Meet the New Chief Residents


The beginning of each new academic year is exciting and unique in its own way. One of the highlights for the Department of Medicine is welcoming our new Chief Residents as they assume their roles.  

This year is no exception with a talented, new team of emerging leaders that includes Ann Cameron Barr, MD, Michael Cosiano, MD, Courtney Dominguez, MD, and Nathan Hirshman, MD.  Learn more about them in our special Meet the New Chiefs Spotlight.   


Ann Cameron Barr, MD
Chief Resident
Duke Regional Hospital and Ambulatory Medicine  

Dr. Barr is a native of Richmond, Va. and a fellow in the division of Rheumatology. She earned her medical degree in 2019 from Emory University School of Medicine, did her residency at Duke and is currently a medical instructor in the department. Dr. Barr and her husband have loved living in Durham so much that they recently purchased a house here and are excited to welcome their first baby soon. Away from work, she enjoys hiking, running, exploring our beautiful national parks (Yosemite is her favorite so far), reading, spending time with her family, and making/eating ice cream. 

Q: One expectation of chief residents is to serve as a mentor. What important advice did you receive from a current or previous mentor? 

ACB: One of the best pieces of advice I’ve received is that, if you’re not failing from time to time in pursuit of your goals, you’re not trying hard enough to achieve them. Hearing this from an accomplished and respected mentor has really helped me to put myself out there and TRY. It has pushed me to apply for positions I never thought I’d be selected for, submit abstracts and papers that I thought would surely be rejected, etc. Some disappointment is to be expected when these things don’t fall into place, but I now view these failures as vital to achieving future success. 

Q: As chief resident in your role, what are your main goals for the year? 

ACB: As chief resident for Ambulatory Medicine/Duke Regional Hospital, one of my main goals is to help enrich and expand outpatient educational opportunities and training for our residents. While the majority of medical care is provided in the outpatient setting, medical training has traditionally focused much more heavily on inpatient medicine. I’m excited that this focus is beginning to shift and to have the opportunity to help teach the outpatient skills I’ve developed over the past year as a rheumatology fellow.   

More generally, the three years I spent as a Duke IM resident were really wonderful; yes, they were challenging, but they were also a time of immense personal and professional growth alongside some of the best people that I get to call colleagues, mentors, and friends. I hope, as a group, that we can support our residents to have similarly wonderful experiences during their medicine training. 


Michael Cosiano, MD
Chief Resident
Durham Veterans Administration Medical Center  

Dr. Cosiano was born and raised in the small, close-knit community of Findlay, Ohio, the oldest of three brothers. His father was as a family physician for over 30 years, and his mother was a teacher and talented flutist. Dr. Cosiano graduated from Weill Cornell Medical School in 2019 and did his residency at Duke. He is a fellow in cardiovascular disease and an instructor in the department. In his free time, he likes to play spots including soccer, basketball, and golf. He is an avid Notre Dame football fan and likes to engage in physical activities to unwind and recharge.  

Q: What led you to a career in medicine? Did you choose medicine, or did it choose you? 

MC: I remember being inspired by my father, who dedicated his life to practicing medicine and serving the community as a family physician. Witnessing the compassion and expertise with which he approached patient care left a lasting impression on me. My admiration for what medicine meant to him and our community, coupled with my innate passion for science and the human body, fueled my interest in pursuing a medical career. Ultimately, the decision to pursue medicine was a conscious choice, but it was also driven by a deep sense of purpose through a modality that involved human interaction, diagnostic reasoning, and continuous learning.  

Q: As chief resident in your respective role, what are your main goals for the year? 

MC: As a chief resident, my main goals for the year encompass several key aspects. These goals revolve around providing exceptional patient care, fostering a supportive learning environment, and promoting professional growth and development among the residents.  


Courtney Dominguez, MD
Chief Resident for Quality and Patient Safety
Durham Veterans Administration Medical Center 

Dr. Dominguez was born and raised in sunny El Paso, Texas. She grew up in a close-knit family alongside her older brother, mother and grandparents, learning the importance of strong bonds and cherished connections. Though the family now lives in different places, they make it a point to visit often. Dr. Dominguez is a 2020 graduate of Texas Tech University Health Sciences Center Medical School, a Duke resident and an instructor in the department.  

In her free time, she loves exploring the great outdoors and hiking alongside her husband and two furry companions. She recently got a bike and has started riding the American Tobacco Trail, and she is an avid fan of recreational soccer and puzzles. 

Q: What led you to a career in medicine? Did you choose medicine or did it choose you? 

CD: A significant turning point in my life was when my brother was involved in a car accident, leading to a lengthy hospitalization. Witnessing the compassionate care he received from medical professionals during that difficult time inspired me to pursue a career in medicine. I'm determined to make a positive impact in healthcare and serve as a mentor to younger generations interested in this field. Through teaching, I hope to empower future healthcare providers and instill in them the importance of patient-centered care.   


Nathan Hirshman, MD
Chief Resident
Duke University Hospital 

Dr. Hirschman was born in Durham, N.C., and subsequently moved throughout the country. But despite a somewhat nomadic upbringing, he returned to North Carolina in 2015 when he started medical school at Duke. He considers the Triangle home and has lived here for the past six years with his wife, Rachel. The couple is expecting their first child this summer, adding to the menagerie of three cats: Heidi, Hughie, and Sabrina, and a dog, Ricky Bobby. For fun he likes to watch ACC basketball, walk the multitude of hiking trails in the area and Harry Potter movies. 

Q: One expectation of chief residents is to serve as a mentor, what important advice did you receive from a current or previous mentor? 

NH: No one cares how much you know, until they know how much you care. As a leader and a physician, it is so important for those who you work with to know how much you care about their desires and goals. I wanted to be a chief resident so that I could help improve the residency and develop relationships with the residents. My knowledge of the program or institution doesn’t matter to them unless they know how much they matter to me. 

Q: As chief resident in your respective roles, what are your main goals for the year? 

NH: I feel very fortunate to be the chief resident of Duke University Hospital. The residents and the program leadership make Duke IM (in my not so unbiased opinion) the best program in the country. I hope to support the resident’s educational and professional development, while fostering a sense of community within the residency and the Department of Medicine. I hope to serve as a mentor for my residents and medical students and support new opportunities for growth throughout the year.