Negative Pressure Wound Therapy:Negative Pressure Wound Therapy:Vacuum of Evidence, Vacuum of Evidence,

Bountiful BiasBountiful Bias

John John StringhamStringham, MD, MD10/5/0910/5/09

Grand Rounds, UCHSCGrand Rounds, UCHSC

NPWT: A Paucity of True EvidenceNPWT: A Paucity of True Evidence

I: Speed of Wound HealingI: Speed of Wound Healing IaIa: Complete Healing of Wound: Complete Healing of Wound IbIb: Decreasing size of Wound: Decreasing size of Wound

II: Local wound effects: angiogenesis, bacterial II: Local wound effects: angiogenesis, bacterial load, decreased wound edema / removal of load, decreased wound edema / removal of exudateexudate

III: CostIII: Cost IV: Adverse OutcomesIV: Adverse Outcomes

NPWT: Problematic DataNPWT: Problematic Data

Very few RCT (15 reports, 13 trials)Very few RCT (15 reports, 13 trials) Issues:Issues:

Small sample sizeSmall sample size No allocation concealmentNo allocation concealment No blinding (Patient, Practitioner, Outcome No blinding (Patient, Practitioner, Outcome

Assessor)Assessor) Arbitrary outcome measures with no universal Arbitrary outcome measures with no universal

endpointsendpoints Use of saline gauze as only controlUse of saline gauze as only control Possible influence by medical equipment Possible influence by medical equipment

manufacturermanufacturer

NPWT: Complete Closure/Coverage NPWT: Complete Closure/Coverage of Woundof Wound

Braakenburg et al: All wound typesBraakenburg et al: All wound types Complete healing 16 days Complete healing 16 days

NPWT vs. 20 days control NPWT vs. 20 days control (p = 0.32)(p = 0.32)

No difference in change in No difference in change in percent granulation tissue percent granulation tissue (1.7 %/day NPWT, 1.6 %/day (1.7 %/day NPWT, 1.6 %/day conventional, p = 0.64)conventional, p = 0.64)

Used multiple modern wound Used multiple modern wound dressings (Alginate, dressings (Alginate, CutinovaCutinova--Foam, Foam, CutinovaCavityCutinovaCavity, etc.), etc.)

Problems: KCI funded, no Problems: KCI funded, no allocation concealment, nonallocation concealment, non--blinded, n = 47 blinded, n = 47

Braakenburg. Plast Reconstr Surg, 2006

NPWT: Complete Closure/Coverage of NPWT: Complete Closure/Coverage of Wound: Studies by Wound Type Wound: Studies by Wound Type

Vuerstaek et al: Chronic leg ulcers Vuerstaek et al: Chronic leg ulcers (venous, atherosclerotic, combined)(venous, atherosclerotic, combined) Complete healing: 29 days NPWT, 45 Complete healing: 29 days NPWT, 45

days conventional (p = 0.001)days conventional (p = 0.001) Problems: KCI funded, nonProblems: KCI funded, non--blinded, blinded,

use of saline gauze as controluse of saline gauze as control

McCallonMcCallon et al: Diabetic foot ulcerset al: Diabetic foot ulcers Complete healing 22.8 days in NPWT Complete healing 22.8 days in NPWT

vs. 42.8 in conventionalvs. 42.8 in conventional Problems: KCI funded, no allocation Problems: KCI funded, no allocation

concealment, nonconcealment, non--blinded, saline gauze blinded, saline gauze onlyonly

Vuerstaek. J Vasc Surg 2006McCallon. Ostomy Wound Manag 2000

Ford et al: Stage IIIFord et al: Stage III--IV IV DecubitusDecubitus UlcersUlcers Complete healing: 10% of NPWT Complete healing: 10% of NPWT

pts, vs. 13% of conservative pts, vs. 13% of conservative management (Healthpoint management (Healthpoint system)system)

Problems: KCI funded, control Problems: KCI funded, control pts older, n = 41pts older, n = 41

Armstrong et al: Acute Wounds Armstrong et al: Acute Wounds (foot amputation 2/2 DM)(foot amputation 2/2 DM) Complete Healing NPWT 56% Complete Healing NPWT 56%

vs. 39% conventional (p = 0.04)vs. 39% conventional (p = 0.04) Problems: KCI funded, nonProblems: KCI funded, non--

blindedblinded

NPWT: Complete Closure/Coverage NPWT: Complete Closure/Coverage of Wound: Studies by Wound Type of Wound: Studies by Wound Type

Ford. Ann Plast Surg 2002Armstrong. Lancet 2005

NPWT: Decrease in Wound Size:NPWT: Decrease in Wound Size:

Braakenburg et al: All wound typesBraakenburg et al: All wound types NPWT reduced wound size by 0.3 cmNPWT reduced wound size by 0.3 cm22/day /day vsvs 0.1 0.1

cmcm22/day conventional (p = 0.83)/day conventional (p = 0.83)

Ford et al: Diabetic Foot UlcersFord et al: Diabetic Foot Ulcers No significant difference (NPWT 51.8% vs. No significant difference (NPWT 51.8% vs.

