• General Information

Effects of laser on subdermal fat tissue

Dr Ana Zulmira et al, Aesth.Plast.Surg.29:281-286,2005.

Dr Ana Zulmira performed a trial treating flanks with liposculpture combining subdermal delivery of Neodymium:YAG at 4 watts, 20 Hz and 150 milli joules per pulse and 1064 nm wavelength, with total power emissions of 1,000 and 3,000 joules in two different areas of one side and no laser on the opposite side. The tissue extracted via abdominoplasty was analysed.

The extracted fat tissue analysed following a dermolipectomy, after the lipoaspiration, reported:

- The area treated with 1,000 joules showed larger adipocytes, measuring 95.69 microns.
- The adipocytes in the area treated with 3,000 joules measured 82.63 microns.
- The area not treated with laser showed a mean diameter of the aspirated adipocytes of 84.54 microns.

The trial concludes that normal liposculpture causes less transitory damage in the adipocytes than when subjected to 1,000 joules. It also reports that under full power at 3,000 joules, there is more irreversible damage to the adipose cells that can be accredited by the presence of cytoplasmatic retraction and disruption of the membranes, reporting the smallest adipocytes in the series.

In the extraction samples subjected to laser lipolysis there are areas of tumefaction with reversible damage, areas of lysis or irreversible damage and reduced bleeding compared with the areas not treated with laser, with greater density of irreversible cell damage in the areas irradiated with laser at full power (3,000 joules).

The laser interaction with tissue is reached by the absorption of laser energy, producing sufficient heat to reach the wanted heat damage. This heat acts in the fat cells, the extracellular matrix and micro-circulation to produce two effects, irreversible and reversible damage, which ease lipoaspiration with less bleeding. Laser lipolysis could cause various types of heat damage, including coagulation of the collagen fibres, thrombosis in the microcirculation, damage to the nerves endings as well as tumefaction and lysis of the fat cells.

Firstly:

The reversible damage affects adipocyte tumefaction, the heat generated by the laser alters the balance of sodium and potassium of the cells membranes providing free transport of liquid from the extracellular atmosphere to the intracellular. The appearance of intracytoplasmic micro vacuoles of the adipocytes that accumulate in its tumefaction is substantiated. This phenomenon is observed in the sample irradiated with 1,000 joules with a mean adipocyte size of 95.69 microns, slightly higher than the normal, untreated sample in which the adipocytes measured 73.48 microns and also larger than the diameter of the adipocytes after a conventional liposuction that measured 84.54 microns. Luminous power is transformed into heat that generates the denaturation of proteins in the cell membranes, culminating in tumefaction and increased cell size. This also occurs with conventional liposculpture but to a lesser degree (since the diameter of the adipocytes after liposuction is greater than in a normal sample, 84.54 versus 73.48 microns).

Secondly:

Irreversible damage appears: More prolonged and intense exposure to the power produces irreversible damage with coagulative necrosis and cellular lysis. In general, most of the intra and extracellular proteins are denaturised between 40 ºC and 100 ºC.

Depending on the exposure time and the temperature reached, the laser delivery causes cellular death through coagulative necrosis. Denaturation of the cells and enzymatic proteins block the proteolysis, there is an immediate contraction phenomenon although the basic cell contour is maintained.

The process of heat damage is obvious at 3,000 joules, with a smaller adipocyte diameter (82.63 microns) with signs of protein denaturation and cell contraction with irreversible damage. The fact that the mean size of the adipocytes of this series is slightly larger than the normal sample without lipoaspiration explains why some of the adipocytes in this area suffer from swelling instead destruction and the mean adipocyte size is partially increased.

In the sequence of effects obtained by the laser, colloquative necrosis or cell destruction is the final extreme effect of the laser heat damage on the irradiated tissue. It occurs when the membranes of the fat cells break. Then the lipases are freed from the adipocytes responsible for tissue liquefaction that aid in the subsequent lipoaspiration.

Therefore, the use of laser for lipoaspiration reduces surgical trauma and the colloquative effect of the lipases aids aspiration without the abrupt and repetitive back and forth movement of the cannula in liposuction.

This study refers to the trial by Grippaudo et al (2000) in which biochemical studies of the material obtained from liposuction via ultrasounds are analysed, given that both methods aim for the destruction of adipocyte membranes by heating. In the ultrasound liposuction sample, large amounts of triglycerides were found which assures the lysis effect of adipocytes.

This is compared with studies by Commonds and Godoy that analyse the feasibility of liposuction according to the capacity for skin contraction of the different anatomical areas and conclude that there is a significant influence in the potential for contraction of the skin by areas. This is also conditioned by the total amount of fat to be extracted from the area.

It also refers to studies by Badin, that has worked with fibre outside of the cannula, in this case the interaction between the laser and the fat tissue produces direct cell disruption before the liposuction and remodelling of the collagen with ensuing retraction. The denatured collagen that makes up the deep dermis reticula and the fibrous collagen septa in the hypodermis constitute “proinflammatory stimuli” which is accompanied by neovascularisation and neocollagenesis.

Dr Zulmira observed good skin contraction a few weeks later due to the reorganisation and maturing of the connective tissue, the homogenous and fast adherence of the skin and subcutaneous tissue to the plane of the superficial fascia which improves the degree of local flaccidity and the patient can usually return to work in 6 days or less and perform mild exercise in 7 days.

This study seems to prove the interest in the technique for reduction in bleeding and for an improved result of the contour avoiding the wrinkled effect of the skin; it is of special interest in areas of potential or existing flaccidity where the capabilities of conventional liposuction were limited.

Dr Ana Zulmira, Diniz Badin, et al. Aesth. Plast. Surg 26:335-339 202

After experiences with 245 patients, they concluded that the most interesting laser lipolysis applications were on these points:

• Small areas.
• Areas with moderate flaccidity. .
• Areas with potential flaccidity under conventional liposculpture. • Multiple regions within highly vascularised areas such as the scapular, waistline and rear flanks.
• Secondary liposuctions in areas with irregularities and/or fibrosis.
• “Difficult” areas o so-called prohibited areas such as the top of the inside thigh, superior abdomen and small areas with minimal fat accumulation in the periumbilical region.

The affirm that the technique is less traumatic and due to the laser effect:

• Damages is produced in the adipocytes due to alterations in the Na/K pump that allows for transport of water to the inside of cells leading to breakage. This is displayed in the histological samples where swollen cells appear (reversible damage) and cells with disrupted membranes (irreversible damage).
• Bleeding is reduced by the coagulation effect of the small vessels of the fat tissue.
• Due to the laser-tissue interaction, the collagen and the subdermal septa display heat effects such as liquefying and rupture of fibres. This induces immediate contraction of the skin and remodelling of the collagen with evident skin retraction.
• Clinically, interaction with the tissue causes less bleeding, improvement in the skin contour and better recovery.
• The only problem is to avoid sub-therapeutic treatment with poor results as well as avoiding heat damage to the skin.

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