End Tidal Anesthetic Concentration in Different Anesthesia Techniques Where Depth of Anesthesia Adjusted With Entropy

End Tidal Anesthetic Concentration in Different Anesthesia Techniques Where Depth of Anesthesia Adjusted With Entropy

Comparison of General Anesthesia and Combined General Thoracic Epidural Anesthesia on End Tidal Volatile Anesthetic Concentration in Cases Which Depth of Anesthesia is Adjusted Using Entropy Monitoring; A Prospective Trial

The aim of this study is to adjust the end tidal inhalation anesthetic concentration by observing the entropy value in patients who will be provided anesthesia maintenance with volatile anesthetics after applying the routine epidural anesthesia technique and to observe the end tidal volatile concentration that will provide to remain in the target entropy limits during the operation.

The hypothesis of this study is that in general anesthesia cases which is combined with thoracic epidural anesthesia (TEA), lower alveolar concentration will be required to reach the same anesthesia depth. The main aim of the study is observing and comparing the alveolar concentrations of anesthetic agents with entropy monitoring which is an anesthesia depth monitor in major abdominal surgeries where general anesthesia is combined or not with TEA. In cases where TEA is combined with general anesthesia or not, anesthesia depth will be effectively monitored by entropy monitoring, in this way the adequate depth of anesthesia will be provided with the use of minimal volatile anesthetics and we will be able to prevent the use of large amounts of volatile anesthetics., It will be determined how much reduction in alveolar concentration is required in cases combined with TEA. Nowadays, with the development of reliable anesthesia machines, "low-flow anesthesia" (LFA) is becoming more widespread, and its benefits on patient health, economy and ecology have been demonstrated. In LFA, the depth of anesthesia should not be too superficial or too deep during the time the alveolar concentration of volatile agent reaches equilibrium. Therefore, alveolar concentrations of volatile anesthetics are monitored in modern anesthesia machines. Some machines may also adjust the depth of anesthesia according to the alveolar concentration of the agent.

Minumum alveoler concentration, Entropy monitorining, General anesthesia, General anesthesia combined with TEA

Patients will be applyed 0.03 mg/kg midazolam, 2 mcg/kg fentanyl, propofol until reaching the appropriate anesthetic depth by observing entropy value (40-60) and 0.5 mg/kg rocuronium for anesthesia induction, after intubation sevoflurane will be used for anesthesia maintenance with low flow anesthesia (0.5 l/min).

Before anesthesia induction epidural catheter will be inserted giving 7 ml bupivacaine %0.25 in saline + 50 mcg fentanyl after confirming the location of catheter, following 15 minutes the standard anesthesia induction will be applied ( 0.03 mg/kg midazolam, 2 mcg/kg fentanyl, propofol until reaching the appropriate anesthetic depth by observing entropy value (40-60) and 0.5 mg/kg rocuronium ). For anesthesia maintenance epidural infusion will be applied ( 7ml/h %0.25 bupivacaine solution) together with low flow (0.5 l/min) sevoflurane anesthesia.

Inhalation anesthetic amount the target concentration reached ( in the period of reaching the set alveolar concentration)

Inclusion Criteria: undergoing major abdominal surgery Patients who will not undergoing operation for thoracic cavity Body Mass Index (BMI) between 20-30 Exclusion Criteria: denial of patients contraindications for thoracic epidural anesthesia patients who are FEV1/FVC < 60 patients with thoracic and lomber vertebrae surgery

Epidural lidocaine decreases sevoflurane requirement for adequate depth of anesthesia as measured by the BIS monitor

Comparison of the effects of thoracic and lumbar epidural anesthesia on induction and maintenance doses of propofol during total i.v. anesthesia