The Impact Opioid Free Anesthesia on Postoperative Pain Intensity and Stress Response After Open Gynecology Surgery

This prospective randomized, controlled clinical study was carried out in the Department of Anesthesiology and Intensive Care Unit and Department of Gynecology at the Cantonal Hospital Zenica, Bosnia and Herzegovina. After obtaining ethical committee approval 80 participants, scheduled for elective open gynecology surgery were included into study. Sample size was estimated using sample size calculator software and power analysis with 90% confidence interval and power of 80%. Statistical significance was considered as p< 0,05. The calculation indicated 35 participants per group would be sufficient to detect a 50% difference for IL-6, cortisol, prolactin and CRP between the groups. Assuming dropout would lead to a total sample size of 80 participants. Before each participant agreed to the join the study, the purpose and procedures of the study were fully explained and informed and written consent was obtained from each participant. A preoperative anesthetic examination was conducted the day before surgery. The interventional group, opioid free anesthesia group(OFA group) and the control group, multimodal balancing anesthesia group (MBA group). Randomization was performed by computer generated randomization codes. The codes which indicated the treatment were held in sealed opaque envelopes. Nurse who conducted randomization and opened the envelopes the night before surgery was blinded to the study protocol as well as the gynecologist, nurses and staff involved in data collection.

The participants of MBA group were undergone to the traditional concept of preoperative and intraoperative anesthesia management with opioid. The participants in the intervention group received opioid free anesthesia and didn't received opioid in peroperativ period. Assessment of clinical parameters started at 06:00 am on the day of surgery (basal value). Peripheral venous blood samples were collected to measure serum levels of glucose, cortisol, prolactin, C-reactive protein, blood count and differential blood count and IL-6, and 06.00 am on the first postoperative day. Six hours post-surgery peripheral venous blood samples were collected to measure serum levels of glucose, cortisol, prolactin, blood count and differential blood count. All patients underwent to opioid free anesthesia will be given TAP block ultrasound guided after intubation and before surgical incision. Consciousness and pain respond monitored by Entropy or CONX device. Analgesia for opioid free arm during surgery will bi provided with combination of medicament (Dexmedetomidine, Ketamine, 2%Lidocaine, Dexamethasone and Magnesium sulfate). Blood pressure and hart rate recorded : before intubation, on intubation, skin incision, before extubation and two hour after extubation.

Assessment of subjective well-being was performed using a 10 cm horizontal Visual Analogue Scales for 1, 2, 4, 6-12 and 12-24 hours post-surgery. Pain at rest, pain with mobilization, thirst, hunger, mouth dryness, anxiety and weakness were evaluated. The patients were explained how to use the scale. Postoperative data included and the time to oral intake. The following data were recorded also: age, sex, body weight, body mass index, American Society of Anesthesiologists (ASA) physical status class, type of surgery.

Inclusion criteria

• participants with ASA physical status class I-II

• aged between 18 years and 65 years
• participants scheduled for elective open gynecology surgery non cancer

Exclusion criteria

body mass index above 30 kg/m2, diabetes mellitus, emergence surgery, cardiopulmonary disease, neuromusular disease, renal disease, vaginal hysterectomy, hepatic or endocrine disease, pregnancy, mental disease, allergy to any study drugs, alcoholic or drug abuse, ASA III and IV, patient's refusal to participate in the study, duration of surgery below 30min and over 90min.