Preclinical Evaluation of Closed Incisional Negative Pressure Therapy on Post-Surgical Oedema and Lymphatic Activity.

Closed incisional Negative Pressure Therapy (ciNPT) has demonstrated improved post-surgical healing with reduced oedema and hematoma/seroma formation in patients. The underlying mechanism of action is poorly understood, although evidence indicates that lymphatics play a role. The effects of ciNPT on oedema and lymphatic recovery were assessed following bilateral, surgical undermining of swine mammary tissues. One incision was treated with ciNPT, and the control covered with clear dressing. Near-infrared fluorescence imaging was used to visualise lymphatic activity. Oedema and lymph node size were measured using ultrasound. LYVE-1 and podoplanin were quantified with ELISA. Analysis of lymphatic activity revealed a contralateral effect of ciNPT on control sites. Statistically higher pulsatile rates were observed at both incisions when ciNPT was active, compared with when it was removed. Separate evaluations with dressings off and on showed no differences between treatments. While not significant, lower surgical site oedema, lymph node volume, and incidence/severity of seroma were observed in treated sites along with increased lymphatic vessel markers in lymph draining tissues. Taken together, evidence suggests that ciNPT may influence watersheds outside the treated area. Similar systemic impacts owing to manual lymphatic drainage have previously been reported in healthy individuals and those with cancer-related lymphedema.