Grants Funded
ASPS/PSF leadership is committed to continuing to provide high levels of investigator-initiated research support to ensure that plastic surgeons have the needed research resources to be pioneers and innovators in advancing the practice of medicine.
Research Abstracts
Search The PSF database to have easy access to full-text grant abstracts from past PSF-funded research projects 2003 to present. All abstracts are the work of the Principal Investigators and were retrieved from their PSF grant applications. Several different filters may be applied to locate abstracts specific to a particular focus area or PSF funding mechanism.
Restoration of Diaphragm Contraction in Acute and Chronic Phrenic Neuropathy
Principal Investigator
Matthew Ramsey MD
Matthew Ramsey MD
Year
2025
2025
Institution
Northwestern University
Northwestern University
Funding Mechanism
Research Fellowship
Research Fellowship
Focus Area
Peripheral Nerve, General Reconstructive
Peripheral Nerve, General Reconstructive
Abstract
Project Summary
The central goal is to prevent chronic ventilator dependence in patients with phrenic neuropathy. We propose to approach the acute patient, within one year of phrenic nerve injury, differently than the chronic patient, greater than one year from injury. This is due to irreversible changes a muscle undergoes when it has lost its innervation for longer than one year. Fortunately, the techniques we propose, nerve and muscle transfers, are quite familiar to the plastic surgery community and are performed daily. Previous work from our group has also validated a rat model of phrenic neuropathy, a nerve transfer that resulted in incomplete diaphragm recovery and a novel, implantable nerve stimulator. This proposal builds on this prior experience and will be directly translated to the bedside. Aim 1 is focused on the acute patient with the goal being to fully reinnervate the diaphragm with the spinal accessory nerve and compare pacing to no pacing. The spinal accessory nerve is near the phrenic nerve, innervates an accessory muscle of respiration and contains adequate axonal density. To assess our results, we will also be using techniques familiar to our group. We will be examining diaphragm movement on ultrasound, the pressure differential across the diaphragm, muscle fiber composition, electrical properties when stimulated and the neuromuscular junction through staining. Aim 2 is focused on the chronic patient with an irreversibly atrophied diaphragm where the goal is to separate the patient from ventilator dependence. To achieve this, a new, healthy contractile muscle must be surgically inset to function as the diaphragm. This constitutes a functional muscle transfer and is a technique very commonly performed by plastic surgeons. We propose rotating the rectus abdominis muscle as it is near, can be sacrificed without any loss of function and has favorably neurovascular anatomy to allow contraction to be preserved. The rectus has never been used for a functional diaphragm reconstruction before, so the surgical technique must be developed and validated. To assess function, we also be examining diaphragm movement on ultrasound as the newly inset rectus will pull it down during inspiration, and pressure across the diaphragm. We expect the muscle to function with the implantable pacer and may observe recovery of voluntary respiration. We firmly believe this treatment paradigm will be readily adopted. This will directly benefit the healthcare system and patients.
Impact Statement
Plastic surgeons are intimately familiar with nerve transfers and functional muscle transfers. This proposal applies these techniques to a new, challenging patient population with phrenic neuropathy threatening ventilator dependence. Ventilator dependence has been shown to result in mortality rates as high as 51.0-71.8% in hospital settings and up to 91.8% in home or nursing home settings. A financial analysis revealed patients requiring prolonged mechanical ventilation accrued a cost of $423,596 per one-year survival. Treating phrenic neuropathy is therefore crucial to lower widespread healthcare costs and mortality rates. And while performed on rats, the techniques we seek to validate in this proposal are directly translatable to the bedside as they are built on foundational
concepts.
