immediately closed. Wounds were treated with either a foam-based system or one of two gauze-based systems.
The use of multiple variants of NPWT systems was the result of inconsistent availability as opposed to a deliberate, controlled choice by the authors. Although no significant difference was identified between system types( p = 0.98), the use of multiple systems and the absence of a control group demonstrate examples of poor study standardisation.
Wound outcome was the primary variable measured, alongside complications associated with NPWT, including pressure loss and damage to tubing due to patient interference. The incidence of complications decreased as staff gained experience with NPWT system application and management, highlighting the importance of appropriate training prior to study commencement.
Overall, 96 % of wounds healed. Two patients died before definitive wound closure, with the deaths being attributed to significant concurrent comorbidities including systemic infection, shock, coagulopathy, and thoracic and neurological trauma. Another dog had significant necrotising wounds due to envenomation and, despite the wound responding well to NPWT, surgical reconstruction failed, leading to amputation of the affected forequarter. The inclusion of patients with severe comorbidities brings into question the lack of clear and robust exclusion criteria. Furthermore, the study lacked a pre-established sedation protocol, leading to variations in the drugs used for sedation at dressing changes, affecting the direct comparability of the results.
Despite these limitations, Pitt and Stanley [ 15 ] conclude that NPWT is well tolerated by canine patients and optimises the wound bed for closure, whether surgically or through second-intention healing. While the study demonstrates positive outcomes for a wide range of cases, its limitations, including poor standardisation and the absence of a control variable, temper the strength of these conclusions, highlighting the need for further controlled research.
A 2015 pilot study by Perry et al. [ 16 ] involved both canine( n = 13) and feline( n = 7) patients, and assessed the effect of postoperative NPWT application in relation to limb circumference and wound discharge following either the stabilisation of high-energy fractures in the distal limb or arthrodesis. Inclusion was narrowed to these specific surgeries as both are localised to the distal limb and can be considered to involve‘ high-risk’ surgical wounds in which wound dehiscence is common. This narrowing minimises variability among cases, allowing the collection of more comparable data with a smaller sample size.
Patients were randomly assigned to either the NPWT or the control group. Both treatments consisted of a modified Robert-Jones dressing for 72 hours, with the
NPWT group additionally receiving vacuum therapy for the first 24 hours. Six measurement sites were assessed morphometrically at 24 and 72 hours postoperatively, and percentage changes were calculated. Wound discharge was also assessed, and pain scoring was conducted throughout. Pain management was well standardised, although the protocol was adjusted in seven cases( escalated: n = 2 control, n = 1 NPWT; de-escalated: n = 1 control, n = 3 NPWT) to ensure optimal patient welfare.
Perry et al. [ 16 ] reported a significant reduction in swelling at all but two measurement sites at both 24 and 72 hours postoperatively in the NPWT group, excluding the joint proximal to the surgical site and the mid-bone measurement at 72 hours. There was also a significant reduction in wound discharge in the NPWT group at 24 hours postoperatively( p = 0.009). There was no significant difference between the groups in reported pain levels, although over one-third of patients had altered pain-management protocols.
This study used a robust, well-controlled methodology, but its small and mixed-species sample population limits the strength of its results. Additionally, the short( 24-hour) duration of NPWT application necessitates further research into longer-term application. Nonetheless, the findings of Perry et al. [ 16 ] support the growing evidence base for the use of NPWT in canine patients, particularly when managing high-risk surgical wounds.
Further evidence was provided by Nolff et al. [ 17 ]. Their retrospective paired analysis compared the progression of paired wounds( n = 50), consisting of wounds treated with either conventional bandages( group A), NPWT( group B) or silver-coated foam dressings( SCFDs)( group C). Wounds were paired between groups, although pairing was not possible between groups A and B due to heterogeneity of wound parameters.
Although retrospective research is considered weaker, due to its inherent uncontrolled variables, it has been suggested that study design plays a larger role in the strength of a clinical study [ 18 ]. Nolff et al. [ 17 ] incorporated well-designed inclusion criteria to maximise available data, including information on dressing changes, time to closure and a minimum 14-day follow-up. However, records were collected from two different hospitals, which may have introduced variability in dressing application and management preferences. Additionally, although the use of a paired study design allows greater comparability, it highlights the limitations of retrospectivity, as it becomes harder to pair wounds based on second-hand data.
Nolff et al. [ 17 ] found that, on average, wounds in the NPWT group closed significantly faster than paired wounds treated with SCFDs( 15.7 days vs 29.9 days; p = 0.02). Wounds treated with SCFDs also closed faster than paired wounds treated with conventional dressings( 14.4 days vs 33.7 days; p = 0.003). A wide variety
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