◆ The Introduction of the Subcutaneous Laser for Rejuvenation of the Face and Neck

The SmartLipo laser (Cynosure, Inc., Chelmsford, MA) was the first laser to be approved by the U.S. Food and Drug Administration (FDA) for laser lipolysis. In addition to its indication for laser lipolysis, the SmartLipo laser is approved for the surgical incision, excision, vaporization, ablation, and coagulation of soft tissue. All soft tissue is included in this indication, which applies to skin, cutaneous tissue, subcutaneous tissue, striated- and smooth-muscle tissue, cartilaginous menisci, mucous membranes, lymph vessels and nodes, organs, and glands. Following the 2006 introduction of subcutaneous laser-based “lipolysis” techniques, many laser manufacturers besides Cynosure have introduced products for laser lipolysis and many have introduced different wavelengths for the specific indication of laser lipolysis. Wavelengths for laser lipolysis other than the 1064-nm and 1320-nm wavelengths described above include 980 nm and 1444 nm.

◆ Subcutaneous Application of Optical Energy and the Laser–Tissue Interaction

The original SmartLipo laser ( Fig. 12.1 ) delivered optical energy at a wavelength of 1064 nm though a 300-μm-diameter fiber at a power of 6W ( Fig. 12.2A ). All subsequent Cynosure SmartLipo and SmartLipo MPX lasers have utilized a 600-μm-diameter optical fiber ( Fig. 12.2B ), and now use a 1000-μm-diameter fiber ( Fig. 12.2C ) for high-power laser lipolysis. The 600-μm optical fiber is introduced into a 1-mm-diameter stainless steel microcannula of variable length and is used for laser-assisted procedures on the face. The laser is fired through the distal end of the optical fiber, which protrudes 2 mm beyond the tip of the microcannula. The distal end of the fiber interacts with the soft tissue of the face and neck. For visualization, an aiming source in the path of the laser beam provides the precise location of the emitting tip of the fiber, indicating where the laser is working. For most anatomical regions of the face and neck, a 6 to 12W, 100-μs pulsed laser beam at a frequency of 40 Hz and energy of 150 mJ has been used. The Smartlipo MPX laser, which can blend the 1064-nm and 1320-nm wavelengths that it is capable of emitting, was used in more recent Smartlifting studies for laser lipolysis and laser-assisted facial and neck lifting, and is currently used in completing these procedures. The Nd: YAG laser produced photomechanical and thermal effects, which dissected treated tissue quickly and easily. In addition to this, the Nd:YAG laser’s hemostatic properties included the coagulation of small blood vessels in the subcutaneous plane with preservation of the vascular dermal plexus.

Multiplexing of the 1064-and 1320-nm wavelengths of laser radiation offers several unique advantages. The SmartLipo technique with the MultiPlex laser (i.e., the SmartLipo MPX) ( Fig. 12.3 ) allows the separate as well as sequential emission of radiation at 1064-nm and 1320-nm. Sequential firing at these two wavelengths in combination with one another maximizes the positive properties of each. The combination of these two wavelengths increases the efficiency of lipolysis and offers a more evenly distributed laser-energy profile, which benefits superficial and deep treatment. When emitted sequentially, energy at these two wavelengths provides more efficient coagulation of vascular blood through the conversion of hemoglobin to methemoglobin.8 In this dual effect, the 1320-nm wavelength heats the blood, converting hemoglobin to methemoglobin, whereas the 1064-nm wavelength has a 3- to 5-fold greater affinity for methemoglobin than for hemoglobin, which increases the radiative energy absorbed by methemoglobin and therefore the efficiency of coagulation, as well as enhancing skin tightening. The SmartLifting technique permitted flap separation in areas of the face that are typically difficult to reaching a full rhytidectomy, such as the buccal–labial folds (BLF), the corners of the mouth, and the infracommissural BLF, also known as the marionette lines. The wavelength characteristics and energy spectrum of the 1064-nm and 1064-/1320-nm muliplexed lasers are shown in Fig. 12.4 .

