Comparison of Negative Pressure Wound Therapy (NPWT) Systems with Wound Pressure-Regulating Technology (PRT): Ability to Maintain Target Pressure Under Varying Test Conditions

Introduction: The ability of NPWT systems to deliver target negative pressure (NP) is challenged by complexities in moving exudate and air from the wound to the therapy unit. Wound PRT monitors wound pressure and adjusts system parameters to ensure set therapy is being administered and fluid is being removed. This regular, controlled system assessment evaluates the potential for exudate pooling by measuring delivered NP and is important when the therapy unit is placed higher than the wound due to the effects of gravity. 
Objective: Evaluate ability of NPWT systems to maintain target pressure under various test conditions. 
Materials and Methods: Three PRT-based NPWT systems (NPWT-A◊, NPWT-B◊◊, NPWT-C◊◊◊) were tested (three units x three dressings each). Tests were performed at clinically relevant target pressures (-75, -125 mmHg), with the units at 36” above the dressing and with a fluid bolus (60 mL) and simulated exudate added to the system (43 mL/hr). Pressures at each condition were assessed for one hour. Standard statistical methods were utilized. 
Results/Discussion: NPWT-A◊ and NPWT-B◊◊ systems maintained average pressures within ±10 mmHg of the target pressure while the NPWT-C◊◊◊ systems did not. At a target pressure of -75 mmHg, the average pressure maintained for NPWT-A◊ systems was -72.3 mmHg, -72.0 mmHg for NPWT-B◊◊ systems, and -60.1 mmHg for NPWT-C◊◊ systems. These average pressures proved to be significantly different when comparing NPWT-A◊ to NPWT-C◊◊◊ (p<0.001) and NPWT-B◊◊ to NPWT-C◊◊◊ (p<0.001). 
At a target pressure of -125 mmHg, the average pressure maintained for NPWT-A◊ systems was -122.8 mmHg, -120.7 mmHg for NPWT-B◊◊ systems, and -107.0 mmHg for NPWT-C◊◊ systems. These average pressures proved to be significantly different when comparing NPWT-A◊ to NPWT-C◊◊◊ (p<0.001) and NPWT-B◊◊ to NPWT-C◊◊◊ (p<0.001). 
Conclusion: PRT-based NPWT systems are not equivalent in performance. NPWT-A◊ and NPWT-B◊◊ systems consistently delivered prescribed therapy levels under challenging experimental conditions. NPWT-C◊◊◊ systems were not capable of doing so.