Experimental dermatological surgery: an animal model for developing skills with dermal fillers.

The importance of laboratory experiments in the formation of physicians is well recognized since they facilitate scientific development and enhance technical skills. Dermal filling procedures are performed for the correction of wrinkles, rhytids, scars, and lipodystrophy. Till date, experimental models for the training of dermal filling techniques have not been studied. To demonstrate an experimental laboratory model for the training of dermal filling techniques in an animal model. The heads of pigs were used for this purpose, together with Carbopol gel at different densities, which was used to simulate the fillers available in the market. Needles and specific cannulas were used to apply the fillers into the creases and other areas of the pig skin. The pig head appears to be a suitable model for this training. Carbopol gel is a good choice for simulating fillers. This model of laboratory experiment requires a minimum of infrastructure; it is a low-cost alternative and facilitates practical training in the application of dermal fillers.

Introduction

The development of skills and training in procedures and/or surgery are not consolidated solely in theoretical exercise. The role of laboratory experiments in contributing toward technical–practical training and enhancement is well recognized.[12] Teaching in laboratory experiments, under supervision and the valorization of ethical aspects, promotes medical learning and training.

In recent decades, great advances have been made in the area of dermatological surgery.[3-5] According to a report published in the USA, dermatology is the specialty that performs most office-based cosmetic procedures, with dermal filling being the second most performed procedure, corresponding to around 17% of the total.[6] Dermal filling is used in the correction of wrinkles, rhytids, scars and lipodystrophy and consists in the injection of biocompatible substances into diverse levels of the skin.[5] There are various types of fillers on the market, with different application techniques. Hyaluronic acid is one of the most widely used.

Till date, experimental models for the training of skin filling techniques have not been studied. The objective of this research is to develop an animal model-based dermatological laboratory experiment for training medical residents in dermal filling techniques.

Materials and Methods

Dermatologists conducted a laboratory session which was attended by physicians training in the specialty. Prior to the practical training, the pupils attended a lecture in which the basic aspects of applying fillers were explained, including a description of the techniques employed, their indications, the expected results and possible complications.

The pig was the animal model selected for the laboratory session. The heads were obtained from recently slaughtered animals, in accordance with the local Health Authority regulations. Once carefully cleaned, the specimens were placed on a surgical table, in a laboratory used exclusively for working with animal models.

In an attempt to simulate high-cost materials available in the market, Carbopol gel prepared at different densities was chosen as the model for the filler. A pharmacist elaborated the materials at four densities: fluid (concentration 0.15%), intermediate (0.25%), dense (0.5%) and very dense (1%). The fillers were applied using siliconate 1 ml syringes with Luer Locks, microcannulas and various sizes and calibers of needles, to be used depending on the density of the Carbopol gel.

Results

The applications were made into the superficial, mid, and deep dermis and subdermal region, making use of the creases, wrinkles and other areas of the pig skin [Figure 1]. Established techniques were used for the application of hyaluronic acid, poli-L lactic acid and other dermal filling substances available in the market, including dermal hydration injection techniques such as intradermotherapy and nappage, net techniques, linear aligning, point-to-point, and support pillars.

Figure 1

The animal model

During the training, it was possible to demonstrate the particularities of each filling technique, the difficulties involved in application and some of the foreseeable complications. Close supervision meant that any technical slips made during the training could be quickly pointed out and corrected. A number of complications[7] were seen, such as hyper and hypo corrections, nodule formation due to the injection of excessive amounts of product and loss of material due to inability to apply or failure to couple the needle to the syringe [Figure 2].

Figure 2

Complication seen during dermal filling

At the end of the activities, the group made an evaluation of the laboratory session training.

Discussion

The pig's head proved to be a suitable model because of the size of the structures and the presence of wrinkles and creases capable of correction with the use of fillers. The results obtained were similar to those found in human skin. The ease with which this model can be obtained and its low cost should be considered significant factors. Carbopol gel is a good choice as a simulator of dermal fillers since it can be prepared at various densities and is also of low cost.

The porcine model is also used in ophthalmology for practical training in eyelid/palpebral surgery with good results, according to Lopes and cols.[8] In dermatology, pigs’ feet have been used for training surgical techniques such as excision and suture, ear correction, compensation of surgical edges, and diverse types of flaps and grafts.[9]

Given the frequency with which dermal filler procedures are carried out in dermatology, both in the corrective and esthetic areas, it is important that the professionals should be familiar the techniques and materials available. Following the training, the pupils considered themselves more confident to perform filler procedures and concluded that the experience had been positive as a practice skills training.

The experimental laboratory model described here requires a minimum of infrastructure and is a low-cost alternative with a high level of satisfaction among the participants. Training with experimental models represents a valuable step between theory and practice, offering important foundation for the performance of procedures in humans.