1
|
Rezazadeh MR, Dastan A, Sadrizadeh S, Abouali O. A quasi-realistic computational model development and flow field study of the human upper and central airways. Med Biol Eng Comput 2024:10.1007/s11517-024-03117-9. [PMID: 38758518 DOI: 10.1007/s11517-024-03117-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Accepted: 05/01/2024] [Indexed: 05/18/2024]
Abstract
The impact of drug delivery and particulate matter exposure on the human respiratory tract is influenced by various anatomical and physiological factors, particularly the structure of the respiratory tract and its fluid dynamics. This study employs computational fluid dynamics (CFD) to investigate airflow in two 3D models of the human air conducting zone. The first model uses a combination of CT-scan images and geometrical data from human cadaver to extract the upper and central airways down to the ninth generation, while the second model develops the lung airways from the first Carina to the end of the ninth generation using Kitaoka's deterministic algorithm. The study examines the differences in geometrical characteristics, airflow rates, velocity, Reynolds number, and pressure drops of both models in the inhalation and exhalation phases for different lobes and generations of the airways. From trachea to the ninth generation, the average air flowrates and Reynolds numbers exponentially decay in both models during inhalation and exhalation. The steady drop is the case for the average air velocity in Kitaoka's model, while that experiences a maximum in the 3rd or 4th generation in the quasi-realistic model. Besides, it is shown that the flow field remains laminar in the upper and central airways up to the total flow rate of 15 l/min. The results of this work can contribute to the understanding of flow behavior in upper respiratory tract.
Collapse
Affiliation(s)
| | - Alireza Dastan
- Department of Mechanical Engineering, Faculty of Engineering, University of Isfahan, Isfahan, Iran
| | - Sasan Sadrizadeh
- Department of Civil and Architectural Engineering, KTH University, Stockholm, Sweden.
- School of Business, Society and Engineering, Mälardalen University, Västerås, Sweden.
| | - Omid Abouali
- School of Mechanical Engineering, Shiraz University, Shiraz, Iran.
- Department of Civil and Architectural Engineering, KTH University, Stockholm, Sweden.
| |
Collapse
|
2
|
Katz I, Milet A, Chalopin M, Farjot G. Numerical analysis of mechanical ventilation using high concentration medical gas mixtures in newborns. Med Gas Res 2020; 9:213-220. [PMID: 31898606 PMCID: PMC7802424 DOI: 10.4103/2045-9912.273959] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
When administered in relatively high concentrations the mechanical properties of inhaled gas can become significantly different from air. This fact has implications in mechanical ventilation where adequate respiration and injury to the lungs or respiratory muscles can worsen morbidity and mortality. Here we use an engineering pressure loss model to analyze the administration of medical gas mixtures in newborns. The model is used to determine the pressure distribution along the gas flow path. Numerical experiments comparing medical gas mixtures with helium, nitrous oxide, argon, xenon, and medical air as a control, with and without an endotracheal tube obstruction were performed. The engineering pressure loss model was incorporated into a model of mechanical ventilation during pressure control mode, a ventilator mode that is often used for neonates. Results are presented in the form of Rohrer equations relating pressure loss to flow rate for each gas mixture with and without obstruction. These equations were incorporated into a model for mechanical ventilation resulting in pressure, flow rate, and volume curves for the inhalation-exhalation cycle. In terms of accuracy, published values of airway resistance range from 50 to 150 cmH2O/L per second for a normal 3 kg infant. With air, the current results are 55 to 80 cmH2O/L per second for 0.3 to 5 L/min. It is shown that density through inertial pressure losses has a greater influence on airway resistance than viscosity in spite of relatively low flow rates and small airway dimensions of newborns. The results indicate that the high-density xenon mixture can be problematic during mechanical ventilation. On the other hand, low density heliox (a mixture of helium and oxygen) provides a wider margin of safety for mechanical ventilation than the other gas mixtures. The argon or nitrous oxide mixtures considered are only slightly different from air in terms of mechanical ventilation performance.
