A Simplified Vacuum Dressing System

Negative pressure wound therapy (NPWT) may not necessarily require sophisticated equipment. In settings with limited medical resources, simplified vacuum dressings have been considered an effective alternative to the gold-standard vacuum-assisted closure system. The aim of this study was to evaluate the performance of a simplified vacuum dressing system in the treatment of complex wounds.Materials and Methods. This was a prospective study in which difficult-to-manage wounds were treated using a simplified vacuum dressing system. Thirty-nine patients with a total of 51 wounds were treated. The main complications were pain (15.7%), bleeding (9.6%), and extremity edema (5.2%). After NPWT, the wounds were closed by skin grafting or with a skin flap in 71.8% of patients. Results. The results of NPWT were considered satisfactory in 87.2% of cases. The use of a simplified vacuum dressing system provided satisfactory results in the treatment of complex wounds in the studied population. Conclusion. The system proved easy to use, had a low complication rate and excellent cost-effectiveness, and it may be considered as an effective alternative to the gold-standard vacuum-assisted closure system for patients requiring prolonged hospitalization due to the presence of extensive wounds that cannot be treated at home.

Vacuum dressings involve the application of a controlled negative pressure on the wound to stimulate granulation tissue formation and wound healing. The method was invented in Germany in 1987 and standardized, patented, and published in the United States in 1997.^1-3 Since then its benefits have been widely evidenced in medical practice, especially in plastic surgery.^4-8

The advanced technology associated with vacuum dressings makes these devices too complex for routine use, which dramatically reduces their use in most countries of the world, because the training is not available to clinicians to enable them to treat patients with the vacuum-assisted closure devices, and the lack of resources makes the device itself unavailable.^9-12 However, less sophisticated yet excellent vacuum dressings without the use of the latest software technologies have been developed.^1,11-16

The aim of this study was to evaluate the performance of a simplified vacuum dressing system in the treatment of difficult-to-manage wounds.

This prospective study was approved by the Institutional Research Ethics Committee and performed in accordance with the ethical standards of the 1964 Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from all patients or their representatives prior to their inclusion in the study and after the objectives, procedures, risks, and benefits related to the use of the vacuum dressing system had been fully explained. Patient anonymity was assured. This study was conducted between June 2012 and March 2014.

The main inclusion criterion was the presence of wounds that were not responding adequately to treatment with complex occlusive dressings such as alginates, hydrocolloids, and hydrofibers in terms of cleanliness, formation of granulation tissue, and scarring. Other inclusion criteria are listed in Table 1. 

Patients with clinical or laboratory evidence of conditions as well as injuries that could be aggravated with negative pressure wound therapy (NPWT) were excluded. These conditions are listed in Table 1. The obtained data were statistically evaluated.

Applying the dressing. Wound antisepsis was performed using 0.5% aqueous solution of chlorhexidine, followed by placement of clean surgical drapes around the wound.

The equipment used was a prototype developed by the authors, as schematically represented in Figure 1. 

The steps for applying a simplified vacuum dressing to the affected area are as follows: (1) the foam dressing is cut to the appropriate size and shape and placed over the wound; (2) a transparent polyurethane dressing is used to cover and hold the foam dressing in place; (3) suction cups joined to drainage tubes are placed covering the two, 2-cm diameter openings made in the polyurethane dressing; (4) the drainage tubes are then connected to a liquid collector, (5) which is coupled to the control unit; (6) the control unit is then connected to the hospital in-wall vacuum system; (7) the timer and (8) suction pressure are adjusted; and (9) the suction device is started and (10) monitored using the vacuum gauge display (Figure 1). The negative pressure was adjusted to -125 mm Hg. The vacuum dressing system was set to continuous suction for the first dressing and to intermittent suction (cycles of 5 minutes on and 2 minutes off) or continuous suction for the subsequent dressings, according to the characteristics of the wound being treated. Dressings were changed 2 to 3 times per week at the bedside. Debridement of devitalized tissue was performed during dressing changes. All dressings were made and monitored daily by the same team of plastic surgeons.

