Mark Oatman, MD
Dr. Mark Oatman has practiced at PPM since July 2019 and he is our Medical Director. He attended the OU College of Medicine where he received his Doctor of Medicine with specialties in emergency and family medicine. He completed his undergraduate and residency at Kansas University at Wichita. Dr. Oatman and his wife reside in Tulsa and he has three sons and four granddaughters.
Preston Hassell, APRN
Preston is a board certified family nurse practitioner. He completed his Master's of Science in Nursing from the University of South Alabama.
He is and optimist and futurist at heart. Preston's hobbies include: nutrition, physical fitness, and spending time with his wife and three young sons.
Cassie Lemaster, MSN APRN FNP-C
Cassie is a board certified nurse practitioner. She graduated with a Master's of Science in Nursing in 2020 from Cox College. She has worked in healthcare for eight years in many different areas; most recently in orthopedics and neurosurgery. When Cassie is not working, she loves traveling with her husband and cycling.
BRYAN VAN DOREN MD, FASAM
Dr. Van Doren is an Addiction Medicine and non-interventional chronic pain specialist at Precision Pain Management. He is the Medical Director for the Tulsa Comprehensive Treatment Center and the Medical Director for the Great Plains Recovery Center in Tulsa. He received his B.S. degrees in Chemistry and Biology at Newman College in Wichita, Kansas and his M.D. degree from the University of Kansas School of Medicine in Kansas City, Kansas. Dr. Van Doren completed his Internal Medicine Residency and Fellowships in Medical Oncology and Hematology at the University of Oklahoma Health Sciences Center in Oklahoma City, OK and worked as a Medical Oncologist & Hematologist in private practice in Oklahoma for over 15 years prior to pursuing Fellowship training in Addiction Medicine at the University of Oklahoma
School of Community Medicine in Tulsa. Dr. Van Doren completed the Fellowship in 2013 and served an Assistant Professor of Internal Medicine and Addiction Medicine at the University of Oklahoma. Dr. Van Doren moved into private
practice in 2016 where he has worked to develop Addiction Medicine programs and provides noninterventional chronic pain management through Pain Management specialty practices. Dr. Van Doren is Board Certified with certification in Internal Medicine through the American Board of Internal Medicine, Addiction Medicine through the American Board of Preventive Medicine, and as a Medical Review Officer through the American Association of Medical Review Officers. An active member of the American Medical Association, American College of Physicians, American Association of
Medical Review Officers, and is a Fellow of the American Society of Addiction Medicine