Pressure injuries

The finding is the absence of findings, and it is worth setting out plainly.

• Complete wound healing: one usable trial, 12 participants, one healed patient in total. RR 3.00 (95% CI 0.15–61.74). Very low certainty. That interval is the arithmetic of a single event.
• Adverse events: RR 1.25 (95% CI 0.64–2.44), very low certainty — no evidence of a difference.
• Changes in ulcer size, ulcer severity, cost and PUSH scores were reported, but no conclusions could be drawn.
• One trial compared NPWT with a series of gel treatments and provided no usable data; one compared it with moist wound healing and reported no primary outcome data; one combined NPWT with internet-plus home care and reported no primary outcome data.
• None of the eight trials reported time to complete healing, health-related quality of life, wound infection, or wound recurrence.

Authors' conclusion: the efficacy, safety and acceptability of NPWT for pressure ulcers are uncertain. NPWT may speed reduction in ulcer size and severity, reduce pain and reduce dressing-change frequency, but trials were small, poorly described, short and at high risk of bias, and "any conclusions drawn from the current evidence should be interpreted with considerable caution."

CAT: OCEBM 1 · The review applies GRADE and rates EVERY outcome very low; this appraisal adopts that and has no basis to disagree. Start High as a Cochrane review of randomised trials, then: −1 risk of bias (six of eight trials at high risk in one or more domains); −2 imprecision (327 participants across eight trials, median 37, and the single usable complete-healing analysis has 12 participants and one event, giving RR 3.00 with an interval of 0.15 to 61.74); −1 indirectness and incompleteness of outcome reporting (four of eight trials contributed no usable primary outcome data, and NO trial reported time to complete healing, health-related quality of life, wound infection or recurrence). VERY LOW, and the rating understates how little is here — this is closer to an absence of evidence than to weak evidence. The correct use of this page is to decline an indication, not to support one.

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"Is negative-pressure wound therapy recommended for the treatment of pressure ulcers?"

Search yield: 90 records screened, 87 excluded, three randomised trials included.

Panel reasoning, verbatim: "Certainty of evidence was very weak because of Risk of bias and Indirectness of evidence… Difficulty in blinding resulted in risk of bias. Thus, the guideline panels proposed to perform negative-pressure wound therapy in the treatment of Stage III or Stage IV pressure ulcers."

One positive primary result was excluded from both meta-analysed outcomes. The one trial reporting a significant benefit — 50% area reduction reached in 2.0 versus 3.5 weeks, p < 0.001 — sits outside the analysis because the panel ranked reduction rate as a less important outcome than cure and adverse events. No sensitivity analysis was performed.

CAT: AGREE II appraisal — recommendation for NPWT is WEAK with VERY WEAK certainty by the guideline's own GRADE · This is a guideline and produces a recommendation rather than an effect estimate, so the wiki records the guideline's own grading and appraises the development with AGREE II. THE NPWT RECOMMENDATION: 'We propose to perform negative-pressure wound therapy in the treatment of Stage III and Stage IV pressure ulcers.' Strength WEAK, certainty VERY WEAK, voting count 7 of 7. The evidence under it is null: cure rate RR 1.09 (0.23-5.26) from two randomised trials and five events in total; adverse events RR 1.20 (0.66-2.17) from three trials. The panel states plainly that certainty was very weak for risk of bias and indirectness, and recommends weakly regardless. This wiki accepts that grading unchanged and regards the behaviour as correct: a weak recommendation with an explicit very-weak certainty is the right output from two trials and five events. Note one distortion: the single trial reporting a significant benefit - 50% area reduction at 2.0 versus 3.5 weeks, p<0.001 - falls outside both meta-analysed outcomes because the panel ranked area reduction as less important than cure and adverse events, and no sensitivity analysis was run.

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Three things in that table are wrong on their face.

First, the abstract misprints the only marginally significant result. It gives "RR=1.32; 95% CI: 1.32-1.70" — an interval whose lower bound equals its point estimate, which cannot happen. Figure 3a gives the real interval: 1.03 to 1.70. Anyone quoting the abstract quotes an impossible number, and the correction matters, because 1.03 is a lower bound that barely clears the null.

Second, the healing result is not robust and the paper says it is. The leave-one-out plot in Figure 3c has an axis running down to a lower confidence limit of 0.97: at least one omitted trial takes the pooled effect across the null. The text says "Sensitivity analysis showed the result was robust". It also says "Articles of Ali and Wang were the sources of heterogeneity" — in an analysis with I² = 0.0%, p = 0.492, where there is no heterogeneity to have a source.

Third, the two enormous standardised mean differences are protocol artefacts. An SMD of −3.61 means the arms are separated by three and a half pooled standard deviations. Table 1 shows why: NPWT dressings were changed every 5 to 7 days, standard dressings once or twice daily, by protocol in nearly every trial. That is not a treatment effect on a biological variable; it is the definition of the two interventions being re-measured as an outcome. The same applies to healing time, where the review's own subgroup analysis shows the estimate moving from −17.42 days where healing meant "complete scab" to −6.39 days where it meant "growth of fresh granulation" — a threefold difference produced entirely by what the word "healed" was taken to mean.

