The Effects of Preoperative Botulinum Toxin A Injection on Respiratory System Function

Overview

Hernias are common complications post-abdominal surgeries, often leading to significant issues such as "loss of domain," where organs shift permanently, reducing abdominal cavity capacity. This complicates surgeries as there is insufficient space to reposition organs. A growing method to address this involves preoperative botulinum toxin A (BTA) injections into lateral abdominal muscles. BTA induces temporary paralysis, expanding the abdominal cavity and aiding muscle approximation for hernia repair. Initiated in 2009, this approach is particularly used for defects over 10cm. However, standardized protocols are lacking, and the impact on respiratory function remains under-researched. This study aims to evaluate the effects of preoperative BTA injections on respiratory volumes. Ten patients will undergo pulmonary function tests before and after BTA injections. The study will focus on changes in respiratory efficiency, given the respiratory challenges associated with large hernias and the "loss of domain" effect.

Hernias are frequent complications following abdominal procedures, particularly in cases of large defects which may lead to the "loss of domain" effect. This phenomenon involves permanent displacement of organs into an alternative space, reducing the effective capacity of the peritoneal cavity. Surgical management of giant hernial sacs is challenging due to insufficient space within the abdominal cavity to accommodate organ repositioning. Abdominal wall reconstruction specialists have developed various techniques to address these complexities. One increasingly utilized method involves the injection of botulinum toxin A (BTA) into the lateral abdominal muscles (external oblique, internal oblique, and transverse muscles). BTA induces temporary muscular paralysis lasting approximately 6-8 months. This paralysis extends the muscle compartment, thereby increasing abdominal cavity volume. This expansion facilitates the approximation of rectus abdominis muscles and the closure of fascial defects. Initial attempts to employ BTA for the treatment of giant abdominal hernias began in 2009. Since then, its role in abdominal wall surgery has grown steadily. Optimal timing for surgery post-BTA injection is typically 3-4 weeks, when maximal muscle extension and abdominal volume increase (up to 20-30%) are observed. Despite widespread clinical use, standardized protocols for BTA application remain lacking due to limited comparative studies and small sample sizes in existing literature. Rare allergic reactions aside, comprehensive documentation of adverse effects from BTA injections remains minimal. However, variability in patient response suggests potential differences in treatment efficacy. Respiratory efficiency poses a significant challenge in patients with giant abdominal hernias, exacerbated by the "loss of domain" effect which impairs diaphragm function and alters respiratory mechanics. Predicting perioperative outcomes is further complicated by advanced age, comorbidities, and obesity among affected patients. To investigate the impact of preoperative BTA injection on respiratory function, a study will assess pulmonary volumes using spirometry in 10 patients with giant hernias of the anterior abdominal wall (classified as W3 by the European Hernia Society). Participants will undergo spirometry before and 4 weeks after lateral muscle group BTA injection as part of preoperative evaluation for abdominal wall reconstruction at the Swissmed Hospital Hernia Centre in Gdansk. The injection of BTA will be performed in outpatient settings, under ultrasound guidance. Each patient received 300 units of BTA (Dysport®, IPSEN, Boulogne-Billancourt, France), with 150 units administered to each side. The BTA administration procedure will begin with drawing lines on the skin to mark the lower edge of the last rib and the upper edge of the iliac crest. Then, a line connecting both marked sections is drawn along the anterior axillary line. On this line, three equally spaced points will be marked. These will be the sites for needle insertion and BTA administration. 300 units of BTA will be dissolved in 150ml of 0.9% saline. This solution will be then divided into six 25ml portions. Each portion is administered at the previously designated points. During the injection at a point, under ultrasound control, we reach the transverse muscle and administer 8ml of the solution. Then, the needle will be withdrawn to the internal oblique muscle, and another 8ml is administered. Finally, the needle will be withdrawn to the level of the external oblique muscle, where the remaining portion of the dose is administered. This procedure is repeated at each point