Negative pressure wound therapy was interrupted in the following situations: 1) the goal was achieved, defined as the wound being healed or ready for surgical closure (ie, clean lesions without infection with bright red granulation tissue covering ≥ 85% of the raw wound and reduction of ≥ 50% in drainage volume); 2) no improvement of wound healing was observed after 2 weeks of treatment; 3) inability to maintain the dressing in place (eg, refusal of treatment, psychiatric patients who had difficulty understanding and following complex medical instructions, or children who were uncooperative with the care plan, regardless of age); and 4) presence of severe complications (eg, local or systemic infection, wound hemorrhage).

Digital photographs were taken before and after every dressing change for surgical documentation. At the end of treatment with NPWT, the authors classified the results as satisfactory if the goal was achieved as previously described and as unsatisfactory in all other cases. The patients were then referred to the specific surgical teams responsible for the definitive treatment of wounds.

Thirty-nine patients with a mean age of 38.3 years and a total of 51 wounds were treated with a total of 115 vacuum dressings. The mean time taken to place the vacuum dressing was 33.2 minutes, and the mean treatment time was 11.7 days (Table 2). 

The wounds were mostly caused by trauma and burns (Figure 2) involving the limbs (Figure 3). Patients were hospitalized for > 30 days, with a mean length of hospital stay of 46 days. 

The main complications were pain (15.7%), bleeding (9.6%), and extremity edema (5.2%) as shown in Figure 4. 

After treatment with NPWT, the wounds were closed   by skin grafting (n = 28) or with a skin flap (n = 1) in 71.8% of patients. 

Of the 51 treated wounds, 23.5% (12/51) were small wounds (< 1% of the total body surface area or < 200 cm²) and 76.5% (39/51) were large wounds (> 1% of the total body surface area or > 200 cm²). A mean reduction in wound size of 25% (range, 10%-50%), determined by visual inspection, was found after the treatment with the simplified vacuum dressing system.

Bacterial cultures obtained from wound exudates up to the third day of vacuum therapy revealed the presence of gram-negative bacteria in 92.3% of cases, with Escherichia coli (25.6%), Acinetobacter baumannii (21.0%), and Pseudomonas aeruginosa (12.8%) being the most commonly found (Table 2). 

The results of NPWT were considered satisfactory in 87.2% of cases. Figures 5,6,7,8 show examples of the results obtained and complications. 

Simplified vacuum dressings have been considered as an effective alternative to the gold-standard vacuum-assisted closure, the V.A.C. Therapy system (KCI, an Acelity Company, San Antonio, TX) in settings with limited access to medical resources and advanced technology.^1,6,11-17 In this context, the authors evaluated a simplified vacuum dressing system with 2 main adaptations to facilitate its use. The first is a control unit with only 2 dials, allowing 1 to control the negative pressure and the other to adjust the cycle of intermittent suction (Figure 1, items 7, 9 and 10). The second adaptation is the connection of the device to the hospital in-wall vacuum system, ensuring uninterrupted suction supply even in cases of prolonged electric power shortage. 

In this study, the treatment with vacuum dressings followed the recommended standards for NPWT including clean or aseptic handling of the wound; use of biocompatible sterile materials, such as transparent vinyl tubing and fluid collector; hypoallergenic acrylic adhesives; viscose screens coated with polytetrafluoroethylene (mesh, 0.5 mm x 0.5 mm); common commercially available foams, but not silver foams, with a pore size of 250 µm and 80% porosity; and transparent, adhesive, polyurethane film dressings. Additionally, a suction control unit with negative pressure ranging from -50 mm Hg to -200 mm Hg was used in continuous or intermittent suction mode with a minimum daily usage time of 22 hours per day, dressing changes  were done 2-3 times per week, and mean treatment time was < 20 days.^4-9,18 

