Opioid-free Anesthesia and Acute Postoperative Pain

Control of intraoperative and postoperative pain with the use of opioids constitutes normal practice. Opioid free anesthesia (OFA) is a relatively recent anesthesiology practice according to which opioids are not administered during surgery and are avoided postoperatively. Opioid free anesthesia seems to provide better quality of postoperative analgesia while protecting the patient from the side effects of opioids such as respiratory depression, postoperative nausea and vomiting (PONV), opioid induced hyperalgesia and postoperative cognitive dysfunction. The aim of this study is to investigate the possible difference in the intensity of postoperative pain (based on the numeric rating scale 0-10) and the presence of PONV in patients undergoing transurethral urologic surgery under general anesthesia, when patients receive randomly either opioid free anesthesia (OFA) or opioid based anesthesia (OBA).

This study aimed to study postoperative pain after opioid free anesthesia or opioid based anesthesia after urologica; procedures. The two study groups opioid free (OFA) and opioid based (OBA) were as follows:

OFA: Anesthesiology technique based on Mulier protocol. Before induction, loading dose of dexmedetomidine 0,25mcg/kg (max 20mcg). Induction with dexmedetomidine 0,1mcg/kg, lidocaine 1mg/kg, ketamine 0,1mg/kg plus propofol 2mg/kg plus rocuronium1mg/kg IBW (if required). Maintenance with dexmedetomidine 0,1mcg/kg/h, lidocaine 1mg/kg/h, ketamine 0,1mg/kg/h and propofol infusion adjusted according to bispectral index indication ( BIS maintained 40-60). 15 minutes prior to end of surgery, the dose of drugs is reduced to dexmedetomidine 0,05mcg/kg/h, lidocaine 0,5mg/kg/h, ketamine 0,05mg/kg/h.

OBA: Total intravenous anesthesia with propofol for maintenance of anesthesia. Fentanyl 2mcg/kg only at induction and infusion of propofol and remifentanil for maintenance, with doses adjusted according to bispectral index indication ( BIS maintained 40-60).

Both groups receive ranitidine 50mg, dexamethasone 4 mg and paracetamol 1g iv 15 min before the end of surgery. Postoperative analgesia for both groups consists of paracetamol 3g/24h iv, rescue analgesia with tramadol 1mg/kg iv max x3, rescue for PONV ondacetron 4 mg iv.

The outcomes assessed were:

Primary outcome:

1. Intensity of acute postoperative pain (NRS 0-10), time frame up to 24h postoperatively
2. Nausea and vomiting

Secondary outcome:

1. Change in minimental state evaluation test, time frame pre-op, 1h post-op, at discharge
2. Severe postoperative adverse effect related to anesthesia (postoperative hypoxemia, ileus, postoperative cognitive dysfunction)

Eligibility Criteria:
Inclusion Criteria:

* Patients aged\>18 years old
* ASA I-III
* Patients scheduled for elective transurethral urologic surgery with general anesthesia

Exclusion Criteria:

* • Patient refusal

  * Use of opioids pre-op
  * Inability to read or write
  * Known psychiatric disease under medication
  * Dementia
  * Severe liver and renal disease
  * Known allergy to drugs used
  * Known arrhythmia (2nd-3rd AV block, acute unstable angina, acute myocardial infarction in the past 6 weeks or severe cardiac problem-condition)
  * Heart rate\<45 bpm
  * Pre-op minimental test\<23
  * Major surgery complications (hemorrhage with need for transfusion)