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THE ANSWER IS D.
Older individuals do not regulate their body temperature as efficiently as younger adults, therefore they can be subject to hypothermia during procedures. Given an elderly patients' impaired thermoregulation, these patients require additional protection from cold during sedation. Any shivering can result in two to three times higher oxygen consumption. This can be discomforting to the patient and increase cardiovascular stress.
The age-related increase in lipid fraction of body mass yields an expansion of the distribution volume for pharmacologic agents that are highly lipid soluble, such as benzodiazepines. In conjunction with reduced hepatic and renal clearance mechanisms, this can lead to a prolonged recovery (A) for elderly patients after sedation. A complex interplay among heightened CNS sensitivity and alterations in drug receptors, volumes of distribution, and intercompartmental transfer contributes to the reduced dosage requirements of all of the standard sedative agents. Drugs used for sedation in older individuals should have a short half-life (C), with minimally active metabolites and limited side effects. Dosing based on mg/kg body weight (B) may produce profound respiratory depression and hypotension.
Rooke GA. Anesthesia for the older patient. In: Barash PG, Cullen BF, Stoelting RK, editors. Clinical Anesthesia, 7th ed. Philadelphia: Lippincott Williams and Wilkins; 2013. P. 891-904