1
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Morin C, Simard É, See W, Sage M, Imane R, Nadeau C, Samson N, Lavoie PM, Chabot B, Marouan S, Tremblay S, Praud JP, Micheau P, Fortin-Pellerin É. Total liquid ventilation in an ovine model of extreme prematurity: a randomized study. Pediatr Res 2024; 95:974-980. [PMID: 37833531 DOI: 10.1038/s41390-023-02841-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 08/16/2023] [Accepted: 09/26/2023] [Indexed: 10/15/2023]
Abstract
BACKGROUND This study aimed at comparing cardiorespiratory stability during total liquid ventilation (TLV)-prior to lung aeration-with conventional mechanical ventilation (CMV) in extremely preterm lambs during the first 6 h of life. METHODS 23 lambs (11 females) were born by c-section at 118-120 days of gestational age (term = 147 days) to receive 6 h of TLV or CMV from birth. Lung samples were collected for RNA and histology analyses. RESULTS The lambs under TLV had higher and more stable arterial oxygen saturation (p = 0.001) and cerebral tissue oxygenation (p = 0.02) than the lambs in the CMV group in the first 10 min of transition to extrauterine life. Although histological assessment of the lungs was similar between the groups, a significant upregulation of IL-1a, IL-6 and IL-8 RNA in the lungs was observed after TLV. CONCLUSIONS Total liquid ventilation allowed for remarkably stable transition to extrauterine life in an extremely preterm lamb model. Refinement of our TLV prototype and ventilation algorithms is underway to address specific challenges in this population, such as minimizing tracheal deformation during the active expiration. IMPACT Total liquid ventilation allows for remarkably stable transition to extrauterine life in an extremely preterm lamb model. Total liquid ventilation is systematically achievable over the first 6 h of life in the extremely premature lamb model. This study provides additional incentive to pursue further investigation of total liquid ventilation as a transition tool for the most extreme preterm neonates.
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Affiliation(s)
- Christophe Morin
- Department of Pharmacology-Physiology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Émile Simard
- Department of Pharmacology-Physiology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Wendy See
- Department of Pharmacology-Physiology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Michaël Sage
- Department of Pharmacology-Physiology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Roqaya Imane
- Department of Pediatrics, Université de Montréal, Montreal, QC, Canada
| | - Charlène Nadeau
- Department of Pharmacology-Physiology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Nathalie Samson
- Department of Pharmacology-Physiology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Pascal M Lavoie
- Division of Neonatology, Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada
| | - Benoît Chabot
- Department of Microbiology and Infectiology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Sofia Marouan
- Department of Pathology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Sophie Tremblay
- Department of Pediatrics, Université de Montréal, Montreal, QC, Canada
| | - Jean-Paul Praud
- Department of Pharmacology-Physiology, Université de Sherbrooke, Sherbrooke, QC, Canada
- Department of Pediatrics, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Philippe Micheau
- Department of Mechanical Engineering, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Étienne Fortin-Pellerin
- Department of Pharmacology-Physiology, Université de Sherbrooke, Sherbrooke, QC, Canada.
- Department of Pediatrics, Université de Sherbrooke, Sherbrooke, QC, Canada.
