TABLE 1.
Summary of preclinical studies
| Reference | Model | Treatment | Methods | Sample size | Timing of Evaluation | Results |
|---|---|---|---|---|---|---|
| Glaser 2012 18 | Porcine | iNPWT (3 or 5 days, but reported as one group) vs SSDs in two spinal incisions. Used Prevena dressings (manufactured by 3M/KCI). | Biomechanical testing (wound strength measurement), histological evaluation of excised wounds, and modified VSS assessment on POD 3 and 5 | N = 8 | POD 3 or 5 but reported as one group | VSS: decreased scar height with iNPWT* |
| Biomechanical testing: increased failure load (4.9, SD 4.0 vs 16.5, SD 14.6 N), energy absorption (8.0, SD 9.0 vs 26.9, SD 23.0 mJ), and ultimate stress capacity (62, SD 53 vs 204, SD 118 N/mm2) | ||||||
| Histology: decreased scar width (236 vs 93 μm) | ||||||
| Kilpadi 2014 17 | Porcine | iNPWT vs SSDs of four pairs of dorsal incisions. Used Prevena dressings (manufactured by 3M/KCI). | Biomechanical testing, histological evaluation of excised wounds on day 40 (n = 12 pairs/group), biopsy for gene‐expression analysis on days 5 (n = 6 pairs/group), 20 (n = 6 pairs/group), and 40 (n = 12 pairs/group) | N = 6 | POD 40 | Histology: More narrow deep dermal scar (1000, SE 131 vs 1313, SE 138 μm), similar upper dermal scar width (605, SE 72 μm vs 645, SE 78 μm) |
| Improved mechanical properties* (strain energy density: 0.21, SE 0.04 N/mm2 vs 0.15, SE 0.02 N/mm2, peak strain: 0.23, SE 0.02 vs 0.18, SE 0.01) | ||||||
| Less upregulation of genes associated with inflammation, hypoxia, retardation of reepithelialization, impaired wound healing and scarring with iNPWT | ||||||
| Shah 2019 19 | Porcine | iNPWT vs inactive iNPWT or a SSD of 3 dorsal incisions and 1 untreated skin area. Used GranuFoam dressings (manufactured by 3M/KCI). | Blinded SBSES, immunohistochemical VEGF assessment, ELISA VEGF assessment | N = 9 | POD 8 | SBSES: improved scar width compared to SSDs* (0.94, SE 0.04 vs 0.47, SE 0.09,), improved scar height compared to inactive iNPWT (0.97, SE 0.03 vs 0.69, SE 0.08), improved color compared to SSDs* (0.91, SE 0.05 vs 0.60, SE 0.09), improved overall appearance compared to SSDs* (0.94, SE 0.04 vs 0.53, SE 0.09) and inactive iNPWT* (0.94, SE 0.04 vs 0.66, SE 0.09). Improved total SBSES score (3.75, SE 0.09) compared to SSDs* (2.38, SE 0.26) and inactive iNPWT* (2.78, SE 0.22) |
|
Immunohistochemistry: Increased VEGF and Factor VIII staining | ||||||
| ELISA: 2.8% vs 1% VEGF* | ||||||
| Suh 2016 16 | Porcine | iNPWT vs SSDs with 2 spinal incisions. Used CuraVAC dressings (manufactured by Daewoong Pharmaceutical Co., Ltd) | Laser Doppler imaging perfusion assessment on days 4, 7, and 21, tensile strength and histology assessment on days 7 and 21 | N = 6 | 4, 7, and 21 | Increased tensile strength at POD 7 (24.6 vs 18.26 N) and POD 21* (61.67 vs 50.05 N) |
| Laser Doppler Imaging: Improved perfusion on days 4*, 7*, and 21* | ||||||
|
Histology: Improved collagen deposition and angiogenesis | ||||||
| Wilkes 2012 12 | Computer model | Prevena model (manufactured by 3M/KCI) | FEA1 (computer model of an incision with a subcutaneous void), FEA2 (computer model of incision with fascial separation), bench testing (synthetic skin model) | NA | NA | FEA1: reduced lateral tension at skin level (from 2.2‐2.5 to 0.9‐1.2 kPa, about 50%) |
| FEA2: decreased lateral stress in epidermis* (28.05, SE 1.98–14.82 kPa, SE 0.58 kPa) and dermis (14.50, SE 0.08–15.34, SE 0.15), decreased shear stress in epidermis* (3.67, SE 0.14–0.12 kPa, SE 0.11 kPa), dermis* (2.16, SE 0.20–0.38 kPa, SE 0.26 kPa), and fat* (1.08, SE 0.27–0.04 kPa, SE 0.01 kPa) | ||||||
| Biomechanical testing: More force needed for disruption of incisions treated with iNPWT* (from 61.7, SE 0.3–92.9 N, SE 2.6 N, a 51% increase) | ||||||
| Loveluck 2016 20 | Computer model | PICO (Manufactured by Smith & Nephew) | FEA (computer model), bench testing (synthetic skin model) | NA | NA | FEA: Reduced force on individual sutures from 1.31 to 0.56 N (43%) and from 1.31 to 0.40 N (31%) with −40 and − 80 mmHg of subatmospheric pressure |
| Biomechanical testing: −80 mmHg resulted in a 55% increase of the amount of force required for incisional deformation |
Abbreviations: ELISA, enzyme‐linked immunosorbent assay; FEA, finite element analysis; iNPWT, incisional Negative Pressure Wound Therapy; POD, postoperative day; SBSES, Stony Brook Scar Evaluation Scale; SSD, standard surgical dressing; VEGF, vascular endothelial growth factor; VSS, Vancouver Scar Scale.
*
Statistically significant result (P < .05).