The concept of applying radiofrequency energy into the skin has changed in the past few years. The “older” methods use a process called “bulk heating” to apply the energy to the surface of the skin which will diffuse to the deeper layers of the dermis. The deficiencies of this method are:
- The heating is not precise, with the depths unknown.
- The epidermis is at risk for too much heat, leading to potential for scarring or pigmentation issues.
- Subdermal fat is at risk if the heating goes too deep.
- The heating is bulk and not fractional, so safety is less.
- The highest temperature achieved is about 45 degrees, enough to minimally stimulate collagen.
The progression of technology with RF heating of the skin has evolved to a process that is more precise. Using microneedles, RF energy is able to be placed at desired depths in the dermis. The deeper, fractional heating is much higher than if placed on the skin surface. It enables the temperatures to get to 65-70 degrees C, enough cause coagulation. Coagulation leads to maximal collagen stimulation and tissue contraction. In regards to the microneedles, there are 2 types of needles used: Insulated and Noninsulated. The noninsulated needles deliver energy only at the exposed tips, completely bypassing the more sensitive epidermis. On the other hand, noninsulated needles allow the energy to transmit along the entire length of the needle, creating a wound that includes the epidermis. When the epidermis is heated to point of coagulation, there is wound care and potential for pigmentation and scarring. The only way these uncoated needles get around potential safety problems is by delivering less energy. The advantages of microneedling insulated delivery of RF are:
- More precise level of RF energy delivery.
- Fractional heating of dermis, which is safer than bulk heating.
- Bypassing the epidermis so darker skin types are more safely treated.
- Higher energies can be placed leading to coagulation and better collagen stimulation.
- Insulation leads to better epidermal protection, less downtime, and potentially higher energies.
The main devices that deliver RF through microneedles with insulated needles are Infini and Profound. There are actually significant differences that might not be apparent to even the most informed providers.
- Infini uses 49 needles while Profound uses 10 needles.
- Infini can treat at 0.25 mm incremental depths between 0.1 – 3.5 mm while Profound has just 2 possible depths.
- Infini’s pulse durations are up to 500 milleseconds while Profound’s pulses are 3-5 seconds.
- Infini uses multiple passes to create thousands of coagulation zones whereas Profound uses only one pass.
What does this all mean? It means that the coagulation wounds placed with the Profound are less in number but much larger in size. The downside to larger wounds is that there is longer healing times because the unaffected tissue which is needed to assist in healing is further from the center of coagulation. With smaller coagulation zones as in the Infini, the wound healing is shorter in duration. In addition, the healing in the desired fashion (without scarring) is easier to control with multiple smaller wounds than it is for fewer, larger wounds. The concept of fractional ablation being safer and with less downtime (popularized by the Fraxel laser) loses it advantage as the wounds get larger.
It boils down to: The Infini creates smaller and many more coagulation zones than the Profound which creates larger and fewer zones. Safety and recovery are improved with the more plentiful, smaller coagulation zones of the Infini.
Source: Dr. Steve Weiner, Facial Plastic Surgeon Blog