نویسندگان

1 دانشجوی کارشناسی ارشد مهندسی پزشکی، بخش مهندسی پزشکی، گروه مهندسی علوم زیستی، دانشکده‌ی علوم و فنون نوین، دانشگاه تهران، تهران

2 دانشیار، بخش مهندسی پزشکی، گروه مهندسی علوم زیستی، دانشکده‌ی علوم و فنون نوین، دانشگاه تهران، تهران

چکیده

برای بیماران مبتلا به بیماری‌های مزمن ریوی، ریه‌ی مصنوعی (که بطن راست قلب جریان خون را به سمت آن پمپاژ می‌کند)، به عنوان یک مرحله‌ی مقدماتی پیش از پیوند ریه به شمار می‌آید. عمل‌کرد این دستگاه با چندین معیار، از جمله کارآمدی دستگاه در تبادل گاز، عدم آسیب‌رسانی به سلول‌های خونی و امپدانس پایین در مقایسه با ریه‌ی طبیعی، سنجیده می‌شود. در این مطالعه، بررسی عددی جریان خون غیرنیوتنی حول آرایه‌هایی از فیبرهای توخالی، به عنوان مدلی از دسته‌فیبرهای موجود در ریه‌ی مصنوعی، به روش حجم-محدود صورت گرفت. دو نوع آرایش مربعی و قطری برای فیبرها در نظر گرفته شد تا اثر آرایش، اثر سرعت ورودی روی توزیع جریان، تنش برشی و غلظت اکسیژن تبادل‌شده بین سطح فیبرها و جریان خون، بررسی شود. مشاهده شد که سرعت جریان و تنش برشی در آرایش قطری به مراتب بیش‌تر از آرایش مربعی است، به طوری که برای بیشینه‌ی سرعت مورد بررسی (cm/s 87/10)، تنش برشی روی فیبرها در آرایش قطری حدود 5/3 برابر مقدار آن در آرایش مربعی است. هم‌چنین، بین نتایج این تحلیل با نتایج مطالعات دیگری که در آن‌ها از تبادل اکسیژن صرف نظر شده بود، اختلاف قابل توجهی دیده شد، که بیان‌گر اهمیت مدل‌سازی تبادل گاز می‌باشد. میزان دبی جرمی اکسیژن در خروجی دامنه‌ی حل، به عنوان ملاک کارآمدی دستگاه (از دید تبادل گاز) مورد بررسی قرار گرفت. بر این اساس، آرایش قطری در تبادل اکسیژن بسیار کارآمدتر است. اما برای آرایش قطری، افت فشار بیش‌تری در عبور از دسته‌فیبرها، نسبت به آرایش مربعی مشاهده شد. نتایج این شبیه‌سازی می‌تواند نقطه‌ی شروع مناسبی برای طراحی بهینه‌ی ریه‌ی مصنوعی باشد و در طراحی بهینه‌ی آزمایش‌های کلینیکی موثر واقع شود.

کلیدواژه‌ها

عنوان مقاله [English]

Numerical Investigation of Oxygen Transfer and Blood Flow over Arrays of 3D Fibers of Artificial Lung

نویسندگان [English]

  • Zahra Mollahoseini 1
  • Bahman Vahidi 2

1 MSc of Biomedical Engineering-Biomechanics, Faculty of New Sciences and Technologies (FNST), University of Tehran, Tehran, Iran

2 Associate Professor of Biomedical Engineering, Faculty of New Sciences and Technologies (FNST), University of Tehran, Tehran, Iran

چکیده [English]

For patients with chronic pulmonary disease, artificial lungs to which right ventricular pumps blood flow is considered as a bridge to lung transplantation. The performance of this device is measured by several criteria, including the efficiency of the device in gas exchange, non-damage to blood cells and low impedance compared to normal lung. In this study, the non-Newtonian blood flow around arrays of hollow fibers, as a model of fiber bundles in artificial lungs, was numerically investigated by finite volume. Two types of square and diagonal arrangements for fibers were considered to examine the effect of arrangement, besides the inlet velocity effect on the flow distribution, shear stress and the exchanged oxygen concentration between the surface of the fibers and the blood stream. It was observed that the flow velocity and shear stress in the diagonal arrangement were far more than the square arrangement that for the maximum velocity (10/87 cm/s), the shear stress on the fibers in the diagonal arrangement was about 3.5 times that of the square arrangement. Also, there was a significant difference between the results of this analysis and the results of other studies in which oxygen exchange was ignored, which illustrates the importance of gas exchange modeling. As a measure of the efficiency of the device, from the viewpoint of gas exchange, the mass flow rate of oxygen was investigated in the output of the domain. As a result, the diagonal arrangement is much more efficient in oxygen exchange. However, there was a higher pressure drop across the fibers, for a diagonal arrangement, in comparison with the square arrangement. The results of this simulation can be a good starting point for optimal artificial lung design and can be effective in optimizing the design of clinical trials.

کلیدواژه‌ها [English]

  • Artificial Lung
  • Hollow Fiber
  • Fiber Arrangement
  • Computational fluid dynamics
  • Gas Transfer
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