Collapse
Affiliation(s)
- Ira Katz
- Medical Research & Development, Healthcare World Business Line, Air Liquide Santé International, Paris Innovation Campus, Les Loges-en-Josas, France
| | - Aude Milet
- Medical Research & Development, Healthcare World Business Line, Air Liquide Santé International, Paris Innovation Campus, Les Loges-en-Josas, France
| | - Matthieu Chalopin
- Medical Research & Development, Healthcare World Business Line, Air Liquide Santé International, Paris Innovation Campus, Les Loges-en-Josas, France
| | - Géraldine Farjot
- Medical Research & Development, Healthcare World Business Line, Air Liquide Santé International, Paris Innovation Campus, Les Loges-en-Josas, France
| |
Collapse
|
3
|
Moore CP, Katz IM, Pichelin M, Caillibotte G, Finlay WH, Martin AR. High flow nasal cannula: Influence of gas type and flow rate on airway pressure and CO 2 clearance in adult nasal airway replicas. Clin Biomech (Bristol, Avon) 2019; 65:73-80. [PMID: 30991233 DOI: 10.1016/j.clinbiomech.2019.04.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 04/01/2019] [Accepted: 04/04/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND High flow nasal cannula therapy is a form of respiratory support which delivers high flow rates of heated, humidified gas to the nares via specialized cannula. Two primary mechanisms of action attributed to the therapy are the provision of positive airway pressure as well as clearance of CO2-rich exhaled gas from the upper airways. METHODS Physiologically accurate nose-throat airway replicas were connected at the trachea to a lung simulator, where CO2 was supplied to mimic the CO2 content in exhaled gas. Cannula delivered either air, oxygen or heliox (80/20%volume helium/oxygen) to the replicas at flow rates ranging from 0 to 60 l/min. Five replicas and three cannulas were compared. Tracheal pressure and CO2 concentration were continuously measured. The lung simulator provided breaths with tidal volume of 500 ml and frequency of 18 breaths/min. Additional clearance measurements were conducted for tidal volume and breathing frequency of 750 ml and 27 breaths/min, respectively. FINDINGS Cannula flow rate was the dominant factor governing CO2 concentration. Average CO2 concentration decreased with increasing cannula flow rate, but above 30 L/min this effect was less pronounced. Tracheal positive end-expiratory pressure increased with flow rate and was lower for heliox than for air or oxygen. A predictive correlation was developed and used to predict positive end-expiratory pressure for a given cannula size as a function of supplied flow rate and occlusion of the nares. INTERPRETATION Compared with administration of air or oxygen, administration of heliox is expected to result in similar CO2 clearance from the upper airway, but markedly lower airway pressure.
Collapse
Affiliation(s)
- C P Moore
- Department of Mechanical Engineering, University of Alberta, Edmonton, AB, Canada.
| | - I M Katz
- Air Liquide Santé International, Paris Innovation Campus, Les Loges en Josas, France.
| | - M Pichelin
- Air Liquide Santé International, Paris Innovation Campus, Les Loges en Josas, France.
| | - G Caillibotte
- Air Liquide Santé International, Paris Innovation Campus, Les Loges en Josas, France.
| | - W H Finlay
- Department of Mechanical Engineering, University of Alberta, Edmonton, AB, Canada.
| | - A R Martin
- Department of Mechanical Engineering, University of Alberta, Edmonton, AB, Canada.
| |
Collapse
|
4
|
Henderson WR, Molgat-Seon Y, Dominelli PB, Brasher PMA, Griesdale DEG, Foster GE, Yacyshyn A, Ayas NT, Sheel AW. Gas density alters expiratory time constants before and after experimental lung injury. Exp Physiol 2016; 100:1217-28. [PMID: 26289254 DOI: 10.1113/ep085205] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 08/17/2015] [Indexed: 01/10/2023]
Abstract
NEW FINDINGS What is the central question of this study? Does the induction of a model of lung injury affect the expiratory time constant (τE) in terms of either total duration or morphology? Does ventilation with gases of different densities alter the duration or morphology of τE either before or after injury? What is the main finding and its importance? The use of sulfur hexafluoride in ventilating gas mixtures lengthens total expiratory time constants before and after lung injury compared with both nitrogen and helium mixtures. Sulfur hexafluoride mixtures also decrease the difference and variability of τE between fast- and slow-emptying compartments before and after injury when compared with nitrogen and helium mixtures. Acute lung injury is characterized by regional heterogeneity of lung resistance and elastance that may lead to regional heterogeneity of expiratory time constants (τE). We hypothesized that increasing airflow resistance by using inhaled sulfur hexafluoride (SF6) would lengthen time constants and decrease their heterogeneity in an experimental model of lung injury when compared with nitrogen or helium mixtures. To overcome the limitations of a single-compartment model, we employed a multisegment model of expiratory gas flow. An experimental model of lung injury was created using intratracheal injection of sodium polyacrylate in anaesthetized and mechanically ventilated female Yorkshire-cross pigs (n = 7). The animals were ventilated with 50% O2 and the remaining 50% as nitrogen (N2), helium (He) or sulfur hexafluoride (SF6). Values for τE decreased with injury and were more variable after injury than before (P < 0.001). Values for τE increased throughout expiration both before and after injury, and the rate of increase in τE was lessened by SF6 (P < 0.001 when compared with N2 both before and after injury). Altering the inhaled gas density did not affect indices of oxygenation, dead space or shunt. The use of SF6 in ventilating gas mixtures lengthens total expiratory time constants before and after lung injury compared with both N2 and He mixtures. Importantly, SF6 mixtures also decrease the difference and variability of τE between fast- and slow-emptying compartments before and after injury when compared with N2 and He mixtures.
