomes of premature infants and extracorporeal life support (ECLS) was introduced for the treatment of term and near-term infants with respiratory or cardiac failure. Despite ongoing medical advances, extremely premature infants continue to suffer a disproportionate burden of mortality and morbidity due to organ immaturity and unintended iatrogenic consequences of medical treatment. With advancing technology and innovative approaches, there has been a resurgence of interest in developing an artificial placenta to further diminish the mortality and morbidity of prematurity. Two related but distinct platforms have emerged to support premature infants by recreating fetal physiology: a system based on arteriovenous (AV) ECLS and one based on veno-venous (VV) ECLS. The AV-ECLS approach utilizes only the umbilical vessels for cannulation. It requires immediate transition of the infant at the time of birth to a fluid-filled artificial womb to prevent umbilical vessel spasm and avoid gas ventilation. In contradistinction, the VV-ECLS approach utilizes the umbilical vein and the internal jugular vein. It would be applied after birth to infants failing maximal medical therapy or preemptively if risk stratified for high mortality and morbidity. Animal studies are promising, demonstrating prolonged support and ongoing organ development in both systems. The milestones for clinical translation are currently being evaluated.

Comparison of supercavity geometry and gas leakage behavior between the double-cavity flow pattern and the wake-closure flow pattern

The objective of this paper is to investigate the effect of two typical supercavity flow patterns (double-cavity and wake-closure) on ventilated supercavity geometry and supercavitating flow structure and further reveal the different mechanisms of gas leakage for these two supercavity flow patterns. An inhomogeneous multiphase model with shear stress transport turbulence was employed to validate the investigation by experimental results. The supercavity geometry was investigated quantitatively between the two supercavity flow patterns by the contrast, and corresponding gas leakage mechanisms were determined. The results show that compared with those of the wake-closure flow pattern, the maximum diameter and full-length of the supercavity with the double-cavity flow pattern decreased by 9.83% and 35.8%, respectively, under the same gas entrainment coefficient. The reason for the apparent difference in the supercavity dimension between the two supercavity flow patterns is that the amount of gas leaking from the closure region is different. For the wake-closure flow pattern, about 6.0% of the ventilated gas leaks from the closure region. However, for the double-cavity flow pattern, more gas leaks from the closure region, which is about four times that of the wake-closure flow pattern. As a result, the mass flow rate of the reverse gas decreases, leading to a decrease in the size of the region where gas flows reversely.

Nocturnal hypoxaemia in interstitial lung disease: a systematic review

BackgroundPatients with interstitial lung disease (ILD) are at risk of developing nocturnal hypoxaemia due to ventilatory restriction and impaired gas exchange that worsen with supine posture and reduced ventilatory drive...

Risk assessment of occupational exposure to anesthesia Isoflurane in the hospital and veterinary settings

Despite the modern ventilation and waste anesthetic gas (WAG) scavenging systems, occupational exposure to common volatile anesthesia, isoflurane, can occur in the hospital and veterinary settings, but limited information exists on potential exposure and health risk of isoflurane. We assessed exposure dose rates and risks among clinicians and veterinary professionals from occupational exposure to isoflurane. Through a critical review of open literature (1965 to 2020), we summarized potential adverse effects and exposure scenarios of isoflurane among the professional groups, including anesthetists, nurses, operating room personnel, researchers, and/or veterinarians. Deterministic United States National Research Council/Environmental Protection Agency's risk assessment framework (hazard identification, dose-response relationship, exposure assessment and risk characterization) was used to compute inhalation Reference Doses (RfDs), Average Daily Doses (ADDs), and Hazard Quotient (HQ) values—an established measure of non-carcinogenic (systemic) risks—from exposure to isoflurane to workers in hospital and veterinary settings. We identified the central nervous system as the main target for isoflurane, and that isoflurane has dose-dependent effects on cardiac hemodynamics, can impair pulmonary functions and potentially cross the utero-placental barrier leading to congenital malformation in fetus. Based on the modelled RfDs (range 0.8003–7.55 mg/kg-day) and ADDs (range 0.071–1.9617 mg/kg-day), we estimated 56 different HQ values, of which 5 HQs were higher than 1 (range 1.099–2.4512) under high exposure scenarios. Our results suggest a significant non-carcinogenic risk from isoflurane exposures among workers in the occupational settings. The findings underscore the need to significantly minimize isoflurane release to protect workers' health in the hospital and veterinary environments.

