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At HCA Houston Healthcare Tomball, our experienced and knowledgeable leadership team is committed to improving the quality of care and helping our community.

Rob Marmerstein

Chief executive officer

Robert Marmerstein joined HCA Houston Healthcare Tomball as the Chief Executive Officer (CEO) in July 2020. He will oversee the management and operations of the hospital ensuring both service line and overall strategic goals align with the development of the organization’s vision and strategic plan.

Marmerstein joined HCA Healthcare in 2009. Previously, he served as Chief Operating Officer (COO) of HCA Houston Kingwood for three years and as COO at HCA Houston Mainland for two years. He also served as an administrative resident at Reston Hospital Center in Reston, Virginia and as associate COO at LewisGale Medical Center in Salem, Va.

Marmerstein earned his bachelor of science degree in hospitality management from the University of Central Florida and a master's degree in Health Administration from Virginia Commonwealth University. He is a member of the American College of Healthcare Executives, a board member for the Kingwood Place West Commercial Association, and recently served as a board member of the Greater East Montgomery County Chamber of Commerce.

Richard Moore

Chief medical officer

Richard Moore, M.D., has served as chief medical officer since May 2024. As CMO, Dr. Moore works with colleagues and physicians to achieve high quality, patient-centered care by leading quality initiatives that support consistent clinical performance and practice standards across the hospital.

Dr. Moore has 28 years of emergency medicine experience. Before joining HCA Houston Healthcare Tomball, he previously served as the Emergency Department Medical Director at Rio Grande Regional Hospital, an HCA Healthcare-affiliated hospital in McAllen, Texas. Over the last 15 years, Dr. Moore has held multiple collaborative leadership positions and helped steer several high performing quality programs and initiatives.

Dr. Moore is a board-certified internist. He earned his medical degree from the University of Texas Southwestern Medical School in Dallas. He is currently pursuing an MBA from the University of Texas - Dallas. He has published numerous papers and has extensive research in the areas of emergency medicine, sepsis and stroke.

Adrian Moreno

Chief operating officer

Adrian Moreno joined HCA Houston Healthcare Tomball as Chief Operating Officer (COO) in November 2021. Previously, he served as the Assistant Chief Operating Officer of HCA Houston Healthcare Kingwood.

During his time at HCA Houston Healthcare Kingwood, Moreno led expansion projects at the hospital, including increasing licensed bed capacity by 32 intensive and intermediate care beds. He also managed the expansion project for the hospital’s outpatient surgery center, increasing the number of operating rooms and endoscopy suites. Moreno served as the division director of project management with HCA Houston Healthcare from 2018 to 2020. He was responsible for monitoring the development and implementation of the Division’s top strategic priorities. Before his time at HCA Houston Healthcare, Moreno worked for six years with Ernst and Young, most recently as Performance Improvement Manager.

Moreno is a graduate of the U.S. Military Academy at West Point and U.S. Army Ranger School. He served as an officer in the U.S. Army where he was stationed in Fort Hood, TX and Bagdad, Iraq. He received his Master of Healthcare Administration from Trinity University in 2019. Moreno currently serves as the co-chair of the HCA Gulf Coast Division Veterans Colleague Network and is a member of the HCA Gulf Coast Division Diversity and Inclusion Council.

Richard Ervin

Chief financial officer

Richard Ervin joined HCA Houston Healthcare Tomball as the Chief Financial Officer (CFO) in 2017. With over 24 years of accounting and finance experience, Ervin oversees management of all financial departments, allocation of resources and preparation of the annual budget including accounting and health information. Before joining HCA Healthcare, Ervin began his career with American Medical International in 1986, which later became Tenet Healthcare, where he served as CFO for 10 years then served as CFO for nine years with Community Health Systems in Tomball, Texas.

Ervin earned a bachelor’s of accounting from Stephen F. Austin State University. He currently serves on the board of directors of TOMGWA Health Care Ministries and is a member of Healthcare Financial Management Association.

Angelle Rhemann

Chief nursing officer

Angelle Rhemann was appointed Chief Nursing Officer (CNO) at HCA Houston Healthcare Tomball in November 2022. Most recently, she served as Interim CNO as well as ACNO at the hospital, where she excelled in driving quality initiatives, nursing engagement and nursing retention.

Previously, Rhemann worked for HCA Gulf Coast Division as Division Vice President of Nursing Practice and Operations. In this role, she oversaw the division dialysis director and was instrumental in leading numerous nursing initiatives. Collectively, she has more than 25 years of healthcare experience.

Rhemann earned her bachelor of science in nursing, master of science as an advanced practice nurse in adult health, and doctor of nursing practice from Texas Woman’s University. She is a graduate of the HCA ACNO Advanced Leadership Development Program. Additionally, Rhemann held faculty appointments to Texas Woman’s University and the University of Houston as a faculty associate and adjunct clinical faculty, respectively.