Impact of gauze‐based NPWT on the patient and nursing experience in the treatment of challenging wounds

Abstract

Negative pressure wound therapy is widely used in the treatment of hard‐to‐heal wounds; however, pain during dressing changes, which is often associated with pain on the commencement and cessation of pressure application and because of in‐growth of new granulation tissue into interstices of foam dressings, is often experienced. Anecdotal reports have suggested that choice of gauze as the negative pressure wound therapy dressing may reduce the pain associated with dressing changes. A prospective, multi‐center, non‐comparative clinical investigation was carried out using gauze‐based negative pressure wound therapy in chronic and acute wounds. Over 152 patients were evaluated. Median duration of therapy was 18 days with 91% of patients progressing towards healing at the end of therapy. Wound pain and odour were significantly reduced (P < 0·001) over the course of therapy. Wound pain during dressing changes was reported to be absent in 80% of dressing removals. No damage to the wound bed following dressing removal was observed in 96% of dressing changes. Dressing applications were considered easy in 79% of assessments and took a median of 20 min to complete. In patients susceptible to pain, gauze‐based negative pressure therapy may be a viable option to maximise patient comfort.

INTRODUCTION

Negative pressure wound therapy (NPWT) is an increasingly used method of treating hard‐to‐heal wounds. It has been shown to be efficacious in improving clinical outcomes in a number of randomised controlled trials in various indications including, diabetic foot ulcers 1, 2, 3, grafted wounds 4, 5, 6 pressure ulcers (7) as well as in mixed indication studies 8, 9, 10. Improvements in clinical outcomes include reduction in wound dimensions 3, 9, 10, stimulation of granulation tissue formation 1, 8, reduction in non‐viable tissue (11) and improved speed to closure 1, 2, 8, 12.

NPWT has also been reported to ease pressures on nursing and improve patients' quality of life. Relevant factors which positively influence quality of life include fewer dressing changes, reduced general wound pain (i.e. background wound pain not necessarily linked to dressing changes) and in some cases improved mobility compared with conventional therapy 13, 14, 15. However, one aspect of NPWT which currently appears to be non‐optimal is the patients' experience of pain during dressing changes 16, 17. NPWT consists of a negative pressure source and a wound filler material, commonly consisting of an open cell, porous polyurethane foam. Several reports have shown that newly formed granulation tissue is able to grow into the polyurethane foam and its removal during dressing changes can be painful as a result and also can result in damage to the wound bed (16). Although reports of this phenomenon are largely anecdotal, several clinical studies record instances in their patient cohorts where patients refused to continue with foam‐based NPWT because of the pain experienced during dressing changes 8, 18. Several strategies have been adopted to reduce pain in foam‐based NPWT including lining the wound with a wound contact layer (WCL) to physically prevent tissue in‐growth (17). Studies have shown, however, that the presence of a WCL may impact on the level of pressure effectively transmitted to the wound bed (19). An alternative strategy commonly adopted includes instilling the wound with analgesic for 30 min prior to dressing removal 17, 20. However, neither of these strategies address the core issue which remains the tendency of granulation tissue to penetrate the interstices of the foam interface NPWT dressing. In order to address the fundamental issue, it is possible that use of alternative wound interface materials may be able to reduce the amount of tissue in‐growth and therefore the amount of pain experienced during dressing changes.

Gauze‐based NPWT has recently been rediscovered and early clinical evaluations have demonstrated that gauze is able to deliver negative pressure to a wound as efficiently as foam (21). Early clinical investigations have shown that gauze‐based NPWT is clinically efficacious 10, 22. Furthermore, it has been suggested that gauze may provide a less painful option compared with foam‐based NPWT during dressing changes as tissue does not appear to grow into the gauze as has been commonly observed with the foam. A recent prospective, randomised trial comparing foam and gauze‐based NPWT systems has shown that although no statistical difference can be observed between the two interface materials with regard clinical efficacy, a significantly reduced amount of pain was experienced by the patients and the amount of pain medication required in the gauze group compared with the foam group (23).

Pain is a very personal experience; some patients undergoing NPWT will experience considerable pain, whereas others will feel none (e.g. neuropathic or paraplegic patients) (17). The experience of the individual is therefore of considerable importance when making clinical decisions relating to management of wound pain. Reduction of pain may also be an important factor in gaining patients commitment to NPWT. When applying NPWT, the choice of wound filler which may alleviate pain in susceptible patients may provide a means of managing each patient's wound according to the needs of each individual patient.

