This randomized control trial aims to assess if Plethysmographic Variability Index (PVI)-based therapy improves patient outcome in terms of reduced amount and type of fluid used, lower postoperative lactate levels, lesser increment in sodium and chloride levels, improvement of blood gases in term of pH and BE, and reduction in serum creatinine as compared to standard monitoring based therapy in patients with severe traumatic brain injury.

This is a single centre, with equal randomisation, single blind, parallel group study conducted in Hospital Universiti Sains Malaysia. The physician allocated to the standard monitoring or PVI group were aware of the allocated arm, wherelse the next of kin were blinded to the allocated arm.

This study took place in Hospital Universiti Sains Malaysia , Kubang Kerian , Kelantan from July 2019 Until October 2020. Patient who presented to emergency department HUSM diagnosed with severe traumatic brain injury based on a GCS ( Glasgow Coma Scale ≤ 8), Brain CT Scan finding (based on Marshall and Rotterdam scoring), and the SAPS (simplified acute physical injury) score and were planned for craniotomies were assessed for eligibility.

Randomisation sequence was already created using the online randomisation application. (www.randomizer.org), with a 1:1 allocation by the primary investigator. Once a patient with severe traumatic brain injury has been posted for an emergency craniotomy, a white envelope was given to the anesthetic medical officer, If the patient fulfils the eligibility criteria, and the next of kin have consented for recruitment to this study, a second sealed white envelope will be given to the anesthetic medical officer in charge, which contains data collection sheets and protocols. The envelope given was sequentially numbered and sealed , with the patients name, identity card, and date of enrolment written on it by the physician. These sealed white envelopes, with the PVI machine was kept in a locked cupboard in the Anesthesia department in Hospital Universiti Sains Malaysia, only accessible to the primary investigator.

Doctors in charge will be given a separate protocol for PVI based and Standard monitoring based which acts a a guide for fluid management in patients in from induction of anesthesia ( 0 H) and 24 hours post induction in the Intensive Care Unit (ICU) (24 H). Data was then collected by the principle investigator at the end of 24 hours, or reevaluated earlier if any adverse reaction was reported by the doctor in charge.

The sample size calculation was performed using Power and Sample Size Calculations System, . From the study by Tat in 2016, the standard deviation for amount of fluid used was 2637.45, with a mean difference of 1361.31. The α value is set at 0.05 and power of study at 80%. The sample size is calculated using t test. Adding a drop out rate of 10%, the number in each arm will be 34. All statistical analysis was performed using Statistical Package for the Social Science (SPSS) version 26. Results were presented as frequency (percentages) for descriptive data, mean ( standard deviation) for total fluids as well as mean (confidence interval) for laboratory parameters.

A total of 64 patient were deemed eligible. The demographic data in between groups were analyzed using descriptive analysis chi square test. Independent t-test was used to analyze the total volume and different types of fluid used. The difference in lactate, pH, BE, Sodium and Chloride- and Creatinine between groups was analysed using the Independent t-test.

Inclusion Criteria:

• Patients who are between 18-60 years old
• ASA (American Society of Anaesthesiology)I and II
• Diagnosed with Severe Traumatic Brain Injury (based on a GCS ( Glasgow Coma Scale ≤ 8) , intubated and consented for neurosurgeries

Exclusion Criteria:

• Patients with serious cardiac arrhythmias
• Patients with peripheral artery disease
• Presence of renal or liver dysfunction
• Presence of concurrent thoracic injury requiring higher ventilator settings with tidal volume > 10 ml/kg or PEEP > 10
• Presence of extracranial major vascular injury ( upper limb, lower limb, intrathoracic or intrabdominal )
• Patients with no valid consent from next of kin or caretaker

next of kin were blinded to the allocated arm