CAT: OCEBM 1 · START HIGH as a meta-analysis of randomised trials, then downgrade on every domain. −2 risk of bias: only 4 of 16 trials describe a randomisation method; the other 12 merely use the word. No trial reports allocation concealment — the review states plainly that 'no study mentioned blind allocations'. No trial is blinded, and the outcomes are pain scores, healing judged by eye and dressing counts, all of which are assessor-dependent. And one included trial is retracted. −2 INCONSISTENCY: I-squared is 98.2% for healing time, 93.5% for pain, 90.7% for cost and 85.4% for dressing-change frequency. The one analysis with I-squared of 0% is the healing rate, and the paper contradicts itself there by naming two studies as 'the sources of heterogeneity' in an analysis with no heterogeneity. −1 imprecision and publication bias: 629 patients across 16 trials is a mean of 39; three studies carry the entire cost result and three carry the entire pain result; and the paper states that its own funnel plot 'showed the evidence of publication bias' for healing time, then draws the conclusion anyway. Net very low. The healing result is not robust and the paper says it is. Figure 3a gives RR 1.32 (95% CI 1.03 to 1.70) — the lower bound is 1.03, so significance is marginal — and the leave-one-out plot in Figure 3c has an axis running down to a lower confidence limit of 0.97, meaning at least one omitted study takes the pooled effect across the null. The text says 'sensitivity analysis showed the result was robust'. THE SMD OF −3.61 for dressing changes and −2.55 for cost are not credible as effect sizes. A standardised mean difference of 3.6 means the two groups are separated by three and a half pooled standard deviations, which in clinical research almost always signals that the standard deviations are wrong, that the outcome is a count rather than a distributed measure, or that protocol and not biology fixed the difference — and here it is the last of those: NPWT dressings were changed every 5 to 7 days by protocol and standard dressings once or twice a DAY, so the 'effect' is the protocol. The cost result is the weakest of all: three Chinese-language trials, I-squared 90.7%, a leave-one-out upper limit of −0.04 that all but touches zero, an SMD that cannot be converted back into money, and hospital cost structures with no bearing on South Africa.

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Both ulcers were Stage 4 after debridement, with tendon loss and no bone involvement.

CAT: OCEBM 4 · Two wounds in one patient, not randomised, unequal at baseline, with no conflict statement from a paper that promotes the comparator dressing. The area reductions (77.8% superabsorbent vs 70.8% NPWT over 8 weeks) are too few and too confounded to compare. Its value is a South African cost figure — NPWT with foam for a trochanteric pressure injury about R25,740 for 8 weeks (average of four SA suppliers, 2015) against R6,280 for the superabsorbent dressing — and the practical point that NPWT needs electricity and a skilled person to change it.

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• Four core mechanisms of action underpin every indication: (1) reduces tissue oedema; (2) increases granulation tissue formation; (3) increased perfusion as a secondary/later effect; (4) with instillation and dwell time can reduce wound contamination.
• Vascular surgery: high-level evidence supports NPWT for infected vessels and prosthetic vascular grafts — strong recommendation for high-risk surgical patients with a fully exposed, infected prosthetic vascular graft, together with debridement and appropriate antibiotics; continuous suction at lower levels (-50 to -100 mmHg) recommended to avoid bleeding.
• Traumatic/surgical wounds: NPWT is first-line for preoperative wound-bed preparation post-debridement, typically 7-10 days before definitive surgery; strong for open fractures that cannot be closed primarily (used between debridement and reconstruction); caution when tendon/bone exposed; do not use if underlying arterial impairment is not addressed (red).
• Diabetic foot ulcers: first-line post-surgical treatment for DFU once ischaemia is excluded (University of Texas Grade A2/A3); consider for chronic DFU not progressing after 4 weeks; contraindicated where ischaemia is due to concomitant peripheral arterial disease (red).
• Sternal dehiscence: NPWT is the method of choice for post-sternotomy mediastinitis (strong); caution in the haemodynamically unstable patient; the open sternum with exposed vulnerable structures is not an indication (red).
• Abdominal / dehisced abdominal wounds: strong for the open abdomen and for dehisced wounds with intact abdominal wall; NPWT with instillation (NPWTi-d) is effective in reducing infection in the infected open/dehisced abdomen (moderate); do not use if size/severity does not merit it.
• Skin grafts, burns, venous ulcers, pressure injuries, enterocutaneous fistulae: NPWT endorsed for wound-bed optimisation before grafting and intra-operative graft stabilisation; acute burn indications supported but not a substitute for grafting; venous ulcers only if <30% area reduction in 4 weeks and ABPI 0.8-1.2 (contraindicated if ABPI <0.6); NPIAP stage 3/4 pressure injuries until surgical closure (moderate); ECF in selected collapsible/low-output cases only, never in unexplored fistulae.
• Closed incisional NPWT (ciNPT): recommended to decrease wound complications, dehiscence, haematoma/seroma and surgical site infection (strong).
• Contraindications listed: clotting disorders, active non-capillary bleeding post-debridement, exposed organs/vasculature/anastomoses, eschar or dry necrosis, neoplastic tissue, untreated osteomyelitis, non-enteric and unexplored fistulae.

AGREE II: Recommended with modifications — Scope 67% · Stakeholders 56% · Rigour 23% · Clarity 67% · Applicability 46% · Independence 25%

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