Healthpoint 42.1% reduction in wound volume, p = Healthpoint 42.1% reduction in wound volume, p = 0.46)0.46)

Braakenburg. Plast Reconstr Surg 2006Ford. Ann Plast Surg 2002

NPWT: Local Wound Effects:NPWT: Local Wound Effects: Decreased wound edema: Decreased wound edema:

Multiple studies: decrease in Multiple studies: decrease in wound edema, increase in wound edema, increase in angiogenesisangiogenesis Thought to be due to decreased Thought to be due to decreased

tissue pressuretissue pressure KairinosKairinos et al: et al: Increased Increased change in change in

tissue pressure in tissues tissue pressure in tissues surrounding NPWT devicesurrounding NPWT device Dangerous implications in tissue Dangerous implications in tissue

with compromised perfusionwith compromised perfusion No KCI fundingNo KCI funding

Increased tissue oxygenation:Increased tissue oxygenation: KairinosKairinos et al: et al: DecreasedDecreased partial partial

pressure of oxygenpressure of oxygen

Kairinos. Plast Reconstr Surg 2008 (I)Kairinos. Plast Reconstr Surg 2008 (II)

Bacterial load in wound:Bacterial load in wound: BraackenburgBraackenburg et al: et al: IncreasedIncreased

bacterial load in NPWT bacterial load in NPWT (85%) (85%) vsvs in conventional in conventional therapy (58%)therapy (58%)

Moues et al: No difference Moues et al: No difference in bacterial load between in bacterial load between NPWT and conventional NPWT and conventional (saline gauze) (saline gauze) txtx groupsgroups NPWT had decreased nonNPWT had decreased non--

lactose fermenting GNR, lactose fermenting GNR, increased increased StaphStaph aureusaureus

NPWT: Local Wound Effects:NPWT: Local Wound Effects:

Braakenburg. Plast Reconstr Surg 2005Moues. Wound Rep Regen 2004.

NPWT: CostNPWT: Cost Moues et al: Moues et al:

Significantly higher material cost in NPWT vs. conventional Significantly higher material cost in NPWT vs. conventional therapy ($601 therapy ($601 vsvs $21, p < 0.0001)$21, p < 0.0001)

No significant difference in total cost ($3249 vs. $3728)No significant difference in total cost ($3249 vs. $3728) Study funded by KCIStudy funded by KCI

Vuerstaek et al: Vuerstaek et al: Conventional dressing total cost significantly more expensive Conventional dressing total cost significantly more expensive

than NPWT ($5452 vs. $3881, p = 0.001)than NPWT ($5452 vs. $3881, p = 0.001) Study funded by KCIStudy funded by KCI

Braakenburg et al:Braakenburg et al: Total greater for NPWT ($513) vs. conventional ($396)Total greater for NPWT ($513) vs. conventional ($396)

Moues. J Wound Care 2005Vuerstaek. J Vasc Surg 2006Braakenburg. Plast Reconstr Surg 2005

NPWT: Adverse EventsNPWT: Adverse Events Braakenburg et al:Braakenburg et al:

Discontinuation of NPWT 2/2 painDiscontinuation of NPWT 2/2 pain Pressure sore associated with wound therapy Pressure sore associated with wound therapy

hosehose Erosion of wound edges 2/2 misplaced spongeErosion of wound edges 2/2 misplaced sponge

Vuerstaek et al:Vuerstaek et al: 40 % of pts with NPWT 40 % of pts with NPWT vsvs 23% with 23% with

conventional therapy developed complicationsconventional therapy developed complications Increased recurrence of chronic leg ulcers in Increased recurrence of chronic leg ulcers in

NPWT group (52%) vs. control (42%)NPWT group (52%) vs. control (42%) Moues et al:Moues et al:

2 pts with sepsis vs. 0 in conventional therapy2 pts with sepsis vs. 0 in conventional therapy Retained sponge leading to severe sepsisRetained sponge leading to severe sepsis

Beral et alBeral et al Saeed et alSaeed et al

Braakenburg. Plast Reconstr Surg 2005Vuerstaek. J Vasc Surg 2006Beral. BMJ 2009Saeed. Int J Low Extrem Wounds 2007

NPWT: A Conclusion:NPWT: A Conclusion:

““At present there is no worthwhile At present there is no worthwhile evidenceevidence to to support the use of TNP [Topical Negative support the use of TNP [Topical Negative Pressure] in the treatment of various wounds. A Pressure] in the treatment of various wounds. A far more rigorous evaluation is needed, largely in far more rigorous evaluation is needed, largely in the form of the form of RCTsRCTs. Until this has been . Until this has been completed, the use of TNP should not become completed, the use of TNP should not become routine or be reimbursed for local wound care.routine or be reimbursed for local wound care.””

Ubbick et al. British Journal of Surgery, 2008

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