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2
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Mondal A, Visner GA, Kaza AK, Dupont PE. A novel ex vivo tracheobronchomalacia model for airway stent testing and in vivo model refinement. J Thorac Cardiovasc Surg 2023; 166:679-687.e1. [PMID: 37156367 PMCID: PMC10524727 DOI: 10.1016/j.jtcvs.2023.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/14/2023] [Accepted: 04/10/2023] [Indexed: 05/10/2023]
Abstract
OBJECTIVES We sought to develop an ex vivo trachea model capable of producing mild, moderate, and severe tracheobronchomalacia for optimizing airway stent design. We also aimed to determine the amount of cartilage resection required for achieving different tracheobronchomalacia grades that can be used in animal models. METHODS We developed an ex vivo trachea test system that enabled video-based measurement of internal cross-sectional area as intratracheal pressure was cyclically varied for peak negative pressures of 20 to 80 cm H2O. Fresh ovine tracheas were induced with tracheobronchomalacia by single mid-anterior incision (n = 4), mid-anterior circumferential cartilage resection of 25% (n = 4), and 50% per cartilage ring (n = 4) along an approximately 3-cm length. Intact tracheas (n = 4) were used as control. All experimental tracheas were mounted and experimentally evaluated. In addition, helical stents of 2 different pitches (6 mm and 12 mm) and wire diameters (0.52 mm and 0.6 mm) were tested in tracheas with 25% (n = 3) and 50% (n = 3) circumferentially resected cartilage rings. The percentage collapse in tracheal cross-sectional area was calculated from the recorded video contours for each experiment. RESULTS Ex vivo tracheas compromised by single incision and 25% and 50% circumferential cartilage resection produce tracheal collapse corresponding to clinical grades of mild, moderate, and severe tracheobronchomalacia, respectively. A single anterior cartilage incision produces saber-sheath type tracheobronchomalacia, whereas 25% and 50% circumferential cartilage resection produce circumferential tracheobronchomalacia. Stent testing enabled the selection of stent design parameters such that airway collapse associated with moderate and severe tracheobronchomalacia could be reduced to conform to, but not exceed, that of intact tracheas (12-mm pitch, 0.6-mm wire diameter). CONCLUSIONS The ex vivo trachea model is a robust platform that enables systematic study and treatment of different grades and morphologies of airway collapse and tracheobronchomalacia. It is a novel tool for optimization of stent design before advancing to in vivo animal models.
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Affiliation(s)
- Abhijit Mondal
- Department of Cardiac Surgery, Boston Children's Hospital, Boston, Mass; Department of Surgery, Harvard Medical School, Boston, Mass.
| | - Gary A Visner
- Division of Pulmonary Medicine, Boston Children's Hospital, Boston, Mass; Department of Pediatrics, Harvard Medical School, Boston, Mass
| | - Aditya K Kaza
- Department of Cardiac Surgery, Boston Children's Hospital, Boston, Mass; Department of Surgery, Harvard Medical School, Boston, Mass
| | - Pierre E Dupont
- Department of Cardiac Surgery, Boston Children's Hospital, Boston, Mass; Department of Surgery, Harvard Medical School, Boston, Mass
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3
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Uslu E, Rana VK, Anagnostopoulos S, Karami P, Bergadano A, Courbon C, Gorostidi F, Sandu K, Stergiopulos N, Pioletti DP. Wet adhesive hydrogels to correct malacic trachea (tracheomalacia) A proof of concept. iScience 2023; 26:107168. [PMID: 37456833 PMCID: PMC10338288 DOI: 10.1016/j.isci.2023.107168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 05/17/2023] [Accepted: 06/14/2023] [Indexed: 07/18/2023] Open
Abstract
Tracheomalacia (TM) is a condition characterized by a weak tracheal cartilage and/or muscle, resulting in excessive collapse of the airway in the newborns. Current treatments including tracheal reconstruction, tracheoplasty, endo- and extra-luminal stents have limitations. To address these limitations, this work proposes a new strategy by wrapping an adhesive hydrogel patch around a malacic trachea. Through a numerical model, first it was demonstrated that a hydrogel patch with sufficient mechanical and adhesion strength can preserve the trachea's physiological shape. Accordingly, a new hydrogel providing robust adhesion on wet tracheal surfaces was synthesized employing the hydroxyethyl acrylamide (HEAam) and polyethylene glycol methacrylate (PEGDMA) as main polymer network and crosslinker, respectively. Ex vivo experiments revealed that the adhesive hydrogel patches can restrain the collapsing of malacic trachea under negative pressure. This study may open the possibility of using an adhesive hydrogel as a new approach in the difficult clinical situation of tracheomalacia.