METHODS

Study design

A prospective, non‐comparative multi‐center evaluation was carried out to assess the performance of gauze‐based NPWT in wounds deemed suitable for treatment with NPWT. The primary objective was to assess wound progress towards closure by measuring three primary clinical variables; granulation tissue formation, exudate management and reduction in wound dimensions. The primary objective has been reported elsewhere. The aim of this report is to assess some of the secondary objectives of this study, in particular those relating to two factors likely to be of importance to patients and nursing professionals entrusted with their care: wound pain and odour. The study was carried out in accordance with guidelines set forth by the Declaration of Helsinki and subsequent revisions. The study was approved by the Ethical Review Boards at all involved institutions and all patients provided informed consent prior to enrollment. Exclusion criteria included the presence of >25% necrotic tissue in the wound bed, untreated osteomyelitis, malignancy, active bleeding, exposed blood vessels or organs and untreated infection in the wound. All patients with wounds suitable for NPWT (as determined by the list of clinical indications available for the chosen apparatus) were included.

Delivery of gauze‐based NPWT

NPWT was delivered using either the EZ‐Care device or the V1STA device (both from Smith & Nephew, St Petersburg, FL). These devices were used at a recommended negative pressure of −80 mmHg. The wound filler used to transmit negative pressure to the wound bed was saline‐moistened anti‐microbial gauze (Kerlix‐AMD; Tyco, Gosport, UK) and was provided as part of a tailored dressing kit from the manufacturer and applied to the wound using the Chariker‐Jeter method of application (24). In all cases, NPWT was delivered using continuous pressure for the stated duration of therapy. Wounds were inspected and dressings changed at 2‐ to 3‐day intervals. During the patients' participation in this study, no aspect of patient care was changed from that which they would have received with alternative NPWT products.

Clinical procedures and outcomes

Information relating to wounds enrolled into the study was captured at baseline and at every dressing change (typically every third day) for the duration of therapy. The study protocol enforced a maximum duration of gauze‐based NPWT of 30 days or 10 dressing changes (whichever occurred first). Clinical judgment determined whether to discontinue NPWT during this 30‐day period according to the achieved level of wound progression and the reason for discontinuation was captured. A single follow‐up assessment was carried out 7 days following discontinuation of therapy. The following information was captured at all assessments: quantitative data relating to wound dimensions (area, depth and volume) and time required to change the dressing; status of wound (whether progressing to healing or not); semi‐quantitative data in the form of a 4‐point category scoring system with regard to wound pain, odour and damage to the underlying wound bed (none, mild/slight, moderate or severe/strong/extensive) and the perceived ease of carrying out the dressing application and initiation of therapy (easy, acceptable, difficult). Debridement was carried out as required, according to the attending physician and information relating to debridement was captured.

Data assessment and statistical evaluation

Continuous data was summarised using means and standard deviations, where the data was normally distributed (e.g. patient age), and medians and ranges, where the data did not follow a normal distribution (e.g. wound duration). Categorical data such as patient sex was summarised using frequency distributions. The Wilcoxon signed‐rank test was used to test for changes in the reference wound area, depth and volume. The Cochran–Mantel–Haenszel test (using the row mean scores differ statistic and modified ridit scores) stratified by patient was used to test for differences in pain and odour levels between baseline and discontinuation of therapy.

RESULTS

In total, 152 eligible patients were recruited. Data evaluated here relates to the secondary objectives of the study, specifically patient and nursing factors including pain and odour. Primary objectives will be reported elsewhere. Patient demographics are described in Table 1. In short, 56% of patients were male, mean age was 58 and mean wound duration prior to onset of therapy was 5 weeks. Common co‐morbidities included diabetes and hypertension in 20% of patients. Wound aetiology was mixed. Fifty‐three patients had chronic wounds (4 venous leg ulcers, 15 diabetic foot ulcers and 34 pressure ulcers) and 78 of patients had acute wounds (63 post‐surgical and 12 trauma and 3 other) and 21 patients received gauze‐based NPWT on top of a split‐thickness skin graft. A variety of care settings were enrolled in the clinical evaluation with 95 (62·5%) patients derived from a hospital setting, 31 (20·4%) from the home setting, 23 (15·1%) in out‐patient wound clinics and 3 (2·0%) in a long‐term care setting. Patient mobility was also recorded. In total, 221 (23%) of dressing changes involved a debridement procedure. The type of debridement used was as follows: Sharp in 180 (18·8%), Versajet Hydrosurgical debridement (Smith & Nephew, St Petersburg, FL) in 8 (0·8%), Autolytic in 5 (0·5%). The remainder were either unspecified or combinations of more than one debridement type.

