Influence of Pre-operative Cognitive Status on Propofol Requirement to Maintain Hypnosis in the Elderly: A Study of 50 Cases

Introduction: In elderly patients decrease in cognitive function after anesthesia has been reported in the literature for over a century. Various studies have implicated agents such as propofol and sevoflurane in the development of post-operative cognitive dysfunction. We evaluated the effect of pre-operative cognitive status by mini–mental state examination (MMSE), on consumption of propofol during anesthesia in the elderly. Materials and Methods: In this prospective observational study, we included 50 patients (65-99 years) undergoing elective abdominal surgeries under general anesthesia. Propofol infusion was adjusted to the bispectral index (BIS) and was maintained within 40-60. Multiple linear regression analysis determined if body mass index (BMI), age, baseline BIS, gender, and preoperative MMSE score were related to the consumption of propofol. Observation: MMSE and BMI scores were significantly related to the mean value of consumption of propofol. A decrease in propofol requirement in patients >65 years of age was associated with a low MMSE score. Effect of age, gender, and baseline BIS on the propofol consumption was insignificant. Conclusion: To maintain hypnosis propofol requirement during general anesthesia appears to decrease with deterioration in the cognitive status in elderly patients. Cerebral cholinergic dysfunction associated with cognitive dysfunction may influence propofol sensitivity in aged patients.