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Affiliation(s)
- Ece Uslu
- Laboratory of Biomechanical Orthopedics, Institute of Bioengineering, School of Engineering, EPFL, Lausanne, Switzerland
| | - Vijay Kumar Rana
- Laboratory of Biomechanical Orthopedics, Institute of Bioengineering, School of Engineering, EPFL, Lausanne, Switzerland
| | - Sokratis Anagnostopoulos
- Laboratory of Hemodynamics and Cardiovascular Technology, Institute of Bioengineering, School of Engineering, EPFL, Lausanne, Switzerland
| | - Peyman Karami
- Laboratory of Biomechanical Orthopedics, Institute of Bioengineering, School of Engineering, EPFL, Lausanne, Switzerland
| | | | - Cecile Courbon
- Department of Anesthesiology, University Hospital, CHUV, Lausanne, Switzerland
| | - Francois Gorostidi
- Department of Otorhinolaryngology, Airway Sector, University Hospital, CHUV, Lausanne, Switzerland
| | - Kishore Sandu
- Department of Otorhinolaryngology, Airway Sector, University Hospital, CHUV, Lausanne, Switzerland
| | - Nikolaos Stergiopulos
- Laboratory of Hemodynamics and Cardiovascular Technology, Institute of Bioengineering, School of Engineering, EPFL, Lausanne, Switzerland
| | - Dominique P. Pioletti
- Laboratory of Biomechanical Orthopedics, Institute of Bioengineering, School of Engineering, EPFL, Lausanne, Switzerland
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4
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Conventional vs High-Frequency Ventilation for Weaning from Total Liquid Ventilation in Lambs. Respir Physiol Neurobiol 2022; 299:103867. [PMID: 35149225 DOI: 10.1016/j.resp.2022.103867] [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: 09/21/2021] [Revised: 02/03/2022] [Accepted: 02/06/2022] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To compare conventional gas ventilation (GV) and high-frequency oscillatory ventilation (HFOV) for weaning from total liquid ventilation (TLV). METHODS Sixteen lambs were anesthetized. After 1 h of TLV with perflubron (PFOB), they were assigned to either GV or HFOV for 2 h. Oxygen requirements, electrical impedance tomography and videofluoroscopic sequences, and respiratory system compliance were recorded. RESULTS The lambs under GV needed less oxygen at 20 min following TLV (40 [25, 45] and 83 [63, 98]%, p = 0.001 under GV and HFOV, respectively). During weaning, tidal volume distribution was increased in the nondependent regions in the GV group compared to baseline (p = 0.046). Furthermore, residual PFOB was observed in the most dependent region. No air was detected by fluoroscopy in that region at the end of expiration in the GV group. CONCLUSION GV offers a transient advantage over HFOV with regards to oxygenation for TLV weaning.
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5
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Soriano L, Khalid T, Whelan D, O'Huallachain N, Redmond KC, O'Brien FJ, O'Leary C, Cryan SA. Development and clinical translation of tubular constructs for tracheal tissue engineering: a review. Eur Respir Rev 2021; 30:30/162/210154. [PMID: 34750116 DOI: 10.1183/16000617.0154-2021] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 07/26/2021] [Indexed: 02/07/2023] Open
Abstract
Effective restoration of extensive tracheal damage arising from cancer, stenosis, infection or congenital abnormalities remains an unmet clinical need in respiratory medicine. The trachea is a 10-11 cm long fibrocartilaginous tube of the lower respiratory tract, with 16-20 tracheal cartilages anterolaterally and a dynamic trachealis muscle posteriorly. Tracheal resection is commonly offered to patients suffering from short-length tracheal defects, but replacement is required when the trauma exceeds 50% of total length of the trachea in adults and 30% in children. Recently, tissue engineering (TE) has shown promise to fabricate biocompatible tissue-engineered tracheal implants for tracheal replacement and regeneration. However, its widespread use is hampered by inadequate re-epithelialisation, poor mechanical properties, insufficient revascularisation and unsatisfactory durability, leading to little success in the clinical use of tissue-engineered tracheal implants to date. Here, we describe in detail the historical attempts and the lessons learned for tracheal TE approaches by contextualising the clinical needs and essential requirements for a functional tracheal graft. TE manufacturing approaches explored to date and the clinical translation of both TE and non-TE strategies for tracheal regeneration are summarised to fully understand the big picture of tracheal TE and its impact on clinical treatment of extensive tracheal defects.
