Dispersion Risk Associated With Surgical Debridement Devices

Introduction. Surgical instrumentation is now available to facilitate wound debridement. The 2 primary options involve different energy applications, but both have the potential to spray. The Versajet II (Smith & Nephew, London, UK) utilizes a high-powered water jet to disrupt tissue and remove debris by means of the Venturi effect. The SonicVac (Misonix, Farmingdale, NY) is a direct-contact, low-frequency ultrasound debriding device. It delivers a high-energy ultrasound to a wound surface via a fluid medium, causing bubble cavitation, a physical effect of rapid pressure waves causing bubbles to form and implode that releases mechanical energy. Objective. This study is designed to assess spray dispersion under ideal and challenging conditions. Materials and Methods. The 2 aforementioned instruments were tested in a laboratory situation. Bacteria (Escherichia coli [ATCC#54288] or Staphylococcus epidermidis [RP62A]) were seeded onto separate pieces of beef steak. Culture plates were set up in a predesignated position around the specimen; the specimen was then treated for 60 seconds at a power setting of 7 and 70% irrigation (ultrasound device) or 10 (waterjet device). After 60 seconds of debridement, about 4 mm to 5 mm of muscle tissue had been removed by the ultrasound device and 2 mm to 3 mm by the waterjet. In the bony specimen, the bone was more exposed after the treatment. The ultrasound device polished but did not remove the bone. Results. Both instruments performed well with minimal dispersion in the ideal setting. In beef steak with bone and grizzle, the waterjet created a lawn of bacterial spray in the plate in front of the surgeon. The ultrasound had a small number of contaminants in the same conditions. Conclusions. Both instruments can be used safely in the proper conditions, but the surgeon needs to be aware of the limitations and risks of spray dispersion.

The 2 most widely used surgical debridement devices were tested to determine how effective they are in containing spray during surgery. The Versajet II (Smith & Nephew, London, UK) is a waterjet device that directs a focused high-energy beam of saline against tissues to be debrided. When the impacted tissue has a cohesive coefficient less than the power of the waterjet, the tissues implode. The resulting stream of fluid is passively removed from the field utilizing the Venturi effect. The SonicVac (Misonix, Farmingdale, NY) is a direct-contact, low-frequency ultrasound device that emits a stream of saline for energy transfer to the impacted tissues. The ultrasound device transmits high-energy ultrasound directly to the tissues, creating vibrations and secondary pressure changes within the tissues at 22.5 kHz. This causes bubbles to form and implode (bubble cavitation), thereby releasing mechanical energy. The handle is wrapped in a sheath that has a vacuum attached for removal of the saline mist and other fluids.

Since both devices deliver high-energy fluids into the operative field, surgeons and operating room personnel are concerned about the potential for spray dispersion and potential for transmission of infectious particles. The objective of this study is to elucidate the ability of the devices to contain spray under a variety of potential operative conditions.

Experiment 1
The waterjet and ultrasound devices were tested. A beef steak free of grizzle, fascia, and bone was inoculated with 100 µL of bacterial solution containing 6 x 10⁴/100 µL of Escherichia coli (ATCC#54288) prior to debridement. Culture plates (3; trypticase soy agar [TSA]) were placed 24 inches to the left, 17 inches above, and 30 inches directly over the beef steak (Figure 1). The inoculated area was then treated with the waterjet device at a power level of 10 for 60 seconds for 3 trials, using normal saline as the fluid vehicle. The same process was followed for the ultrasound device at a power level of 7 and 70% irrigation on a separate steak of similar consistency. The plates were incubated for 24 hours and colony forming units (CFUs) were counted. 

Experiment 2
The waterjet device and the ultrasound device were tested. Beef steaks containing areas of grizzle and bone were inoculated with 100 µL of bacterial solution containing 10⁹/100 µL of Staphylococcus epidermidis (RP62A) prior to debridement. Three culture plates (TSA, enhanced with yeast extract) were placed 24 inches to the left, 17 inches above; 12 inches away and in front of the surgeon; and 30 inches directly over the specimen (Figure 1). The inoculated areas were then treated with the waterjet device at a power level of 10 for 60 seconds and the ultrasound device at a power level of 7 with 70% irrigation for 60 seconds for 1 trial each on separate steaks of similar consistency, using normal saline as the fluid vehicle. It was immediately apparent that the device spray, primarily from the waterjet, was directed towards the surgeon. After the 60-second trial, the waterjet removed about 2 mm to 3 mm of meat and the ultrasound device removed about 4 mm to 5 mm of meat. The bone was not removed, but the ultrasound device polished and smoothed out the bone. Consequently, the subsequent 2 trials had the 12-inch plate placed in front of the surgeon. In each trial, the area treated contained bone and grizzle. The study was terminated after the 2 trials for safety reasons due to excessive spray escaping under the door of the safety hood. The plates were incubated for 24 hours, and CFUs derived from a single bacterium were counted.

