Spinal Anesthesia-Induced Hypotension, Cerebral Oxygenation
Conditions
Keywords
Ondansetron, Spinal anesthesia, Regional cerebral oxygen saturation, Near-infrared spectroscopy, Urologic surgery, Older adults
Brief summary
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.
Detailed description
This is a single-center, prospective, randomized, double-blind, placebo-controlled, three-arm parallel-group clinical trial in adults aged 65 years or older undergoing endoscopic urologic surgery under spinal anesthesia. Spinal anesthesia may cause hypotension and bradycardia because of sympathetic blockade, reduced venous return, and activation of reflex mechanisms including the Bezold-Jarisch reflex. Ondansetron is a 5-hydroxytryptamine type 3 (5-HT₃) receptor antagonist that may attenuate these hemodynamic changes. Participants will be randomized to receive one of three study strategies: intravenous ondansetron 8 mg before spinal anesthesia, intravenous ondansetron 8 mg after spinal anesthesia, or placebo. Study solutions will be prepared in a blinded manner so that participants and relevant clinical and outcome-assessment personnel remain unaware of treatment allocation. Cerebral oxygenation will be assessed using bilateral frontal near-infrared spectroscopy. Left and right regional cerebral oxygen saturation (rSO₂) values will be recorded before spinal anesthesia and at 5-minute intervals during the first 60 minutes following spinal anesthesia. Hemodynamic variables, including blood pressure and heart rate, will be monitored throughout the study period. The need for vasopressor treatment, total vasopressor dose, bradycardia, and atropine use will also be recorded. Postoperative outcomes will include nausea and vomiting, rescue antiemetic use, post-spinal headache, and postoperative delirium assessed using the 4AT. The study is designed to compare the effects of different timings of ondansetron administration on cerebral oxygenation and hemodynamic stability during the early period after spinal anesthesia.
Interventions
DRUGOndansetron 8 mg
Ondansetron 8 mg will be administered intravenously according to the assigned study arm. In the early ondansetron arm, the drug will be administered approximately 10 minutes before completion of the intrathecal injection. In the late ondansetron arm, the drug will be administered approximately 5 minutes after completion of the intrathecal injection.
Placebo will be administered intravenously in the same volume and appearance as the active study drug according to the blinded study protocol.
Sponsors
Istanbul University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Masking description
tudy solutions will be prepared in identical volumes and appearance by personnel not involved in clinical care or outcome assessment. Treatment allocation will remain concealed from participants, care providers, investigators involved in data collection, and outcome assessors.
Intervention model description
Participants will be assigned to one of three parallel groups: ondansetron administered before spinal anesthesia, ondansetron administered after spinal anesthesia, or placebo.
Eligibility
Sex/Gender
MALE
Age
65 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Male sex. * Age 65 years or older. * ASA physical status I-III. * Scheduled for elective transurethral resection of the prostate (TUR-P) or transurethral resection of bladder tumor (TUR-BT) under spinal anesthesia. * Ability to provide written informed consent.
Exclusion criteria
* Known hypersensitivity or contraindication to ondansetron. * Corrected QT interval (QTc) \>480 ms. * Significant cardiac conduction abnormality. * Concomitant use of medications known to prolong the QT interval. * Severe ischemic heart disease. * Severe chronic obstructive pulmonary disease. * Skin lesion, wound, or other condition preventing placement of frontal NIRS sensors. * Contraindication to spinal anesthesia.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Bilateral Frontal Regional Cerebral Oxygen Saturation (rSO₂) | Before spinal anesthesia (baseline) and at 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 minutes after spinal anesthesia | Regional cerebral oxygen saturation (rSO₂, %) will be measured bilaterally over the frontal cortex using near-infrared spectroscopy. Left and right rSO₂ values will be recorded at each prespecified assessment time point. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Incidence of Hypotension | During the first 60 minutes after spinal anesthesia | Hypotension will be defined as a mean arterial pressure (MAP) below 65 mmHg and/or a reduction in systolic blood pressure of at least 30% from baseline. |
| Time to First Hypotensive Episode | During the first 60 minutes after spinal anesthesia | Time from completion of spinal anesthesia to the first episode meeting the predefined criteria for hypotension. |
| Requirement for Ephedrine | During the first 60 minutes after spinal anesthesia | Proportion of participants requiring intravenous ephedrine for treatment of hypotension. |
| Total Ephedrine Dose | During the first 60 minutes after spinal anesthesia | Total cumulative dose of intravenous ephedrine administered for treatment of hypotension, measured in milligrams. |
| Incidence of Bradycardia | During the first 60 minutes after spinal anesthesia | Bradycardia will be defined as a heart rate below 45 beats per minute. |
| Requirement for Atropine | During the first 60 minutes after spinal anesthesia | Proportion of participants requiring intravenous atropine for treatment of bradycardia. |
| Minimum Regional Cerebral Oxygen Saturation | From baseline to 60 minutes after spinal anesthesia | The lowest recorded frontal regional cerebral oxygen saturation (rSO₂, %) value during the observation period will be determined from the prespecified bilateral NIRS measurements. |
| Maximum Relative Decrease in Regional Cerebral Oxygen Saturation | From baseline to 60 minutes after spinal anesthesia | Maximum percentage decrease in frontal regional cerebral oxygen saturation (rSO₂) from the corresponding pre-spinal baseline value. |
| Incidence of Cerebral Desaturation | From baseline to 60 minutes after spinal anesthesia | Cerebral desaturation will be defined as a decrease in frontal regional cerebral oxygen saturation (rSO₂) of at least 20% from the corresponding pre-spinal baseline value at any prespecified measurement time point. |
| Postoperative Nausea Severity | From the end of surgery through the first postoperative day | Postoperative nausea severity will be assessed using an 11-point Numeric Rating Scale (NRS), ranging from 0 to 10, where 0 indicates no nausea and 10 indicates the worst possible nausea. Higher scores indicate worse nausea. |
| Requirement for Rescue Antiemetic Treatment | From the end of surgery through the first postoperative day | Proportion of participants requiring rescue antiemetic medication for postoperative nausea or vomiting. |
| Post-Spinal Headache Severity | During the first postoperative day | Post-spinal headache severity will be assessed using an 11-point Numeric Rating Scale (NRS), ranging from 0 to 10, where 0 indicates no headache and 10 indicates the worst possible headache. Higher scores indicate worse headache. |
| Incidence of Postoperative Delirium | In the post-anesthesia care unit, approximately 12 hours after surgery, and on the first postoperative day | Postoperative delirium will be assessed using the 4 'A's Test (4AT), which ranges from 0 to 12. Higher scores indicate a greater likelihood of delirium. A score of 4 or greater will be considered positive for possible delirium. The 4 'A's Test (4AT) assesses alertness, abbreviated mental test-4, attention, and acute change or fluctuating course. |
Countries
Turkey (Türkiye)
Contacts
CONTACTEzgi Budak Ozyalcin, Anesthesiology Specialist
CONTACTFatiş Altındaş, Professor of Anesthesiology
PRINCIPAL_INVESTIGATOREzgi Budak Ozyalcin, Anesthesiology Specialist
Istanbul University-Cerrahpasa, Cerrahpasa Faculty of Medicine, Department of Anesthesiology and Reanimation
Outcome results
None listed