Burns

114 children randomised. Ten discontinued early, which the authors attribute to the treatment burden of NPWT.

CAT: OCEBM 1 · START HIGH — a prospectively registered, randomised, single-centre trial with blinded photographic outcome assessment, which is the hardest thing to achieve in NPWT research and is the reason most of this literature is downgraded. NOT downgraded for risk of bias on the primary outcome: allocation was randomised and the assessor could not see which arm a photograph came from. MINUS 1 for imprecision and single-centre conduct: 114 children in one unit, with the primary estimate a 22% reduction in expected time to closure whose interval runs from 7% to 34% — a wide band around a real effect. MINUS nothing for indirectness WITHIN its population and EVERYTHING for indirectness outside it: small-area thermal burns in children have no counterpart in an adult vascular caseload. NET MODERATE for the population studied. The scar-referral outcome is rated lower, at Low: a 60% relative reduction with an interval of 18 to 81% is a secondary endpoint with few events, referral is a clinician decision rather than a measured state, and it was not the trial's primary question.

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Every figure in the GRADE table reconciles (recomputed). 10/266 = 3.76 per cent against a printed 3.8 ✓; 26/247 = 10.53 against 10.5 ✓; 41/346 = 11.85 against 11.8 ✓; 55/321 = 17.13 against 17.1 ✓. The absolute effects reconcile too, converting each odds ratio against the control risk: infection 91 fewer per 1,000 (103 fewer to 12 fewer) — recomputed 91.1, 102.7 and 12.4 ✓; overall complications 63 fewer per 1,000 (139 fewer to 138 more) — recomputed 62.5, 139.2 and 138.2 ✓. The arithmetic of this paper is sound. Its inferences are not.

The infection estimate is far more extreme than its own raw counts. Crude, unweighted, the odds ratio recomputed from 10/266 against 26/247 is 0.33. The pooled random-effects estimate is 0.12, with I² of 78 per cent across two studies — one of which shares its title with the other. The distance between 0.33 and 0.12 is entirely a product of how two heterogeneous studies were weighted.

The two subgroups a clinician would actually act on are both null. Adding NPWT to a split-thickness skin graft made no difference (SMD 0.63, −0.86 to 2.13, I² 86 per cent), and adding NPWT to a dermal-substitute-plus-graft construct made no difference (SMD 0.20, −0.40 to 0.79). The significant subgroups are the ones in which NPWT replaces something rather than being added to it — NPWT against a dermal substitute alone, or against a conventional dressing alone. The abstract reports only the pooled 2.62 and the review's own Conclusion recommends incorporation into burn guidelines.

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CAT: OCEBM 1 · START HIGH — a meta-analysis of randomised trials. −2 risk of bias, which is a full two-step downgrade and is deliberate. By the review's own section 4.5, allocation concealment was at LOW risk in ONE of six trials, unclear in one and high in the remaining four; blinding of participants and personnel was at low risk in NONE; blinding of outcome assessment was at low risk in ONE. Two of the six are Chinese-language reports, one of which is a single-page entry in an electronic literature journal attributed to a surname with no initials. And two of the six carry the identical title, raising a duplicate-publication question the review never asks. −1 inconsistency for the primary outcome. I-squared is 94 per cent for the overall graft-take estimate and 86 per cent for the split-thickness-graft subgroup. The GRADE table rates this 'not serious'. −1 indirectness of the pooled comparison. The overall graft-take estimate combines four different contrasts with four different comparators — dermal substitute alone, split-thickness graft alone, conventional dressing, and graft plus dermal substitute — into one number, which is not an estimate of any single clinical decision. −1 imprecision for the two complication outcomes. Infection rests on two studies, of which one has an identical title to the other, with 36 events in total; overall complications on four studies with 96 events and an interval running from 0.16 to 2.17. Net very low for all three outcomes. The direction is plausible and should be said: NPWT probably improves early graft take on a burn wound and probably does not increase complications, which is consistent with the wiki's separate skin-graft evidence. What this paper cannot support is a magnitude — A standardised mean difference of 2.62, let alone the subgroup value of 8.52, is not a credible effect size for a graft-take percentage and is an artefact of pooling trials that report standard deviations of 1.0 and 0.3.