In experiment 1, which represents optimal wound conditions, both devices averaged < 1 CFU per collection plate (range, 0–7 CFUs). Experiment 2 represented a high-bacterial density wound containing soft tissues of varying densities and exposed bone within the field. The waterjet device trials demonstrated the following: the plates located 24 inches to the left and 17 inches above the specimen contained a mean of 9.3 CFUs (range, 3–18 CFUs); the plates 30 inches over top contained a mean of 7.3 CFUs (range, 2–17 CFUs); and the plates directly in front of the surgeon 12 inches from the specimen contained a lawn of bacteria, a CFU too numerous to count (Figure 2A). The ultrasound device trials demonstrated the following: the plates 24 inches to the left and 17 inches above the specimen contained a mean of 0 CFUs (range, 0 CFUs); the plates 30 inches over top contained a mean of 1 CFU (range, 0–3 CFUs); and the plates 12 inches from the specimen in front of the surgeon grew a mean of 21.7 CFUs (range, 5–45 CFUs; Figure 2B). A statistical difference between CFUs of the waterjet device and the ultrasound device culture plates in front of the surgeon could not be calculated, because there were so many bacteria growing in the waterjet device treatment plates that the colonies were inseparable into individual CFUs. 

Both debridement devices used in this study employ a stream of fluid, typically saline, to deliver energy to the targeted tissues. In the case of the waterjet device, this consisted of a high-powered water jet delivering energy of up to 15 000 psi. Under optimal conditions, this device performs well with excellent removal of tissue and clearing of fluid from the wound. There is minimal dispersion. However, when faced with dense tissue types that the water jet is insufficiently powerful to implode, the water jet is simply deflected and creates a spray. This spray has the potential to carry bacteria as well as other hazardous materials. Since the waterjet device handle orients the spray towards the surgeon, when it is deflected, the spray directly impacts on the surgeon. The spray is, furthermore, dispersed towards other members of the operative team. 

The ultrasound device utilizes a different energy source than the waterjet device. The direct-contact, low-frequency ultrasound device uses a slow stream of fluid that is aerosolized around the tip of the implement to transfer the ultrasonic energy to the targeted tissues. Ultrasonic energy implodes tissue by bubble cavitation and acoustic microstreaming. The spray does not get visibly deflected by the varied density of tissues in the operative field. The ultrasound device was designed to actively suction away the mist that would otherwise gather around the tip of the device. Similar to the waterjet device, the ultrasound device performs well in an optimal setting by debriding tissue with minimal spray dispersion. Under the more normal condition of tissues with different densities, the ultrasound device continues to debride well, even removing some of the bone and most of the grizzle with minimal dispersion. In 30% of the trials, however, there was detectable spray directed towards the surgeon. 

Most wound surgeons agree that the advent of high-powered debridement technologies has greatly advanced their ability to efficiently and precisely prepare wound beds for definitive closure.^1-4 However, since the primary technologies employ energized fluids, dispersion containment has been a major safety concern for the surgeons and operating room staff. Some surgeons noted concern of disease transmission using the waterjet device, and they recommended using enhanced personal protective equipment (PPE).^5,6 One study cultured air samples after a waterjet device debridement and noted levels of 950 CFUs to 16 780 CFUs while using the waterjet device compared with a baseline of 582 CFUs.⁷ The elevated CFU count was noted in air samples 1 hour postoperatively.⁷ In another study,⁸ dispersion of epithelial cells during a deepithelialization procedure was implicated in later cyst formation.

The limitations of this study include the low number of trials and the fact that under certain conditions the spray from the waterjet device was escaping from the hood and posed a potential hazard to the laboratory personnel. In addition, clinical conditions vary considerably and are not identical to the simulated conditions of these experiments.

Surgeons are clearly interested in improving their surgical efficacy for enhanced patient care; debridement technologies enable them to do so. This study demonstrates that spray dispersion carrying bacterial pathogens is a real potential risk when operating on a bacterially dense field with varied tissue densities. In order to minimize this risk, the recommendations based on the data herein are to use the ultrasound device whenever the wound has tissues of varied densities, particularly bone, tendon, and/or fascia. Nevertheless, as currently configured, even the ultrasound device demonstrates a small degree of dispersion in some trials. To date, there are no reports in the literature that the authors could find and the manufacturers have not reported any such incidents. Consequently, due to the theoretical risk of bacterial transmission, the use of adequate PPE is advised for all operating room personnel in the area of the surgical field. Additional modifications of the instrumentation are recommended to further minimize dispersion.

Affiliations: Rutgers New Jersey Medical School, Newark, NJ; Tipul Biotechnology, El Cerrito, CA; and Rutgers School of Dental Medicine, Newark, NJ 

Correspondence:
Mark Granick, MD
140 Bergen Street
Suite 1620
Newark, NJ, 07039
mgranickmd@rutgers.edu

Disclosure: This paper was presented as a poster at the Symposium on Advanced Wound Care Spring 2017. The Department of Oral Biology, Rutgers School of Dental Medicine, received a $5000 unrestricted educational grant from Misonix, Inc (Farmingdale, NY) to fund the study. Drs. Granick and Rubinsky are consultants for Misonix, Inc.