My research centers on respiratory muscle physiology and the mechanics of breathing. In general, I address clinical questions related to respiratory muscle function and dysfunction and my research integrates principles of basic science with clinical medicine. Specifically I 1) apply principles of skeletal muscle function to determine mechanisms that set respiratory muscle endurance, 2) evaluate diaphragm dysfunction in varied disease states including respiratory failure, 3) developed ultrasound as a technique to non-invasively assess diaphragm function and 4) use chest wall displacements to make non-invasive measurements of ventilation.
My research interests include respiratory muscle training, mechanical behavior and neural activation patterns of the respiratory muscles, effects of disease or injury on respiratory function (e.g., diaphragm paralysis, spinal cord injury, Parkinson disease, flail chest, muscular dystrophy), and the estimation of ventilation from body surface measurements. I have been a leader in advancing the science of measuring ventilation from body surface measurements and that of imaging the diaphragm using ultrasound.
The majority of my work has been directed at evaluating respiratory muscle function in health and disease. My initial research in this area focused on evaluating determinants of respiratory muscle endurance in healthy individuals. Among my significant contributions in this area were the findings that mean inspiratory flow rate, operational lung volume, and muscle energetics were key determinants of inspiratory muscle endurance. By extending these observations to patients with tetraplegia, Parkinsons Disease, diaphragm paralysis, and flail chest, we obtained a better understanding of respiratory muscle dysfunction in patients with varied diseases of the chest wall. While completing the above studies, it became apparent that the tools available to assess respiratory muscle function were limited due to their invasive nature. Consequently I became interested in developing ultrasound as a non-invasive tool to assess diaphragm function. After determining that diaphragm thickness could be accurately measured using ultrasound, I found that measurements of thickness had physiologic relevance. Specifically in a series of studies we noted that 1) the resting cross-sectional area of the diaphragm was proportional to its strength, 2) changes in diaphragm thickness during inspiration were proportional to its shortening, 3) disuse of the diaphragm leads to atrophy, 4) strength training and anabolic steroids result in diaphragm hypertrophy, and 5) diaphragm paralysis can be accurately and non-invasively diagnosed using ultrasound, and 6) ultrasound can be employed to assess diaphragm activity during mechanical ventilation. Finally, I have been active developing non-invasive means of monitoring ventilation. By utilizing models that we developed, changes in chest wall dimensions can provide measurements of ventilation with an accuracy of 15% in ambulatory individuals. Quantitating ventilation using such non-invasive means would improve current methods of assessing risk from environmental exposures to air-borne particulates and toxic gases.
1. Principal Investigator, "Effects of SRS and Leukotrienes on Tracheal Epithelial Ion Transport."
National Institutes of Health (NIH) Biomedical Research Support Grant (BRSG), 4/83-3/85. $20,000.
2. Principal Investigator, "Respiratory Muscle Endurance in Normal Subjects."
NIH HL34149, 5/85-4/88. $107,500.
3. Principal Investigator, "Respiratory Muscle Performance."
American Lung Association (ALA) Trudeau Scholarship, 7/85-6/88. $75,000.
4. Co-Investigator, "Respiratory Dysfunction in Spinal Cord Injury."
Veterans Affairs (VA) Merit Review, 5/86-4/89. $166,000.
5. Principal Investigator, "Respiratory Muscle Dysfunction in Parkinson's Disease."
BRSG NIH S07RR05862, 7/86-6/88. $16,624.
6. Co-Investigator, "Respiratory Dysfunction in Spinal Cord Injury."
VA Merit Review, 5/89-4/94. $310,000.
7. Principal Investigator, "Inspiratory Pump: Pressure, Flow, Volume Performance."
NIH R01 6/89-7/92. $249,000.
8. Principal Investigator, "Pressure Flow Performance During Submaximal Inspiratory Efforts."
NIH BRSG, 7/89-6/90. $6,860.
9. Principal Investigator, "Measurement of Ventilation in Freely Ranging Subjects."
Health Effects Institute, 7/89-6/93. $130,231.
10. Co-Investigator, "Respiratory Dysfunction in Spinal Cord Injury."
VA-Merit Review, 5/94-4/99. $250,000.
11. Principal Investigator, "Non-Invasive Measurements of Ventilation."
Electric Power Research Institute, 11/96-12/98. $218,000.
12. Principal Investigator, "Non-Invasive Measurements of Ventilation."
Electric Power Research Institute, 1/99-5/00. $56,609.
13. Co-Investigator, "Evaluation of Oxandrin Therapy on Body Weight, Pulmonary Function and the Serum Lipid Profile in Subjects with Tetraplegia"
Bio-Technology General Corporation, 5/99-4/00. $129,409.
14. Principal Investigator, "Evaluation of Breathing Pattern and Dyspnea in Subjects with Tetraplegia."
American Paraplegia Society, 12/99 - 11/00. $10,000.
15. Principal Investigator, "The Use of Oxandrolone to Facilitate Liberation from Mechanical Ventilation."
Bio-Technology General Corporation, 7/00 - 6/01. $31,000
16. Principal Investigator, "Evaluation of Breathing Pattern During Sleep."
Electric Power Research Institute, 11/00-10/01. $42,744.
17. Co-Investigator, "Anabolic Therapies: New Hope for Treating the Secondary Disabilities of SCI."
VA-Merit Review, VA Medical Center, Bronx New York 7/01-6/06. $3,634,411.
