Study of the Relationship Between Curarization and Pneumoperitoneum in Laparoscopic Surgery

Laparoscopic Surgery, Neuromuscular Blocking Agents, Pneumoperitoneum

pneumoperitoneum pressure, curarization

The number of surgical procedures is increasing worldwide (1). Laparoscopic surgery is one of the surgical techniques that has become indispensable. Laparoscopic surgery is less invasive than laparotomy. Laparoscopic surgery is performed in several stages, one of which involves the creation of a peritoneal detachment. This detachment is achieved by the addition of a gas (CO2), which requires total relaxation of the abdominal muscle fibers. To achieve this, it is advisable to administer a muscle relaxant called curare (2). Curare-induced neuromuscular block, its depth and its release must be monitored during surgery. Curares act as acetylcholine antagonists, inducing neuromuscular block by competing with this neurotransmitter. In France, only one type of device, called an accelerometer, is used to monitor curarization. This device couples electrical stimulation of a nerve with an accelerometer. Curarization can be said to be deep, moderate, residual or absent. Despite curarization appearing deep to the accelerometer, operating conditions do not always seem ideal for abdominal contraction. Indeed, the muscles tested with this device do not concern the muscles involved in laparoscopic surgery. A currently unexploited surgical parameter, variation in insufflation pressure, could change our approach to intraoperative curarization.

Curarization is a fundamental part of surgical management. The administration of these drugs enables intubation and facilitates surgical work. However, these molecules need to be monitored at every stage, from anesthetic induction to patient awakening. Today, a single device is used in operating theatres to monitor the depth of patient curarization. This tool is used on a daily basis, and its use is strongly recommended by the various learned societies associated with anesthesia. Its use in operating theatres is compulsory by law. The device is used either on the ulnar nerve, generating a contraction of the adductor muscle of the thumb, or on the facial nerve, generating a contraction of the orbicularis muscle of the eye. This reflects the curarization of the laryngeal and diaphragmatic muscles. The device delivers repetitive electrical stimulation to these nerves, producing a muscle contraction. The number of muscle contractions in response to these stimulations, and the strength developed by the fourth response compared with the first, indicates the depth of curarization. These measurements are called a train of four. While performing a train-of-four on the thumb adductor produces measured, quantifiable data, this is absolutely not the case for the orbicularis of the eye, which provides only crude, unreliable data intraoperatively. Laparoscopic surgery, on the other hand, is a minimally invasive technique that has become increasingly popular in recent decades. It requires deep intraoperative curarization. This surgical technique can be used for a wide range of urological, visceral and gynecological procedures. During laparoscopic surgery, insufflation pressure is delivered via trocars into the patient's abdominal cavity. This pressure comes from a column supplied via a carbon dioxide (CO2) cylinder. Initially, a pressure is generated and adjusted at the surgeon's request (3). This pressure creates a space known as the pneumoperitoneum. In the event of insufficient pneumoperitoneum to enable surgery to be performed under optimum conditions, potentially due to a lack of deep curarization, the insufflation pressure is increased at the surgeon's request. This surgical technique is nonetheless prone to causing significant projected pain. As Madsen's study (4) suggests, lowering the insufflation pressure could therefore result in less pain. By hypothesizing that imperfect curarization would lead to contraction of the abdominal muscles, generating intra-abdominal overpressure. This study investigates the role of intra-abdominal pressure variation in laparoscopic surgery and its correlation with the accelerometer used in current practice. If this hypothesis proves to be true, the expected benefits would be improved operating conditions for surgeons, reduced intra-operative risks of perforation and organ damage, and improved patient comfort in the post-operative period.

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