Lower energy and pulse stacking. A safer alternative for skin tightening using fractional CO<sub>2</sub> laser

: Three decreasing settings of a fractional CO2 laser were applied to the abdomen of Twenty five Wistar rats divided into three groups. Group I (n=5) was histologically evaluated for microthermal zones dimensions. Groups II and III (n=10 each) were macroscopic evaluated with freeware ImageJ for area contraction immediately and after 30 and 60 days.

RESULTS

: No statistical significance was found within microthermal zone histological dimensions (Group I) in all settings studied. (Ablation depth: 76.90 to 97.18µm; Coagulation depth: 186.01 to 219.84 µm). In Group II, macroscopic evaluation showed that all settings cause significant immediate skin contraction. The highest setting cause significant more intense tightening effect initially, contracting skin area from 258.65 to 179.09 mm². The same pattern was observed in Group III. At 30 and 60 days, the lowest setting significantly sustained contraction.

CONCLUSION

: Lower fractional CO₂ laser energies associated to pulse stacking could cause consistent and long lasting tissue contraction in rats.

Lasers, Gas; Skin Aging; Laser Therapy; Rats

	Power	Exposure Time	Stack	Fluence	Energy/MTZ
Area 1	-	-	-	-	-
Area 2	30W	900 µs	1	3.74 J/cm2	27 mJ
Area 3	20W	300 µs	3	2.49 J/cm2	18 mJ
Area 4	10W	300 µs	3	1.87 J/cm2	13.5 mJ

Region	Settings	Ablation Depth - Median	Range
1	No treatment	-	-
2	27 mJ - single pulse of 900 µs	89.08 µm	56-98 µm
3	18 mJ - 3 stacked pulses of 300 µs	97.18 µm	80-118 µm
4	13.5 mJ- 3 stacked pulses of 300 µs	76.90 µm	75-120 µm

Region	Settings	Coagulation Depth - Median	Range
1	No treatment	-	-
2	27 mJ - single pulse of 900 µs	219.84 µm	127-241 µm
3	18 mJ - 3 stacked pulses of 300 µs	210.47 µm	166-274 µm
4	13.5 mJ- 3 stacked pulses of 300 µs	186.01 µm	185-219 µm

Region	Settings	Surface damage width - Median	Range
1	No treatment	-	-
2	27 mJ - single pulse of 900 µs	412,33 µm	305-450 µm
3	18 mJ - 3 stacked pulses of 300 µs	430.70 µm	273-581 µm
4	13.5 mJ- 3 stacked pulses of 300 µs	406.14 µm	372-454 µm

Region	Settings	MTZ volume - Median	Range
1	No treatment	-	-
2	27 mJ - single pulse of 900 µs	8.48 x 10^-3 mm³	4-13 x 10^-3 mm³
3	18 mJ - 3 stacked pulses of 300 µs	11.2 x 10^-3 mm³	7-14 x 10^-3 mm³
4	13.5 mJ- 3 stacked pulses of 300 µs	8.62 x 10^-3 mm³	6-10 x 10^-3 mm³

Region	Pre-Treatment	Immediately after	30 days after
1	249.58 mm²	262.87 mm²	291.99 mm²
2	258.65 mm²	179.09 mm²	296.92 mm²
3	242.92 mm²	179.89 mm²	254.83 mm²
4	258.05 mm²	190.81 mm²	243.49 mm²

Region	Pre-Treatment	Immediately after	60 days after
1	256.63 mm²	246.05 mm²	323.52 mm²
2	256.95 mm²	179.61 mm²	307.75 mm²
3	247.59 mm²	191.17 mm²	267.78 mm²
4	261.18 mm²	198.19 mm²	256.43 mm²

Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia https://actacirbras.com.br/ - São Paulo - SP - Brazil
E-mail: actacirbras@gmail.com

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[1] Correspondence: Prof. Dr. Paulo Kharmandayan Rua Tessália Vieira de Camargo, 126 Cidade Universitária "Zeferino Vaz" Caixa Postal: 6111 13083-887 Campinas - SP Brasil Tels.: (55 11)95020-2080 / (55 19)3521-7092 Fax: (55 19)3521-8043 pkharmand@hotmail.com