Bilateral Rectus Sheath Catheters Following Midline Laparotomy. A Randomized, Placebo-controlled Trial

Recruitment Patients are recruited during the anesthesiology consultation. Patients who provided written informed consent. fulfill all inclusion and no exclusion criteria will be included in the study.

Allocation of study medication After inclusion in the study, each patient receives a patient number, which is noted on the Case Report Form (CRF). The randomization list was generated via www.random.org (Randomness and Integrity Services Ltd., Dublin, Ireland). Random assignment to groups 1 (verum) and 2 (placebo) was performed on the day of surgery using the sealed envelope technique. The sealed envelope is opened by a doctor not involved in the study immediately before bilateral placement of the rectus catheters catheters. This colleague prepares the study medication (verum or placebo, unlabeled, blinded to the observer and patient).

Anesthesia and perioperative monitoring After a peripheral or central venous line is inserted, a balanced electrolyte solution is connected and the following parameters are monitored until complete postoperative recovery: blood pressure (plethsymographic or via arterial line), electrocardiogram, pulse oximetry.

The surgical procedures are performed under general anesthesia (sevoflurane 0.7-1.0 MAC). Sufentanil (0.2-0.4 microg/kg), propofol (1.5-2 mg/kg) and cisatracurium (0.1-0.15 mg/kg) are administered to induce anesthesia The multimodal analgesia concept includes the intraoperative administration of 4 mg dexamethasone (antiemetic, coanalgesic) and two non-opioids: 1 g metamizole (40 mg parecoxib if contraindications exist) and 1 g paracetamol.

Study intervention Bilateral RSC are placed intraoperatively after closure of the median laparotomy under aseptic conditions, before the wound dressing is applied. For imaging, we use an ultrasound device (FUJIFILM Sonosite, Bothel, WA, USA) with a linear transducer (38mm, 6-13MHz), which is placed obliquely on the upper edge of the median laparotomy. The puncture (puncture direction from medial-cranial to lateral-caudal) is initially performed with an ultrasound-optimized single-shot cannula (SonoPlex 22G50mm to 21G100mm, Pajunk, Geisingen, Germany) in order to reliably identify the compartment of the posterior rectus sheath. After verification of the correct spread of the local anesthetic, the catheter (SonoLong Echo 19G 50-100mm, 20G 50cm catheter, Pajunk, Geisingen, Germany) is placed at the lateral edge of the posterior rectus sheath and again the correct spread of the local anesthetic in the target compartment is verified by ultrasound.