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Affiliation(s)
- Luis Soriano
- School of Pharmacy and Biomolecular Sciences, RCSI University of Medicine and Health Sciences, Dublin, Ireland.,Tissue Engineering Research Group, Dept of Anatomy and Regenerative Medicine, RCSI University of Medicine and Health Sciences, Dublin, Ireland.,SFI Centre for Research in Medical Devices (CÚRAM), RCSI University of Medicine and Health Sciences, Dublin, Ireland.,Joint first authors
| | - Tehreem Khalid
- School of Pharmacy and Biomolecular Sciences, RCSI University of Medicine and Health Sciences, Dublin, Ireland.,Tissue Engineering Research Group, Dept of Anatomy and Regenerative Medicine, RCSI University of Medicine and Health Sciences, Dublin, Ireland.,SFI Advanced Materials and Bioengineering Research (AMBER) Centre, RCSI University of Medicine and Health Sciences and Trinity College Dublin, Dublin, Ireland.,Joint first authors
| | - Derek Whelan
- Dept of Mechanical, Biomedical and Manufacturing Engineering, Munster Technological University, Cork, Ireland
| | - Niall O'Huallachain
- School of Pharmacy and Biomolecular Sciences, RCSI University of Medicine and Health Sciences, Dublin, Ireland
| | - Karen C Redmond
- National Cardio-thoracic Transplant Unit, Mater Misericordiae University Hospital and UCD School of Medicine, Dublin, Ireland
| | - Fergal J O'Brien
- Tissue Engineering Research Group, Dept of Anatomy and Regenerative Medicine, RCSI University of Medicine and Health Sciences, Dublin, Ireland.,SFI Centre for Research in Medical Devices (CÚRAM), RCSI University of Medicine and Health Sciences, Dublin, Ireland.,SFI Advanced Materials and Bioengineering Research (AMBER) Centre, RCSI University of Medicine and Health Sciences and Trinity College Dublin, Dublin, Ireland.,Trinity Centre for Biomedical Engineering, Trinity College Dublin, Dublin, Ireland
| | - Cian O'Leary
- School of Pharmacy and Biomolecular Sciences, RCSI University of Medicine and Health Sciences, Dublin, Ireland.,Tissue Engineering Research Group, Dept of Anatomy and Regenerative Medicine, RCSI University of Medicine and Health Sciences, Dublin, Ireland.,SFI Centre for Research in Medical Devices (CÚRAM), RCSI University of Medicine and Health Sciences, Dublin, Ireland.,SFI Advanced Materials and Bioengineering Research (AMBER) Centre, RCSI University of Medicine and Health Sciences and Trinity College Dublin, Dublin, Ireland.,Trinity Centre for Biomedical Engineering, Trinity College Dublin, Dublin, Ireland.,Both authors contributed equally
| | - Sally-Ann Cryan
- School of Pharmacy and Biomolecular Sciences, RCSI University of Medicine and Health Sciences, Dublin, Ireland .,Tissue Engineering Research Group, Dept of Anatomy and Regenerative Medicine, RCSI University of Medicine and Health Sciences, Dublin, Ireland.,SFI Centre for Research in Medical Devices (CÚRAM), RCSI University of Medicine and Health Sciences, Dublin, Ireland.,SFI Advanced Materials and Bioengineering Research (AMBER) Centre, RCSI University of Medicine and Health Sciences and Trinity College Dublin, Dublin, Ireland.,Trinity Centre for Biomedical Engineering, Trinity College Dublin, Dublin, Ireland.,Both authors contributed equally
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Subramaniam DR, Oren L, Willging JP, Gutmark EJ. Evaluating the biomechanical characteristics of cuffed-tracheostomy tubes using finite element analysis. Comput Methods Biomech Biomed Engin 2021; 24:1595-1605. [PMID: 33761806 DOI: 10.1080/10255842.2021.1902511] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The objective of this study was to perform finite element analysis (FEA) of cuff inflation within an anatomically accurate model of an adult trachea in four different cuffed-tracheostomy tube designs. The leakage quantified by the distance between the cuff and trachea was largest for the Tracoe cuff and smallest for the Portex cuff. The smooth muscle stresses were greatest for the Portex and least for the Distal cuff, respectively. The proposed FEA model offers a promising approach to virtually evaluate the sealing efficacy of cuffed-tracheostomy tubes and the tracheal wall stresses induced by cuff inflation, prior to application.
