Evaluation of clinical effectiveness of MIST ultrasound therapy for the healing of chronic wounds.

OBJECTIVES

(1) To determine the incidence of wound closure for chronic nonhealing lower extremity wounds of various etiologies using MIST ultrasound therapy, a 510(K)-approved, low-frequency, noncontact ultrasound device indicated for the cleansing and debridement of chronic wounds. (2) To determine the optimum treatment duration for therapy with this low-frequency, noncontact ultrasound device, quantifying end points that correlate with a maximal clinical response and identifying potential synergistic therapies that could be used in conjunction with this therapy. (3) To analyze the impact of low-frequency noncontact ultrasound therapy on the microcirculatory flow patterns within the wound bed.

DESIGN

A noncomparative clinical outcomes trial utilizing low-frequency, noncontact ultrasound.

SETTING

A tertiary-referral hospital-based wound clinic.

PATIENTS

Twenty-three patients from a single tertiary-referral hospital-based wound clinic. Control data were obtained from a previously published, prospectively collected database from the same clinic.

INTERVENTIONS

During an 8-month period, a total of 29 lower extremity wounds in 23 patients who met criteria for inclusion were treated with low-frequency, noncontact ultrasound therapy. Standard of care was provided for 2 weeks for all wounds screened for the study. A failure to achieve an area reduction greater than 15% qualified the patient for enrollment to the trial and the addition of low-frequency, noncontact ultrasound therapy to the current treatment regimen.

MAIN OUTCOME MEASURES

Wound healing, area and volume reduction, and laser Doppler-derived mean voltage (a marker for microcirculatory flow) are the main outcome measures for the study.

RESULTS

Overall, 69% of the wounds in the study were healed using an intent-to-treat model. When low-frequency, noncontact ultrasound was used as a stand-alone device, median time to healing was 7 weeks. Historic controls were healed with a median time to healing of 10 weeks; however, a statistically significant number of these patients required wound-related hospitalization and surgical procedures to achieve closure compared with the wounds in the present study.

CONCLUSIONS

Treatment with low-frequency, noncontact ultrasound achieved healing in chronic wounds when used as a stand-alone device or in combination with moist wound care in 69% of cases. Response to low-frequency, noncontact ultrasound was evident within 4 weeks of therapy. Earlier transition to secondary procedures and decreased utilization of inpatient care might result in more cost-effective wound healing than the current standard of care. A well-designed health economic-based trial is warranted to assess this technology.