Final answer:
The preferred anesthetic technique for an elderly patient with hypertension, aortic stenosis, and dementia undergoing hip surgery is spinal anesthesia, as it reduces the risks associated with general anesthesia and is more hemodynamically stable.
Step-by-step explanation:
The most appropriate anesthetic technique for an 82-year-old female with a significant medical history of hypertension, moderate aortic stenosis, and dementia undergoing open reduction of a left intratrochanteric fracture is Spinal anesthesia (B). This method is typically preferred in elderly patients with multiple comorbidities, as it carries fewer risks of systemic complications compared to general anesthesia.
In patients with aortic stenosis, spinal anesthesia can help avoid the hemodynamic fluctuations often associated with induction and maintenance of general anesthesia. Additionally, the risk of cognitive dysfunction postoperatively, which could exacerbate the patient's existing dementia, is generally lower with regional techniques like spinal anesthesia. Opioid-based and volatile-based general anesthesias (options A and C) increase the risk of respiratory depression and hemodynamic instability. Epidural anesthesia (D) could be considered, but spinal anesthesia is technically less complex and typically has quicker onset for the urgent nature of hip surgery.