INTRODUCTION
Intense Pulsed Light (IPL) is a conventional technology for hair reduction. Effective permanent hair reduction treatments with IPL necessitates working with high energies. Applying high energies activates pain receptors in the skin and sharp and acute pain sensation follows.

For over 5 years we have applied analgesic creams (EMLA) to reduce the pain associated with permanent hair removal. However, we have applied the cream only over small areas, due to the risks associated with analgesic creams when applied to large areas. Patients suffered and treatment speed was considerably reduced.

The current article presents a 10 month summary of the utilization of a novel Pneumatic Skin Flattening (PSF) chamber (Serenity, Inolase/Candela) which naturally reduces the transmission of pain to the brain during otherwise painful skin procedures. So far we have treated 148 patients with the PSF.

PNEUMATIC SKIN FLATTENING OPERATING PRINCIPLES

Pneumatic skin flattening utilizes an evacuation chamber located at the distal end of the treatment IPL. The evacuation chamber is covered by a flat Sapphire window through which the IPL treatment light is delivered.

High vacuum which is automatically generated on the surface of the skin once the handpiece contacts the skin, elevates the skin and generates a very tight flattening of the skin against the window. The skin flattening induces sensation of suction on tactile and pressure receptors in the skin, resulting in afferent inhibition of pain transmission in the dorsal horn.

According to the gate control theory of pain transmission, nerve impulses from pain receptors and their sensory fibers (slower and thinner A-delta or C fibers) arrive to synapses in the spinal cord in their way to the brain. Larger diameter and faster myalinated sensory neurons (A-beta fibers) carrying vacuum sensation and tactile information from the surrounding skin site activate secondary neurons which secrete endogenous opioids into the pain synapse, thus suppressing the flow of pain information up to the brain.

The pneumatic skin flattening also expulses blood from the IPL treatment beam pathway inside the skin. Skin becomes more transparent which may enhance treatment efficacy. Blood expulsion also reduces skin heating and post treatment erythema which are produced by absorption of light by hemoglobin which is an unwanted competing chromophore.