ultrasound guided preoperative Inferior Vena Cava, subclavian vein collapsibility and aorta canal index for prediction of hypotension in geriatric patients undergoing orthopaedic surgery under central neuraxial block

Central neuraxial block is the oldest and most commonly used anaesthetic technique for lower limb orthopaedic  surgeries . While there are certain advantages to regional anaesthesia like it provides adequate analgesia and muscle relaxation , it can be easily administered  and the mental functions of the patient do not get altered , patients can be mobilized and discharged earlier and there are lower chances of deep vein thrombosis , it ensures better postoperative pain management lesser chances of nausea vomiting , less need of polypharmacy. Hypotension after administration of spinal anaesthesia is due to vasodilation causing a decrease in systemic vascular resistance and cardiac output  which occurs due to blockade of pre ganglionic sympathetic fibres or when the spinal anesthesia reaches T4 to T6 level causing a decrease in systemic vascular resistance (SVR) by 23-26% , left ventricular end diastolic volume by 20 %, central venous pressure by 2-3 mmhg. In addition, as the age advances, the risk of hypotension after central neuraxial block increases significantly . This could be due to higher degree of resting sympathetic tone which explains the greater decrease in SVR after sympathetic blockade when compared to younger patients.