Effect of Intravenous Sedation with Dexmedetomidine on Postoperative Delirium in Elderly undergoing Endoscopic Urological Surgeries under Spinal Anesthesia – A Randomized Controlled Trial.

INTRODUCTIONPostoperative delirium is a common complication seen during the postoperative course especially in elderly and has a deep impact on the healthcare of patientsand thus on the healthcare financial management. Incidence of Postoperative Delirium (POD) is 7.8- 21.23% in endoscopic urological studies. Various studies have been demonstrated a reduced incidence of postoperative delirium with dexmedetomidine in cardiac and non-cardiac surgeries like orthopedic, abdominal and spine surgeries etc. Its impact in patients undergoing endoscopic urological surgeries is unexplored. We expect that the usage of dexmedetomidine sedation in elderly patients undergoing endoscopic urological surgeries will reduce the incidence of postoperative delirium.METHODOLOGYPatients satisfying the inclusion criteria will be included in the study after obtaining informed written consent. Baseline cognition status will be evaluated using the Mini-cog tool on the previous day. On arrival to the OR, standard ASA monitors [pulse oximeter, non-invasive blood pressure (NIBP), electrocardiography (ECG)] will be attached. Intravenous access will be secured, and the patient will be positioned in lateral decubitus for spinal anesthesia. Under sterile aseptic precautions, the subarachnoid blockade will be administered at L3/4 0r L4/5 with a 25-gauge Quincke needle in the lateral decubitus position. After confirmation of free flow of clear cerebrospinal fluid, 10-15mg of 0.5% hyperbaric bupivacaine will be administered intrathecally. The patient will be turned to supine position and a forced air warming blanket will be applied to the upper body to maintain normothermia. After ensuring adequate level of blockade (at least T10) and hemodynamic stability, study participants will be randomly divided into two groups: Group D and Group C. Entropy sensors will be attached to patients prior to start of drug infusion. Study participants in Group D will receive Dexmedetomidine infusion at 0.2-0.4mcg/kg/hr. and those in Group C will receive 0.9% Normal Saline infusion at the same rate. Drug infusion will be titrated to maintain entropy between 60-80. Modified observer’s assessment of alertness/sedation (OAA/S) score will noted at every 15 minutes. All patients will receive supplemental oxygen via nasal prongs (3L O2). Study drug infusion will be stopped at the end of surgery. Vital parameters including blood pressure, heart rate and oxygen saturation will be monitored at baseline (before administration of spinal), start of infusion and throughout the surgery. Side effects such as hypotension, bradycardia, desaturation and oversedation will be noted. Patients who develop hypotension (systolic blood pressure less than 20% from the baseline or less than 90 mmHg) will be treated with an intravenous 3 mg bolus dose of mephentermine and the number of boluses will be noted. When the heart rate (HR) falls to less than 45 beats/min and is associated with hypotension, atropine (0.6 mg) will be administered. The patient will be shifted to PACU and will be monitored in PACU for 2hours and then shifted to ward. Vital parameters will be monitored every 6 hours for 24 hours. The confusion assessment method (CAM-ICU) will be used to determine the occurrence of postoperative delirium at 24, 48 and 72 hours. Psychiatric consultations will be scheduled for patients who develop delirium to ensure they receive the appropriate treatment. All patients will receive intravenous paracetamol 15mg/kg q8h and pain will be assessed using VAS score at 2, 6, 12, and 24 hours. In patients with a VAS score of more than 5, a bolus of 25mg tramadol IV will be given. Catheter-induced bladder discomfort intensity will be assessed at using a 3-point scoring system (1-comfortable, 2-uncomfortable but bearable, 3-uncomfortable, and unbearable)12at 2, 6, 12, and 24 hours and the urologist will be informed if it is grade 3.