Collapse
Affiliation(s)
- William R Henderson
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Yannick Molgat-Seon
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Paolo B Dominelli
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Penelope M A Brasher
- Centre for Clinical Epidemiology & Evaluation, Vancouver Coastal Health Research Institute, Vancouver, British Columbia, Canada
| | - Donald E G Griesdale
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Glen E Foster
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Alexandra Yacyshyn
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Najib T Ayas
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| |
Collapse
|
5
|
Häussermann S, Schulze A, Katz IM, Martin AR, Herpich C, Hunger T, Texereau J. Effects of a helium/oxygen mixture on individuals' lung function and metabolic cost during submaximal exercise for participants with obstructive lung diseases. Int J Chron Obstruct Pulmon Dis 2015; 10:1987-97. [PMID: 26451096 PMCID: PMC4590345 DOI: 10.2147/copd.s88965] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Helium/oxygen therapies have been studied as a means to reduce the symptoms of obstructive lung diseases with inconclusive results in clinical trials. To better understand this variability in results, an exploratory physiological study was performed comparing the effects of helium/oxygen mixture (78%/22%) to that of medical air. METHODS The gas mixtures were administered to healthy, asthmatic, and chronic obstructive pulmonary disease (COPD) participants, both moderate and severe (6 participants in each disease group, a total of 30); at rest and during submaximal cycling exercise with equivalent work rates. Measurements of ventilatory parameters, forced spirometry, and ergospirometry were obtained. RESULTS There was no statistical difference in ventilatory and cardiac responses to breathing helium/oxygen during submaximal exercise. For asthmatics, but not for the COPD participants, there was a statistically significant benefit in reduced metabolic cost, determined through measurement of oxygen uptake, for the same exercise work rate. However, the individual data show that there were a mixture of responders and nonresponders to helium/oxygen in all of the groups. CONCLUSION The inconsistent response to helium/oxygen between individuals is perhaps the key drawback to the more effective and widespread use of helium/oxygen to increase exercise capacity and for other therapeutic applications.
