Electronic Thesis and Dissertation Repository


Doctor of Philosophy


Health and Rehabilitation Sciences


Pamela E Houghton



To determine in a population with lower extremity wounds associated with vasculopathy if: (1) previously proposed clinical signs of infection are valid indicators of wound infection; (2) low frequency (22.5 kHz) contact ultrasound debridement (LFCUD) is well tolerated and feasible to apply in a nurse-led vascular wound clinic; (3) healing outcomes are improved for patients receiving LFCUD in comparison to patients receiving usual care (UC).


A total of 80 patients were in the study. First, a pilot group of ten patients were followed to determine tolerability, feasibility and wound response of 4 weekly LFCUD treatments. Then 70 patients were randomly allocated into LFCUD plus UC (n= 33), or UC (n = 37). Clinical signs of wound infection were compared to tissue culture and physician evaluation. Outcomes included mean percentage decrease in wound surface area (%WSA), change in wound appearance (revised Photographic Wound Assessment Tool [revPWAT]), and change in pre- to post-treatment pain scores by Visual Analogue Scale (VAS).


No individual clinical sign was both highly sensitive and specific to indicate infection. The presence of three combined signs yielded the highest positive likelihood ratio (7.2), but absence of signs was uninformative. LFCUD is well tolerated and feasible for nurse-application. After 4 treatments the between-group change in %WSA was not statistically significant. The LFCUD group showed a significant linear trend in WSA reduction with each treatment visit (p = < 0.01), and a significant improvement in wound appearance for the LFCUD group (4.36 revPWAT points, 2.07-6.66, 95% CI, p = 0.01) compared to UC. There was no significant decrease in wound infections between groups. There was a significant decline in VAS pain score of 16.56mm (± 32.5, t(31) = 2.89,p = 0.007, 95% CI) in the LFCUD group but this was not significant in the UC group. There were no treatment-related adverse effects.


Clinical signs of infection are specific, but inadequately present for screening the vascular population. LFCUD is well tolerated and resulted in superior wound appearance with consistent trending of WSA reduction. It was not determined that LFCUD reduces infection, improves healing times or supports wound closure.

Available for download on Tuesday, August 29, 2017