Change of protocol title

This study investigates the effect of low dose S+ketamine compared to placebo on cumulative morphine consumption at 24 hours in women undergoing open abdominal hysterectomy with remifentanil-propofol target controlled infusion. It compares the adverse effect profile in patients receiving S+ketamine as compared to those who did not. Participants are randomly distributed in two groups of 45 patient's each.

In recent times it has been suggested that NMDA receptor antagonist like ketamine when used in small doses helps reducing postoperative pain and opioid consumption without compromising wakefulness and or causing its psycho mimetic adverse effect .

The clinical utility of S+ ketamine as an adjuvant intra-operatively remains controversial. The NMDA receptor activation and subsequent biochemical process has been proven to play an important role in both hyperalgesia after tissue injury and the development of opioid tolerance. Various studies have reported the advantage of S+ ketamine over traditional balanced anaesthesia, but may lead to secondary hyperalgesia and increased opioid requirement in post operative period in both animals and healthy human volunteers. Other studies showed that 48 hours continuous administration of small-dose ketamine, together with patient-controlled analgesia (PCA) with morphine, or systemic, epidural co-administration of ketamine and opiates markedly reduced cumulative morphine. However, the dosage, route and timing of administration of S+-ketamine varied in different setting.

Inclusion Criteria:

• Females above the age of 21 years old scheduled undergoing open abdominal hysterectomy with remifentanil-propofol TCI in KKH for benign condition (fibroids, adenomyosis),
• Be willing and able to give written informed consent for participation in this study
• ASA I/II patient's.

Exclusion Criteria:

• Patient with contraindications to the use of S+ketamine, as listed in the product label e.g. untreated or insufficiently treated thyroid hyperfunction, unstable angina pectoris or myocardial infarction within the last 6 months, diseases of the CNS, increased intraocular pressure and perforating ocular injuries, surgical procedures in the upper respiratory tract, etc
• Patients with a h/o drug or alcohol abuse
• Regular use of analgesics, or use of opioids within 12 hours of surgery
• Patient on chronic use of benzodiazepine or neurololeptics
• Patient on thyroid replacement hormone
• H/o IHD,HTN,Thyroid disorder.
• BMI> 30kg/m2.
• H/o Psychiatric disorder.
• Laproscopic surgery converted to open surgery.
• Pregnant or breast feeding female's.