Spinal anesthesia is a common and preferred anesthetic technique for lower extremity orthopedic surgery in elderly patients. However, it can cause a significant drop in blood pressure (hypotension), especially in high-risk older patients with multiple medical conditions. This complication can lead to serious consequences such as heart attack, stroke, or death in vulnerable patients.
This study investigates whether keeping patients in a lateral (side-lying) position for 15 minutes after spinal anesthesia - instead of immediately turning them onto their back (supine position) - can reduce the risk of hypotension. When a patient lies on their side after receiving spinal anesthesia with a heavy (hyperbaric) local anesthetic, the medication tends to stay concentrated on the lower (operative) side, resulting in a more limited nerve block. This may help preserve blood pressure stability.
We will enroll 70 patients aged 65 years or older with high anesthetic risk (ASA physical status III or IV) scheduled for unilateral lower extremity orthopedic surgery under spinal anesthesia. Patients will be randomly assigned to two groups: one group will be kept in the lateral decubitus position (operative side down) for 15 minutes before being turned supine, and the other group will be turned supine immediately after spinal anesthesia. Blood pressure, heart rate, and oxygen saturation will be monitored continuously. The primary outcome is the incidence of hypotension during the first 15 minutes after spinal anesthesia.
Age 65 years or older
ASA physical status classification III or IV
Scheduled for unilateral lower extremity orthopedic surgery (hip fracture, femur fracture, knee arthroplasty, tibia-fibula fracture, or similar procedures)
Eligible for spinal anesthesia
Contraindications to spinal anesthesia (coagulopathy, recent anticoagulant or antiplatelet use without adequate washout period, local infection at injection site)
Severe neurological disease or pre-existing motor or sensory deficit
Significant spinal deformity (severe scoliosis, kyphosis) or history of previous spinal surgery
Known allergy to local anesthetics
Parallel
Lateral Decubitus Positioning
Other interventionAfter spinal anesthesia with 12 mg of 0.5% hyperbaric bupivacaine administered in the sitting position, patients are immediately placed in the lateral decubitus position with the operative side down. This position is maintained for 15 minutes to allow gravity-dependent concentration of the hyperbaric local anesthetic on the operative side, achieving predominantly unilateral sympathetic block. Patients are then repositioned supine for surgery.
Immediate Supine Positioning
Other interventionAfter spinal anesthesia with 12 mg of 0.5% hyperbaric bupivacaine administered in the sitting position, patients are immediately placed in the supine position. This results in bilateral distribution of the hyperbaric local anesthetic and serves as the active comparator.
Incidence of Hypotension
Hypotension defined as a decrease of 20% or more from baseline mean arterial pressure (MAP) or MAP below 65 mmHg, occurring at any time point between 1 and 15 minutes after spinal anesthesia.
Incidence of Bradycardia
Bradycardia defined as heart rate below 50 beats per minute at any time point during the study period, treated with intravenous atropine 0.5 mg bolus.
Ephedrine Requirement
Total dose of ephedrine (mg) administered intravenously for treatment of hypotension. Ephedrine given as 5-10 mg IV bolus, repeated if necessary.
Atropine Requirement
Total dose of atropine (mg) administered intravenously for treatment of bradycardia. Atropine given as 0.5 mg IV bolus when heart rate falls below 50 beats per minute.
Maximum Sensory Block Level
Highest dermatomal level of sensory block assessed by pin-prick test on the operative side, recorded as thoracic dermatome level (T6-T12).
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