Lighting the way
How watching a baseball game led to a discovery that made laser surgery possible
In the early 1990s, surgeons like Nelson were attempting to adapt laser technology for medical use, and the Beckman Laser Institute & Medical Clinic served as an epicenter for this effort. It was, at the time, the only facility in the world to house basic science and engineering labs and an outpatient clinic under one roof, letting researchers and surgeons quickly translate findings into patient-care breakthroughs.
As medical director of the BLIMC, Nelson had been striving to improve laser treatments for disfiguring vascular birthmarks, such as port-wine stains, in infants and young children. Laser’s utility was limited because its intense light also injured the fragile top layer of skin, causing pain, scarring and pigmentation changes. The challenge was to find a way to protect the outer skin while maximizing the destruction of the deeper blood vessels that create a birthmark.
Nelson and his BLIMC colleagues at the time – postdoctoral researcher Thomas Milner and visiting Norwegian engineer Lars Svaasand – had tried using ice cubes, running cold water and even the application of chilled metal plates to cool the skin’s superficial layer before laser exposure. Unfortunately, all of these methods proved too cumbersome and, more importantly, also cooled the targeted blood vessels, which inhibited the laser’s effectiveness.
“We needed to get something very cold onto the skin surface in perfect thermal contact and then off the skin surface – all within a fraction of a second,” Nelson said. “I remembered what I saw watching a baseball game.”
Over a Friday night dinner at the former Rusty Pelican restaurant in Irvine, he told his colleagues how, when a batter fouled a baseball off his foot or ankle, a trainer would emerge from the dugout and spray ethyl chloride onto the injury site to numb the pain. The three agreed that spray cooling might be effective with lasers if the cryogenic agent evaporated very quickly and, therefore, only affected the topmost layer of skin.
During the weekend, Milner and Svaasand hashed out ideas on how this concept could work; on Monday, they went to Pep Boys and purchased a Toyota Camry fuel injector valve, a hose clamp and air conditioning coolant to build the first prototype of the Dynamic Cooling Device.
To determine the optimal cryogen spurt duration and interval between spurt termination and laser exposure, all three researchers tested the DCD on themselves. “We still have scars on our arms to prove it,” Nelson said.
“It was a fairly simple construction,” said Milner, who is now the Olga Keith Wiess Professor of Surgery and director of the Michael E. DeBakey Center for Nano-Biophotonics at the Baylor College of Medicine in Houston. “That’s the beauty of the invention: It’s so simple and works so well.”
The device is incorporated into the laser’s handpiece and sprays a nonflammable, environmentally compatible freon substitute onto the skin surface, forming a liquid pool with a temperature of -60 degrees Celsius. This pool almost immediately evaporates, and milliseconds later, the skin is exposed to the laser. The process is repeated before each pulse of light.
“Because the spurt durations are so short, the cooling remains confined to the skin’s most superficial layer and does not affect the deeper targeted blood vessels causing the vascular birthmark,” Nelson explained. “This allows much higher laser light dosages to be used, while at the same time minimizing injury to the skin and pain to the patient.”
The DCD was patented in September 1998 and subsequently licensed to Candela Laser Corp. for commercial development and marketing. The patent expired in 2020. It’s now standard on more than 47,000 Candela lasers sold worldwide, as well as on the lasers of other companies around the world.
Between 2001 and 2010, the device was among the 10 top-earning licensed inventions in the University of California system – and in 2005 and 2006, it ranked second and third, respectively. To date, the DCD generated nearly million in royalties for UC Irvine.
“The combination of basic research, engineering and clinical testing that went into the Dynamic Cooling Device is exactly what was envisioned over 30 years ago when the idea of the BLIMC was first conceived,” said Michael Berns, the Arnold & Mabel Beckman Chair in Laser Biomedicine and institute co-founder, to ZotZine in 2011.
While DCD-equipped lasers are utilized for several cosmetic procedures – the removal of unwanted hair, scars and rosacea, for example – Nelson is pleased that his invention primarily benefits individuals born with port-wine stains. At the BLIMC’s world-renowned Vascular Birthmarks & Malformations Diagnostic & Treatment Center, he has handled more than 20,000 such cases.
“The technology has made possible the early, painless, safe and effective treatment of port-wine stains and other disfiguring vascular birthmarks in infants and young children in ways that Tom, Lars and I could never have imagined,” Nelson said. “That’s what I’m most proud of.”
Updated from the original story published in ZotZine Vol. 4, Iss. 2
Click here to read the full article in UC Irvine News.