The limited effectiveness of bedside positive pressure irrigation on pistol projectile wound contaminant: A biomechanics study

Background: Pistol caliber gunshot wounds (PC GSW) are the most common mode of firearm injury treated in the civilian emergency setting, but there is a paucity of data guiding best practice treatment. The goal of this study was to examine the effect of bedside positive pressure irrigation (PPI) on removal of gross debris from PC GSW. Methods: Fourteen bovine shanks were prepared with metal impregnated fabric placed in front of the impending impact zones to mimic radio-opaque clothing-like material. They were then shot with a 9 mm bullet from a distance of 3 meters. Specimens were imaged three separate times with standardized computer tomography: immediately after impact, after 250 ml irrigation, and after a total of 750 ml of irrigation. Scanned images were examined for change in radio-opaque contamination at both the entry site and within the wound cavity. Results: No samples demonstrated a decrease of debris contamination within the cavity of the wound after 250 ml of irrigation and only one did after 750 ml. Six (42.86%) samples demonstrated a shift of debris without decrease in cavity contamination after 250 ml of irrigation and ten after 750 ml total irrigation. Five samples demonstrated decrease in debris at the entry site of the gunshot projectile wound after 250 ml of irrigation and two showed further superficial decrease with additional irrigations up to 750 ml. No statistically significant differences were found between 250 ml and 750 ml PPI treatments in both superficial and cavity contamination categories. Conclusion: Positive pressure irrigation with up to 750 ml of 0.9% normal saline at a rate of 20 ml/sec has limited effect on the removal of gross debris within the cavity of pistol caliber gunshot wounds. The data within this study bring into question the benefits of attempted removal of pistol caliber gunshot wound contaminants utilizing bedside positive pressure irrigation.