Effect of high frequency transcutaneous electrical nerve stimulation on viability of random skin flap in rats

Non-invasive physical therapy as salvage measure for ischemic skin flap: A literature review

This review focuses on the available evidence regarding the molecular mechanisms and treatment potential of several non-surgical physical therapies for managing flap ischemia to propose a non-invasive, economical, and simple treatment to improve flap survival. A review of the literature was conducted on the topics of various non-invasive methods for the treatment of ischemic necrosis of the distal end of the flap between 1988 and 2019. A total of 52 published studies were reviewed on the applications of hyperbaric oxygen therapy, electrical stimulation therapy, heat stress pretreatment, phototherapy, and vibration therapy to manage skin flap necrosis. The underlying molecular mechanisms of these physical therapies on revitalizing the dying skin flaps were discussed and preliminary clinical uses of these therapies to salvage the necrotic skin flaps were pooled and summarized for clarifying the safety and feasibility of these methods. Various physical therapy regimens have been ushered to manage necrotic development in cutaneous flaps. With the refinement of these new technologies and enhancement of related basic science research on vascular revitalization, the prevention and treatment of flap ischemia will enter a new era.

Effects of microneedle length and duration of preconditioning on random pattern skin flaps in rats

To date, the surgical delay of skin flaps is the most common and reliable method that increases skin flap survival. In this study, we aimed to increase skin flap viability using preconditioning by microneedling. Seventy-two Sprague Dawley rats were randomly divided into control, surgical flap delay (SFD), and four microneedling groups (7 or 14 days of preconditioning with 0.5 mm or 1 mm needles). Modified McFarlane flaps were raised on the back of rats. In Group I, a caudal pedicled skin flap was raised and the flap survival rate was assessed on postoperative day 14. In the SFD group, a bipedicled flap was created and after 14 days of surgical delay, all skin flaps were raised. In the microneedling groups, 0.5 mm or 1 mm needles were used for 7 or 14 days. The flap survival rates of all microneedling and SFD groups were significantly higher than the control group. The plasma levels of vascular endothelial growth factor (VEGF) did not significantly differ between groups, but the VEGF level of skin samples in the SFD group was higher than the control group. The vessel counts of all microneedling and SFD groups were statistically higher than the control group in all skin samples taken before raising the flaps, but skin samples taken 14 days after raising the skin flap did not show any difference between groups. We showed that preconditioning by microneedling can be used to improve the viability of critical ischemic skin flaps at a level similar to surgical delay.

Effect of High- and Low-Frequency Transcutaneous Electrical Nerve Stimulation on Angiogenesis and Myofibroblast Proliferation in Acute Excisional Wounds in Rat Skin

OBJECTIVE

This study evaluated the effects of high- (HF) and low-frequency (LF) transcutaneous electrical nerve stimulation on angiogenesis and myofibroblast proliferation in acute excisional wounds in rat skin.

DESIGN

This was an experimental controlled and randomized study.

PARTICIPANTS

An excisional wound was made on the back of 90 adult male EPM1-Wistar rats using an 8-mm punch.

INTERVENTIONS

The animals were randomly assigned to the HF group (80 Hz), LF group (5 Hz), or control group. Transcutaneous electrical nerve stimulation (pulse duration, 200 microseconds; current amplitude, 15 mA) was delivered (session length, 60 minutes) on 3 consecutive days.

MEAN OUTCOME MEASURE

Immunohistochemistry was performed on postoperative days 3, 7, and 14 for counting blood vessels and myofibroblasts.

MEAN OUTCOME RESULTS

The LF group had significantly more blood vessels than the HF group on day 3 (P = .004). The HF group had significantly less blood vessels than did the control group on days 7 (P = .002) and 14 (P = .034) and less myofibroblasts than did both the LF and control groups on day 3 (P = .004) and less than did the control group on day 7 (P = .001).

CONCLUSION

There seems to be a benefit to the use of LF transcutaneous electrical nerve stimulation in the healing of acute excisional wounds, but further studies are warranted.

