1.    Introduction: 

Many techniques and drugs have been proposed to blunt airway and haemodynamic responses during tracheal extubationbut none have been completely successful. Tracheal extubation in deep plane is one such technique to blunt haemodynamic response and airway hyper-responsiveness, but, it increases the chances of airway obstruction and aspiration. Other techniques to blunt such responses are endotracheal tube (ETT) exchange to laryngeal mask airway (LMA) and “No-Touch” extubation. Pharmacological therapies likelignocaine (intravenous, intra-cuff alkalinized, intra-cuff non-alkalinized, topical, endotracheal application), α-adrenergic agonists (clonidine, dexmedetomidine), β-adrenergic blockers (esmolol, labetalol), calcium-channel blockers(verapamil, diltiazem), vasodilators (nitroglycerin), opioids (remifentanil, fentanyl) and propofol have been used to attenuate such responses, however, with variable success rate and different side effects.

In  

DMethodology: In this study,100 patients will be randomly allocated into 4 groups in 1:1 ratio. Preoperatively, lignocaine (0.1 ml) will be injected subcutaneously in all the patients to test for allergic reaction. The patients will be kept nil per oral for atleast 8 hours prior to scheduled surgery. On the morning of surgery, all patients will receive tablet ranitidine 150 mg orally with sips of water. Premedication will be done with glycopyrrolate 0.2mg via intra muscular route 30 minutes prior to surgery. Standard monitors such as non-invasive blood pressure (NIBP), electrocardiogram (ECG), and pulse oximetry (SpO₂) will be attached. An intravenous cannula(18 or 20 G) will be inserted and patency will be confirmed. After pre-oxygenation with 100% oxygen for 3 minutes, general anaesthesia will be induced with fentanyl 2 mcg/kg IV and propofol 2-3 mg/kg IV titrated to the loss of verbal responsiveness.Vecuronium 0.1 mg/kg IV will be administered to facilitate tracheal intubation with a cuffed endotracheal tube having appropriate internal diameter. Ventilator settings will be done to deliver a tidal volume of 8 ml/kg and respiratory rate will be adjusted to maintain an end-tidal carbon dioxide (EtCO₂) value between 35-40mm of Hg (volume controlled ventilation). Maintenance of anaesthesia in all the 4 groups will be done with oxygen and air (fraction of inspired oxygen being 0.5), sevoflurane titrated to maintain minimum alveolar concentration (MAC) between 0.8-1.2 and intermittent doses of vecuronium (0.02 mg/kg IV).An orogastric catheter will be inserted for gastric decompression after the tracheal intubation. Intraoperative body temperature will be maintained between 36-37.5°C and will be monitored by a probe placed in the axilla. Intraoperative fluid therapy will be done with crystalloids and colloids, whenever required. Ondansetron (0.1 mg/kg IV) and paracetamol (1 gram IV over 15 minutes) will be administered 30 minutes prior to completion of surgery. At the end of the surgery, sevoflurane will be discontinued and fast alveolar washout will be done [discontinuing sevoflurane, flushing the breathing circuit with 100% oxygen and maintenance of 100% oxygen at 10 litres/min] [25].Reversal of neuromuscular (NM) blockade will be done with neostigmine (0.05-0.07 mg/kg IV) and glycopyrrolate (0.01 mg/kg IV) when train of four (TOF)count is atleast 2 or greater [26].

Any change in HR and BP more than 20% of the pre-induction values during the period from induction till completion of surgery will be treated with appropriate drugs. Hypertension and/or tachycardia will be treated with 0.25 μg/kg of intravenous fentanyl, if MAC is between 0.8-1.2within the study range. Patients not responding to fentanyl will be administeredintravenous labetalol in incremental doses of 5 mg. Hypotensive episodes will befirst managed with bolus of 200 ml crystalloids. In non-respondents, 3 mg of intravenous mephentermine will be administered in incremental doses. Atropine (0.6 mg IV) will be used for bradycardia associated with hypotension.

Group allocation, randomisation and blinding

In this study, the patients will be randomised into four groups: group 1 (saline), group 2 (1mg/kg IV lignocaine), group 3 (1.5 mg/kg IV lignocaine) and group 4 (2 mg/kg IV lignocaine) using a computer generated randomisation chart based on block randomisation with variable size. Opaque sealed enveloped will be used for group allocation.The patients and the investigator will be blinded to the study drugs. Samples will be decoded for statistical analysis after the completion of the study.

DDrug preparation and intervention

The study drugs will be prepared and labelled with sequential number (as per randomisation chart) by an independent anaesthesiologist who is not involved in the study. For blinding purpose, calculated dose of study drug will be diluted to 5ml with saline in a 5cc syringe. The prepared drug will be handed over the investigator (anaesthesiologist conducting the case). After the administration of the NM blocking reversal agent, the investigator will administer the study drug when the patients open eyes to verbal commands and generates tidal volume of atleast 6 ml/kg followed by the extubation of trachea after 90 seconds.