Effect of Adding Magnesium Sulphate to Bupivacaine in Laparoscopic Periportal Preperitoneal Local Infiltration in Laparoscopic Sleeve Gastrectomy

Obesity isn't just a cosmetic issue, it is a medical condition, sometimes considered a disease in which excess body fat has accumulated to an extent that can potentially have negative effects on health, The increasing prevalence of obesity has become a significant concern worldwide. It increases the risk of many other diseases and health problems that include heart diseases, diabetes, high blood pressure, fatty liver, apnea, even certain cancers.

Bariatric surgery has become the most effective way to lose weight. Health care providers recommend bariatric surgery if other conservative weight loss methods have failed. Surgical weight loss operations have been performed over the last 20 years. Bariatric surgery procedures include gastric bypass, gastric band, duodenal switch and sleeve gastrectomy, Laparoscopic sleeve gastrectomy (LSG) is an effective procedure for weight loss. It has become the most commonly performed bariatric surgery with low morbidity without long term malabsorptive risks.

In patients undergoing LSG, postoperative pain management is essential for reducing complications due to excessive opioid use, early mobilization and shortening hospital stays, Multimodal analgesia seems to be the gold standard in the treatment of acute pain, particularly for bariatric surgery patients who frequently have numerous coexisting conditions, one of these conditions is obstructive sleep apnea (OSA) which is common among obese individuals, making safe analgesic treatment a bit challenging.

Perioperative multimodal analgesia uses a combination of analgesic medications that act on various sites and pathways in an additive or synergistic manner to achieve pain relief with minimal or no opioid consumption, The clinical practice trends are now shifting towards opioid sparing anaesthesia.

Local infiltration analgesia is widely used as a component of multimodal analgesia. It involves the injection of a local anaesthetic near the surgical incision site to provide analgesia. Periportal preperitoneal local anaesthetic infiltration is a technique that was first described by Dean et al, for pain relief in laparoscopic hernia repair and is now gaining popularity.

The pre-incisional periportal laparoscopic preperitoneal local anaesthetic technique (PLPLAT) is an effective technique to reduce postoperative pain and can decrease the postoperative opioid consumption after surgery, promoting early mobilization and patient satisfaction due to fewer side effects.

Intra-peritoneal instillation of bupivacaine with or without adjuvants is one of popular modalities used to prevent post-operative pain. The local anaesthetic agents provide antinociception by affecting nerve membrane-associated proteins and by inhibiting the release and action of prostaglandins, which stimulate the nociceptors and cause inflammation, blocking of visceral pain conduction. Absorption from a large peritoneal surface may be the mechanism of analgesia.

One of these adjuvants is magnesium sulfate which is used in combination with local anaesthetics to help reduce onset of effect, prolong the duration of action and to increase the chance of successful blockade.

Administration of magnesium sulfate (MgSO4) through different routes has been used in anaesthetic practice for decreasing perioperative pain. Although magnesium has mild sedative effects, it lowers intraoperative anaesthetics requirements, this is advantageous in reducing the residual anaesthetic effects in obese patients.

Magnesium sulfate also has been used to attenuate the adverse haemodynamic changes associated with pneumoperitoneum which is created during laparoscopy. These changes include abrupt elevation of mean blood pressure, heart rate and systemic vascular resistance, this is because MgSO4 prevents the adrenal medullary release of catecholamines as well as their secretion from adrenergic nerve endings, in addition, it has a direct effect on blood vessels producing vasodilatation with a subsequent reduction in blood pressure. Apart from that, it also has the ability to attenuate vasopressin-mediated vasoconstriction. In addition, carbon dioxide reacts with the tissue and activates the emergence of sour products which put local pressure on the nerve endings of the peritoneum, noxious stimulation leads to the release of glutamate and aspartate which bind to various subclasses of excitatory amino acids receptors including (NMDA) receptors. Magnesium inhibits calcium entry into the cell through a noncompetitive blockade of the N-methyl-d aspartate (NMDA) receptor, this may explain how magnesium works when it is given intraperitoneally.

The present work will study the effect of adding magnesium sulphate to bupivacaine in periportal preperitoneal local anaesthetic infiltration in laparoscopic sleeve gastrectomy. magnesium will prolong duration of analgesia and decrease total amount of analgesia needed will decrease time of stay at PACU and stay at hospital