Negative pressure wound therapy with instillation: a pilot study describing a new method for treating infected wounds

Abstract

This data review reports the results of 15 patients who were treated with Vacuum-Assisted Closure (VAC) negative pressure therapy system in addition to the timed, intermittent delivery of an instilled topical solution for management of their complex, infected wounds. Prospective data for 15 patients treated with negative pressure wound therapy (NPWT)-instillation was recorded and analysed. Primary endpoints were compared to a retrospective control group of 15 patients treated with our institution's standard moist wound-care therapy. Culture-specific systemic antibiotics were prescribed as per specific patient need in both groups. All data were checked for normality of distribution and equality of variance and appropriate parametric and non parametric analyses were conducted. Compared with the standard moist wound-care therapy control group, patients in the NPWT-instillation group required fewer days of treatment (36.5 +/- 13.1 versus 9.9 +/- 4.3 days, P < 0.001), cleared of clinical infection earlier (25.9 +/- 6.6 versus 6.0 +/- 1.5 days, P < 0.001), had wounds close earlier (29.6 +/- 6.5 versus 13.2 +/- 6.8 days, P < 0.001) and had fewer in-hospital stay days (39.2 +/- 12.1 versus 14.7 +/- 9.2 days, P < 0.001). In this pilot study, NPWT instillation showed a significant decrease in the mean time to bioburden reduction, wound closure and hospital discharge compared with traditional wet-to-moist wound care. Outcomes from this study analysis suggest that the use of NPWT instillation may reduce cost and decrease inpatient care requirements for these complex, infected wounds.

Figure 1

Vacuum‐Assisted Therapy (VAC^® Instill™) therapy set‐up for irrigation of silver nitrate. All tubing and bottles are covered by dark bags or aluminium foil.

Figure 2

Kaplan–Meier survival graphs showing proportion of patients over time for days to wound infection clearance (A), days to wound closure (B), days of treatment (C) and days to discharge (D). The negative pressure wound therapy (NPWT) installation therapy group had highly significantly (P < 0·001) less time to endpoint compared with the control therapy group.

Figure 3

Regression analysis of ‘days to wound infection clearance’ and ‘days to wound closure’. The regression line is significant (P < 0·001) for predicting rate of wound closure for the control therapy group. NPWT, negative pressure wound therapy.

Figure 4

Case 1. An 84‐year‐old male with abdominal necrotising fasciitis (A). The necrotic tissue was resolved in 24 hours and negative pressure wound therapy instillation was initiated on day 2 with normal saline solution for irrigation. Following confirmation of positive cultures, silver nitrate irrigation was started. On day 5, healthy granulation tissue was present and the wound was noticeably contracted (B). On day 14 (C), the patient was taken to the operating room and the wound was primarily closed. The patient was discharged back to his nursing home facility on day 17 with a closed wound (D).

Figure 5

Case 2. A 65‐year‐old male with infected open right knee joint with exposed hardware (A). Infection present for 3 months following an open reduction with internal fixation procedure. Negative pressure wound therapy instillation was initiated (B) with normal saline irrigation, and followed on day 3 with silver nitrate irrigation. By day 5, the wound culture returned negative, and the knee was closed via local flap on day 10. (C) illustrates the granulating knee the day it was closed and (D) shows the knee closed and viable at 6‐month follow‐up.