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Affiliation(s)
| | - Liran Oren
- Department of Otolaryngology-Head and Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - J Paul Willging
- Division of Pediatric Otolaryngology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Ephraim J Gutmark
- Department of Aerospace Engineering and Engineering Mechanics, University of Cincinnati, Cincinnati, OH, USA.,Department of Otolaryngology-Head and Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, OH, USA
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7
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Sage M, Stowe S, Adler A, Forand-Choinière C, Nadeau M, Berger C, Marouan S, Micheau P, Tissier R, Praud JP, Fortin-Pellerin É. Perflubron Distribution During Transition From Gas to Total Liquid Ventilation. Front Physiol 2018; 9:1723. [PMID: 30555353 PMCID: PMC6283896 DOI: 10.3389/fphys.2018.01723] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 11/15/2018] [Indexed: 11/13/2022] Open
Abstract
Total liquid ventilation (TLV) using perfluorocarbons has shown promising results for the management of neonatal respiratory distress. However, one important safety consideration for TLV is a better understanding of the early events during the transition to TLV, especially regarding the fate of residual air in the non-dependent-lung regions. Our objective was to assess perflubron distribution during transition to TLV using electrical impedance tomography, complemented by fluoroscopy, in a neonatal lamb model of induced surfactant deficiency. Eight lambs were anesthetized and ventilated in supine position. Surfactant deficit was induced by saline lung lavage. After deflation, lungs were filled with 25 ml/kg perflubron over 18 s, and TLV was initiated. Electrical impedance tomography data was recorded from electrodes placed around the chest, during the first 10 and at 120 min of TLV. Lung perfusion was also assessed using hypertonic saline injection during apnea. In addition, fluoroscopic sequences were recorded during initial lung filling with perfluorocarbons, then at 10 and 60 min of TLV. Twelve lambs were used as controls for histological comparisons. Transition to TLV involved a short period of increased total lung volume (p = 0.01) secondary to recruitment of the dependent lung regions. Histological analysis shows that TLV was protective of these same regions when compared to gas-ventilated lambs (p = 0.03). The non-dependent lung regions filled with perflubron over at least 10 min, without showing signs of overdistention. Tidal volume distribution was more homogenous in TLV than during the preceding gas ventilation. Perflubron filling was associated with a non-significant increase in the anterior distribution of the blood perfusion signal, from 46 ± 17% to 53 ± 6% (p = 0.4). However, combined to the effects on ventilation, TLV had an instantaneous effect on ventilation-perfusion relationship (p = 0.03), suggesting better coupling. Conclusion: transition to TLV requires at least 10 min, and involves air evacuation or dissolution in perflubron, dependent lung recruitment and rapid ventilation-perfusion coupling modifications. During that time interval, the total lung volume transiently increases. Considering the potential deleterious effect of high lung volumes, one must manage this transition phase with care and, we suggest using a real-time monitoring system such as electrical impedance tomography.