Effect of high- and low- frequency transcutaneous electrical nerve stimulation (TENS) on angiogenesis and wound contraction in acute excisional wounds in rat skin

Abstract Introduction: Transcutaneous electrical nerve stimulation (TENS) can alter the local temperature, increase skin blood flow and induce the release of vasodilator neuropeptides and growth factors. These changes may be related to the effects of TENS on the tissue repair process. Objective: To assess the effect of high- and low-frequency TENS on angiogenesis and the contraction of acute excisional wounds in rat skin. Methods: Fifty-four young adult male EPM1-Wistar rats were used in the study. An excisional wound was performed on the back of each animal using an 8mm punch. The animals were randomly assigned to three groups: the High-frequency Group (HG: 80 Hz), Low-frequency Group (LG: 5 Hz), and Sham Group (SG: TENS turned off). TENS was delivered on three days consecutives. Pulse duration and current intensity were 200 µs and 15 mA. The length of each TENS session was 60 minutes. Microscopic and macroscopic assessments were performed on 3, 7 and 14 postoperative (PO) days. Hematoxylin-eosin staining was utilized to quantify the neoformed blood vessels. Photographs were taken to determine the percentage of wound contraction. After assessment, the animals were painlessly sacrificed. Results: There were increases in angiogenesis in the HG on the 3 PO day, and in the LG on the 14 PO day. No significant differences in wound contraction were found between the groups on the different PO days. Conclusion: High frequency TENS improved angiogenesis, and neither frequency of TENS had any influence on the contraction of acute excisional wounds in rat skin.

A current affair: electrotherapy in wound healing

New developments in accelerating wound healing can have immense beneficial socioeconomic impact. The wound healing process is a highly orchestrated series of mechanisms where a multitude of cells and biological cascades are involved. The skin battery and current of injury mechanisms have become topics of interest for their influence in chronic wounds. Electrostimulation therapy of wounds has shown to be a promising treatment option with no-device-related adverse effects. This review presents an overview of the understanding and use of applied electrical current in various aspects of wound healing. Rapid clinical translation of the evolving understanding of biomolecular mechanisms underlying the effects of electrical simulation on wound healing would positively impact upon enhancing patient’s quality of life.

Low-intensity pulsed ultrasound stimulation in different regions in the viability of myocutaneous flaps

Background

Low-intensity pulsed ultrasound (LIPUS) has presented good results in the healing of chronic wounds. The objective of this study was to compare the effect of LIPUS on the viability of transverse rectus abdominal muscle (TRAM) flap in different regions (central and epigastric) in rats.

Methods

Twenty-one Wistar male rats were homogeneously distributed into three groups as follows: group 1 (control), animals submitted to surgery only; group 2, animals submitted to surgery and application of LIPUS at the center of the flap; and group 3, animals submitted to surgery and application of LIPUS at the flap area corresponding to the right inferior epigastric artery pedicle. Stimulation was performed immediately after the surgery and within the following 2 days. The percentage of flap necrosis was evaluated by using the ImageJ® software as well as by measuring the temperature variation with infrared thermography (FLIR® T300).

Results

In the percentage calculation of the necrosis area, the application of LIPUS at the center of the flap (group 2) showed significantly smaller difference (26.2 %) compared to group 1 (54.50 %) and group 3 (44.01 %). Analysis of the temperature variation between the groups was performed by using the one-way ANOVA followed by Tukey’s test. The results showed that both forms of LIPUS application showed significant differences compared to the control group.

Conclusions

In view of our results, one can conclude that the application of LIPUS at the center of the flap was effective for the viability of TRAM flap in reducing the necrosis area.

Flap Preconditioning by Electrical Stimulation as an Alternative to Surgical Delay: Experimental Study

Partial flap failures are unpredictable complications of reconstructive surgery. Electrical stimulation increases blood flow, capillary density, angiogenesis and vascular endothelial growth factor, anti-inflammatory effects while decreasing oxygen tension in tissues. In this study, we investigated these effective properties of electrical stimulation preoperatively on flap surgery instead of the surgical delay procedure.Modified McFarlane flaps were raised on the backs of 50 Sprague-Dawley rats. In the control group, a skin flap was made and flap survival rate was assessed on the seventh day. In the surgical delay group, 14 days after creating the bipedicled flap, the flap was totally elevated and flap survival rate was assessed on the 21st day. In the preconditioning by electrical stimulation group, the flap was created after application of electrical stimulation for 7 days. Flap survival rate was assessed on the 14th day. In the electrically stimulated ischemic flap group, the flap was created and afterward, electrical stimulation was applied for 7 days. After that, flap survival rate was assessed on the seventh day. In the surgical delay plus electrical stimulation group, following the elevation and suturing of the bipedicled flap back into its bed, electrical stimulation was applied in the first 7 days of delay, the flap was created on the 14th day, and then flap survival rate was assessed on the 21st day. In all groups, blood flow was evaluated at particular times. After completing these procedures, the flap vascularities of 5 animals from each group were assessed with microangiography.The flap survival rate of the preconditioning by electrical stimulation group was significantly higher than those of the other groups (P < 0.05). According to the blood flow estimates, except the preconditioning by electrical stimulation group and surgical delay plus electrical stimulation group, blood flow decreased in all the other groups after the postprocedure. In the microangiographic assessment of the preconditioning by electrical stimulation group, there were thin but numerous networks like vascular structures.Electrical stimulation applied to the normal area before flap elevation increased the flap survival. This increase is paramount to surgical delay which is, so far, widely known as the most effective method of improving flap vascularity.

