Laparoscopic cholecystectomy (LC), which has acquired widespread acceptance, has emerged as the gold standard for the surgical management of symptomatic cholelithiasis. Anaesthesia methods can significantly affect the total cost of surgical procedures.The optimal anaesthetic for surgery must provide a secure intraoperative time, easy recovery, while yet being cost-effective. Sevoflurane and Isoflurane, two inhalational anesthetics, have been shown to be useful as feasible anaesthetics for maintaining anaesthesia , as well as ecofriendly comparative to other inhalational agents. Being anaesthesiologists, we must consider the life cycle of drugs in order to include environmental impacts into clinical decisions.

Sevoflurane as an inhalational anesthetic has less respiratory irritation and more rapid emergence in comparison to isoflurane. Isoflurane is 2-3 times more economical than equipotent concentrations of sevoflurane at equivalent doses; therefore, a therapeutic benefit of sevoflurane over isoflurane must be demonstrated in order to justify the cost of using it, in comparison to isoflurane, which is more affordable in a cost sensitive country like India.

Isoflurane and sevoflurane have similar greenhouse gas (GHG) emission profiles. For both gases, life cycle GHG emissions are dominated by waste anesthetic gas. When O2/air is used, isoflurane has higher associated emissions than sevoflurane, in large part because its GWP100 factor ( Global Warming potential of 100 years horizon) is nearly 4 times as high.

The erector spinae plane block is one of the novel techniques , where a local anaesthetic is injected beneath the erector spinae muscles, into the fascial plane. The bilateral ultrasound guided ESP block leads to effective analgesia and a decreased inhalational agent and post operative opioid consumption in patients undergoing LC.

Even though various methods were tried to reduce inhalational agent usage, there is existing knowledge lacunae on the effect of ESP on various inhalational agents and cost, we aim to evaluate the effect of ESPB on consumption of inhaled agents with entropy guidance for uniform depth of anaesthesia. We will prospectively investigate perioperative anesthetic requirements (intraoperative anesthetics and analgesics) by randomizing adult patients for LC surgeries to either sevoflurane- or isoflurane-based entropy guided anesthesia receiving ESP block. Anesthetic consequences will also be considered - intraoperative hemodynamic response, measure depth of anesthesia and estimate clinically significant value indirectly related to cost.