Spinal Anesthesia Induced Hypotension

This study will evaluate whether the timing of intravenous ondansetron administration affects cerebral oxygenation and hemodynamic stability in older adults undergoing endoscopic urologic surgery under spinal anesthesia. Participants aged 65 years or older will be randomly assigned to one of three groups: ondansetron administered before spinal anesthesia, ondansetron administered after spinal anesthesia, or placebo. Ondansetron will be administered intravenously at a dose of 8 mg. Cerebral oxygenation will be assessed using bilateral frontal near-infrared spectroscopy (NIRS). Regional cerebral oxygen saturation (rSO₂) will be recorded before spinal anesthesia and at 5-minute intervals during the first 60 minutes after spinal anesthesia. The study will also evaluate blood pressure, heart rate, vasopressor requirements, bradycardia, postoperative nausea and vomiting, post-spinal headache, and postoperative delirium. The aim is to determine whether the timing of ondansetron administration influences cerebral oxygenation and hemodynamic stability after spinal anesthesia.

This study compares the efficacy and safety of intravenous dexamethasone versus intravenous ondansetron in preventing low blood pressure (hypotension) following spinal anesthesia in pregnant women with preeclampsia undergoing scheduled cesarean delivery. Spinal anesthesia is the preferred anesthetic method for cesarean delivery, but it frequently causes a sudden drop in maternal blood pressure. In patients with preeclampsia, post-spinal hypotension can compromise blood flow to the placenta and vital organs. While traditional vasopressor medications are used to restore blood pressure, non-adrenergic prophylactic agents such as dexamethasone and ondansetron may help maintain hemodynamic stability through different physiological pathways. Participants will be randomly assigned to receive either intravenous dexamethasone (8 mg) or intravenous ondansetron (4 mg) 15 minutes prior to the initiation of spinal anesthesia. Blood pressure, heart rate, vasopressor requirements, optic nerve sheath diameter, and maternal and neonatal outcomes will be monitored throughout the surgery and during the immediate postoperative period.

This prospective observational study aims to investigate the role of the baseline perfusion index (PI) in predicting spinal anesthesia-induced hypotension (SAIH) in ASA I-II patients undergoing day-case knee arthroscopy. Spinal anesthesia is a widely preferred technique for lower extremity surgeries, including knee arthroscopy. However, sympathetic blockade during spinal anesthesia frequently leads to significant hemodynamic instability, particularly hypotension, which can result in adverse perioperative outcomes. While age and baseline blood pressure are traditional risk factors, they often fail to accurately predict the onset of hypotension in healthy populations. The perfusion index (PI), a non-invasive parameter measured via pulse oximetry, reflects peripheral vascular tone and baseline sympathetic activity. An elevated baseline PI indicates baseline vasodilation and a higher susceptibility to sympathectomy, potentially offering an early and non-invasive prediction of SAIH before the hemodynamic collapse occurs. The primary outcome of the study is the incidence of spinal anesthesia-induced hypotension (defined as a mean arterial pressure \< 65 mmHg or a decrease in systolic blood pressure \> 25% from baseline). Secondary outcomes include the onset time of sensory block, and intraoperative ephedrine and fluid requirements.

This prospective, single-center observational study aims to evaluate the predictive value of the internal jugular vein collapsibility index (IJVCI) for spinal anesthesia-associated hypotension in preeclamptic parturients (gestational age ≥28 weeks) undergoing cesarean delivery classified as Lucas category 3-4. Preoperative IJVCI will be measured using ultrasonography before spinal anesthesia during spontaneous and deep respiration. The incidence of hypotension within the first 20 minutes after spinal anesthesia will be recorded. The diagnostic performance of IJVCI in predicting hypotension will be analyzed.

Spinal anesthesia-induced hypotension is a common and clinically significant complication in geriatric patients. Accurate preoperative assessment of intravascular volume status may help identify patients at risk. Internal jugular vein (IJV) ultrasonography is a noninvasive and easily applicable bedside method that reflects venous volume status. This prospective observational study aims to evaluate the role of preoperative IJV ultrasonographic measurements in predicting hypotension following spinal anesthesia in geriatric patients. Patients aged 65 years and older undergoing elective surgery under spinal anesthesia will be included. Preoperative IJV diameter, cross-sectional area, and collapsibility index will be measured using ultrasonography. Hemodynamic parameters will be monitored intraoperatively, and the occurrence of hypotension after spinal anesthesia will be recorded. The predictive value of IJV ultrasonographic parameters for post-spinal hypotension will be analyzed

The goal of this clinical trial is to find out whether height-based dosing of spinal anaesthesia provides better hemodynamic stability and anesthetic outcome than conventional fixed dosing in elderly patients undergoing lower limb orthopaedic surgery.The main questions this study aims to answer are: 1. Does height-based spinal anaesthetic dosing reduce the risk of hypotension and bradycardia during surgery as compared to conventional fixed dosing? 2. Does it improve anaesthetic outcomes, such as the onset and duration of sensory and motor block?

Spinal anesthesia-induced hypotension remains a common and significant complication during cesarean sections, posing risks for both mother and fetus. Vitamin D deficiency, frequently observed in pregnant women, is associated with altered vascular function and potential hemodynamic instability. This prospective observational study aims to investigate whether vitamin D deficiency is associated with an increased incidence and severity of spinal anesthesia-induced hypotension in pregnant women undergoing elective cesarean delivery. Vitamin D levels will be measured preoperatively, and intraoperative hemodynamic parameters will be closely monitored. The findings could contribute to improved management strategies for pregnant patients at risk of severe hypotension.

Acute kidney injury (AKI) is a significant postoperative complication. Risk factors for AKI include impaired renal perfusion, decreased functional renal reserve, as well as advanced age, peripheral arterial disease, diabetes mellitus, renovascular disease and congestive heart failure. Mean arterial pressure (MAP) below 55-60 mmHg has been associated with postoperative AKI. Traditional diagnostic criteria for AKI include increased serum creatinine levels and oliguria. However, creatinine levels do not rise until more than half of renal function is lost. Serum and urine NGAL levels rise earlier-within 24-48 hours-making it a promising early biomarker. In our study, hypotension is defined as systolic blood pressure \<100 mmHg or a \>30% decrease in MAP. Patients requiring ephedrine under these conditions will be evaluated as the hypotension group and compared with non-hypotensive patients in terms of NGAL, BUN (blood urea nitrogen), creatinine, and GFR (Glomerular Filtration Rate) values at baseline and at the 4th postoperative hour.

The goal of this clinical trial is to learn if norepinephrine is more effective than phenylephrine for prevention of spinal anesthesia induced hypotension. The main questions it aims to answer are: Does norepinephrine lower the incidence of spinal anesthesia induced hypotension in emergency obstetrical patients? We will compare effectiveness of norepinephrine and phenylephrine for the prevention of spinal anesthesia induced hypotension. Participants will: Be administered prophylactic boluses of both drugs right after spinal anesthesia induction and maternal hemodynamic parameters and neonatal APGAR scores will be recorded