Inhibitory effects of low-level laser therapy on skin-flap survival in a rat model

Background

Although several studies have demonstrated the effects of low-level laser therapy (LLLT) on skin flap viability, the role of higher doses has been poorly investigated.

Objective

To investigate the inhibitory effect of the LLLT (λ=670 nm) on the viability of random skin flaps in a rat model using an irradiation energy of 2.79 J at each point.

Methods

Sixteen Wistar rats were randomly assigned into two groups: sham laser irradiation (n=8); and active laser irradiation (n=8). Animals in the active laser irradiation group were irradiated with a 670 nm diode laser with an energy of 2.79 J/point, a power output 30 mW, a beam area of 0.028 cm2, an energy density of 100 J/cm2, an irradiance of 1.07 W/cm2 for 93 s/point. Irradiation was performed in 12 points in the cranial skin flap portion. The total energy irradiated on the tissue was 33.48 J. The necrotic area was evaluated on postoperative day 7.

Results

The sham laser irradiation group presented a mean (± SD) necrotic area of 47.96±3.81%, whereas the active laser irradiation group presented 62.24±7.28%. There was a significant difference in skin-flap necrosis areas between groups (P=0.0002).

Conclusion

LLLT (λ=670 nm) increased the necrotic area of random skin flaps in rats when irradiated with an energy of 2.79 J (100 J/cm2).

Electrical Stimulation of Wound Healing: A Review of Animal Experimental Evidence

Significance: Electrical stimulation (ES) is a therapeutic intervention that may help specialists facilitate wound healing rates. The purpose of this section is to compile the available animal research regarding the effectiveness of ES on the injury potential, healing rate, cellular and molecular proliferation, mechanical properties, and survival rate of skin flaps. Recent Advances: Regardless of the type of ES current and polarity used, most of the animal experimental evidence suggests that application of ES can facilitate wound healing. However, treatment time should be sufficiently long to attain good mechanical strength of regenerated tissue, because tensile strength is not consistent with augmented collagen deposition. ES improves the survival rate and skin blood flow of animal flaps, but clinical studies are needed to substantiate the findings from these animal experiments. Critical Issues: Impaired or delayed healing is a major clinical problem that can lead to wound chronicity. ES with various strategies has been used to facilitate the healing process, but many aspects remain controversial. Despite much research, no consensus exists regarding the detailed effects of ES on wound healing. Nevertheless, ES has been approved by the Center for Medicare and Medicine Services for reimbursement of the treatment of some chronic ulcers. Future Directions: Exogenous ES may promote the directional migration of cells and signaling molecules via electrotaxis; however, its underlying mechanism is still poorly understood. Future studies that further elucidate the mechanisms regulating electrotaxis will be necessary to optimize the use of ES in different wound states.

The effect of TENS on random pattern flap survival in nicotinized rats

The adverse effects of cigarettes, due to their nicotine content, may cause important ischemic complications in flaps. Electrical stimulation increases blood flow in ischemic tissues, the level of vascular endothelial growth factor, capillary density, and angiogenesis while decreasing oxygen tension in tissues. Electrical stimulation is also known to increase survival rate in flaps. In this study, which tests the hypothesis that TENS (a type of electrical stimulation) contributes to enhancement of flap viability by eliminating the adverse effects of nicotine, 40 rats were divided into 4 groups of 10 rats. Nicotinization was achieved by subcutaneous administration of 2 mg/kg per day to the rats, other than those in the Control group, for 4 weeks. The rats in one of the nicotinized groups received 20 mA, 80 Hz TENS (TENS1 group) for 1 hour daily throughout the last week before McFarlane flaps of random pattern were made in the backs of all the rats. Another nicotinized group was subjected to TENS in a similar dose after flap elevation (TENS2 group). Flap blood flow was measured before and 48 hours after their construction, and their fluorescein perfusion was measured immediately after the flap elevation. The comparison of the survival rates of the flaps revealed that, although the blood flow in the Nicotine group was significantly lower than in the Control group, it was significantly higher in the TENS1 group than in both the Control and Nicotine groups. The proportion of the area stained with fluorescein, immediately after the elevation of flaps, was significantly reduced in the Nicotine group compared to the Control group. In the TENS1 group, however, it was greater than in the nicotine and TENS2 groups. Flap viability rates decreased significantly in the Nicotine group compared with the Control group. In the TENS2 group, however, an increase was observed compared with the Nicotine group.These findings suggest that although TENS performed before flap elevation does not contribute to flap survival, despite causing a rise in blood flow, it enhances flap survival when applied postoperatively. Given the practicality and low cost of TENS, it can be concluded that it may be possible to use it in the management of ischemic complications in flap operations in smokers.

