Clinical evaluation of needle-free electronic pneumatic hyaluronic acid injection treatment for facial atrophic acne scars: A prospective, randomized comparative trial

Acne scars are common but difficult to treat, and an effective new treatment strategy is desired. This prospective, split-face randomized controlled trial was designed to compare the safety and efficacy of needle-free electronic pneumatic hyaluronic acid injection (EPI-HA) treatment for acne scars. Thirty Japanese subjects with moderate to severe facial atrophic acne scars underwent EPI-HA treatment on a randomized side of their face. Three treatment sessions were carried out at 1-month intervals, and the subjects were followed-up for 3 months after the final treatment. Three months after the final treatment, 48.3% of treated sides met the criteria for success, compared with 0% for the control sides (P < 0.0001). Rolling type scars were much improved compared with boxcar types and icepick types. Satisfaction (or better) was reported by 55.2% of subjects at the 3-month follow-up after the final treatment, which was similar to the physicians' assessment. Three-dimensional in vivo imaging analysis detected significant difference in scar reductions between the treated and control sides in the mean scar area, scar depth, and maximum depth of the biggest scar at 1 and 3 months after the final treatment (all P < 0.05). In conclusion, EPI-HA treatment significantly improved rolling facial atrophic acne scars in our Japanese subjects, with minimal side effects.

Clinical endpoints of needle-free jet injector treatment: An in depth understanding of immediate skin responses

Objectives

Needle‐free jet injectors have been used in dermatological practice for many years. However, predefined clinical endpoints that guide physicians to choose optimal device settings have not been clearly defined. Here, we evaluate immediate skin responses as clinical endpoints for needle‐free jet injector treatments.

Methods

We injected methylene blue in ex vivo human skin using an electronically‐controllable pneumatic injector (EPI; 3–6 bar, 50–130 µl; n = 63), and a spring‐loaded jet injector (SLI) with fixed settings (100 µl; n = 9). We measured the immediate skin papule (3D‐camera), residual surface fluid (pipette), dermal dye distribution by estimating depth and width, and subcutaneous dye deposition.

Results

EPI with 4 bar and 100 µl resulted in the largest skin papule of 48.7 mm³ (35.4–62.6 mm³) and widest dermal distribution of 8.0 mm (5.5–9.0 mm) compared to EPI with 6 bar and 100 µl (p < 0.001, p = 0.018, respectively). The skin papule volume showed a significant moderate to high positive correlation with the width and depth of dye distribution in the dermis (r_s = 0.63, r_s = 0.58, respectively; p < 0.001 for both correlations). SLI showed high variability for all outcome measures. Finally, a trend was observed that a small skin papule (≤7 mm) and little residual surface fluid (≤10% of injection volume) were warning signs for subcutaneous deposition.

Conclusions

The immediate skin papule and residual surface fluid correspond with dermal drug deposition and are relevant clinical endpoints for needle‐free jet injector treatments in dermatological practice.

Comparison of Normal Saline Injection with Pneumatic Injector to Subcision for the Treatment of Atrophic Acne Scars

BACKGROUND: Acne scarring is a concerning consequence of acne with a prevalence of 11 to 14 percent after acne resolution. Needle subcision is usually used by clinicians to treat acne scars due to its safety and simplicity. Recently, normal saline injection with a pneumatic injector has shown compatible outcomes in treating acne scars. OBJECTIVE: This study compared the effectiveness of acne scar treatment with a pneumatic injector and that of hypodermic needle subcision. METHODS: Twenty patients with moderate to severe atrophic acne scars were voluntarily enrolled. All consecutive patients were randomly selected and treated with normal saline injection by using a pneumatic injector on one side of the face during three sessions, separated by a four-week interval. The other side of the face was treated with needle subcision at the end of the first week of the protocol. Subjective assessments were performed by self-evaluation and two blinded dermatologists. For objective assessment, the depth and volume of acne scars were estimated by an ultraviolet A light video camera and Vernier calipers at baseline and four, eight, and 12 weeks. Pain score and adverse reactions were also noted at each visit. RESULTS: Eighteen patients with Fitzpatrick Skin Type III or IV completed the study. Differences in the resolution in diameter and the volume of boxcar and rolling acne scars over 12 weeks of follow-up between the pneumatic injection and needle subcision groups were statistically significantly improved relative to at baseline; however, there was no statistically significant difference in the efficacy between the two modalities. Satisfaction with each modality was not statistically different. No serious adverse effects occurred. Minor reactions such as minor hematoma and subcutaneous emphysema resolved within two weeks. CONCLUSIONS: The efficacy of normal saline injection with a pneumatic injector is not statistically different from that of needle subcision in treating boxcar and rolling acne scars; however, less side effects were recorded. Given this advantage, the use of pneumatic injectors should be considered for treating acne scars.

Needle-free pneumatic injection device; histologic assessment using a rat model and parameter comparison in predicting collagen synthesis degree

BACKGROUND

Needle-free pneumatic injections have been recently introduced to the field of dermatology to inject such substances as hyaluronic acid. However, data on the influence of various pneumatic injection parameters on collagen synthesis are lacking.

OBJECTIVE

Compare the effect of diameter, pressure, and volume of a pneumatic injection jet on collagen synthesis and fluid dispersion pattern using a rat model. Investigate if the total work force of the injection jet is useful in predicting the degree of collagen synthesis.

MATERIALS AND METHODS

We injected fluid with 1 mg/ml of hyaluronic concentration to adult rats. Different injection pressures and volumes were tested using devices with nozzles of different diameters. Collagen synthesis areas were then measured, and statistical analyses were performed.

RESULTS

The area of collagen fibers increased for up to two months. The injection pressure and volume did not correlate with the degree of collagen synthesis. The nozzle diameter showed a significant after two and four weeks of injection. The total work force correlated with collagen synthesis 2, 4, and 8 weeks post-injection. (P = 0.043, 0.027, and 0.000, respectively).

CONCLUSION

Collagen formation is more prominent 2 months post-hyaluronic acid injection than after 1 month when using a needle-free pneumatic injection device. The total work force, which is affected by both the nozzle diameter and injection pressure, can be helpful in predicting the degree of collagen synthesis. Lasers Surg. Med. 51:278-285, 2019. © 2019 Wiley Periodicals, Inc.