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Affiliation(s)
- Michaël Sage
- Departments of Pediatrics and Pharmacology/Physiology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Symon Stowe
- Department of Computer Engineering, Carleton University, Ottawa, ON, Canada
| | - Andy Adler
- Department of Computer Engineering, Carleton University, Ottawa, ON, Canada
| | - Claudia Forand-Choinière
- Departments of Pediatrics and Pharmacology/Physiology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Mathieu Nadeau
- Department of Mechanical Engineering, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Claire Berger
- Department of Medicine, Université de Poitiers, Poitiers, France
| | - Sofia Marouan
- Department of Pathology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Philippe Micheau
- Department of Mechanical Engineering, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Renaud Tissier
- INSERM, Unité 955, Equipe 03, École Nationale Vétérinaire d'Alfort, Université Paris-Est Créteil, Paris, France
| | - Jean-Paul Praud
- Departments of Pediatrics and Pharmacology/Physiology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Étienne Fortin-Pellerin
- Departments of Pediatrics and Pharmacology/Physiology, Université de Sherbrooke, Sherbrooke, QC, Canada
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8
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Safshekan F, Tafazzoli-Shadpour M, Abdouss M, Shadmehr MB. Viscoelastic Properties of Human Tracheal Tissues. J Biomech Eng 2017; 139:2552974. [PMID: 27618230 DOI: 10.1115/1.4034651] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Indexed: 01/23/2023]
Abstract
The physiological performance of trachea is highly dependent on its mechanical behavior, and therefore, the mechanical properties of its components. Mechanical characterization of trachea is key to succeed in new treatments such as tissue engineering, which requires the utilization of scaffolds which are mechanically compatible with the native human trachea. In this study, after isolating human trachea samples from brain-dead cases and proper storage, we assessed the viscoelastic properties of tracheal cartilage, smooth muscle, and connective tissue based on stress relaxation tests (at 5% and 10% strains for cartilage and 20%, 30%, and 40% for smooth muscle and connective tissue). After investigation of viscoelastic linearity, constitutive models including Prony series for linear viscoelasticity and quasi-linear viscoelastic, modified superposition, and Schapery models for nonlinear viscoelasticity were fitted to the experimental data to find the best model for each tissue. We also investigated the effect of age on the viscoelastic behavior of tracheal tissues. Based on the results, all three tissues exhibited a (nonsignificant) decrease in relaxation rate with increasing the strain, indicating viscoelastic nonlinearity which was most evident for cartilage and with the least effect for connective tissue. The three-term Prony model was selected for describing the linear viscoelasticity. Among different models, the modified superposition model was best able to capture the relaxation behavior of the three tracheal components. We observed a general (but not significant) stiffening of tracheal cartilage and connective tissue with aging. No change in the stress relaxation percentage with aging was observed. The results of this study may be useful in the design and fabrication of tracheal tissue engineering scaffolds.
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Affiliation(s)
- Farzaneh Safshekan
- Faculty of Biomedical Engineering, Amirkabir University of Technology, 424 Hafez Avenue, Tehran 15875-4413, Iran e-mail:
| | - Mohammad Tafazzoli-Shadpour
- Faculty of Biomedical Engineering, Amirkabir University of Technology, 424 Hafez Avenue, Tehran 15875-4413, Iran e-mail:
| | - Majid Abdouss
- Chemistry Department, Amirkabir University of Technology, 424 Hafez Avenue, Tehran 15875-4413, Iran e-mail:
| | - Mohammad B Shadmehr
- Tracheal Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Darabad Avenue, Shahid Bahonar Roundabout, Tehran 19558-41452, Iran e-mail:
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9
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Hollister SJ, Hollister MP, Hollister SK. Computational modeling of airway instability and collapse in tracheomalacia. Respir Res 2017; 18:62. [PMID: 28424075 PMCID: PMC5395879 DOI: 10.1186/s12931-017-0540-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 03/28/2017] [Indexed: 11/24/2022] Open
Abstract
Background Tracheomalacia (TM) is a condition of excessive tracheal collapse during exhalation. Both acquired and congenital forms of TM are believed to result from morphological changes in cartilaginous, fibrous and/or smooth muscle tissues reducing airway mechanical properties to a degree that precipitates collapse. However, neither the specific amount of mechanical property reduction nor the malacic segment lengths leading to life threatening airway collapse in TM are known. Furthermore, the specific mechanism of collapse is still debated. Methods Computational nonlinear finite element models were developed to determine the effect of malacic segment length, tracheal diameter, and reduction in tissue nonlinear elastic properties on the risk for and mechanism of airway collapse. Cartilage, fibrous tissue, and smooth muscle nonlinear elastic properties were fit to experimental data from preterm lambs from the literature. These elastic properties were systematically reduced in the model to simulate TM. Results An intriguing finding was that sudden mechanical instability leading to complete airway collapse occurred in airways when even a 1 cm segment of cartilage and fibrous tissue properties had a critical reduction in material properties. In general, increased tracheal diameter, increased malacic segment length coupled with decreased nonlinear anterior cartilage/fibrous tissue nonlinear mechanical properties increased the risk of sudden airway collapse from snap through instability. Conclusion Modeling results support snap through instability as the mechanism for life threatening tracheomalacia specifically when cartilage ring nonlinear properties are reduced to a range between fibrous tissue nonlinear elastic properties (for larger diameter airways > 10 mm) to mucosa properties (for smaller diameter airways < 6 mm). Although reducing posterior tracheal smooth muscle properties to mucosa properties decreased exhalation area, no sudden instability leading to collapse was seen in these models.
