Evaluation of the Stress Response in Bariatric Surgery With and Without the Use of Opioids
Phase: NA
Conditions: Opioid Use, Unspecified, Bariatric Surgery Candidate
Sponsor: G.Gennimatas General Hospital

Evaluation of the Stress Response in Bariatric Surgery With and Without the 
Use of Opioids 
Last update: 10 January 2023, Athens, Greece 
NCT number: N/A 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
Study protocol 
Objective 
Opioid Free Anaesthesia (OFA) has attracted the attention of clinicians since 
the outbreak of the opioid pandemic in the USA. It has been correlated with 
less intraoperative and postoperative opioid use. The Nociceptive Level Index 
algorithm allows for the intraoperative monitoring of the nociceptive pathways 
and targeted pain management. Furthermore, it is known that morbidly obese 
patients may be benefit from opioid sparing. Our objective is to investigate 
whether the implementation of an OFA intraoperative strategy affects 
postoperative pain scores in morbidly obese patients undergoing laparoscopic 
sleeve gastrectomy. 
 
Design 
This is a randomized, double blind, clinical trial.  Participants are allocated 
using electronic software to be managed with either OFA or Opioid Based 
Anesthesia. Seventy adult patients (18-75 years old, ASA II-III) scheduled for 
elective laparoscopic sleeve gastrectomy will be recruited. Informed consent 
will be obtained by all patients. Exclusion criteria re preoperative bradycardia, 
bundle branch block, QTcF>470msec, Stop-BANG score >5, history of 
depression, chronic corticosteroid use or intraoperative administration of more 
than 8mg of prednisolone or equivalent. Patients will known bone marrow 
dysfunction will be also excluded.   
  
Methods  
All patients will be managed by the same surgical team and the same 
anesthesiologist. The anesthesiologist will be masked for the infusion given. 
Similar preparations will be prepared by an experience anesthetic nurse.  The 
surgeon and the outcomes assessor will be blinded as to the intervention.  
Group OFA 
This arm will receive: 
• 40mg magnesium sulfate in 100 ml N/S infusion 
• 0.4 mcg/kg, max total dose 50mcg in 50 ml N/S infusion 
• 0.3 mg/kg ketamine in 10 ml volume 
• 0.2 ml/kg of the Multimix regimen in 100 ml N/S infusion The 
Multimix regimen consists of 50mcg dexmedetomidine, 500 mg 
lidocaine and 50mg ketamine.  
Group OBA 
This arm will receive: 
 

• 2mcg/kg fentanyl in 10 ml volume 
• 0.2 mL/kg/h remifentanil infusion 
• 0.1 mg/kg morphine 
Except for standard analgesic strategies, both groups will receive fentanyl as 
a rescue dose (1mcg/kg) based on a NOL value > 25 or elevation of Heart 
Rate and/or Blood Pressure >20%. 
Statistical Αnalysis Plan  
The SPSS v.26.0 software (SPSS, Inc., Chicago, Ill, USA) will be employed. 
The significance level is set at p≤0.05. Normality tests will be performed and 
data will be subsequently managed as appropriate. Independent samples T-
test and/or independent samples Mann-Whitney test will be performed for 
group comparisons. The Fisher’s Exact test and x2 test will be used for 
comparisons of groups relative to qualitative variables. Data for biological 
markers will be explored within General Linear Models with the ANOVA 
method according to the model which involves one factor between patients 
(factor “Group” with two levels) and one factor within patients (factor “Time” 
with appropriate levels, with repeated measures).