The Influence of the Magnitude of Neuromuscular Blockade on the Surgical Conditions During Laparoscopic Sleeve Gastrectomy

In laparoscopic bariatric procedures, CO2 is used to insufflate the peritoneal cavity and increase the intra-abdominal pressure for optimal exposure and a suitable operating field. However, the increased intra-abdominal pressure during pneumoperitoneum has profound physiological effects including a reduction in urine output,portal venous flow,respiratory compliance,and cardiac output.

Abdominal muscle relaxation and changes in abdominal wall compliance, produced by the use of anesthetics and muscle relaxants, are important contributors for the achievement of optimal surgical field using minimal abdominal pressure. A practical dilemma is how to maintain good surgical conditions till the end of the operative procedure by deep anesthesia and muscle relaxation on one hand, and to have an awake and spontaneously breathing patient at the end of surgery on the other.

Reversal agents are often used to ensure the reversal of nondepolarizing neuromuscular blockade (NMB). The most widely used is the acetylcholinesterase inhibitor neostigmine (Prostigmin®, Vagostigmin®). However, neostigmine is only partially effective when NMB is deep (less then 1 response using train of four monitoring) and may also be associated with adverse effects, such as cholinergic cardiovascular and gastrointestinal events.Sugammadex (bridion®) is a modified gamma cyclodextrin specifically designed for the reversal of NMB induced by the aminosteroid muscle relaxants including rocuronium bromide (Zemuron®, Esmeron®). Sugammadex (bridion®) acts by encapsulating unbound rocuronium bromide (Zemuron®, Esmeron®)molecules and reducing their concentration at the neuromuscular junction.Studies in surgical patients have shown that sugammadex (bridion®) rapidly and safely reverses rocuronium bromide (Zemuron®, Esmeron®)induced NMB. Unlike acetylcholinesterase inhibitors, sugammadex (bridion®) is also effective in the reversal of deep NMB (no response in train of four monitoring or even no response in post tetanic count monitoring).

Laparoscopic weight reduction surgery requires the appropriate use of muscle relaxation; however, uncertainty remains including indeterminate dosing and unpredictable effect. Additionally, the time to the recovery to a train of four (TOF) ratio of 0.9 in the obese [25.9 (6.7, 13.5-41.0) min] and the overweight groups [14.6 (7.7, 3.3-28.5) min] were significantly longer than that in the normal weight group [6.9 (2.0, 3.0-10.7) min]. Therefore, obese patients are at increased risk for residual muscle relaxation following surgery. Sugammadex (bridion®) has recently been found to reach a peak effect faster than neostigmine(Prostigmin®, Vagostigmin®), in obese patients. In this study, the time to a TOFR ≥ 0.9 was 13 min with 50 μg/kg neostigmine (Prostigmin®, Vagostigmin®)and only 1.7 min with 2 mg/kg sugammadex. Therefore, it appears that sugammadex (bridion®) may more predictably prevent the occurrence of residual muscle relaxation compared to neostigmine (Prostigmin®, Vagostigmin®).

The aim of the present study is to prospectively assess whether deep NMB (zero response to train of four and a post tetanic count of no more than 10 responses using a nerve stimulator monitoring) till the end of surgery, followed by sugammadex (bridion®) reversal is superior to the present practice of gradual NMB reduction at the end of surgery followed by neostigmine (Prostigmin®, Vagostigmin®)reversal, in patients undergoing laparoscopic sleeve gastrectomy. The investigators hypothesize that providing deep NMB throughout the procedure creates better conditions for surgery, while reversal of deep muscle relaxation with sugammadex (bridion®) will enable quick and full reversal of relaxation and fewer postoperative respiratory events as compared to neostigmine (Prostigmin®, Vagostigmin®) reversal. Surgical conditions will be assessed by the surgeons, blinded to the treatment given to the patients, on a 1-4 Likert scale in 5 minutes intervals from abdominal insufflation with gas till the end of surgery (estimated time of 120 minutes). Participants will be followed for respiratory adverse events from admission to the post anesthesia care unit to discharge to the surgical department (continuous measurement of hemoglobin oxygen saturation and respiratory rate for an expected average of 3 hours) and from admission to the surgical department till the time of home discharge (measurement of hemoglobin oxygen saturation and respiratory rate every 6 hours for an expected average of 5 days).