Controlled mechanical ventilation in equine anaesthesia: Physiological background and basic considerations (Part 1)

SummaryControlled mechanical ventilation (CMV) is routinely used in equine anaesthesia, with many different options available to mechanically deliver breaths. The complexity of respiratory pathophysiology in anaesthetised horses and the wide range of devices available is described in this scoping review. The first part of the review outlines basic equine respiratory physiology and pathophysiology during anaesthesia to illustrate what makes horses prone to inefficient gas exchange and ventilation when they are recumbent. The difference between spontaneous ventilation and CMV is reviewed and basic considerations of CMV are explored in more detail.

Combining Invasive Cardiopulmonary Exercise Testing with Computational Fluid Dynamics to Better Understand LVAD Fluid Mechanics during Exercise

<h3>Purpose</h3> Invasive cardiopulmonary exercise testing (iCPET) is helpful in evaluating dyspnea but is infrequently utilized in patient supported by left ventricular assist devices (LVAD). Computational fluid dynamics (CFD) allows for a more thorough analysis of fluid mechanics including shear stress (SS) and shear rate (SR). The additive information from iCPET and CFD may allow for optimal understanding of the pump-patient interaction during exercise. <h3>Methods</h3> Hemodynamic and ventilatory gas measurements were recorded as part of an iCPET study on a patient with a HeartMate 3 (HM3). Exercise using a bicycle ergometer by increments of 20 watts every 2 minutes was performed. An anatomical model of the vasculature was reconstructed from computed tomography (CT) images, and the LVAD outflow cannula was used as the inflow boundary. The LVAD outflow was calculated separately using a lumped-parameter-model (LPM) of the circulation. Ventricular volumes were reconstructed from CT and the patient's hemodynamic tracings. The contribution of flow from the HM3 was implemented in the LPM via published H-Q curves. CFD simulations were then carried out over the stages of exercise. Blood velocities, SS and SR were quantified in the vascular beds. <h3>Results</h3> Compared to rest, blood volume exposed to SR >1000 s⁻¹ increased 2.8 fold (0.47 to 1.31 cm³), while average SS increased 1.45 fold (2.61 to 3.79 Pa) in the cannula, 1.48 fold (0.89 to 1.31 Pa) in the ascending aorta, and 1.61 fold (0.67 to 1.08 Pa) in the aortic arch and cerebral circulation. Compared to rest, peak velocities increased nearly 5 fold in the aortic arch. <h3>Conclusion</h3> CFD applied to iCPET provides valuable information about variations in flow to the vasculature with exercise as well as shear rate and shear stress augmentation. This patient-specific information may help with optimization of LVAD speeds to meet the physiological needs of exercise.

Fast and Accurate Multiscale Reduced-Order Model for Prediction of Multibreath Washout Curves of Human Respiratory System

The curve of exhaled inert gas concentration against exhaled volume is called gas washout curve. The slope at the end part of gas washout curve (Sₙ) is a measure of structural abnormalities. Sₙ depends on the spatial concentration distribution and dynamic of gas washout, which depends on several mechanisms including asymmetry of airways, nonhomogeneous ventilation, sequential emptying, and gas exchange with blood. Due to a large number of airways in human lungs, using simplified models is inevitable. On the other hand, these simplified models cannot capture some of the mentioned mechanisms and subsequently were not able to predict experimental trend of change in Sₙ with breath number in multibreath washout. The present study proposes a novel, accurate, and fast model of gas transport in human lungs, which can accurately predict this trend for the first time. The model consists of a proxy model of conducting airways and a reduced-order model of respiratory airways. A correlation is proposed for the estimation of model parameters, which are all functions of inert gas properties, ventilation, and structure of lung acini. The performance of the proposed model is validated in the prediction of Sₙ’s of various inert gases and lung clearance index. The obtained results show that the proposed model outperforms the previous ones based on both accuracy and required computational time. The effects of gas properties, functional residual capacity, and tidal volume on Sₙ are also investigated. The proposed model is fast where simulation of one breath nitrogen washout takes ∼0.18 s. Furthermore, it is flexible and can range from fully symmetric to detailed asymmetric airways.

