CTRI

After arrival of the patient in the operating room, standard monitoring - pulse oximetry, non-invasive arterial blood pressure and electrocardiography will be attached. With all aspectic precautions radial artery will be cannulated under local anaesthesia for continous invasive blood pressure monitoring. Baseline vital parameters like heart rate (HR), systolic blood pressure(SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), and arterial O₂ saturation( SpO₂) will be recorded in all patients. An i.v line will be secured with 18 gauge peripheral venous cannula and all patients will be preloaded with 10 ml/kg of crystalloid. All patients will be premedicated with i.v glycopyrrolate 0.2 mg, dexamethasone 0.15 mg kg^-1 and fentanyl 2 Âµg kg^-1. General anaesthesia will be induced with propofol 2-3 mg kg^-1till loss of verbal response and tracheal intubation will be facilitated by vecuronium 0.1mg kg^-1, intravenously. After induction of anaesthesia, under all aseptic precautions right subclavian vein will be cannulated using seldingers technique. The sitting position will be made gradually over a period of 5 min with continous arterial pressure monitoring.

HR, SBP, DBP, MBP, SpO₂, EtCO₂ will be continuously monitored and will be recorded at baseline, after induction, after tracheal intubation, before making sitting position, during process of making sitting position every min till 5 min, after sitting position at 1, 2,3,4,5, 10 and 15 min. Subsequently, anaesthesia will be maintained using isoflurane achieving end-tidal concentration of 1.0 to 1.2% in a mixture of 50% air with 50% O₂. Neuromuscular relaxation will be maintained with intermittent vecuronium bolus (0.02 mg/kg every 30 minutes). Ventilation will be adjusted to maintain EtCO₂ between 30 and 35 mm Hg. Intraoperative rescue analgesia will be provided by intravenous fentanyl 0.5-1 Î¼g/kg boluses as judged by increase in heart rate or systolic blood pressure by more than 20% of the baseline. All patients will be given Injection ondansetron 0.1mg/kg prophylactically 30 minutes before reversal. At the end of surgery, patients will be turned supine and residual neuromuscular blockade will be reversed with i.v. neostigmine 50 Âµg.kg^-1 and glycopyrrolate 10 Âµg.kg^-1 and the trachea will be extubated when the patient is fully awake and breathing adequately and will be shifted to postanaesthesia care unit(PACU).

To evaluate occurrence of haemodynamic changes, an episode of hypotension will be defined as a decrease in the mean arterial pressure(MAP) 20% below baseline. Bradycardia will be defined as decrease in HR< 40 beats/min. Venous air embolism will be diagnosed by sudden and sustained drop of 5 mmHg of the end-tidal carbon dioxide (EtCO2). If hypotension (MBP<20% of baseline) would occur, 5 mg of ephedrine will be administered i.v. If hypotension would persist or recur three minutes after ephedrine injection, 50 Âµg of phenylephrine will be repeated every three minutes till blood pressure stabilizes. In the event of bradycardia 0.6 mg of atropine will be administered i.v. If VAE would occur, appropriate therapeutic measures will be taken immediately which involves, aspiration of air via the right atrial catheter, irrigation and packing of the wound, identification and coagulation of vessels.

Intraoperative and postoperative complications of sitting position which include hypotension, VAE, PAE, quadriplegia, macroglosia and peripheral neuropathy will be noted in all patients and incidence of each complication will be calculated. Intraoperative blood loss and need for blood transfusion, total duration of surgery, will be noted. Need of postoperative ventilation and total days of ventilation and ICU stay will also be noted.

All the observations will be recorded in the proforma attached and analyzed statistically using appropriate statistical test.