Exploring the effects of Inhalational and intravenous anaesthesia on postoperative delirium in the geriatric population: insights from biomarkers and cognitive assessment

Background Postoperative delirium is a common complication among elderly patients undergoing surgery under general anaesthesia. The choice of anaesthetic technique may influence the development of this condition. Inhalational anaesthesia and total intravenous anaesthesia are two standard methods used in general anaesthesia. However, their comparative effects on the incidence of postoperative delirium in elderly patients are not well established. This randomised, double-blinded, controlled trial aims to compare the impact of inhalational anaesthesia and total intravenous anaesthesia on the incidence of postoperative delirium in elderly patients undergoing surgery at a tertiary care centre. The assessment will be done both clinically and through serum biomarkers.

Methodology This is a prospective, randomised, double-blinded, controlled trial involving 80 participants aged 60 years and above, classified as American Society of Anesthesiologists physical status I to III. These patients, scheduled for elective surgery under general anaesthesia, will be randomly assigned to one of two groups. Group I will receive inhalational anaesthesia, and Group T will receive total intravenous anaesthesia. Each group will consist of 40 participants. The incidence and severity of postoperative delirium will be evaluated using the Mini Mental Status Examination preoperatively, and the Confusion Assessment Method Short and Confusion Assessment Method for Intensive Care Unit postoperatively. Serum samples will also be analysed for diagnostic biomarkers of delirium. Statistical analysis will include tests such as Kolmogorov Smirnov test, paired sample t test, analysis of variance, Kruskal Wallis test, Pearson correlation, Fisher exact test, chi square test, and odds ratio.

Discussion The use of anaesthesia is increasing in the elderly surgical population. Postoperative delirium, which is characterised by impaired awareness and attention, can affect up to 60 percent of elderly patients within 24 to 72 hours following surgery. Another related complication is postoperative cognitive dysfunction, which involves persistent cognitive decline after surgery. Inhalational anaesthesia involves the use of volatile agents, while total intravenous anaesthesia with agents like propofol offers benefits such as faster recovery and less postoperative nausea and vomiting. Target controlled infusion provides a precise method for administering intravenous anaesthetics. However, its effects on cognitive outcomes in elderly patients remain uncertain.

Recent experimental studies in aged animals with delayed neurocognitive recovery have shown changes in protein expression in brain regions associated with cognition. Dysregulated proteins such as haptoglobin, caseinolytic protease, and alpha two macroglobulin were found to be increased, while levels of 14 three 3 beta alpha and biliverdin reductase A were decreased. These findings were validated using multiple techniques. Similar patterns were observed in serum samples from elderly patients with postoperative delirium and from aged animals with delayed neurocognitive recovery. The altered levels of these proteins may serve as biomarkers for diagnosing postoperative neurocognitive disorders. These findings provide insights into the underlying mechanisms, but the ideal anaesthetic technique for preventing cognitive complications in elderly surgical patients remains unclear. Further research is necessary to determine the most effective anaesthesia strategy in this population.

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