The effect of the depth of neuromuscular block and pneumoperitoneum on postoperative pain after a gastric bypass

Aim of this pilot study is to determine which intervention groups are feasible in a larger trial which aims to compare postoperative pain and complication rates in moderate versus deep neuromuscular blockade, and normal versus low intra-abdominal pressure, in a double-blinded, randomized controlled pilot study. We will be comparing 4 groups of 15 patients, undergoing laparoscopic bariatric surgery with deep neuromuscular block versus normal neuromuscular block and normal-pressure pneumoperitoneum versus low-pressure pneumoperitoneum in a 2x2 table design. Patient and surgeon are blinded. The anesthesiologist is not blinded in order to control the depth of the neuromuscular block and pressure. The study will be performed in a large secondary hospital (Franciscus Gasthuis & Vlietland, Rotterdam area, the Netherlands). Obese patients found suitable for bariatric surgery according to the current guidelines, undergoing a primary gastric bypass, will be included in the study. Patients unwilling to give informed consent or with allergies for used medication, neuromuscular comorbidities or a medical history of pain disorders will be excluded. Patients will receive either deep neuromuscular block, measured with post-tetanic count (PTC), or moderate neuromuscular block, measured with Train-of-Four (TOF). They will be operated under either normal pressure pneumoperitoneum (20 mmHg in our centre) or low pressure pneumoperitoneum (12 mmHg). In case of unacceptable surgical conditions, either neuromuscular block or pneumoperitoneum or both will be increased, depending on the group for which the patient has been randomised. The primary endpoint is quality of the surgical field (Graded on the Leiden Surgical Rating Scale), to be scored directly after sign out procedure. Secondary endpoints are post-operative pain, the influence of pain on readiness for discharge and length of hospital stay, and complications during surgery or within 1 month postoperatively; i.a. bleeding, leakage.

When using deep neuromuscular blockade, less intraabdominal pressure will be needed for good surgical overview, which will lead to a decrease in postoperative pain.

During surgery (overview), day 1-7 for postoperative pain scores.

Patients will receive either deep or moderate neuromuscular blockade and either standard or low pressure pneumoperitoneum.