Table 1.

Patient demographics

Mean age (years)	58 (20–92)
Male:Female	85:66
Wound type (%):
Surgical site	63 (41)
Trauma	12 (8)
Pressure ulcer	34 (22)
Diabetic ulcer	15 (10)
Leg ulcer	4 (3)
Skin graft	21 (14)
Other	3 (2)
Median wound duration (weeks)	5 (0–364)
Principle co‐morbidities (%):
Diabetes	56 (37)
Hypertension	61 (40)
Peripheral vascular disease	30 (20)
Mobility (%):
Walks unaided	63 (41·4)
Walks with aid	36 (23·7)
Chair bound	21 (15·4)
Bed bound	32 (21·1)
Treatment setting (%):
Hospital	95 (62·5)
Home	31 (20·4)
Wound clinic	23 (15·1)
Long‐term care	3 (2·0)
n	152

Efficacy

The study protocol dictated that the duration of therapy should be no more than 30 days or 10 dressing changes (whichever occurred first). The clinicians' judgement determined whether to discontinue NPWT during this 30‐day period according to the achieved level of wound progression. The reason for discontinuing NPWT was recorded and is shown in Table 2. In short, 60% of patients had either achieved wound closure or had progressed sufficiently to warrant progression onto other less intensive therapies within the maximum study period. At the end of therapy, 136 (91%) of patients were either closed or progressing towards closure as determined by the attending physician with the remaining 14 (9%) not progressing. Median duration of therapy was 18 days. Median percentage reduction in area, depth and volume of 27·3%, 50·% and 65·3%, respectively (n = 147, 137, 136 respectively) were observed (data not shown). Twenty seven patients were withdrawn: Five were withdrawn because of poor compliance, three because of lack of clinical response, one at patients own request, nine patients were lost to follow‐up (largely because of change of clinical setting) and two patients died (for reasons unrelated to NPWT), five patients withdrew for other reasons and two patients withdrew because of a product complaint both complaints related to inability to create a seal because of the anatomical position of the wound.

Table 2.

Wound progression and wound status at the end of therapy. ‘Sufficient progress' denotes the point where a patients wound has progressed sufficiently with negative pressure wound therapy (NPWT) to be transferred onto a less‐intensive advanced wound therapy (e.g. dressings). Median duration of therapy was 18 days

Reason for discontinuation of therapy	Number of patients (%)
Reason for treatment discontinuation
Wound healed	23 (16)
Sufficient progress	64 (44)
End of 30 days treatment regime	31 (24)
Withdrawn	27 (19·0)
Overall	145 (100) *
Wound status at treatment discontinuation
Progressing to healing	136 (91)
Not progressing	14 (9)
Overall	151 (100)

^*Reason for treatment discontinuation was captured for 145 patients.

Patient pain and comfort

The level of pain experienced by all patients at every dressing change throughout the course of therapy was assessed and results are shown in Figure 1. Patients reported no pain during initiation of negative pressure in 85% of dressing changes and no pain on dressing removal in 80% dressing removals. No damage to the wound bed was observed in 95·9% of dressing removals with only minimal damage in a further 3% of dressing removals and moderate damage in 1% of dressing removals.

Figure 1.

Low levels of pain experienced during gauze‐based negative pressure wound therapy (NPWT). Data relating to the severity of pain and damage to the wound bed caused during dressing changes was captured at every dressing change (850) for 152 patients.