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Affiliation(s)
- Scott J Hollister
- Wallace A. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Rm 2102 UA Whitaker Biomedical Engineering Bldg, 303 Ferst Drive, Atlanta, GA, 30332, USA.
| | | | - Sebastian K Hollister
- Department of Biomedical Engineering, The University of Michigan, Ann Arbor, MI, USA
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10
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Safshekan F, Tafazzoli-Shadpour M, Abdouss M, Shadmehr MB. Mechanical Characterization and Constitutive Modeling of Human Trachea: Age and Gender Dependency. MATERIALS 2016; 9:ma9060456. [PMID: 28773579 PMCID: PMC5456771 DOI: 10.3390/ma9060456] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 05/16/2016] [Accepted: 06/02/2016] [Indexed: 11/16/2022]
Abstract
Tracheal disorders can usually reduce the free lumen diameter or wall stiffness, and hence limit airflow. Trachea tissue engineering seems a promising treatment for such disorders. The required mechanical compatibility of the prepared scaffold with native trachea necessitates investigation of the mechanical behavior of the human trachea. This study aimed at mechanical characterization of human tracheas and comparing the results based on age and gender. After isolating 30 human tracheas, samples of tracheal cartilage, smooth muscle, and connective tissue were subjected to uniaxial tension to obtain force-displacement curves and calculate stress-stretch data. Among several models, the Yeoh and Mooney-Rivlin hyperelastic functions were best able to describe hyperelastic behavior of all three tracheal components. The mean value of the elastic modulus of human tracheal cartilage was calculated to be 16.92 ± 8.76 MPa. An overall tracheal stiffening with age was observed, with the most considerable difference in the case of cartilage. Consistently, we noticed some histological alterations in cartilage and connective tissue with aging, which may play a role in age-related tracheal stiffening. No considerable effect of gender on the mechanical behavior of tracheal components was observed. The results of this study can be applied in the design and fabrication of trachea tissue engineering scaffolds.
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Affiliation(s)
- Farzaneh Safshekan
- Faculty of Biomedical Engineering, Amirkabir University of Technology, 424 Hafez Ave, Tehran 1587-4413, Iran.
| | - Mohammad Tafazzoli-Shadpour
- Faculty of Biomedical Engineering, Amirkabir University of Technology, 424 Hafez Ave, Tehran 1587-4413, Iran.
| | - Majid Abdouss
- Chemistry Department, Amirkabir University of Technology, Tehran 1587-4413, Iran.
| | - Mohammad B Shadmehr
- Tracheal Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran 1956944413, Iran.
