Our Pediatricians

At Lone Tree Pediatrics, we are dedicated to helping you and your child feel at home from the moment you walk through the door. We pride ourselves in being an exceptional pediatric practice where your children come first. Our pediatricians and medical staff are highly trained professionals and maintain the highest level of accreditation in pediatrics to address the special needs of infants, children, and teens.
dr debra berry md pediatrician Debra M. Berry, M.D.

Dr. Debra Berry is a warm, compassionate board-certified pediatrician treating patients in Lone Tree, Colorado, and the surrounding communities. Her primary goal as a physician is to help each of her patients live a healthy life and grow into a happy productive adult. She treasures being a part of every stage of a child’s life — from the early days of a newborn’s life through childhood and into the formative teenage years.


Dr. Berry graduated Phi Beta Kappa from the University of North Carolina at Chapel Hill. She attended the University of Tennessee College of Medicine on a full academic scholarship as part of the Gooch Scholar program. At UT, she also received the Dorothy Snider Award and was named the Outstanding Medical Student in Pediatrics. Dr. Berry completed her internship program and residency training at the University of Colorado here in Denver. She holds certification from the American Board of Pediatrics, was named to the Alpha Omega Alpha Medical Honor Society and is a member of the American Academy of Pediatrics.


Dr. Berry has been named Best of the Best of Pediatricians in Lone Tree and currently serves as the chair of pediatrics at Sky Ridge Medical Center. When she is not treating patients, Dr. Berry enjoys trail running, mountain biking, hiking, reading, and spending time with her husband, son, and daughter.

dr emily vangeti md pediatrician Emily Vangeti, M.D.

Dr. Emily Vangeti grew up in the Monument area and graduated from Lewis Palmer High School. As a physician, she strives to connect with each of her patients and their families. She cherishes playing a role in lives of children of all ages. Dr. Vangeti is a board-certified pediatrician.


Dr. Vangeti graduated from the University of California – Santa Barbara and was also a member of Phi Beta Kappa. She received her Bachelor of Science in Biological Science and then went on to earn a Master’s of Science in Physiology at Georgetown University. She attended medical school at Jefferson Medical College in Philadelphia. While there, she received the Edward J. Moore Award for Aptitude in Pediatrics. She completed her residency in Delaware at A.I. DuPont Hospital for Children. She holds a certification from the American Board of Pediatrics.


Dr. Vangeti met her husband in medical school, and they were overjoyed to welcome their daughters, Neela, in 2014 and Ella, in 2017.  As a newer mom, Dr. Vangeti understands the concerns and worries that come with being a parent. When Dr. Vangeti is not practicing pediatrics, she enjoys spending time with her family, along with reading, traveling, exercising and cooking.

dr david roos md pediatrician David Roos, M.D.

Dr. David Roos is a board-certified pediatrician, and has been a practicing pediatrician since 1982. With over thirty years of experience, Dr. Roos provides the best caliber of care to his patients. He places a great deal of emphasis on the physical and emotional well-being of each of his patients.


Dr. Roos received his degree from the University of Colorado Medical School. He completed his Internship and Residency in the Denver area as well. His particular pediatric interests include: diabetes, care of the premature infant, and the treatment of behavioral and emotional issues, including ADD/ADHD. Dr. Roos was the Chief of the Pediatrics Department at the Medical Center of Aurora South. In addition, he served on the board of Colorado Pregnancy Centers in Aurora, CO as the Vice President, and was a board member of the Inner City Health Center in Denver, CO. He holds a certification with the American Board of Pediatrics. His other memberships include: American College of Pediatricians, Colorado Medical Society, American Association of Pro-Life Pediatricians, and served as President of the Colorado Chapter of the Christian Medical/Dental Society.


When Dr. Roos isn’t at the practice, you’ll find him with his wife, Janie, and their four children and six grandchildren. In addition to quality family time, Dr. Roos plays guitar, gardens, skis, and enjoys traveling.

vona lantz cpnp pediatrics Vona Lantz CPNP

Vona Lantz is a kind, understanding board-certified pediatric nurse practitioner. While she started out as a registered nurse at The Children’s Hospital, she became a nurse practitioner in 1993. In a career that’s spanned over two decades, the health and wellness of each of her patients at every age continues to be a top priority for her.


Vona received her education as a nurse practitioner, along with a master’s of science in nursing at the University of Colorado Health Sciences Center. She completed her undergraduate degree in nursing at Loretto Heights College in Denver. During her time in pediatrics she has developed special interests in: well child care, preventative health medicine, immunizations for children and adolescents, obesity and nutrition, and dermatology. Vona is a certified through the Pediatric Nursing Certification Board. She is recognized on the Advanced Practice Registry of the Colorado State Board of Nursing. Vona has completed Pediatric Advanced Life Support (PALS). Vona is also a member of the National Association of Pediatric Nurse Practitioners and the Colorado Chapter of NAPNAP, where she has also held the office of president and secretary.