The level of wound pain experienced by the patient at the beginning of therapy was also compared with the level of pain experienced at the end of therapy (Figure 2). There was significant evidence (P < 0·001) of a reduction in wound pain from baseline to treatment discontinuation, with the percentage of patients experiencing no reference wound pain increasing from 41% patients at baseline to 75% patients at treatment discontinuation. In 73 (49%) patients there was a reduction in reference wound pain from baseline to treatment discontinuation, 71 (47%) patients' wound pain did not change from baseline to treatment discontinuation and in 6 (4%) patients there was an increase in wound pain from baseline to treatment discontinuation. At the 7‐day follow‐up assessment, wound pain remained significantly lower (P < 0·001) than at baseline (Figure 2).

Figure 2.

Reduction in pain experienced during gauze‐based negative pressure wound therapy (NPWT). Pain at baseline (n = 151), end of therapy (n = 151) and at a 7‐day follow‐up (n = 90) was assessed and expressed as a percentage ^* P < 0·001 compared to onset.

The majority of patients scored their wound as comfortable during 87% of all dressing changes with a further 11·7% of dressing changes acceptable to the patient. Only 11 (1·3%) of a total of 854 dressing changes were identified as uncomfortable by the patients. There was no obvious trend between the level of comfort reported and the wound type (data not shown).

The use of analgesic was recorded at each dressing change. A small number of patients included in the analysis were insensate to wound pain or had reduced pain response: four patients had diabetic neuropathy in the region of the wound, two patients were paraplegic and one quadriplegic; however, this small number of patients also was not sufficient to account for the high percentage of patients experiencing no pain at any point during the evaluation.

Odour

The degree of odour in all wounds at every dressing change was assessed and results are shown in Figure 3. There was significant evidence (P < 0·001) of a reduction in wound odour from baseline to treatment discontinuation, with the percentage of patients with no odour increasing from 98 (64%) patients at baseline to 126 (84%) patients at the end of therapy. In 41 (27%) patients, there was a reduction in reference wound odour from baseline to treatment discontinuation. This included all six patients whose wounds had strong odour at baseline. By end of therapy, five of these wounds had no odour and one wound had slight odour. In 98 (65%) patients wound odour did not change from baseline to treatment discontinuation and in 11 (7%) patients there was an increase in wound odour from baseline to treatment discontinuation. Following the discontinuation of therapy, wounds continued to improve incrementally. At the 7‐day follow‐up assessment, wound odour remained significantly lower (P < 0·001) than at baseline (Figure 2).

Figure 3.

Reduction in wound odour during treatment with gauze‐based negative pressure wound therapy (NPWT). Odour at baseline (n = 152), end of therapy (n = 150) and at a 7‐day follow‐up (n = 82) was assessed and expressed as a percentage. ^* P < 0·001 compared to onset.

Nursing time

The amount of time taken to change each gauze‐based NPWT dressing and reinitiate therapy was captured in a total of 863 dressing changes. Median time for a dressing change and to initiate therapy was 20 min (data not shown). The ease with which the attending physician was able to change the dressing and reinitiate therapy was assessed and is shown in Table 3. Application of the dressing was considered easy in 682 of a total of 862 dressing changes (79%) and difficult in only 28 (3%) dressing changes. Ease of set up of the device was also monitored and was considered easy in 730 of a total of 861 (85%) of dressing changes and difficult only in 8 (1%) dressing changes.

Table 3.

Ease of application and set up of the gauze‐based negative pressure wound therapy (NPWT) for all dressing changes

	Ease of application	Ease of set up
Easy	682 (79·1%)	730 (84·8%)
Acceptable	152 (17·6%)	123 (14·3%)
Difficult	28 (3·2%)	8 (0·9%)
Total	862 (100%)	861 (100%)

The number of personnel required to assist with each dressing change was also recorded. Only one person was required in 610 (74%) of dressing changes, and two people were required in a further 195 (24%) of changes. One dressing change (1/821) required four people.

DISCUSSION

It is widely acknowledged that lessening of wound associated pain is an important contributor to patient quality of life and that this may have a knock‐on effect on a patient's recovery and compliance with therapy. Pain can impact on ability to sleep, loss of appetite, depression and anxiety, loss of mobility and independence. Wound‐related factors can also lead to social isolation; pain can lead to reluctance to mobilise, odour can cause embarrassment and a reluctance to socialise 16, 25, 26. There is a suggestion that these negative emotional and physiological factors can impact negatively on the rate of healing. Improving the quality of life of a patient should, therefore, be an important aspect of care and any technology which has the ability to improve clinical outcomes while also reducing patient pain with resulting effects on quality of life should be welcomed.

