Effect of Atracurium and Rocuronium on the State and Response Entropy During Isoflurane Anesthesia

Anesthesia will be induced by atracurium (dose 0.5 mg/kg).After equilibrium for 30 minutes SE, RE and the difference between them will be recorded at MAC 0.8 and MAC 1 at two levels of muscle relaxation assessed by TOF value of 50% and 100%. Atracurium (dose 0.005-0.01 mg/kg/min) will be administered as a continuous IV infusion adjusted until 50% and 100% depression of T1 ( first twitch by acceleromyography) will be observed. The entire experiment ended before the start of surgery. In case of hypotension (drop of blood pressure ˃20% of baseline reading), 10-30 mg of ephedrine diluted over 10 ml normal saline 0.9% will be given intravenously by titration according to the blood pressure. In case of bradycardia (heart rate less than 60 beat per minute), when it is associated with hypotension or any signs of impaired perfusion, 0.01 - 0.02 mg/kg of atropine will be given

Anesthesia will be induced by rocuronium (dose 0.6 mg/kg).After equilibrium for 30 minutes SE, RE and the difference between them will be recorded at MAC 0.8 and MAC 1 at two levels of muscle relaxation assessed by TOF value of 50% and 100%. Rocuronium (dose 0.01-0.012 mg/kg/min ) will be administered as a continuous IV infusion adjusted until 50% and 100% depression of T1 ( first twitch by acceleromyography) will be observed. The entire experiment ended before the start of surgery. In case of hypotension (drop of blood pressure ˃20% of baseline reading), 10-30 mg of ephedrine diluted over 10 ml normal saline 0.9% will be given intravenously by titration according to the blood pressure. In case of bradycardia (heart rate less than 60 beat per minute), when it is associated with hypotension or any signs of impaired perfusion, 0.01 - 0.02 mg/kg of atropine will be given.

No premedication will be given. After the patients enter the operating room, a venous cannula will be inserted into a large peripheral vein. Data from routine monitoring, including non-invasive arterial blood pressure, oxygen saturation, and end-tidal oxygen concentration (ETO2) and end-tidal carbon dioxide concentration (ETCO2) will be collected. Neuromuscular blockade will be continuously assessed by acceleromyography using the Train-of-Four-watch SX system , starting when the patients will be unconscious. RE and SE will be monitored using a Datex Ohmeda Entropy Module (M-Entropy) and the Entropy Sensor system.

After the patients enter the operating room, a venous cannula will be inserted into a large peripheral vein. Data from routine monitoring, including non-invasive arterial blood pressure, oxygen saturation, and end-tidal oxygen concentration (ETO2) and end-tidal carbon dioxide concentration (ETCO2) will be collected. Neuromuscular blockade will be continuously assessed by acceleromyography using the Train-of-Four-watch SX system, starting when the patients will be unconscious. RE and SE will be monitored using a Datex Ohmeda Entropy Module (M-Entropy) and the Entropy Sensor system.