SmartLifting Evolves on the Basis of Clinical Observations

Until early 2008, most in-office procedures using the Smart-Lipo laser involved lipolysis and the concurrent tightening of facial soft tissues through the tissue coagulation that follows laser lipolysis. However there was no clear definition of what should constitute the clinical endpoints of these procedures. In early 2008 we were contacted by a patient who had an interest in SmartLipo-based techniques for the treatment of her lower neck ( Fig. 12.5 ), which had lost tone and tightness and had accumulated adipose tissue. At the time of our initial consultation we thought that laser lipolysis would benefit this patient, but that the degree of her facial laxity exceeded the contraction that we could expect with such treatment. We then suggested that her best result might be achieved by combining the laser lipolysis of her lower neck and face with a minimal-incision, short-flap and short-scar facelift. She consented to the combination of these procedures. At the time, and although it is conceptually implied that the 1064-nm laser should promote hemostasis if used before the elevation of a facial flap, we didn’t expect to see a profound hemostatic effect of pretreatment with the laser on this elevation. We at first considered the profound hemostatic effect and lack of bleeding that we observed ( Fig. 12.6 ) to have come from other factors, such as the use of tumescent anesthesia and/or interpatient variability. Similar observations made during the elevation of facial flaps in most of our subsequent rhytidectomies led us to conclude that the pulsed 1064-nm and pulsed 1064-/1320-nm wavelengths of laser radiation were profoundly hemostatic when used in advance of the elevation of facial flaps.

◆ Clinical Study Establishes That Some Lasers Used in Lipolysis Are Not Strongly Hemostatic

Subsequent to the observations of early 2008 described above, and following discussions with the Cynosure Corporation about the clinical hemostatic properties we had observed with its lasers, we began to investigate other lasers’ intrinsic hemostatic properties when used before the elevation of a facial flap, and whether other fiber lasers showed an equal or proportionate hemostatic effect. With proper patient consent we compared the effects of the pulsed 1064-nm and pulsed 1064-/1320-nm lasers with those of a 980-nm continuous-wave (CW) diode laser. In these clinical studies we set the power of the lasers at 10W and completed the procedures we were examining. The results of our study indicated that although the 980-nm laser beam passed through subcutaneous tissue somewhat more easily that the 1064-nm or 1064-/1320-nm beams, the net hemostasis it produced was poor and the blood loss in the procedure was about the same as in a standard rhytidectomy without laser-enhanced hemostasis. Photographic documentation of our findings is shown in Figs. 12.7 and 12.8 . The study was quantified on the basis of sponge use in completing the facelift procedure in which we compared the different lasers, and we found that roughly five times as many sponges were used in procedures done with the 980-nm CW diode laser as with the pulsed 1064-nm and 1064-/1320-nm lasers ( Figs. 12.7B; 12.8C ). Other clinical findings were that the patients treated with the 980-nm laser had more prolonged bruising, swelling, and induration after subcutaneous treatment with this laser than did those treated with the other two lasers, most probably from greater extravasation of blood into the superficial soft tissues. We also compared the SmartLipo lasers with a 1444-nm pulsed laser, which also failed to demonstrate hemostatic properties as significant as those of the 1064-nm laser and 1064-/1320-nm multiplexed laser.

◆ SmartLifting Techniques

SmartLifting evolved from the application of two new technologies in facial surgery. The first is the use of subcutaneous laser techniques for hemostasis and for developing the facial flap of rhytidectomy in the best possible plane. The laser helps define the facial flap and creates a dissection plane by creating multiple microdissection tunnels ( Fig. 12.9 ). We initially accomplished this with a low-wattage Nd:YAG laser and optical fiber introduced through a stainless steel cannula and operating at 6W. The advent of more powerful instruments for laser lipolysis has made it possible to use more optical energy, but rarely should the laser power setting for hemostasis and flap development exceed 15W. We generally use 9 to 12W of power for most areas of the face, and reserve the higher settings for possible use in patients with heavy necks, taking caution in treating necks with a very thin midline.

The second new technology introduced in facial surgery is the barbed suture, which is used in “open” surgeries as opposed to the earlier “closed” techniques. A problem with barbed sutures in closed procedures was the inability of repositioned tissue to remain in place, owing to the considerable attachments of the skin to deeper soft tissues and the tendency of these dermal attachments to return repositioned tissue to its original position. The dermal attachments eventually result in a gradual descent of the repositioned tissue, making the subtle results of closed surgical procedures on the face very short-lived. The ability to undermine tissue with a laser and to elevate a skin flap from its dermal attachments in most open procedures releases the deeper tissue and permits a more durable repositioning of deeper soft tissues. Concurrent excision of skin also contributes to more durable results in a minimally invasive procedure. The ability to use internal barbed sutures in the open technique is a work in progress, and the capacity to release the skin from deeper tissues in an atraumatic and hemostatic fashion will lead to different suturing patterns in the search for an ideal pattern of suture plication or imbrication, defined as the pattern that gives the longest-lasting aesthetically pleasing results and permits a rapid recovery from surgery.