Project Summary
The central goal is to prevent chronic ventilator dependence in patients with phrenic neuropathy. We propose to approach the acute patient, within one year of phrenic nerve injury, differently than the chronic patient, greater than one year from injury. This is due to irreversible changes a muscle undergoes when it has lost its innervation for longer than one year. Fortunately, the techniques we propose, nerve and muscle transfers, are quite familiar to the plastic surgery community and are performed daily. Previous work from our group has also validated a rat model of phrenic neuropathy, a nerve transfer that resulted in incomplete diaphragm recovery and a novel, implantable nerve stimulator. This proposal builds on this prior experience and will be directly translated to the bedside. Aim 1 is focused on the acute patient with the goal being to fully reinnervate the diaphragm with the spinal accessory nerve and compare pacing to no pacing. The spinal accessory nerve is near the phrenic nerve, innervates an accessory muscle of respiration and contains adequate axonal density. To assess our results, we will also be using techniques familiar to our group. We will be examining diaphragm movement on ultrasound, the pressure differential across the diaphragm, muscle fiber composition, electrical properties when stimulated and the neuromuscular junction through staining. Aim 2 is focused on the chronic patient with an irreversibly atrophied diaphragm where the goal is to separate the patient from ventilator dependence. To achieve this, a new, healthy contractile muscle must be surgically inset to function as the diaphragm. This constitutes a functional muscle transfer and is a technique very commonly performed by plastic surgeons. We propose rotating the rectus abdominis muscle as it is near, can be sacrificed without any loss of function and has favorably neurovascular anatomy to allow contraction to be preserved. The rectus has never been used for a functional diaphragm reconstruction before, so the surgical technique must be developed and validated. To assess function, we also be examining diaphragm movement on ultrasound as the newly inset rectus will pull it down during inspiration, and pressure across the diaphragm. We expect the muscle to function with the implantable pacer and may observe recovery of voluntary respiration. We firmly believe this treatment paradigm will be readily adopted. This will directly benefit the healthcare system and patients.
Impact Statement
Plastic surgeons are intimately familiar with nerve transfers and functional muscle transfers. This proposal applies these techniques to a new, challenging patient population with phrenic neuropathy threatening ventilator dependence. Ventilator dependence has been shown to result in mortality rates as high as 51.0-71.8% in hospital settings and up to 91.8% in home or nursing home settings. A financial analysis revealed patients requiring prolonged mechanical ventilation accrued a cost of $423,596 per one-year survival. Treating phrenic neuropathy is therefore crucial to lower widespread healthcare costs and mortality rates. And while performed on rats, the techniques we seek to validate in this proposal are directly translatable to the bedside as they are built on foundational
concepts.
Biography
I believe I possess the required knowledge, skills, motivation, and support to successfully complete this proposal. I have now been actively participating in and completing research projects for over eight years across three benchtop labs and four clinical faculty mentors. I successfully led my first independent project as a senior in college, just my second year of lab experience, which was published. I am now consistently leading medical students through clinical projects, writing textbook chapters, conceptualizing new projects within plastic surgery and presenting work at national conferences. Through college and medical school, I have also consistently been in leadership positions of high-functioning teams such as accreditation committees with Deans and a medical device innovations collaboration across the four major graduate schools of Northwestern. These diverse experiences have and will continue to prove valuable. Of note, I also intimately understand from previous academic and professional endeavors when I have personally reached a limit of my own knowledge or skill. I have learned how and when to ask for proactive assistance and have no doubt in my ability to work with my faculty sponsor. I am incredibly excited for this opportunity, firmly believe that I possess the necessary attributes to be successful, and fully intend to follow-up the data collected from this proposal as I begin my academic career.
I believe I possess the required knowledge, skills, motivation, and support to successfully complete this proposal. I have now been actively participating in and completing research projects for over eight years across three benchtop labs and four clinical faculty mentors. I successfully led my first independent project as a senior in college, just my second year of lab experience, which was published. I am now consistently leading medical students through clinical projects, writing textbook chapters, conceptualizing new projects within plastic surgery and presenting work at national conferences. Through college and medical school, I have also consistently been in leadership positions of high-functioning teams such as accreditation committees with Deans and a medical device innovations collaboration across the four major graduate schools of Northwestern. These diverse experiences have and will continue to prove valuable. Of note, I also intimately understand from previous academic and professional endeavors when I have personally reached a limit of my own knowledge or skill. I have learned how and when to ask for proactive assistance and have no doubt in my ability to work with my faculty sponsor. I am incredibly excited for this opportunity, firmly believe that I possess the necessary attributes to be successful, and fully intend to follow-up the data collected from this proposal as I begin my academic career.