Postoperative delirium (POD) is a known complication of inhalational agents used to anaesthetise patients for surgery with potential long term implications.The incidence of postoperative delirium in spine surgery is 3.3% to 3.8%.The purpose of this study is to compare the occurrence of postoperative delirium with inhalational anaesthetics namely isoflurane and desflurane in spine surgery patients.

The patient will be randomized to receive isoflurane or desflurane anaesthesia prior to surgery. All the patients involved in the study will be blinded to group allocation. Screening for preoperative cognitive dysfunction will be done using the mini-cog test which includes a three word recall test and clock drawing test.The primary outcome variable will be assessment of delirium at day one and day three following surgery. Post operative delirium will be diagnosed using the 3D- CAM(Confusion Assessment Method) which tests for four features with a series of questions. The features include 1) acute onset and fluctuating course,2) inattention,3) disorganized thinking and 4) altered level of consciousness. Diagnosis of delirium is made if features 1 and 2 and either 3 or 4 are present. Similarly the severity of postoperative delirium will be assessed on day one and day three following surgery. Severity of postoperative delirium will be assessed using the CAM-S(Confusion Assessment Method-severity)long form delirium severity score.It assesses ten features including 1) acute onset and fluctuating course,2)inattention,3)disorganized thinking , 4)altered level of consciousness, 5) disorientation, 6)memory impairment ,7)perceptual disturbances ,8)psychomotor agitation, 9)psychomotor retardation and 10) altered sleep-wake cycle. The scores range from 0 to 19.

The demographic data of the patients,type and site of surgery will be noted. Preoperative hemoglobin, serum electrolytes and blood urea will be recorded. The intraoperative factors like duration of surgery and anaesthesia,use of intravenous fluids ,blood loss, number blood units transfused and opioid use will be studied at the time of surgery. The time to emergence and extubation following the completion of surgery will be noted.

The postoperative factors like postoperative pain, nausea and vomiting, fever,hemoglobin,serum electrolytes and blood urea will be noted.

Preoperative and postoperative pain will be assessed using the numerical rating score on a scale of one to ten.

The association of various preoperative,intraoperative and postoperative factors with POD will be determined.

Inclusion Criteria:

• Patients scheduled for spine surgery.
• Age between 18-65 years
• American Society of Anaesthesiologists (ASA) Grade I and II patients
• Patients with Glasgow Coma Scale (GCS) of 15
• Postoperative Aldrette score > 9

Exclusion Criteria:

• Cardiorespiratory disorders
• Associated cerebral disease
• Psychiatric illness
• Electrolyte and hormonal imbalance
• History of drug abuse
• Postoperative meningitis
• Administration of high dose steroids

18 months

1. Small sample size
2. Postoperative delirium was assessed only up to to 72 hours post surgery. POD can persist for months following surgery.