Ketamine for Postoperative Pain in Bariatric Surgery

Study Overview
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Brief Summary
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The aim of this study was to evaluate an effect of pre - incisional single injection of low-dose ketamine on postoperative pain after remifentanil infusion in patients undergoing laparoscopic gastric bypass and gastric plication surgery. Ketamine is an old general anaesthetic. Low doses of it might be used as a adjunct in postoperative analgesia.The investigators expect that the low-dose ketamine reduces postoperative pain after bariatric surgeries.

Detailed Description
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Effective postoperative pain management enhances early postoperative rehabilitation and may improve outcomes of surgical treatment. New analgetic medications and combinations of these are sought for optimal analgesia with lowest possible incidence of side effects. One of the method of multimodal analgesia is a combination of opioids and adjuvant agents, such as ketamine. To our knowledge, the role of ketamine in the treatment of postoperative pain after bariatric surgeries is poorly researched. The investigators hypothesize that ketamine, acting through the N-methyl-D-aspartate receptor (NMDA) and opioid receptors, provides favourable conditions for adequate post-operative pain management.

Official Title
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The Effects of Ketamine on Postoperative Pain After Intraoperative Remifentanil Infusions in Bariatric Surgery

Conditions
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Pain, Postoperative, Bariatric Surgery Candidate

Intervention / Treatment
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* Drug: Ketamine
* Drug: Saline
* Drug: Ketamine
* Drug: Ketamine
* Drug: Ketamine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: II or III The American Society of Anesthesiologists (ASA) physical status age > 18 years bariatric surgery with general remifentanil anesthesia Exclusion Criteria: anamnesis of using opioids for the treatment of chronic pain opioid dependence younger than 18 years

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Treatment1<br>0,15 mg/kg (LBM) of intravenous pre-incisional single bolus injection of ketamine given for bariatric patients in the operating room. | Drug: Ketamine<br>* 0,15 mg/kg pre-incisional single bolus dose of ketamine in the operating room.<br>* Other names: Ketamine hydrochloride;|
| Active Comparator: Treatment2<br>0,3 mg/kg (LBM) of intravenous pre-incisional single bolus injection of ketamine given for bariatric patients in the operating room. | Drug: Ketamine<br>* 0,3 mg/kg pre-incisional single bolus dose of ketamine in the operating room.<br>* Other names: Ketamine hydrochloride;|
| Active Comparator: Treatment3<br>0,15 mg/kg (LBM) of intravenous pre-incisional single bolus injection, followed by continuous infusion of 1mg/kg ketamine given for bariatric patients in the operating room. | Drug: Ketamine<br>* 0,15 mg/kg pre-incisional single bolus dose of ketamine, followed by continuous infusion of 1 mg/kg in the operating room.<br>* Other names: Ketamine hydrochloride;|
| Placebo Comparator: Control<br>The same amount of intravenous single pre-incisional injection of saline for bariatric patients in the operating room. | Drug: Saline<br>* Intravenous injection given pre-incisional in the operating room.<br>* Other names: Sodium chloride;|
| Active Comparator: Treatment4<br>0,3 mg/kg (LBM) of intravenous pre-incisional single bolus injection, followed by continuous infusion of 1mg/kg ketamine given for bariatric patients in the operating room. | Drug: Ketamine<br>* 0,3 mg/kg (LBM) of intravenous pre-incisional single bolus injection, followed by continuous infusion of 1mg/kg ketamine given for bariatric patients in the operating room.<br>* Other names: Ketamine hydrochloride;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Postoperative pain intensity | Comparison of pain intensity will be recorded in both groups every 15 min in Post Anesthesia Care Unit (PACU) for 2.5 hours. Postoperative pain was treated with boluses of i.v. morphine (3 mg) at 3 min. intervals on request, if pain intensity exceeded the score of 5 according to the Numeric Pain Rating Scale (NPRS) (0-10). After the transfer of patient's to a regular unit, pain intensity was recorded every 6 hours. | On the first postoperative day | 
| Postoperative morphine requirements | Postoperative morphine requirements will be recorded in both groups in the PACU for 2.5 hours. | On the first postoperative day | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of side effects | Incidence of side effects will be recorded in both groups on the first postoperative day. | On the first postoperative day | 
| Patients' satisfaction with postoperative analgesia | Patients' satisfaction with postoperative analgesia will be recorded in both groups on the second postoperative day.The subject could express their level of satisfaction in five possible levels, from very satisfied to very dissatisfied. | On the second postoperative day |