A Highly Portable and Biocompatible Pulmonary Assist System for Long-Term Respiratory Support
Abstract
The goal of this project is to develop a pulmonary assist system (PAS) to support Veterans with long-term, incurable lung disease for a period of months to years. Over 12 million patients in the U.S. suffer from these lung diseases. The function of these patients’ lungs declines gradually over time, and these patients also experience recurring, temporary periods with a severe loss in lung function. These periods typically follow a lung infection or breathing in harmful particulate matter. Veterans are 1.5 to 3 times more likely than the general population to develop these long-term lung diseases, and they are the fourth most prevalent disease in the Department of Veterans Affairs (VA) patient population. Treating these diseases resulted in approximately $5.2 billion of annual VA spending as of 2008. The only treatment capable of restoring a relatively normal lifestyle for these patients is lung transplantation, but fewer than 2,000 donor organs are available in the U.S. each year. Furthermore, only half of patients receiving these donated lungs survive 5 years, which is worse than all other transplanted organs. Our goal, therefore, is to develop a pulmonary assist system (PAS) that supports these patients for years at home. This system uses a small pump to pump blood from a patient’s body through a small artificial lung and back to the patient. Patients suffering a temporary, life-threatening worsening of their lung disease would have a PAS attached within the hospital. This would allow them to recover from their loss in lung function and rehabilitate more effectively. Patients suffering from significant, debilitating lung disease would be maintained on the PAS and transitioned to home-based care with assistance from a visiting nurse. Every 2-3 months, the patient would return to the hospital to have the artificial lung portion of the PAS replaced. The PAS system would allow the patient to return to a relatively normal life and increase the patient’s lifespan. First and foremost, the PAS must transfer adequate oxygen and carbon dioxide. Unfortunately, previous systems providing long-term support have (i) caused blood to clot rapidly within the artificial lung, clogging it and causing it to fail and (ii) damaged blood cells as they pass through the system, requiring the patients to receive blood transfusions. There is currently no system available for permanent support for these reasons. However, artificial lung designs from our laboratory have demonstrated very low rates of clot formation and negligible blood damage. One way they accomplish this is to pack the membranes providing oxygen and carbon dioxide exchange very loosely. The loose packing allows blood clotting factors generated by the membrane to be diluted by fresh blood efficiently, which slows the rate of clot formation. The loose packing also creates a very small resistance to blood flow, which keeps blood cells from being destroyed. The PAS gas exchanger utilizes these concepts while also shrinking the amount of gas exchange membrane to reduce its generation of molecules that cause clotting and utilizing a unique blood inlet to the artificial lung that efficiently washes out molecules that accelerate clot formation. These features, coupled with surface coatings that reduce clot formation, should allow the PAS gas exchanger to function normally for months. To extend support for years, it would be replaced every 2-3 months. Our laboratory’s preliminary studies demonstrate the feasibility of this concept. The proposal will build upon this work through the following studies. First, we will optimize the blood flow patterns within the artificial lung to efficiently wash out clot-inducing molecules, reduce clot formation, and enhance longevity. Second, we will verify that the PAS will deliver enough oxygen and carbon dioxide to support patients with any form of long-term lung disease. Third, we will test the PAS for 60 days in sheep to
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 29, 2018
- Source ID
- W81XWH1710609
Entities
People
- Keith Cook
Organizations
- Massachusetts Institute of Technology
- United States Army