Pulsed radio frequency energy (PRFE) use in human medical applications

Abstract

A number of electromagnetic field-based technologies are available for therapeutic medical applications. These therapies can be broken down into different categories based on technical parameters employed and type of clinical application. Pulsed radio frequency energy (PRFE) therapy is a non invasive, electromagnetic field-based therapeutic that is based on delivery of pulsed, shortwave radio frequency energy in the 13–27.12 MHz carrier frequency range, and designed for local application to a target tissue without the intended generation of deep heat. It has been studied for use in a number of clinical applications, including as a palliative treatment for both postoperative and non postoperative pain and edema, as well as in wound healing applications. This review provides an introduction to the therapy, a summary of clinical efficacy studies using the therapy in specific applications, and an overview of treatment-related safety.

Keywords::

• Postoperative pain and edema
• Non postoperative pain and edema
• Wound healing
• Clinical efficacy studies
• Safety
• Electromagnetic field
• Radio frequency

Acknowledgements

We would like to thank Jill Munsinger for analysis, writing, and editing contributions, Teresa Nelson for analysis contributions, and John Moffett for editing contributions as well as insightful discussions during manuscript preparation.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.

Notes

¹ U.S. Food and Drug Administration, Code of Federal Regulations, Title 21, Part 890, Section 890.5290.

² Shortwave, in this context, refers to this specific carrier frequency range designated by the FDA for this medical device category. In other contexts, such as in engineering, shortwave refers to a much wider range of the radio spectrum.

³ Table 4 provides a description of abbreviations used in the text.

⁴ Asterisk (*) indicates that the p-value was calculated based on data provided in the article.

⁵ There is statistical evidence that neutral outcomes in some PRFE efficacy studies may be a consequence of insufficient energy dosing (Guo, L., Kubat, N.J., Nelson, T.R., and Isenberg, R.A. Meta-Analysis of Clinical Efficacy of Pulsed Radio Frequency Energy Treatment. Submitted.).

⁶ Percentage and p-values were calculated based on the information available in the literature.

⁷ Conservatively used p-value associated with overall comparison. This action is conservative because the publication reported an 81 patient single arm study that validated the results seen in the all but abdominal surgery subgroup. The analysis for the all but abdominal surgeries subgroup in the double-blind study reported the following proportion of treated patients with suture removal as compared to control (Treatment: 89%, Control: 13%, p < 0.0001). Within the subgroup with abdominal surgery, the proportion with their sutures removed by 5 days was not found to differ between groups (Treatment: 28%, Control: 21%, p = 0.5704). The lack of a significant effect in the abdominal surgery subgroup as reported in the publication is due to conservative behavior on the part of the surgeon to avoid possible wound dehiscence. The 81 patient single arm study results reported 86% of patients with sutures removed by day 5.

⁸ p-value reported in publication is in error and is reported to be between 0.05 and 0.25.

⁹ The ANSI/IEEE Standard references a larger literature database shared between the American National Standards Institute, The Institute of Electrical and Electronic Engineers, and the World Health Organization. While this database includes articles relevant to the discussion of the risks of shortwave diathermy, it also includes extensive literature pertaining to other RF frequency bands (extending from 3 kHz–300 GHz). The findings of the literature review and conclusions pertain directly to shortwave diathermy as well as the larger defined RF frequency spectrum.

¹⁰ The risk to technicians and clinicians operating the medical devices.

¹¹ PRFE therapy typically delivers RF by means of an electromagnetic field that does not involve direct contact with the body, unlike other technologies that deliver energy by use of electrodes in direct contact with the body (e.g., surgical instruments for RF ablation and cutting, certain bone growth stimulators).

¹² A search of the FDA's MDR and MAUDE databases was performed by searching for reports under the FDA assigned product code ILX through June 30, 2009.

¹³ Development of squamous cell carcinoma (SCC) in the wound bed (a chronic ulcer of 51-year duration), likely as a complication known as Marjolin's Ulcer, a rare, spontaneous complication arising in chronic cutaneous ulcers of long duration, occurred 10 months after a 1½ year PRFE treatment regimen. Whether PRFE was a contributing factor is unknown.

¹⁴ The former article (Bentall and Eckstein) involved use of PRFE. The thermal character of the diathermy device in the latter article (Zhao) is not discussed.