The difficulty in maintaining the seal over the wound has been regarded as a major issue related to the use of simplified vacuum dressings.^18-20 This results in exudate accumulation and further damage to injured tissues.^2,18-20 In addition, few studies have been conducted on simplified vacuum dressings.^1,6,9,11-16 These factors have compromised the reliability of these devices.¹⁷ 

Pain and bleeding were the main complications found in this study. In 18 (15.6%) dressings, severe pain was associated with removal of the foam dressing, from collapse and adhesion of the foam to the wound bed caused by negative pressure, as well as from circumferential dressings on the arms or legs. All cases resolved either spontaneously or with intravenous analgesia (tramadol, 50 mg, single dose) after applying the dressing. In the authors’ study, no dressing was discontinued because of this problem. In other studies, pain on removal of the foam have also been frequently observed and occasionally required general anesthesia.^1,2,5,14

In all dressings, bleeding occurred with the removal of the foam attached to the wound bed, with most of the bleeding incidents corresponding to limited bleeding due to rupture of small blood vessels. However, abundant bleeding (> 100 mL or > 20% of blood volume) occurred in 11 (9.6%) dressings and was also associated with the removal of the foam. There was only 1 case of frank hemorrhage with hemodynamic instability requiring medical intervention. The hemorrhage occurred shortly after wound debridement of an amputation stump in a polytraumatized patient who was using low-molecular-weight heparin as prophylaxis against thrombosis (Figure 8). The problem was treated by immediate interruption of the vacuum therapy, surgical evacuation of the hematoma, wound irrigation with 3,000 mL of 0.9% saline solution, hemostasis of bleeding vessels, IV fluid replacement with 3,500 mL of Ringer’s lactate, red blood cell transfusion (2 units of red blood cell concentrate), and use of compressive dressings. The patient evolved with complete recovery in 6 hours without late complications. In the references reviewed by the authors, bleeding rates have not been reported.^1-29

Other complications found in this study were infrequent and self-limiting. A discreet edema (5.2% of dressings) occurred in hands, ankles, or feet, distal to the circumferential wounds (Figure 6) and has been assigned to the compression dressings and partial blockade of lymphatic drainage. The problem was managed with elevation of the limbs and disappeared with the end of vacuum therapy. Exudate leakages through the edges of the dressings (3.5% of dressings) were easily solved with the application of adhesive films on the streaming sites. Maceration (ie, epithelial detachment) of the skin around the wound (3.5% of dressings) was caused by the accumulation of moisture between the skin and the adhesive films. Allergic contact dermatitis has been identified by redness and itching of the skin under the bandage (3.5% of cases). Maceration and dermatitis appeared in therapies that lasted more than 2 weeks. Macerated skin and contact dermatitis were protected with hydrocolloid dressings until the complete resolution of these problems. A small cutaneous necrosis of 1 cm x 1 cm occurred in an elderly patient (1.8% of dressings) with diabetes (compensated) due to improper compression of the suction cups (Figure 1, item 3) on the healthy skin. The problem was approached with local debridement and continuity of vacuum therapy. From that case, the authors avoided positioning the suction cups on healthy skin around the wound. Obstruction of drainage tubes (Figure 1, item 4) from blood or serous clots also occurred in a few dressings (1.8%). This was solved with the replacement of drainage tubes and routine use of drainage tubes of a larger caliber (8 mm diameter). Skin excoriation has been observed under the bandages of a burnt child (1.8%), being caused by compression of the distal edge of the dressing on the swollen skin. The injury was very mild and healed in 3 days, leaving no scars.

Despite complications, several studies have identified the potential benefits of simplified vacuum dressing systems, which are similar to those of other vacuum-assisted closure systems.^5-7,15,21-23 The benefits include arterial vasodilation, stimulation of vascular proliferation, increase in local blood flow, drainage of exudates, removal of edema, reduction in bacterial colonization, decreased inflammation, and creation of a moist microenvironment beneficial to wound closure.^5-7,15,21-23

The authors’ results confirmed the efficiency of simplified vacuum dressings (Figures 5,6,7,8). Vacuum dressings led to increased coverage with granulation tissue, decreased wound exudate, fibrin, and necrosis, and reduced wound area. There was also a decrease in the depth of the lesions. The authors were able to maintain a seal, control the negative pressure within the recommended limits, and drain wound exudates without the need for early dressing changes. Vacuum dressings were intact and fully functioning for up to 7 days before changes were required.