As a Colorado native Vona enjoys all of the activities the Rocky Mountains have to offer. Whether she is climbing one of our fifty-three fourteeners, mountain biking, or skiing, she enjoys being active. When she’s not found outdoors, Vona enjoys spending time with her family and close friends.

dr lisa haynes md pediatrician Lisa Haynes, M.D.

We are so excited to have Dr. Lisa Haynes as part of the team! She joined the Lone Tree family in 2015.

Dr. Haynes is a board-certified pediatrician who comes to us with 18 years of experience in pediatrics. She graduated from the University of Arkansas College of Medicine at Little Rock, where she also completed her residency in 2002. She then went on staff at the Arkansas Children’s hospital where she continued to develop her passion for pediatric medicine. Dr. Haynes specializes in adolescent medicine and has three years of experience working in a pediatric ER. In addition to this, she also has significant experience with neurology as she spent a year in a neurology clinic. Lisa has been in private practice since 2012 and is affiliated with Children’s Hospital Colorado, Littleton Adventist Hospital, Skyridge Medical Center and Swedish Medical Center.

When not in the office she enjoys teaching about pediatrics and spending time with her three children.

lisa singer np pediatrics Lisa Singer, NP. Lone Tree Pediatrics

We are so excited to have Lisa Singer, NP as part of our team!


Dr. Lisa Singer began her career in healthcare as a Registered Nurse. She worked for several years in Infection Prevention, Home Health and Medical Surgical Nursing at a large acute care hospital in Henderson, Nevada.

Having a love for children and continued education she decided to pursue a Master of Science in Nursing to become a Family Nurse Practitioner (FNP) from the University of Nevada, Las Vegas. She feels this is the perfect fit for her as she enjoys teaching children and their families to promote health and happiness through preventive care. She is board certified and a member of the American Nurse Association.

Lisa loves living in beautiful Colorado with her husband, four children, four step-children, and two active dogs. She enjoys running, hiking, gardening, serving in her church and spending time with her family.


For more information on Lisa Singer NP. call our office!

rachel vaivoda np pediatrics Rachel Vaivoda, NP

Rachel Vaivoda is an energetic and compassionate board-certified Pediatric Nurse Practitioner, who joined Lone Tree Pediatrics in 2016.


Rachel completed her Bachelor of Science degree in Biology at Bates College in Lewiston, Maine, and worked for several years in Immunology and Inflammation research at Massachusetts General Hospital in Boston, Massachusetts. She attended Yale University in New Haven, Connecticut for her Registered Nurse and Pediatric Nurse Practitioner degree, where she graduated with honors, and as a member of the Sigma Theta Tau Delta Mu Nursing Honor Society. While at Yale, Rachel volunteered with the HAVEN Clinic, a student-run clinic that provides free care to the uninsured population in New Haven.

Rachel has clinical interests in adolescent medicine, contraception counseling and reproductive health, and eating disorders. Prior to joining Lone Tree Pediatrics, Rachel has worked as a Registered Nurse at the Tyler Hill Summer Camp in Pennsylvania, and at the Urgent Care Center through Beth Israel Deaconess Medical Center in Massachusetts.

When Rachel’s not in clinic, you’ll find her hiking with her dog, doing yoga, mountain biking, and skiing as much as possible.

Nancy Taoka, M.D. Nancy Taoka, M.D.

Dr. Nancy Taoka has been a pediatrician in the Littleton area for almost 20 years and has just joined Lone Tree Pediatrics. She grew up I Kansas and attended the University of Kansas Medical School (and is a huge Jayhawk basketball fan!). She came out to Denver for Pediatrics Residency at the University of Colorado and now can’t imagine living anyplace but Colorado. She enjoys traveling, however, and expresses her artistic side through scrapbooks of her travels. Her scrapbooks also show her skiing, serving the community with her Rotary Club, or cheering at a Rockies baseball game.


Matthew Hadeed, DO Matthew Hadeed, D.O.

Matthew Hadeed, D.O. is board certified in Pediatrics.
He earned his medical degree from Western University of Health Sciences. He completed residency at UCSF Fresno where he won the award for Highest Individual Patient Continuity.

Dr. Hadeed’s professional interests include newborn and neonatal medicine. Additionally, he is also interested in improving emergency response and preparedness in outpatient pediatric settings with limited resources. He also focuses on global health and working with Spanish-speaking populations.

He has volunteered his time for many organizations including UCSF Fresno’s Mini Med School, providing sports physicals at Clovis Unified School District, and the Special Olympics North California as a coach and medical volunteer.

Dr. Hadeed’s hobbies include snowboarding, wakeboarding, rock climbing, trail running, cooking, fishing, camping, and photograph. He is fluent in Spanish.