P0398 / #971: CHEST PHYSIOTHERAPY FOR SLIDE TRACHEOPLASTY PATIENTS IN PAEDIATRIC INTENSIVE CARE

Aims & Objectives: Long segment congenital tracheal stenosis is a rare, life threatening malformation, which is treated with slide tracheoplasty (STP) surgery. Chest physiotherapy (CPT) is part of postoperative ICU care for these patients, however there is minimal evidence to guide treatment. This study aims to explore current CPT practice in paediatric STP patients. Methods: Retrospective cohort study, at a single tertiary centre, over a 3 year period. Patient demographics, surgical procedures and clinical variables were recorded. Main outcome measures: Types of CPT and adjuncts Prevalence of gas trapping Focal pathology on initial postoperative chest x-ray (CXR) Results: A total of 43 children were included, all received standard CPT whilst ventilated. Mucolytics were used in two patients whilst ventilated, and four once extubated. Fourteen patients (33%) required chest wall decompression due to gas trapping and ventilation difficulties. Subgroup analysis demonstrated that these patients were smaller (median weight 5.6 vs 8 kg, p = 0.015) and younger (median age 6 vs 12 months, p = 0.006) than those who did not require decompression. Focal pathology was present on initial CXR in 54% of children, with 61% of cases involving the upper lobes. Conclusions: This experience highlights that CPT is a routine component of STP postoperative care. Additional adjuncts were used infrequently, suggesting standard CPT was sufficient. It was the smaller children who required chest wall decompression; hence physiotherapists should adopt a proactive approach with these patients. Lung pathology on CXR was most commonly seen in the upper lobes. Further research is needed including investigation into decompression techniques.

Numerical Simulation of Gas Ventilation Mode in Highway Gas Tunnel

When the mountain tunnel projects passing through the complex formation with coal, it happened along with disaster accidents such as gas outburst, gas combustion, and gas explosion. These disasters should seriously threaten the safety and life of the construction personnel and affect the normal operation of the tunnel construction. Ventilation is the most effective means to control gas, fire, dust, heat, and other disasters. To study the effects of different ventilation modes in highway gas tunnels, Fluent software was used to simulate forced ventilation, exhaust ventilation, and mixed ventilation in a high gas tunnel of a highway in Hunan. The distribution law of the airflow velocity and gas concentration of these three ventilation modes were obtained to determine the optimal ventilation system. It was shown that vortex zones of different ranges formed in the tunnel for all three ventilation modes, and the gas concentration was higher in the vortex zone than in other regions. Mixed ventilation of them is superior to the other two modes, showing the best ventilation effect with regard to airflow velocity and gas concentration.

Imaging the Respiratory Transition at Birth: Unraveling the Complexities of the First Breaths of Life.

Rationale: The transition to air breathing at birth is a seminal respiratory event common to all humans, but the intrathoracic processes remain poorly understood. Objectives: The objectives of this prospective, observational study were to describe the spatiotemporal gas flow, aeration, and ventilation patterns within the lung in term neonates undergoing successful respiratory transition. Methods: Electrical impedance tomography was used to image intrathoracic volume patterns for every breath until 6 minutes from birth in neonates born by elective cesearean section and not needing resuscitation. Breaths were classified by video data, and measures of lung aeration, tidal flow conditions, and intrathoracic volume distribution calculated for each inflation. Measurements and Main Results: A total of 1,401 breaths from 17 neonates metall eligibility and data analysis criteria. Stable FRC was obtained by median (interquartile range) 43 (21-77) breaths. Breathing patterns changed from predominantly crying (80.9% first min) to tidal breathing (65.3% sixth min). From birth, tidal ventilation was not uniform within the lung, favoring the right and nondependent regions; P < 0.001 versus left and dependent regions (mixed-effects model). Initial crying created a unique volumetric pattern with delayed midexpiratory gas flow associated with intrathoracic volume redistribution (pendelluft flow) within the lung. This preserved FRC, especially within the dorsal and right regions. Conclusions: The commencement of air breathing at birth generates unique flow and volume states associated with marked spatiotemporal ventilation inhomogeneity not seen elsewhere in respiratory physiology. At birth, neonates innately brake expiratory flow to defend FRC gains and redistribute gas to less aerated regions.

