Shuler, Michael S.

Background. Negative pressure wound therapy promotes wound healing through fluid removal, edema reduction, and mechanical contraction. A novel thermoplastic elastomer (TPE) dressing has been developed to improve exudate evacuation and reduce tissue ingrowth, but its effect on wound contraction compared with reticulated open cell foam (ROCF) remains unclear. Objective. To compare the degree of wound contraction with the TPE dressing, ROCF, or no filler at different wound depths and negative pressure settings in a porcine explant model. Materials and Methods. The effect of the materials or lack thereof on wound contraction was investigated at 2 wound depths (shallow, deep) and 3 negative pressure settings (−50 mm Hg, −80 mm Hg, and −125 mm Hg). Wound width was measured at 3 standardized locations before and during therapy. Univariable and multivariable linear regression analyses were performed to identify factors associated with contraction. Results. A total of 810 measurements were obtained. Both the TPE dressing and ROCF demonstrated statistically significantly greater contraction than no filler. In deep wounds, greater contraction was noted with the TPE dressing compared with ROCF. Higher negative pressure and increased wound depth were independently associated with greater contraction. Absolute differences in contraction between dressings were small (<3 mm across all conditions). Conclusion. The TPE dressing provides equivalent or greater wound contraction compared with ROCF, particularly in deep wounds, without impairing macrodeformation. Given the small magnitude of differences, the clinical relevance of this finding likely depends on additional factors, which should be evaluated in future in vivo studies.

ABSTRACT Negative pressure wound therapy relies on suction, commonly set to −125 mmHg, to evacuate wound fluid, but dysvascular and pressure injuries often respond unpredictably. Newton's third law indicates that negative pressure applies an equal and opposite contact pressure on the wound surface, and this study quantified this contact pressure across dressing types, wound configurations and suction levels. Using a porcine explant model, central and peripheral contact pressure measurements were obtained beneath black reticulated open cell foam, white foam and a novel thermoplastic elastomer dressing across plexiglass, intact skin, shallow and deep wounds under −50, −75 and −125 mmHg. Contact pressure increased proportionally with negative pressure, and multivariable modelling demonstrated that dressing type, wound type and suction level significantly influenced pressure, with negative pressure explaining most of the variance (0.77 and 0.68). Thermoplastic elastomer at −50 mmHg in deep wounds produced the lowest contact pressure, whereas black reticulated open cell foam and white foam at −125 mmHg generated elevated contact pressures of approximately +125 to +195 mmHg. These findings show that black reticulated open cell foam at conventional −125 mmHg can create hypoperfusion conditions, whereas thermoplastic elastomer consistently produces the lowest pressures and may enhance perfusion at lower suction levels, offering a physiologic explanation for improved clinical outcomes in dysvascular and pressure injuries treated with reduced negative pressure.

AimsThe aim of this study was to evaluate near-infrared spectroscopy (NIRS) as a continuous, non-invasive monitor for acute compartment syndrome (ACS).Patients and MethodsNIRS sensors were placed on 86 patients with, and 23 without (controls), severe leg injury. NIRS values were recorded for up to 48 hours. Longitudinal data were analyzed using summary and graphical methods, bivariate comparisons, and multivariable multilevel modelling.ResultsMean NIRS values in the anterior, lateral, superficial posterior, and deep posterior compartments were between 72% and 78% in injured legs, between 69% and 72% in uninjured legs, and between 71% and 73% in bilaterally uninjured legs. In patients without ACS, the values were typically > 3% higher in injured compartments. All seven limbs with ACS had at least one compartment where NIRS values were 3% or more below a reference uninjured control compartment. Missing data were encountered in many instances.ConclusionNIRS oximetry might be used to aid the assessment and management of patients with ACS. Sustained hyperaemia is consistent with the absence of ACS in injured legs. Loss of the hyperaemic differential warrants heightened surveillance. NIRS values in at least one injured compartment(s) were > 3% below the uninjured contralateral compartment(s) in all seven patients with ACS. Additional interventional studies are required to validate the use of NIRS for ACS monitoring. Cite this article: Bone Joint J 2018;100-B:787–97.