Intraoperative low dose ketamine infusion for postoperative pain relief in laparoscopic surgeries – A Prospective Randomised Double Blind Clinical Trial.

1. Title of the dissertation: Intraoperativelow dose ketamine infusion for postoperative pain relief in laparoscopic surgeries – A Prospective Randomised Double Blind Clinical Trial.

2. Introduction:

Patients who undergo laparoscopic surgery experience less pain, less scarring, early ambulation and short recovery in comparison to the traditional open abdominal surgeries. However, there are undesirable side effects like postoperative pain, especially in the abdomen, back and shoulder tip due to stretching of intra-abdominal cavity leading to stimulation of sympathetic nerves and also because of hypercarbia and irritation of the phrenic nerve by residual carbon dioxide in the peritoneum. It is reported that 50% to 70% of laparoscopic surgery patients experience moderate to severe postoperative pain.

N- Methyl D Aspartate receptor activation is considered to be one of the reasons for postoperative pain through both central and peripheral effects. Ketamine, a phencyclidine derivative is a non-competitive NMDA receptor antagonist that produces dissociative anaesthesia and ketamine induced analgesia.

In most published studies, ketamine has been used in varying doses for postoperative pain relief in laparoscopic surgeries. However, it is seen that the psychosensory side effects of ketamine increases at doses above 0.3 mg/kg and low doses less than or equal to 0.1mg/kg were found to be prophylactically ineffective.

Ketamine has been used both as a single preemptive bolus dose as well as repeated bolus doses throughout the period of surgery for postoperative pain relief. Literature search did not reveal many studies that had used ketamine as continuous infusion intraoperatively. So we aim to study a low dose ketamine bolus followed by infusion throughout the period of surgery assuming the infusion of ketamine would maintain a steady state plasma concentration and thus provide a better postoperative pain relief. In addition to analgesic benefits of ketamine, it has also been found to reduce opioid consumption postoperatively thus resulting in reduced incidence of sedation and nausea vomiting in these patients.

3. Research hypothesis:

Intraoperative low dose ketamine bolus followed by infusion  is effective in  reducing  postoperative pain in laparoscopic surgeries.

4.   Study procedure:

After obtaining ethical committee clearance of Pondicherry institute of medical sciences and informed as well as written consent ,52 patients aged 18-60 years  belonging to ASA I or ASA II will be enrolled in the study .A thorough pre-anaesthetic check up including detailed history, general and systemic examination and review of routine investigations will be conducted a day before surgery. All the patients will be shown the Numerical Rating Scale (NRS) preoperatively and instructed about its use as a tool for measuring and grading postoperative pain after ensuring nil per oral for a period of 8 hours. The selected patients will be split into two groups. One group will receive 0.2mg / kg ketamine bolus and then 0.1mg / kg / hour ketamine infusion until end of surgery. The other group will receive a similar amount of 0.9% NaCl. In the Operation Theater blood pressure, heart rate and oxygen levels will be monitored and recorded. An I V cannula will be secured for injecting medication. A face mask will be placed for the oxygen supply. After that they will be anaesthetized. Once unconscious, a tube is placed through the mouth . The air entry will be checked. Subsequently, the drug prepared will be provided under  supervision until the end of surgery. After surgery all the anaesthetic agents will be cut, oxygen will be given and the tube will be removed. After regain of consciousness, patients will be transferred to the recovery room , they will be questioned if there is pain or any side effects of the study drug, and will be evaluated according to the pain criteria explained  before the day of surgery. If there is pain after surgery, analgesics will be given.

5.  Parameters to be studied

a)     Postoperative pain

b)     Haemodynamic parameters

c)     Postoperative opioid consumption

d)     Grade of sedation

e)     Record of adverse effects if any.

6.   Expected Outcome:

Determination of the efficacy of low dose Ketamine for postoperative pain relief in laparoscopic surgeries.