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Every pooled estimate reproduced exactly by a hand-coded DerSimonian-Laird routine — the meta-analytic arithmetic is sound. What does not survive is the interpretation.

Converted to natural units, healing time is a pooled mean difference of −3.73 days (−5.40 to −2.06), I² 97.3%, with study-level differences from −10.7 days to +0.6 days.

CAT: OCEBM 1 · Start HIGH (meta-analysis of randomised trials). -1 risk of bias: Thirteen of fourteen pooled comparison entries used Chinese vacuum sealing drainage OR improvised suction rather than a commercial regulated NPWT system, at pressures printed anywhere from 0.02 kPa to -53 kPa, including one arm where 'no external negative pressure was needed'; two included designs do not meet the review's own randomised-only eligibility criterion, one being indexed as a comparative study with a historical control and self-assigning Level IV, and the other describing a SINGLE-ARM SERIES in its own abstract while being entered as 25 against 25, the same 25 children before and after; and blinding is low-risk in only two studies for participants and personnel and three for outcome assessment. -1 inconsistency: I-squared runs from 68% to 98.4%, and the review's single attempted subgroup analysis did not explain it. -1 indirectness: the device conflation above means the pooled estimates do not describe the therapy a South African motivation would fund. Net LOW for healing time and dressing changes, which are the two outcomes that reproduce, hold in every leave-one-out permutation and are large. For the other four outcomes there is nothing to GRADE, because they are null and are reported as significant. Recomputed effect p-values: healing rate 0.059, positive bacteria 0.269, adverse reactions 0.110, treatment costs 0.487. And the cost result is inverted - SMD +0.92 means costs were HIGHER in the NPWT arm, and the abstract lists it among 'significant reductions' while the Results text says NPWT 'significantly reduced costs'. It is neither a reduction nor significant.

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Two separate operations, two separate endpoints, the same answer: −80 mmHg beats −125 mmHg.

This vault has argued the low-pressure position from Evangelista 2013 (>95% take at 50–125 mmHg), Nakamura 2018 (50 mmHg) and Mowers 2026 (contraction rises with pressure).

Huang adds something none of those supply: a comparative clinical finding, in humans, at scale, from an independent guideline panel — that the higher setting is not merely unnecessary but does not work as well.

CAT: OCEBM 1 (national consensus guideline with GRADE appraisal and registered protocol) / GRADE not applicable to a guideline as a whole — AGREE II applied. The guideline's own per-recommendation Evidence Levels and Recommendation Strengths are reported verbatim below · GRADE is not the instrument for a guideline and must not be applied to it as a whole — AGREE II IS, and it is set out below. What can be reported is the guideline's own grading of each recommendation, which it states transparently. The recommendations this vault will actually use: vascular reconstruction and interventional procedures — prophylactic NPWT recommended to reduce inguinal SSI, evidence level II, recommendation strength b, covering endovascular aortic repair, thoracic endovascular aortic repair and lower extremity revascularisation, with the explicit limitation that against conventional dressings NPWT shows NO significant difference in readmission, 30-day mortality, antibiotic cost or length of stay. Skin graft and tendon OR bone exposure — artificial dermis with NPWT then split-thickness graft in two stages, evidence level i, strength a. Sternal — NPWT for sternal infection promotes healing, reduces mortality and shortens stay, LEVEL II STRENGTH B; prophylaxis in cardiac surgery level II strength b. Diabetic foot — recommended with strict pressure monitoring at 50 to 100 mmHg, level i strength a, and current evidence does not support irrigated over non-irrigated NPWT. Abdominal surgery — reduces SSI and seroma but NOT wound-healing problems, seroma formation or readmission, level II strength b. Pressure injuries — LEVEL III STRENGTH C, the weakest recommendation in the document and correctly graded so. The document's central contribution to this vault is the two convergent pressure comparisons favouring minus 80 over minus 125 mmHg, described in the integrity note.

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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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