Negative pressure wound therapy results in few severe complications, with the most common being skin maceration.^2,5 In this study, 15 (38.5%) patients had at least 1 complication with the use of the simplified vacuum dressing system, with 14 (35.9%) of them having self-limiting problems (Figure 4), and only 1 patient (2.6%) having a major problem (hematoma), as shown in Figure 8. There were no deaths related to the use of vacuum dressings. Few data are available on complications related to the use of simplified vacuum dressing systems; total complication rates range from 0% to 18%.^2,13,24-27

In 28 (71.8%) patients, the wounds were closed by skin grafting or with a skin flap following NPWT, showing the importance of vacuum dressings in plastic surgery.^1-9

The cost of NPWT per person has been estimated to range from $700.00 to $3,450.00 per week.¹⁵ This cost can be significantly reduced with the use of simplified vacuum dressings.^15,28 In the present study, the weekly cost was about $391.30 per person and $173.5 per vacuum dressing. One reason for this was that the device was connected to the in-wall vacuum system available in hospital wards, which bypassed the need for highly complex machinery.

Few studies were found containing guidelines for vacuum-dressing placement, as well as reporting the time taken to place the dressing.^5,28 This is probably because the treatment is usually applied by nonsurgical personnel.² The lack of detailed information resulted in an initial difficulty for the application of the vacuum dressing^1,5,29 and a mean time spent on its placement (10.5 minutes/day) was longer than the 4.8 minutes/day reported in the literature.²⁸ However, the final time was reduced to about 5.44 minutes/day as the authors became more skillful in applying the dressing.

In 3 patients (7 dressings, 6.1%) with wounds in the lower limbs and using external fixators, the time spent on dressing placement was 1.08 to 2.08 hours. Patients with large wound surface areas (345-400 cm²) required additional time (41.2-89.6 minutes) compared to those with small wounds due to the extreme difficulty to obtain a complete seal of the dressings around the fixation pins. Besides these exceptional cases, the time taken to place the dressings was similar to that described in literature (5.44 minutes/day vs 4.8 minutes/day).²⁸

Levels of satisfaction with the use of NPWT were not available in extensive reviews on the subject.^4-9,18 In this study, treatment with a simplified vacuum dressing system was considered satisfactory in 33 (87.2%) patients. Patient tolerance to standard vacuum dressings has been reported as 93.75%.²⁵ Discontinuation of therapy due to a lack of patient cooperation has been estimated to occur in 13% of cases.⁵

Based also on evidence from previous studies,^{1-9,11-17,20,21,27-29} the simplified vacuum dressing system showed a performance similar to that of a vacuum-assisted closure system in most features, but with many advantages (Table 3), especially for patients requiring prolonged hospitalization (> 30 days) due to the presence of extensive wounds (> 200 cm²) that cannot be treated at home. 

The use of the simplified vacuum dressing system led to satisfactory results in the treatment of complex wounds in 87.2% of patients in this group. Its advantages include ease of use, excellent cost-effectiveness, and low complication rates.

The authors would like to thank Dr. Sérgio Ricardo Matos Rodrigues da Costa, Dr. José Humberto Oliveira Campos, and Vitor Araújo Felzemburgh for critically reviewing the manuscript.

From the Bahia State General Hospital, Salvador, Bahia, Brazil; and Private Consultant, São Paulo, Brazil

Address correspondence to:
Sandro Cilindro de Souza, MD
Rua Conselheiro Correia de Menezes 182, Horto Florestal
CEP 40295-030
Salvador, BA, Brazil
sandrocilin@gmail.com

Disclosure: The authors disclose no financial or other conflicts of interest.