Hemodynamic Effects of Bilateral and Unilateral Spinal Anesthesia Using the Continuous Pressure Recording Analytical Method.

Comparison of the Hemodynamic Effects of Bilateral and Unilateral Spinal Anesthesia in Hip Arthroplasty Surgeries in Elderly Patients Using the Continuous Pressure Recording Analytical Method.

This randomized controlled study aims to compare the intraoperative hemodynamic effects of unilateral and bilateral spinal anesthesia in elderly patients undergoing elective total hip arthroplasty. Seventy-four patients aged 65 years and older will be randomized into two groups: unilateral spinal anesthesia (n=37) and bilateral spinal anesthesia (n=37).

Hemodynamic parameters including cardiac output, stroke volume, stroke volume variation, pulse pressure variation, and systemic vascular resistance will be continuously monitored using the Pressure Recording Analytical Method (PRAM)-based MostCare monitoring system. Intraoperative fluid requirements and vasopressor consumption will also be evaluated.

The study seeks to determine whether unilateral spinal anesthesia provides greater hemodynamic stability and reduces the need for fluid administration and vasopressor support compared with conventional bilateral spinal anesthesia in elderly patients undergoing hip arthroplasty.

Hip arthroplasty is a commonly performed orthopedic procedure in elderly patients. Due to age-related physiological changes and the high prevalence of cardiovascular comorbidities, maintenance of intraoperative hemodynamic stability is essential in this population. Spinal anesthesia is widely used for lower extremity orthopedic surgery; however, sympathetic blockade may result in hypotension and impaired tissue perfusion, particularly in elderly patients.

Unilateral spinal anesthesia has been proposed as an alternative technique that may reduce the extent of sympathetic blockade and provide greater cardiovascular stability compared with conventional bilateral spinal anesthesia. Nevertheless, evidence regarding the advanced hemodynamic effects of these two techniques remains limited.

This prospective randomized controlled study aims to compare the hemodynamic effects of unilateral and bilateral spinal anesthesia in patients aged 65 years and older undergoing elective total hip arthroplasty. A total of 74 patients will be randomized to receive either unilateral spinal anesthesia (n=37) or bilateral spinal anesthesia (n=37).

Before spinal anesthesia, all participants will receive standard sedation with fentanyl (1-2 mcg/kg) and midazolam (0.015-0.03 mg/kg). Hemodynamic monitoring will be performed using the MostCare monitoring system based on the Pressure Recording Analytical Method (PRAM) through a radial arterial catheter.

The following hemodynamic parameters will be recorded at baseline, immediately after spinal anesthesia, and at predefined intraoperative time points: heart rate (HR), mean arterial pressure (MAP), peripheral oxygen saturation (SpO2), cardiac index (CI), stroke volume index (SVI), stroke volume variation (SVV), pulse pressure variation (PPV), systemic vascular resistance (SVR), oxygen delivery (DO2), oxygen delivery index (DO2I), maximal pressure rise during systole (dP/dtmax), cardiac cycle efficiency (CCE), and arterial elastance (Ea).

In addition, intraoperative vasopressor requirement (ephedrine use) and operative duration will be recorded and compared between study groups.

The primary objective is to determine whether unilateral spinal anesthesia provides superior hemodynamic stability compared with bilateral spinal anesthesia in elderly patients undergoing hip arthroplasty. The investigators hypothesize that unilateral spinal anesthesia will be associated with reduced hemodynamic fluctuations and lower vasopressor requirements compared with bilateral spinal anesthesia.

Inclusion Criteria:

1. Adults aged 65 years and older.
2. Patients scheduled for elective total hip arthroplasty.
3. Patients with an American Society of Anesthesiologists (ASA) physical status classification of II, III, or IV.
4. Patients with a Glasgow Coma Scale (GCS) score of 13-15 who are conscious and able to cooperate.
5. Patients with suitable peripheral arterial anatomy for PRAM monitoring.
6. Patients who provide written informed consent to participate in the study.
7. Patients without any clinical contraindication to spinal anesthesia. -

Exclusion Criteria:

1. Glasgow Coma Scale (GCS) score <13.
2. Age below 65 years.
3. History of previous major neurosurgical intervention.
4. Anatomical abnormality, vascular defect, or infection at the site intended for arterial catheter placement for PRAM monitoring.
5. Severe spinal deformity (e.g., severe scoliosis, previous spinal fusion surgery, or spinal trauma).
6. Current anticoagulant therapy or coagulopathy (INR >1.5 or platelet count <75,000/mm³).
7. Presence of skin infection or systemic infection/sepsis.
8. Severe hypovolemia or decompensated cardiac disease in which spinal anesthesia is contraindicated.
9. Known allergy or hypersensitivity to local anesthetics or sedative agents.
10. Local infection or wound at the planned spinal puncture site.
11. Clinical contraindication to spinal anesthesia (e.g., increased intracranial pressure, septicemia, or severe hypotension). -