LAKE BUENA VISTA, FLA. – Contrary to prior results, use of onabotulinumtoxinA did not improve primary fascial closure rates after damage control laparotomy in a multicenter, prospective study.
“Botox injections were safe, but they did not have any effect on our primary or secondary endpoints,” Dr. Martin D. Zielinski said at the annual scientific assembly of the Eastern Association for the Surgery of Trauma (EAST).
Dr. Zielinski and his colleagues at Mayo Clinic, Rochester, Minn., previously published retrospective data showing that use of Botox-induced paralysis of the abdominal wall musculature resulted in a primary fascial closure rate of 83% among 18 patients with open abdomen (OA) and 89% if injected within 24 hours of the initial OA procedure (Hernia 2013;17:101-7).
In contrast, the primary closure rate was just 66% in a prospective American Association for the Surgery of Trauma study involving 572 patients requiring OA management after damage control laparotomy (J. Trauma Acute Care Surg. 2013;74:113-20).
Though negative pressure dressings and use of patches have been shown to increase primary closure by facilitating the midline tension, up to 30% of patients will not achieve primary fascial closure. Botox injections block the release of acetylcholine, thereby preventing a rush of calcium to the abdomen and inducing flaccid paralysis of the lateral abdominal wall muscles, Dr. Zielinski explained.
To test their hypothesis that Botox would improve rates of primary fascial closure, decrease hospital stay, and enhance pain control, 46 patients who had undergone damage control laparotomy were randomly assigned to six separate injections of their external, oblique, internal oblique, and transverse abdominal muscles with 150 cc/injection of Botox A or sodium chloride 0.9%.
The two groups were well matched, with the exception of Botox patients having a significantly lower body mass index (BMI) than did controls (30 kg/m2vs. 26.3 kg/m2) and receiving more intraoperative packed red blood cells (8 units vs. 4.8 units).
Primary fascial closure rates were unexpectedly high, but did not differ between the Botox and control groups (96% vs. 93%; hazard ratio, 1.0), Dr. Zielinski said.