The effect of intravenous dexamethasone on postoperative pain management in patients undergoing unilateral total knee arthroplasty under subarachnoid block

Patients will be randomly allocated to either of the two groups [ Group D or Group P] using computer generated random sequence of numbering. Concealment of allocation will be ensured by sequentially numbered opaque sealed envelopes.                                         On the day of surgery, patients in Group D will receive 0.1mg/kg Dexamethasone (rounded up to the nearest milligram dose) diluted up to 5 ml with normal saline before performance of spinal anaesthesia, whereas Group P will receive 5ml of normal saline. The drug will be administered by the posted anaesthetist in the OR immediately following establishment of IV access. All standard monitors will be attached and baseline HR, SBP, MAP will be recorded. Blood sugars will be checked using GRBS before administration of spinal anaesthesia and at 2 hourly intervals intraoperatively. All patients will receive spinal anaesthesia with bupivacaine 0.5%(H) 3ml + fentanyl 25mcg (0.5ml). After confirming adequate blockade, patient will be positioned for surgery. At the end of surgery under aseptic precautions and USG guidance adductor canal block will be given with ropivacaine 0.2% 20 ml and catheter placed. Post operatively Group D will receive another dose of dexamethasone 0.1mg/kg (rounded upto the nearest milligram dose) diluted up to 5 ml, 8 hours after the initial dose whereas group P will receive 5ml of normal saline. The study drug as well as placebo will be loaded in a 5ml unlabelled syringe (by the operating room anaesthetist) labelled as study drug and administered by the ICU anaesthetist. Both the ICU anaesthetist and the staff nurse will be blinded to the study group. All patients will receive IV paracetamol 1-gram IV TID along with buprenorphine patch 10mg.

Patients will receive IV fentanyl or morphine as rescue analgesic as decided by the duty anaesthetist to keep the VAS score below 4. The cumulative opioid consumption for each patient for the first 48 hours after surgery will be recorded as morphine equivalents.

Other perioperative complications documented will be –

Post operative Nausea and vomiting using simplified PONV impact scale.

Significant PONV will be managed by IV ondansetron 0.1mg/kg Q8h

Incidence of post operative pruritus and hyperglycaemia (sugars more than 180 mg% on two consecutive occasions post-operatively)

Hyperglycaemia postoperatively will be managed with delta protocol insulin infusions as routinely prescribed along with previously prescribed oral hypoglycaemics as directed by the ICU anaesthetist.

Wound issues (healing / as assessed by the surgical team at discharge will also be documented.