Tess Barbach, FNP
Tess Barbach is a family nurse practitioner who earned her degree in 2017 at the University of Vermont. Before joining Hill Health in 2026, Tess worked at Marin Community Clinics on their Complex Care team, and at the Ritter Center. She has spent a good amount of her career serving patients that have experienced poverty, homelessness, mental health challenges, substance use, and complex trauma. Tess believes that being healthy means different things to different people. Her approach prioritizes putting her patients in the driver’s seat of their own care, and partnering with them to set and accomplish meaningful goals. Ultimately, she strives to act as a guide and advocate, so her patients feel confident making well-informed choices. Outside of work, Tess loves to garden, make pottery, cook, and spend quality time with her family.
Dr. Siqi Ma, D.O.
Dr. Siqi Ma, D.O., is a board-certified family medicine provider. Dr. Ma provides
comprehensive care for adults and pediatric patients older than 2. She is passionate
about preventive care, the diagnosis and management of acute and chronic illnesses, and
caring for children in her practice. She is fluent in Mandarin and speaks
conversational German. Outside of her practice, she enjoys outdoor activities like hiking
and swimming.
Gregg Pottorff, M.D.
Dr. Gregg Pottorff has been in orthopedic surgical practice for over 32 years. He is the Specialty Medical Director for Hill Physicians Medical Group in the Bay Region. In addition to being the President of Hill Physicians and the Chair of its Board, he is a chair or member of numerous administrative committees that help to maintain the recognized status of Hill Physicians as a medical organization of the highest quality.
Dr. Pottorff received his Bachelor of Arts in Physics and Economics from the University of California, Santa Cruz, in 1982 and earned his Medical Doctor degree in 1986 from Stanford University. He then stayed on to complete his orthopedic surgery residency at Stanford. Instead of going straight into practice, he then added an additional Fellowship in Sports Medicine from the Kerlan-Jobe Orthopedic Clinic in Los Angeles, helping to care for the Dodgers, Lakers, Rams, Kings, USC, Loyola, and other local LA area sports teams.
His specialty is now office-based orthopedics, and he will do his absolute best to help patients avoid surgery whenever possible. He loves playing tennis, hiking, and traveling with his family when he’s not with patients.
Justin Dumouchel, M.D.
Dr. Justin Dumouchel is a highly skilled and experienced pulmonary and critical care physician with 8 years of experience. He holds a Bachelor of Science degree in Biochemistry from Georgetown University, where he also completed a second major in History. After completing his Internal Medicine Residency at the University of Pittsburgh Medical Center, Dr. Dumouchel completed his Pulmonary and Critical Care Fellowship at the University of California San Diego.
He specializes in treating a range of respiratory issues, including asthma, acute and chronic lung disease, lung cancer screening, respiratory system testing, and pulmonary rehabilitation. Dr. Dumouchel’s dedication to healthcare is reflected in the numerous awards he has received, including Phi Beta Kappa, Alpha Omega Alpha (Medical School Honor Society), Phi Alpha Theta (History Honor Society), and Sigma Xi (Chemistry Honor Society). Prior to joining Hill Physicians as an outpatient pulmonary physician in 2021, Dr. Dumouchel worked at Alta Bates Summit in Berkeley and Oakland, and previously was part of a group outpatient practice for seven years.
He is passionate about his profession and believes in offering personalized care to each of his patients. When not working, Dr. Dumouchel enjoys hiking and water sports. He and his wife are fans of the Oakland Roots Sports Club, the local soccer team playing at Laney College Football Stadium.
Ryan J. Anderson, M.D.
Dr. Ryan Anderson MD completed his Critical Care and Pulmonary fellowship at Stanford University where he pursued a sub-fellowship in Pulmonary Hypertension at the Stanford Vera Moulton Wall Center for Pulmonary Vascular Disease.
He has privileges to perform right heart catheterizations for diagnosis of PH at Summit Medical Center, and he has experience in initiation and management of oral and inhaled pulmonary vasodilator thera¬pies for qualifying patients. Dr. Anderson can help to determine what cases require higher level therapy (i.e. subcutaneous and intravenous prostanoid therapy) or referrals.
Carene Parulan, N.P.
Carene became a valued member of Hill Health in 2022, leveraging her time here to gain extensive experience as a pulmonary nurse practitioner. She holds a master’s degree in nursing from California Baptist University, obtained her bachelor’s degree in nursing from the University of Santo Tomas, and is board-certified by the American Academy of Nurse Practitioners. With over 12 years of experience as a registered nurse in critical care settings, Carene has a wealth of knowledge in primary care.
Her approach to healthcare is patient-centered, ensuring she takes the time to listen to her patients’ concerns and collaborates with them to create personalized treatment plans that meet their needs and goals. Outside the clinic, Carene is an adventurer at heart. She loves spending quality time with her family, hiking through scenic trails, exploring diverse cultures through travel, experimenting with new recipes in the kitchen, and unwinding with a good movie.