The aim of this non inferiority trial is to assess the efficacy of CompuFlo® technology to identify the thoracic epidural space in relation to the gold standard loss of resistance technique.

This non inferiority trial shouts to adress whether the CompuFlo® technology to identify the thoracic epidural space is less efficacious to the gold standard loss of resistance technique (LOR). After informed signed consent patients that will be subjected to gynecological operations and meet the inclusion criteria will be eligible to participate. All operations will be performed under general anesthesia and thoracic epidural analgesia regardless of study arm. Patients will be randomly allocated into two study groups. In the first study group (Group LOR) the thoracic epidural space will be identified by the LOR technique and in the second study group (Group C) by the CompuFlo® technology. The primary outcome is the percentage of thoracic epidural space identification success in either study group.

Inclusion Criteria:

American Society of Anesthesiologists (ASA) Physical Status Classification System I-III Body mass index: 18 -35 kg/m2 Gynecological laparotomy with midline incision under general anesthesia and thoracic epidural analgesia

Exclusion Criteria:

Patients' denial to participate in the study ASA Physical Status Classification System >IV Contraindications to epidural analgesia Patients with sepsis Patients with pre-existing neurologic deficits Pre-existing operations in the thoracic spinal cord Emergency operations Patients with end-stage cancer

Member of the study group that assesses the epidural's success