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Dr. Dwight Zabel, MD 


Dr. Zabel is a 1997 graduate of the University of Kansas School of Medicine and is board certified in Nephrology. He is the Medical Director for our Harrison Dialysis facility and our Branson Home programs.


Dr. Zabel is a die-hard Jayhawks fan and is happy to talk Jayhawks for hours. He and his wife are extremely active in their church, and they are always out and about helping our community.

Dr. John Martinez, MD

Dr. Martinez is a 1985 graduate from the University of Kansas Nephrology program and is board certified in the treatment of kidney diseases. He is a proud Army veteran, and he worked at the VA Medical Center in Kansas City to give back to our veterans.

He loves his KC Chiefs and KU Jayhawks. You can find him spending his time off with his family at Table Rock Lake.


Dr. Michael Selby, MD


Dr. Selby graduated medical school from the University of Missouri-Columbia in 2008. He is board certified in Internal Medicine and Nephrology, and he completed his training at the Mayo Clinic in Rochester, MN in 2011 and 2014 respectively. He has a special interest in glomerulonephritis, hypertension, and nephrolithiasis.

Dr. Selby is also a big sports fan! He enjoys Kansas City Chiefs and University of Missouri-Columbia football games.


Johnna Manna, PA-C


Johnna graduated from Missouri State University with a master’s degree in Physician Assistant Studies. Johnna has been a member of our team since 2009 and was instrumental in starting our Chronic Kidney Disease Stage IV Education program.

She is very active in our dialysis facilities, especially our Harrison Dialysis clinic where she partners with our doctors to ensure all patients receive excellent care and attention. She is licensed in Missouri and Arkansas.


Lavonne Burrows, APRN CNS


LaVonne received her Bachelor of Science in Nursing in 1978 from the University of Missouri in Columbia and her Master of Science in Nursing at the University of Kansas School of Nursing. She became board certified as a Clinical Nurse Specialist in Adult Health in 1997.

LaVonne has served in many roles from the Home Training Coordinator at Cox Medical Center to the Director of Clinical Operations for the Kidney Disease Centers of the Ozarks.


She has a passion for patient education and believes patients need and deserve to know all the facts when making decisions about their kidney disease.


Robert L. Muller,  NP - C


Robert graduated magna cum laude in 1995 from Southwest Baptist University in Bolivar, Missouri. He completed his Master of Science in Nursing as a Family Nurse Practitioner in 1998 from the University of Missouri-Kansas City.

Robert has an extensive career working with patients who are facing difficult life challenges, such as kidney failure, hospice, or palliative care. His compassion and experience have proven him to be an essential member of our team.

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