The effects of transcutaneous electrical nerve stimulation on tissue repair: A literature review

Background

Transcutaneous electrical nerve stimulation (TENS) consists of a generic application of low-frequency, pulsed electrical currents transmitted by electrodes through the skin surface. It is a therapeutic modality that is nonpharmacological, noninvasive, inexpensive, easy to use and widely applied in clinical practice.

Objective

To narratively review the scientific evidence of the effects of TENS on tissue repair with respect to wound healing, skin flap viability and tendinous repair.

Methods

The study was conducted using the MEDLINE, Lilacs and Scielo databases, without limit to the period of publication, and was completed in November 2011. Inclusion criteria were randomized or nonrandomized, controlled or noncontrolled clinical trials, and experimental trials involving rats subjected to TENS for tissue repair.

Results

Thirty articles on tissue repair were found and, among these, 14 reported on wound healing, 14 reported on skin flaps and two analyzed tedinous repair.

Discussion

It was suggested that TENS stimulates skin wound healing and tendon repair, as well as the viability of random skin flaps. Such effects may be due to the release of substance P and calcitonin gene-related peptide, which would increase blood flow and, consequently, hasten the events leading to tissue repair.

Conclusions

Based on the scientific evidence regarding the effects of TENS on tissue repair, the findings of the present literature review were inconclusive because data from the randomized controlled clinical trials were insufficient to confirm such effects.

Current status of the use of modalities in wound care: electrical stimulation and ultrasound therapy

Wound healing is a complex pathway that requires cells, an appropriate biochemical environment (i.e., cytokines, chemokines), an extracellular matrix, perfusion, and the application of both macrostrain and microstrain. The process is both biochemically complex and energy dependent. Healing can be assisted in difficult cases through the use of physical modalities. In the current literature, there is much debate over which treatment modality, dosage level, and timing is optimal. The mechanism of action for both electrical stimulation and ultrasound are reviewed along with possible clinical applications for the plastic surgeon.

Mechanical stimulation improves survival in random-pattern skin flaps in rats

This was a study on the effects of 3-MHz ultrasound at 16- and 100-Hz pulse repetition frequencies on angiogenesis and viability of random-pattern skin flaps in rats. A cranially-based dorsal skin flap was raised in 60 EPM-Wistar rats, which were randomly divided into four groups: control, sham, 16-Hz and 100-Hz groups. The mean percentage of necrosis was as follows: control, 42% ± 13%; sham, 18% ± 13%; 16-Hz group, 13% ± 10%; and 100-Hz group, 15% ± 7%, with significant differences between the control and the other groups (p < 0.001). The mean vascular density was as follows: control, 5% ± 2%; sham, 7% ± 2%; 16-Hz group, 21% ± 4%; and 100-Hz group, 24% ± 10%, with significant differences between control and ultrasound groups, and between the sham and ultrasound groups (p < 0.001). Both ultrasound treatments (16- and 100-Hz PRFs) induced angiogenesis, and sham and ultrasound treatments improved viability of random-pattern skin flaps in rats.

Histamine iontophoresis on the viability of random skin flap in rats

PURPOSE: To evaluate the effects of the histamine iontophoresis on the random skin flap viability in rats. METHODS: Sixty adult male Wistar rats were used. A cranially-based dorsal skin flap measuring 10 x 4 cm was raised and a plastic barrier was placed between the flap and its bed. After the surgical procedure, the animals were randomized into four groups (G1-G4) (n=15 each group) as follows: G1 (control) - sham electrical stimulation, G2 (electrical stimulation) - direct current electrical stimulation, G3 (histamine) - histamine and sham electrical stimulation and G4 (histamine iontophoresis) - transdermal iontophoresis of histamine. In all groups the procedures were performed immediately after the surgery and on the two subsequent days. The percentage of flap necrosis was measured on the seventh postoperative day. RESULTS: The mean and the respective standard deviation of the percentage of flap necrosis areas were as follows: G1 (control) - 47.87 ± 9.13%, G2 - 51.49 ± 8.19%, G3 - 46.33 ± 8.32% and G4 - 30.82 ± 11.25%. The G4 group presented a significantly smaller amount of flap necrosis when compared to the other groups (p<0.001). CONCLUSION: The topical administration of the histamine by iontophoresis was effective to increase the viability of the random skin flaps in rats.