Ambulatory Care Network

About Us

In April 2010, the Los Angeles County Board of Supervisors approved recommendations to restructure Department of Health Services (DHS) ambulatory and managed care services. In August 2010, the Board approved the DHS ambulatory care work plan. In June 2011, DHS established the Ambulatory Care Network (ACN). The Ambulatory Care Network includes:

• DHS outpatient clinics (1 Regional Health Center, 6 Comprehensive Health Centers, 6 Health Centers, 2 Community Clinics and 1 School-Based Clinic)

• Division of Research and Innovation (Former Clinical Resource Management)

Executive Staff:

Nina Park


Nina J. Park, M.D.
Chief Executive Officer

Dr. Nina Park is a physician leader in the Los Angeles County Department of Health Services. She brings extensive experience in building sustainable and coordinated care models with a deep understanding of the DHS patient population.

In February, 2011, Dr. Park was appointed Interim Chief Medical Officer, and then in June 2011, was appointed Chief Medical Officer of the department’s newly formed Ambulatory Care Network. Building on her experience in medical administration, performance improvement and patient safety, she has been a key architect in visioning the significant change in clinical processes undertaken by the department as it prepares to meet new mandates under health reform and the creation of patient centered medical homes throughout DHS primary care clinics.

Among her recent accomplishments, Dr. Park has successfully transitioned all primary care clinics within the Network to patient-centered medical home teams that will be taking care of over 190,000 empaneled patients. The teams will soon be supported by an electronic registry tool to facilitate care management, as well as newly-classified Certified Medical Assistants.

Prior to her appointment in the Ambulatory Care Network, Dr. Park spent 15 years in leadership capacities at Olive View-UCLA Medical Center and its affiliated ValleyCare clinics. Dr. Park was instrumental in implementing physician electronic charting in all inpatient areas, and designed a new peer review structure to meet regulatory and accreditation requirements. Her oversight of quality improvement, patient safety, and risk management programs was instrumental in three consecutive successful Joint Commission surveys.

Dr. Park is happily married to a pulmonary/critical care physician. She has two daughters and is a full-time weekend volleyball mom.

Quentin O'Brian


Quentin O’Brien
Chief Operation Officer

Quentin O’Brien serves as the Chief Operating Officer for the Los Angeles County Department of Health Services Ambulatory Care Network (ACN). He directs specific operational activities related to program planning, human resources, facilities management, contracts and materials management and oversees Healthy Way LA, Communications and Planning for the ACN.

He served as Director of Health and Mental Health Services (HMHS) for the LA Gay & Lesbian Center (LAGLC), the largest non-profit in the United States serving the lesbian, gay, bisexual and transgender population, for ten years. He was responsible for the leadership, administration and management of the the Jeffrey Goodman Special Care Clinic and Pharmacy.

Mr. O’Brien previously worked, in various roles for more than ten years, with the Los Angeles County Department of Health Services (DHS) where he served in multiple positions including Assistant Director of Public Health Planning, Executive Assistant to the Chief of Staff in the Office of the Director, Acting Director of the Corporate Office of Human Resources Management. Significant efforts over this time included working with executive management to develop and implement planning efforts designed to improve system efficiencies, conducting a comprehensive evaluation of Los Angeles County Jail Medical Services, and working with SEIU and others to develop the Workforce Development Program.

Mr. O’Brien also worked with the Health Crisis Manager and subsequently as a member of the Public-Private Partnership team to develop, monitor and evaluate contracts for the provision of primary care to low-income uninsured residents of Los Angeles County.

Mr. O’Brien originally joined DHS with the Tobacco Control Program, where he worked on the development and evaluation of public health programs targeted at preventing smoking related illnesses, providing technical assistance and support for community based agencies, and implementation of public policies to control tobacco use.

He holds a Bachelor’s of Science degree in Public Health from the University of California Los Angeles.

Jeff Guterman


Jeffrey Guterman, M.D.
Chief Research and Innovation Officer

Jeffrey J. Guterman, M.D., M.S. is the Chief Research and Innovation Officer in the Ambulatory Care Network of the Los Angeles County Department of Health Services. He is a Clinical Health Sciences Professor of Medicine and Emergency Medicine at the David Geffen School of Medicine at UCLA. In Dr. Guterman’s former role as Chief of Ambulatory and Community Medicine at Olive View – UCLA Medical Center, he was responsible for developing and operating the primary and managed care delivery network in the San Fernando and Santa Clarita Valleys. His research focus on the application of information technology to enhance the efficiency and effectiveness of medical care resulted in practiced in practical and implementable solutions that are changing the way care is delivered.

He pioneered the development of the first nationally distributed program for the computerized collection of patient information for Poison Control Centers. His current research is on the integration of computer technology into the management of the continuum of care for patients who present to the Emergency Department and on automated clinical monitoring of patients at home via telephone voice recognition systems.

Through cooperative efforts with pharmaceutical and medical industry leaders and health care providers, Dr. Guterman has developed medical decision support products encompassing comprehensive preventive health care, automated remote monitoring for disease management programs, integrated Internet-based referral systems, and miniaturized accelerated polymerase chain reaction instruments. The goals of these efforts are to provide lower cost, better health care with improved patient satisfaction.

Debra Duran


Debra Duran
Chief Nursing Officer (interim)

Debra Duran was appointed to the interim Chief Nursing Officer position in February, 2015. She has worked for Los Angeles County for over twenty years. During her tenure she served as a Public Health Nurse at Edward R. Roybal Comprehensive Health Center. She later became a case manager, then a Nursing  Supervisor  and promoted to a Nurse Manager. She became Nursing Director in 2005 at El Monte Comprehensive Health Center.

She graduated from the University of Southern California with a Nursing, B.S.; completed a Masters in Business Administration with an emphasis in Health Care Management from the University of Phoenix.
Debra has been with the Ambulatory Care Network since its inception.  She is grateful for the experience of working amongst so many dedicated and talented people who day in and day out show up to deliver safe, quality care to the patients we serve.

Guillermo Diaz


Guillermo Diaz, M.D.
Chief Medical Information Officer

Guillermo Diaz, MD is the Chief Medical Information Officer for the Ambulatory Care Network (ACN). He is also a practicing pediatrician at H. Claude Hudson Comprehensive Health Center. He trained and completed his pediatric residency at Harbor-UCLA Medical Center.

As the CMIO he is responsible for leading the implementation of ORCHID, electronic health records, throughout all ACN clinics. Prior to his position with ACN he served as the Chief Medical Information Officer and Chief Medical Officer of QueensCare. He successfully led the implementation and adoption of ambulatory electronic medical record and electronic prescribing systems and began the implementation process for a patient portal. He has sat on various Health Information Technology (HIT) panels, committees at the local, state and national level.