Sucesso e falha de extubação em recém-nascidos prematuros até 32 semanas de idade gestacional

INTRODUÇÃO: Os benefícios da ventilação mecânica em neonatos prematuros se complementam com o sucesso na sua retirada. OBJETIVO: Avaliar os parâmetros ventilatórios e gasométricos pré extubação e identificar possíveis fatores que possam contribuir na decisão da extubação endotraqueal em recém-nascidos prematuros até 32 semanas. MÉTODOS: Trata-se de um estudo prospectivo, de caráter observacional. A amostra do estudo foi selecionada de forma não probabilística. Foram incluídos prematuros com idade gestacional até 32 semanas, e em ventilação mecânica invasiva por no mínimo 24 horas. E os critérios de exclusão foram recém-nascidos com malformações, cardiopatias e os transferidos para outros hospitais antes da primeira extubação eletiva. Os dados sobre o diagnóstico clínico, dados vitais, parâmetros da ventilação mecânica e gasometria arterial, registrado em uma ficha elaborada pelos pesquisadores e coletados diariamente, uma vez por dia desde o primeiro dia de ventilação mecânica invasiva até o momento de retirada do tubo endotraqueal, sendo o recém-nascido acompanhado até 7 dias após a extubação. O desmame e a extubação seguiu o protocolo da Unidade de Terapia Intensiva Neonatal (UTIN) (presença de respiração espontânea regular e com reflexo de tosse, FiO2 &lt; 40% para manter saturação 90%; pressão inspiratória entre 15 – 18 cmH2O; FR=15 a 20 ipm; pH &gt; 7,25 mmHg e PaCO2 &lt; 50 mmHg). RESULTADOS: Dos 20 recém-nascidos prematuros incluídos no estudo, 14 eram do sexo masculino, a média de idade gestacional foi de 28,9± 2,12 semanas e a média do peso ao nascimento foi 1069,5g ± 375,5. Em 75% dos casos a intubação foi devido a síndrome do desconforto respiratório neonatal. Do total da amostra, 40% apresentaram. Não houve diferença significativa entre os grupos sucesso e falha na extubação, quanto aos dados ventilatórios e gasométricos analisados pré e pós extubação (p&gt;0,05). Na regressão logística observou-se que a fração inspirada de oxigênio (p= 0,03) e a pressão média de vias aéreas (p= 0,03) apresentaram significância como preditor para extubação. O tempo de uso da ventilação mecânica invasiva não apresentou significância estatística (p=0,06), para o desfecho avaliado. CONCLUSÃO: Neste estudo os parâmetros mínimos ventilatórios como FiO2 e MAP se relacionam diretamente com o sucesso da extubação, bem como estar atento as condições clínicas do paciente auxiliam a equipe a nortear o desmame e programar uma extubação mais criteriosa e segura.

Energy-saving-orientated ventilation optimization under safely feasible water-gas compartment in urban utility tunnels

Building an independent gas compartment in utility tunnel will require spending additional costs for construction, which is often hindered by the public budget limitations. To lay gas pipelines together with water pipelines compartment in utility tunnel was proposed, forming a water-gas compartment. Persistent ventilation consumes too much energy to cope with small possibility accident. Hence, the diffusion law of potential gas leakage and effect of the present combustible gas detection, alarming and ventilation systems were examined by a numerical simulation using the software Fluent based on computational fluid dynamics (CFD). The volume fraction of leaking methane accumulation law without ventilation were obtained. The results revealed that the present emergency measures for a single gas pipe compartment can be safely applied to the proposed water-gas compartment to guarantee the safety, which provides novel insights into and an important basis for the improvement of the related urban engineering design and relevant standards. Optimization scheme of ventilation was proposed and energy saved was calculated quantitatively.

Compatibility and Safety Implications Associated with Interfacing Medical Devices in Neonatal Respiratory Care: A Case Example Using the Inhaled Nitric Oxide Delivery System.

Over the past decade, international organizations have instituted strict regulations for the safe use of connected medical devices. The International Organization for Standardization and the Medical Device Single Audit Program instituted certifications to ensure that connected devices are compatible and operate within their proper clinical parameters. These efforts came about, in part, as a consequence of clinicians’ decisions to use nonstandard, modified, or improvised devices for purposes outside the original manufacturers’ approved parameters. Unapproved device modifications can be associated with increased risk of dosing errors, monitoring errors, tubing misconnections and serious or potentially fatal adverse events; furthermore, health care providers who implement unapproved device modifications may assume legal and financial liability should harm come to patients as a consequence of the modification. Using the inhaled nitric oxide delivery system as an example, the objective of this paper is to raise awareness of the potential dangers associated with unapproved modification and interfacing of therapeutic gas delivery systems and ventilators in the neonatal intensive care unit setting. The paper also highlights the rationale and necessity for rigorous validation processes that ensure that interfaced medical devices perform as intended in the clinical setting.