Effect of Warmed versus Room-Temperature Intravenous Fluid Co-loading on Spinal Anesthesia-Induced Hypotension in Elderly Hypertensive Patients Undergoing Orthopedic Surgery

To compare warmed versus room-temperature intravenous fluid co-loading on spinal anesthesia-induced hypotension in elderly hypertensive patients undergoing orthopedic surgery.

Randomized, double-blind, parallel-group clinical trial. Sample size 70 (35 per group). Block randomization with sealed envelopes. Single center.

Conducting at Al-Karkh Teaching Hospital, Baghdad, Iraq. Elderly hypertensive patients undergoing elective lower limb orthopedic surgery under spinal anesthesia are enrolled after informed consent and randomized to warmed or room-temperature Ringer's lactate co-loading. Standard monitoring includes electrocardiography, pulse oximetry, and non-invasive blood pressure. Participants, anesthesiologist, outcome assessor, and data analyst are blinded; fluids are prepared by a non-blinded nurse and covered with opaque materials.

Inclusion: age ≥65, hypertension on medication, ASA II/III, elective lower limb orthopedic surgery under spinal anesthesia. Exclusion: severe hyperkalemia, severe hepatic impairment, lactic acidosis, inability to cooperate.

Group W: Ringer's lactate warmed to 37-38°C. Group R: Ringer's lactate at room temperature (20-24°C). Both co-loaded 10-15 mL/kg over 15-20 minutes after spinal block.

Primary: incidence of spinal anesthesia-induced hypotension (systolic blood pressure drop ≥20% or <90 mmHg) within 30-45 minutes. Secondary: number of hypotensive episodes, vasopressor requirement, time to first episode.

Method of randomization: Block randomization with a fixed block size determined by the statistician. Unit of randomization: Individual participants. Randomization strata: No stratification was used. Tools used for randomization: Random Allocation software (or a random number table) and sequentially numbered, opaque, sealed envelopes. How the random sequence was built: The randomization sequence was generated in advance by a statistician who was not involved in participant enrollment or data collection. Block randomization was used to ensure balance between the two study groups. Allocation concealment: Yes. The generated allocation sequence was placed in sequentially numbered, opaque, sealed envelopes. These envelopes were opened in order by a research assistant who was not involved in data collection or outcome assessment. The envelopes were opened only after the participant had been enrolled and written informed consent had been obtained.

Participants, the attending anesthesiologist (care provider), the investigator, the outcome assessor, and the data analyst are blinded to group allocation. The intravenous fluids are prepared and coded by a nurse who is not involved in data collection or outcome assessment. The fluid bags and infusion tubing are covered with opaque insulating materials to prevent identification of fluid temperature. Only the nurse responsible for preparing the study fluids is aware of the intervention assignment. The allocation codes are kept confidential until completion of data collection and statistical analysis. The Data and Safety Monitoring Board is not involved in this study.

Deidentified individual participant data (IPD), data dictionary, study protocol, statistical analysis plan, and informed consent form. The IPD set includes all collected data on demographics, clinical characteristics, hemodynamic parameters (systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, oxygen saturation), incidence and number of hypotensive episodes, time to first hypotensive episode, vasopressor dose and frequency, and patient satisfaction and comfort scores. All data will be deidentified before sharing. The data dictionary will contain variable names, definitions, coding, and units. The study protocol describes the full methods. The statistical analysis plan describes the planned analyses. The informed consent form is the version approved by the ethics committee.

Data will become available 6 months after publication of the primary results and will remain available for 5 years.

Researchers working in academic institutions, research centers, or healthcare organizations. Applicants from the industry may also apply if they provide a methodologically sound proposal.

Data will be shared for secondary analyses that are methodologically sound and approved by the principal investigator. Requests must include a written proposal describing the research question, analysis plan, and intended use. A signed data access agreement is required. Data may not be used for commercial purposes or to re-identify participants. Requests will be reviewed by the principal investigator and the research team.Data will be shared for secondary analyses that are methodologically sound and approved by the principal investigator. Requests must include a written proposal describing the research question, analysis plan, and intended use. A signed data access agreement is required. Data may not be used for commercial purposes or to re-identify participants. Requests will be reviewed by the principal investigator and the research team.

Data and documents are obtainable by contacting the principal investigator: Dr. Ali Khalafi Department of Anesthesia Technology, School of Paramedical Sciences, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. Email: khalafi-a@ajums.ac.ir Telephone: 09163359407

Applicants should send a written request by email to the principal investigator, including a brief research proposal, the intended analysis plan, and the institutional affiliation. The request will be reviewed by the principal investigator and the research team within 4 weeks. If approved, a data access agreement will be sent to the applicant for signature. After the signed agreement is received, the deidentified data and requested documents will be transferred electronically within 2 weeks. The entire process is expected to take approximately 6 to 8 weeks.