There is conflicting evidence currently in the literature describing the impact of NPWT on pain. This study has reported wound progression towards healing and a reduction in wound dimensions along with significant reductions in general wound pain (i.e. background wound pain not necessarily associated with dressing changes) during the course of gauze‐based NPWT compared with baseline. This is supported by several studies reporting reduced pain in wounds treated with NPWT compared with standard care 13, 14. Conversely, however, Fife et al. (27) reported that there was no difference in pain medication between diabetic foot ulcer patients treated with foam‐based NPWT or standard care.

An additional factor raised in this report relates specifically to the degree of pain experienced during cessation of therapy and removal of the gauze‐based NPWT dressing (dressing changes). By using negative pressure of −80 mmHg, a ‘lower’ level than the −125 mmHg level commonly used pain experienced during the initiation of therapy may be considerably reduced. Furthermore, pain levels were reportedly very low during dressing changes which was consistent with the observed low degree of damage to the underlying granulation tissue. It was possible to observe damage even in circumstances where pain may have been masked, for example where neuropathy or analgesic use were present, making it a less subjective measure than pain. Several previous assessments have cited pain during dressing changes as a disadvantage of NPWT 16, 17, however all of these studies refer to foam‐based NPWT. In addition, a randomised controlled trial comparing foam and gauze‐based NPWT showed that while clinical outcomes were similar, significantly lower levels of pain were reported in patients receiving gauze‐based NPWT compared with foam (23). The low levels of pain reported during dressing changes in this study suggest that gauze applied along with −80 mmHg may provide a relatively pain‐free treatment option. This concept may be of benefit when choosing an appropriate NPWT dressing for use in a patient with particular sensitivity to pain, or in particularly sensitive anatomical locations or where continued compliance with NPWT may be in question. It may also be a viable option to use a gauze‐based dressing at the beginning of therapy, to potentially reduce the amount of pain experienced during dressing changes at a time when the wound is most vulnerable to pain sensation or in response to a patient's complaints about pain during dressing changes. A decision could be made at later dressing changes to switch to foam‐based dressings when background wound pain has subsided and any pain experienced during dressing removal better tolerated. Further investigation is required to confirm the clinical benefit of these proposed clinical pathways.

Pain is dependent on many clinical variables including the presence of analgesic, neuropathy, paraplegia, sedation or anaesthesia. Future studies investigating pain during NPWT should ensure that information is collected pertaining to all of these factors, which describes the ability of the patient to experience pain. Further investigations into the effect of gauze‐based NPWT on other areas of patient quality of life are also warranted.

CONCLUSION

Minimal pain during therapy and during dressing changes was reported during treatment with gauze‐based NPWT. A principle reason for this may be that no damage to the granulating surface was observed in the majority of dressing changes. With a choice of NPWT dressings currently available, clinicians now are able to exercise informed decisions relating to the dressing material used tailored to each individual patient's unique needs. In the case of patients experiencing painful wounds, gauze‐based NPWT may be a viable option to maximise patient comfort.

ACKNOWLEDGEMENTS

The authors thank the following clinicians for contribution to this study: R. Dunn (Division of Plastic Surgery, UMASS Medical School, Worcester, MA), V. Vasquez (Laredo Medical Center, Laredo, Texas, USA), C. LaRosa (Virtua Health, New Jersey, US), D. Brokaw (OrthoIndy, Indianapolis, USA), P. Cancillieri (Community Medical Centre, Scranton, PA, USA), I. Reiss (South Miami Hospital Baptist Health System, Florida, USA), M. Despatis (Cape Breton Regional Hospital, Sydney, Nova Scotia, Canada), K. Leak (Doncaster & Bassetlaw Hospitals NHS Foundation Trust, UK), L. Jacks (Inverclyde Royal Infirmary, Scotland, UK), A. Johnstone (Glasgow Royal Infirmary, Scotland, UK), R. Robbins (Queen Margaret Hospital, Fife, Scotland, UK), Also, authors thanks Gary Smith, Alan Rossington for data handling and analysis, Jeanette Milne for co‐ordination of the European centers and Robin Martin for critical review of the article (Smith & Nephew, Hull, UK).