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11
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Index-matched measurements of the effect of cartilaginous rings on tracheobronchial flow. J Biomech 2016; 49:1601-1606. [DOI: 10.1016/j.jbiomech.2016.03.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 03/22/2016] [Accepted: 03/24/2016] [Indexed: 11/18/2022]
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12
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Bonfanti M, Cammi A, Bagnoli P. Gas transfer model to design a ventilator for neonatal total liquid ventilation. Med Eng Phys 2015; 37:1133-40. [DOI: 10.1016/j.medengphy.2015.09.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 06/12/2015] [Accepted: 09/11/2015] [Indexed: 11/25/2022]
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Nadeau M, Sage M, Kohlhauer M, Vandamme J, Mousseau J, Robert R, Tissier R, Praud JP, Walti H, Micheau P. Thermal Dynamics in Newborn and Juvenile Models Cooled by Total Liquid Ventilation. IEEE Trans Biomed Eng 2015; 63:1483-91. [PMID: 26552070 DOI: 10.1109/tbme.2015.2496938] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Total liquid ventilation (TLV) consists in filling the lungs with a perfluorocarbon (PFC) and using a liquid ventilator to ensure a tidal volume of oxygenated, CO 2 -free and temperature-controlled PFC. Having a much higher thermal capacity than air, liquid PFCs assume that the filled lungs become an efficient heat exchanger with pulmonary circulation. OBJECTIVE The objective of the present study was the development and validation of a parametric lumped thermal model of a subject in TLV. METHODS The lungs were modeled as one compartment in which the control volume varied as a function of the tidal volume. The heat transfer in the body was modeled as seven parallel compartments representing organs and tissues. The thermal model of the lungs and body was validated with two groups of lambs of different ages and weights (newborn and juvenile) undergoing an ultrafast mild therapeutic hypothermia induction by TLV. RESULTS The model error on all animals yielded a small mean error of -0.1 ±0.4 (°)C for the femoral artery and 0.0 ±0.1 (°)C for the pulmonary artery. CONCLUSION The resulting experimental validation attests that the model provided an accurate estimation of the systemic arterial temperature and the venous return temperature. SIGNIFICANCE This comprehensive thermal model of the lungs and body has the advantage of closely modeling the rapid thermal dynamics in TLV. The model can explain how the time to achieve mild hypothermia between newborn and juvenile lambs remained similar despite of highly different physiological and ventilatory parameters. The strength of the model is its strong relationship with the physiological parameters of the subjects, which suggests its suitability for projection to humans.
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Effect of intermediate ZrO2-CaO coatings deposited by cold thermal spraying on the titanium-porcelain bond in dental restorations. J Prosthet Dent 2014; 112:1201-11. [DOI: 10.1016/j.prosdent.2014.05.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 05/02/2014] [Accepted: 05/05/2014] [Indexed: 11/20/2022]
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Walenga RL, Longest PW, Sundaresan G. Creation of an in vitro biomechanical model of the trachea using rapid prototyping. J Biomech 2014; 47:1861-8. [PMID: 24735504 DOI: 10.1016/j.jbiomech.2014.03.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 03/11/2014] [Accepted: 03/11/2014] [Indexed: 01/25/2023]
Abstract
Previous in vitro models of the airways are either rigid or, if flexible, have not matched in vivo compliance characteristics. Rapid prototyping provides a quickly evolving approach that can be used to directly produce in vitro airway models using either rigid or flexible polymers. The objective of this study was to use rapid prototyping to directly produce a flexible hollow model that matches the biomechanical compliance of the trachea. The airway model consisted of a previously developed characteristic mouth-throat region, the trachea, and a portion of the main bronchi. Compliance of the tracheal region was known from a previous in vivo imaging study that reported cross-sectional areas over a range of internal pressures. The compliance of the tracheal region was matched to the in vivo data for a specific flexible resin by iteratively selecting the thicknesses and other dimensions of tracheal wall components. Seven iterative models were produced and illustrated highly non-linear expansion consisting of initial rapid size increase, a transition region, and continued slower size increase as pressure was increased. Thickness of the esophageal interface membrane and initial trachea indention were identified as key parameters with the final model correctly predicting all phases of expansion within a value of 5% of the in vivo data. Applications of the current biomechanical model are related to endotracheal intubation and include determination of effective mucus suctioning and evaluation of cuff sealing with respect to gases and secretions.
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Affiliation(s)
- Ross L Walenga
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, United States
| | - P Worth Longest
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, United States; Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, United States.
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