Left to Right Sarah Blake, LPN; Mandi Barnes, FNP-C; Tena Hill; Dr. Zachary; Pat Steel, LPN; Tiffany Koehn, CPC

Our Staff

Manhattan Gastroenterology is made up of a dedicated and hardworking staff that is driven by a desire to provide quality healthcare within a Christian context. Each staff member has years of expertise in their field and seeks to foster a welcoming and compassionate environment for all patients.

Left to Right Sarah Blake, LPN; Mandi Barnes, FNP-C; Tena Hill; Dr. Zachary; Pat Steel, LPN; Tiffany Koehn, CPC

Dr. Paul Zachary

Dr. Paul Zachary grew up in Chillicothe, Missouri, and graduated in 1988, from the University of Missouri – Kansas City School of Medicine. He completed his Internal Medicine residency in 1991, at Truman Medical Center in Kansas City. He went on to complete a Gastroenterology Fellowship in 1993, at Kansas University Medical Center. During his training he was the recipient of a number of awards: Alpha Omega Alpha Honor Society, Humanitarianism in Medicine Award, Missouri State Medical Association Honor Graduate, Resident of the Year, and the Sirridge Award for Excellence in Clinical Medicine.

From 1993-1997, Dr. Zachary was Assistant Professor of Internal Medicine at St. Louis University School of Medicine, and for three of those years, he was the Gastroenterology Fellowship Director. He had clinical and research responsibilities, as well as teaching responsibilities for medical students, residents, and fellows.

In 1997, Dr. Zachary, wanting to provide specialized care in a private rather than an academic setting, moved his growing family to the wonderful university town of Manhattan. He has continued in a private gastroenterology practice since that time.

He maintains Board Certification in both Internal Medicine and Gastroenterology, and is a Fellow of the American College of Gastroenterology.

Dr. Zachary enjoys spending time with his wife and eight kids, serving in his church, and occasionally going on hikes or bike rides.

Mandi Barnes, FNP-C

Mandi Barnes grew up in Elkhart, Kansas. In 1998 she earned an Associate’s Degree of Nursing and worked for many years at the emergency room in Liberal, Kansas. In 2003 she and her family moved from southwest Kansas to Springfield, Missouri. She completed her Bachelor’s Degree in 2008 from the University of Missouri and then her Master’s Degree in Nursing from Missouri State University in 2010. She is a Board Certified Family Nurse Practitioner.

In Springfield she worked in a large gastroenterology practice until May 2015, when she moved to Manhattan to join Manhattan Gastroenterology and to be closer to her extended family. Mandi and her husband, Jared, have three children and love the Manhattan area. She enjoys spending time with her family, going to the lake, camping, hiking, reading, playing sports, watching sporting events, and taking care of people.


Pat Steel, LPN

Pat has been providing nursing care alongside Dr. Zachary since 2002. Pat was a stay-at-home mom, raised three boys, and worked with her husband in a family business until 1992. Prior to working with Dr. Zachary, she worked at Kensington Assisted Living in Beatrice, Nebraska. In 2002, prior to the opening of Manhattan Gastroenterology, Pat began working alongside Dr. Zachary. Since the opening of Manhattan Gastroenterology in 2011, she has continued to provide efficient and compassionate nursing care. Pat finds her second career very fulfilling and enjoys working in the medical field.

Outside of the office, Pat enjoys spending time with her husband, kids, and grandkids. She also enjoys church activities, music, and traveling.

Tiffany Koehn, CPC

Tiffany has been the Office Administrator at Manhattan Gastroenterology since its opening in 2011. Tiffany was born and raised in Manhattan, Kansas. She received a Career Diploma in Coding and Billing from Penn Foster in 2008, and she obtained her Certified Professional Coder certificate in 2009. In 2012 she completed an Associates Degree in Health Information Technology at Rasmussen University. She has also passed the ICD 10 Proficiency Test offered by the AAPC. Tiffany is excited about managing the office operations for many years to come.

Outside of the office Tiffany enjoys spending time with her son, fishing with her husband, and helping out with her family's restaurant.

Sarah Blake, CNA

Sarah joined Manhattan Gastroenterology in March 2015. She is a Certified Nurse Assistant and also has a Certified Medication Aide certification. She has worked in the medical field in varied settings since 2005, and she hopes to become a registered nurse in the future. Sarah is dedicated to providing the most compassionate care possible.

Outside of the office she enjoys spending time with her husband, son, and two dogs. Sarah and her family enjoy the great outdoors. They love camping, hunting, fishing, and going on scenic country drives. Sarah and her family are also avid K-State fans. Go K-State!

Tena Hill

Tena moved to Kansas in 1989 from Kissimmee, Florida. Prior to joining Manhattan Gastroenterology she worked in a dental office for 20 years. She joined Manhattan Gastroenterology in June 2015 and helps with a variety of office duties.

Outside of the office she enjoys spending time with her husband, one son, four stepchildren, and twelve grandchildren. Tena also enjoys cooking, camping, and fishing.

Our Mission & Vision