Effects of intravenous Magnesium sulphate and lignocaine on intracranial pressure in adults undergoing elective laparoscopic and robotic surgery in trendelenberg position - A randomised control trial

After obtaining approval from the Postgraduate research monitoring committee (PGMRC) and Institute Ethics committee (IEC), the study will be registered in Clinical trials registry-India (CTRI). Patients who match the eligibility criteria after informed consent will be enrolled and randomised into three groups (Group A, Group B and Group C). Routine preoperative assessment will be performed by the attending anesthesiologist a day prior to the surgery. The operating surgeon will be informed regarding study a day Prior to the surgery. Informed written consent will be taken during pre-anesthetic checkup visit on the day prior to proposed surgery. Preoperative fasting instructions and Premedication’s like Tab.Famotidine 20mg and Tab.Diazepam 5mg will be given on the day before surgery and on the day of surgery. After shifting the patient to Operation theatre, ASA standard monitoring devices like pulse oximetry, ECG, and non-invasive Blood pressure, Entropy sensors will be connected and baseline parameters will be obtained. NIBP will be measured every 10min. All patients will be administered 0.02 mg/kg i.v. Midazolam before induction, after adequate pre-oxygenation, patients will be induced with  Inj.Fentanyl 2 ug.kg1 followed by Propofol 2-3 mg.kg1 titrated to the loss of response to verbal commands and will be paralyzed with Inj. Vecuronium 0.08 mg.kg1. Depth of neuromuscular blockade will be monitored at the wrist with neuromuscular monitor [Train of Four (TOF)].  After placement of endotracheal tube (ETT),  the appropriate placement of ETT will be confirmed with auscultation and capnographic tracing. Intraoperative anaesthesia will be maintained with air: oxygen mixture and depth of anaesthesia will be achieved with inhalational agent isoflurane at a minimum alveolar concentration (MAC) of 0.7-1 titrated to achieve entropy value of 40 to 60. Ventilation will be adjusted to deliver a tidal volume of 8 ml/kg of ideal body weight (IBW) and the plateau pressure will be maintained <30 cmH2O. The respiratory rate will be adjusted to maintain the end-tidal CO2 (EtCO2) between 35 and 40 mmHg. After the induction of anaesthesia, patients allocated to Group  A, lignocaine will be given as a continuous infusion @1.5 mg/kg/hr and in other group B, MgSO4 will be given as a continuous infusion with 10 mg/kg/hr and in Group C,  0.9% NS @5ml/hr continuous infusion will be given till the end of the surgery. Pneumoperitoneum will be created with intraperitoneal insufflation of CO2 with the patient in supine position. Then the patient will be positioned in the trendelenburg position slowly and surgery will be performed in the position where the target structures are visualised optimally by the operating surgeon. The degree of trendelenburg position will be measured with the help of a goniometer. Analgesia will be maintained with intermittent bolus of fentanyl 0.5ug/kg  to maintain response entropy (RE) between 40-60 and vecuronium will be administered at the dose of 1 mg when TOF count reaches 2.

The optic nerve sheath diameter (ONSD) will be assessed using a linear probe (6-13 MHz) with a small amount of gel applied gently to the upper eyelids to prevent undue pressure.  The ONSD will be measured 3 mm behind the eye globe. The ONSD will appear as a vertical hypoechoic band surrounded by retrobulbar echogenic fat tissue on the monitor, aligned perpendicularly to the ultrasonic probe.

ONSD measurement will be performed at time points Tb: after  induction, T1:after giving Trendelenberg position, T2: after 1 hour of trendelenburg position; T3: every one hourly, Te: at the end of surgery during the closure of ports.

We will not be giving intervention after  the onset of rise in ICP as the increase in ONSD is expected to raise from the baseline which is not clinically significant. In this study, we are including patients who do not have any risk factor for developing adverse outcomes

Due to trivial increase in ICP (Ex: Patients with intracranial space occupying lesions, any previous craniotomy surgeries, patents with hydrocephalus will be excluded from this study).

Neuromuscular recovery time is  defined as the duration from the administration of reversal agents to the point where the train-of-four ratio (TOFr) reaches 0.9.

Time to first analgesia refers to the duration between a patient’s transfer from the Post-Anesthesia Care Unit (PACU) and the administration of the initial dose of analgesic medication.