About Us

At Guardian Medical, all of our staff value customer service and patient satisfaction. A patient that is respected and understands their injuries and plan for care are best able to see their path to recovery.

Coordinate all care. Working with specialty providers allows for Our Medical team to coordinate all care for patients.

As Part of Medical Management, Guardian Providers prescribe medications only, when necessary, after extensive patient education, with your agreement, knowledge, and consent with the ultimate goal of identifying & treating the underlying problem.

All medical records are created quickly and efficiently and can be provided to referring physician and/or other providers,  work, school, or any other entities as requested, with your authorization. Any necessary medical paperwork, such as occupational restrictions, releases and insurance forms will be completed as required on a timely basis.

Dr. David Wiebe is a board-certified physician in Emergency Medicine with over two decades of experience practicing in major trauma centers across Colorado. He began his medical training at the University of Colorado and Denver Health in 2000, where he developed a strong foundation in acute care and emergency response.

Over the past 10 years, Dr. Wiebe has expanded his expertise into aesthetic medicine, serving as the medical director for multiple high-performing aesthetic centers. He also leads a specialized pain management and sedation clinic, where he integrates advanced techniques to improve patient comfort and outcomes.

In addition to his clinical roles, Dr. Wiebe is frequently called upon as a medical expert witness in injury-related legal cases, offering authoritative insights grounded in years of hands-on experience.

Outside of medicine, Dr. Wiebe enjoys spending time in nature with his partner and their two golden retriever puppies—often exploring Colorado’s forests, lakes, and scenic trails.

Dr. Castro is a board-certified Physical Medicine & Rehabilitation (PM&R) specialist who has been serving the Denver metro area since 2001. She is dedicated to helping individuals recover from illness or injury and regain function, mobility, and independence as they reintegrate into their communities. In addition to her expertise in rehabilitation, Dr. Castro is passionate about identifying the root causes of illness and empowering her patients through education and lifestyle-based strategies to support long-term health and wellness. Her approach emphasizes health ownership and personalized care.

Outside of her professional life, Dr. Castro is married and a proud mother of four. She enjoys spending quality time with her family in the beautiful Colorado outdoors. Her other interests include live music, travel, cooking, and discovering hidden gems off the beaten path.

Dr. Massey attended Baylor College of Medicine, where he completed a surgery internship followed by an anesthesia residency at UHC Denver. He specialized in cardiovascular and regional anesthesia and played a key role in establishing several programs at Parkview Medical Center, including cardiac anesthesia, obstetric epidurals, and pain management. Dr. Massey served as the head of the anesthesia department from 1985 to 2000 before becoming the Medical Director of the Pueblo Surgery Center. Board-certified in pain management since 1994, Dr. Massey has performed over 30,000 pain procedures over the course of his 39-year career, treating a wide range of conditions including spinal disorders, joint pain, and chronic pain syndromes. He has also led seminars on spinal cord stimulator placement and, more recently, has focused on personal injury cases, gaining experience in court testimony and Independent Medical Examination (IME) reviews.

Ryan Mansholt is certified physician assistant. Ryan brings a wealth of experience to Guardian Medical with greater than 18 years experience. His medical career began in Chicago Illinois where he practiced orthopedic surgery working with fellowship trained orthopedics surgeons for nine years. This included managing complex orthopedic surgery cases at a level 2 trauma center as well as extensive experience in spinal surgery. He then went on to work with prestigious sports medicine surgeon focusing on complex sports medicine surgery with high-level athletic and Worker’s Compensation patients.

Upon moving to Colorado, Ryan begin working within the field of interventional pain treating muscularskeletal injuries without surgery. He has developed and extensive skill set in regards to the management of acute and chronic injury using state-of-the-art treatment including regenerative medicine options.

Ryan’s commitment to patient care has shown throughout his career. He brings a patient centered focus spending extensive time on patient education and building relationships to truly understand the physical and emotional needs of each patient.

Shavonne Simonich is a board-certified Family Nurse Practitioner with a strong background in fitness, nursing, and pain management. She earned her Bachelor of Science in Exercise Science from the University of Montana and spent over five years working as a personal trainer and fitness director, helping individuals achieve their health and wellness goals.

Pursuing her passion for patient care, she completed a Bachelor of Science in Nursing at the University of Northern Colorado. For more than 13 years, Shavonne provided compassionate care on the Surgical Unit of a Level II Trauma Center, where she gained extensive experience in managing acute and post-operative patients.

She later earned her Master of Science in Nursing from the University of Cincinnati, becoming a certified Family Nurse Practitioner through the American Academy of Nurse Practitioners. She is also a proud member of the American Association of Nurse Practitioners (AANP) and the Colorado Nurses Association (CNA).

Shavonne’s clinical expertise includes both acute and chronic pain management, with a special interest in interventional techniques. She takes a whole-person approach to care—addressing not just symptoms but overall wellness. By partnering closely with her patients, she helps them achieve their highest level of physical, mental, and emotional health. Her greatest passion is empowering patients to reclaim their lives and return to doing what they love.

Brent Turner has been a Physician Assistant for over 20 years. He did his undergraduate work in Kinesiology at the University of Colorado. He became a Certified Athletic Trainer in 1994. Brent later graduated from the University of Oregon with a Masters of Science of Exercise and Movement Sciences. At both CU of OU, Brent provided Sports Medicine care for football, Track and Field and Wrestling. He graduated from Emory University School of Medicine with a Masters of Medical Sciences in Physician Assistant Studies. Since then, he has worked in various Emergency Rooms and Urgent Care clinics throughout the greater Denver area. Brent started his training in personal injury medicine in 2007. Despite being a Colorado native and avid Broncos and CU fan, Brent and his family spent the past 3 years in Hawaii working in a small urgent care and family medicine clinic on Oahu. Since his return this year, Brent worked at UC Health urgent care and is now working at a critical access Emergency Room in rural Colorado. Brent is married to his wonderful wife who he works alongside in the Emergency Room at the critical access hospital.

Brent has the unique perspective of being both a provider and a patient in personal injury. He was involved in a significant car accident in 2015 which lead him to become a patient in his own practice.   He experienced the stressors associated with the injuries, coordinating medical care, the insurance company and the legal components.  He is dedicated to providing comprehensive and compassionate care in order to streamline the process so his patients can focus on recovering from their injuries. Understanding what it is like to be a car accident patient, he has become an advocate for personal injury patients.

In his free time, Brent enjoys spending his time traveling with his wife to warm destinations and exploring Colorado with their two dogs