Collapse
Affiliation(s)
| | | | - Ira M Katz
- Medical R&D, Air Liquide Santé International, Centre de Recherche Paris-Saclay, Les Loges-en-Josas, France ; Department of Mechanical Engineering, Lafayette College, Easton, PA, USA
| | - Andrew R Martin
- Department of Mechanical Engineering, University of Alberta, Edmonton, AB, Canada
| | | | | | - Joëlle Texereau
- Medical R&D, Air Liquide Santé International, Centre de Recherche Paris-Saclay, Les Loges-en-Josas, France
| |
Collapse
|
6
|
Gouinaud L, Katz I, Martin A, Hazebroucq J, Texereau J, Caillibotte G. Inhalation pressure distributions for medical gas mixtures calculated in an infant airway morphology model. Comput Methods Biomech Biomed Engin 2014; 18:1358-66. [DOI: 10.1080/10255842.2014.903932] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
7
|
Katz I, Pichelin M, Montesantos S, Majoral C, Martin A, Conway J, Fleming J, Venegas J, Greenblatt E, Caillibotte G. Using helium-oxygen to improve regional deposition of inhaled particles: mechanical principles. J Aerosol Med Pulm Drug Deliv 2014; 27:71-80. [PMID: 24383961 DOI: 10.1089/jamp.2013.1072] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Helium-oxygen has been used for decades as a respiratory therapy conjointly with aerosols. It has also been shown under some conditions to be a means to provide more peripheral, deeper, particle deposition for inhalation therapies. Furthermore, we can also consider deposition along parallel paths that are quite different, especially in a heterogeneous pathological lung. It is in this context that it is hypothesized that helium-oxygen can improve regional deposition, leading to more homogeneous deposition by increasing deposition in ventilation-deficient lung regions. METHODS Analytical models of inertial impaction, sedimentation, and diffusion are examined to illustrate the importance of gas property values on deposition distribution through both fluid mechanics- and particle mechanics-based mechanisms. Also considered are in vitro results from a bench model for a heterogeneously obstructed lung. In vivo results from three-dimensional (3D) imaging techniques provide visual examples of changes in particle deposition patterns in asthmatics that are further analyzed using computational fluid dynamics (CFD). RESULTS AND CONCLUSIONS Based on analytical modeling, it is shown that deeper particle deposition is expected when breathing helium-oxygen, as compared with breathing air. A bench model has shown that more homogeneous ventilation distribution is possible breathing helium-oxygen in the presence of heterogeneous obstructions representative of central airway obstructions. 3D imaging of asthmatics has confirmed that aerosol delivery with a helium-oxygen carrier gas results in deeper and more homogeneous deposition distributions. CFD results are consistent with the in vivo imaging and suggest that the mechanics of gas particle interaction are the source of the differences seen in deposition patterns. However, intersubject variability in response to breathing helium-oxygen is expected, and an example of a nonresponder is shown where regional deposition is not significantly changed.
Collapse
Affiliation(s)
- I Katz
- 1 R&D Medical Gases Group , Air Liquide Santé International, Les-Loges-en-Josas, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Martin AR, Katz IM, Jenöfi K, Caillibotte G, Brochard L, Texereau J. Bench experiments comparing simulated inspiratory effort when breathing helium-oxygen mixtures to that during positive pressure support with air. BMC Pulm Med 2012; 12:62. [PMID: 23031537 PMCID: PMC3527263 DOI: 10.1186/1471-2466-12-62] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 09/20/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Inhalation of helium-oxygen (He/O2) mixtures has been explored as a means to lower the work of breathing of patients with obstructive lung disease. Non-invasive ventilation (NIV) with positive pressure support is also used for this purpose. The bench experiments presented herein were conducted in order to compare simulated patient inspiratory effort breathing He/O2 with that breathing medical air, with or without pressure support, across a range of adult, obstructive disease patterns. METHODS Patient breathing was simulated using a dual-chamber mechanical test lung, with the breathing compartment connected to an ICU ventilator operated in NIV mode with medical air or He/O2 (78/22 or 65/35%). Parabolic or linear resistances were inserted at the inlet to the breathing chamber. Breathing chamber compliance was also varied. The inspiratory effort was assessed for the different gas mixtures, for three breathing patterns, with zero pressure support (simulating unassisted spontaneous breathing), and with varying levels of pressure support. RESULTS Inspiratory effort increased with increasing resistance and decreasing compliance. At a fixed resistance and compliance, inspiratory effort increased with increasing minute ventilation, and decreased with increasing pressure support. For parabolic resistors, inspiratory effort was lower for He/O2 mixtures than for air, whereas little difference was measured for nominally linear resistance. Relatively small differences in inspiratory effort were measured between the two He/O2 mixtures. Used in combination, reductions in inspiratory effort provided by He/O2 and pressure support were additive. CONCLUSIONS The reduction in inspiratory effort afforded by breathing He/O2 is strongly dependent on the severity and type of airway obstruction. Varying helium concentration between 78% and 65% has small impact on inspiratory effort, while combining He/O2 with pressure support provides an additive reduction in inspiratory effort. In addition, breathing He/O2 alone may provide an alternative to pressure support in circumstances where NIV is not available or poorly tolerated.
Collapse
Affiliation(s)
- Andrew R Martin
- Medical Gases Group, Air Liquide Santé International, Centre de Recherche Claude-Delorme, Jouy-en-Josas, France.
| | | | | | | | | | | |
Collapse
|