Evaluation of the effectiveness of oral caffeine compared to aggressive hydration in preventing post-spinal anesthesia headache in cesarean section surgeries

To compare the effectiveness of oral caffeine versus aggressive hydration in preventing post‑spinal headache (PDPH) in women undergoing elective cesarean section.

Double‑blind, parallel RCT, two arms (caffeine vs. placebo), block randomization (size 4) with computer‑generated numbers in sealed envelopes, 1:1 allocation, 68 participants (34/group), single‑center.

The trial will be conducted in teaching hospitals affiliated with Ahvaz Jundishapur University. Recruitment is planned over 4 months. Participants, investigators, care providers, and outcome assessors are blinded. An independent pharmacist prepares identical capsules. The allocation sequence is concealed in sealed envelopes and opened after enrollment. Outcomes are assessed at 24, 48, and 72 hours post‑surgery by trained assessors unaware of group assignment.

Inclusion criteria: Pregnant women 20–40y, ASA I‑II, singleton, no CVD, coagulopathy, caffeine allergy, gestational hypertension, migraine, no caffeine in prior 12h, willing to consent. Exclusion criteria: Refusal, conversion to general anesthesia, complications, SBP<100 mmHg, non‑cooperation.

Caffeine group: Oral caffeine capsule (200 mg) 30 minutes before spinal anesthesia, plus standard aggressive hydration (4000 mL normal saline over 24 hours). Control group: Identical placebo capsule 30 minutes before spinal anesthesia, plus the same hydration protocol.

Primary: Incidence and severity of PDPH assessed by the Verbal Category Scale (VCS) at 24, 48, and 72 hours post‑surgery. Secondary: Time to headache onset; frequency of associated symptoms (neck stiffness, nausea, vomiting, photophobia, tinnitus, phonophobia); and adverse effects or intolerance to treatments.

Method of randomization: Block randomization with a block size of 4 will be used to ensure balanced allocation between the two groups.Unit of randomization: Individual participant (each pregnant woman).Randomization strata: No stratification will be applied, as the study population is homogeneous based on inclusion criteria (ASA I-II, elective cesarean section, etc.).Tools used in randomization: A computer-generated random number sequence will be produced using statistical software (e.g., SPSS or Excel). The allocation sequence will be concealed in opaque, sealed, sequentially numbered envelopes.How the random sequence was built: An independent research assistant, not involved in patient recruitment or outcome assessment, will generate the random allocation sequence using a computer algorithm. The sequence will determine assignment to either the intervention group (oral caffeine) or the control group (aggressive hydration) in a 1:1 ratio.Allocation concealment: The sealed envelopes will be opened sequentially by the same research assistant only after the patient has provided informed consent and all baseline data have been collected. This ensures that neither the enrolling clinician nor the patient knows the allocation in advance (concealed allocation).

This is a double-blind, randomized controlled trial. The following individuals/groups will be blinded to the allocation of participants to the intervention (oral caffeine) or control (aggressive hydration) groups: Participants (patients): All participants will receive a capsule 30 minutes before spinal anesthesia. The intervention group receives a 200 mg caffeine capsule, while the control group receives a placebo capsule that is identical in size, shape, color, and taste. Neither the patients nor their families will know which capsule they have received. Investigators and care providers: The research team members who recruit participants, obtain informed consent, administer the capsules, and provide perioperative care will be blinded to the group allocation. The capsules will be prepared and coded by an independent pharmacist who is not involved in any other aspect of the study. The allocation code will be kept sealed until the final data analysis is completed. Outcome assessors: The trained research assistants who assess headache incidence and severity (using the Verbal Category Scale) and record associated symptoms (neck stiffness, nausea, photophobia, etc.) at 24, 48, and 72 hours post-surgery will be blinded to the group assignment. They will have no access to the randomization list or the capsule codes. Data analysts (optional): To further reduce bias, the statistician who performs the final data analysis will also be blinded. The data file will be coded with group labels (e.g., Group A and Group B) without revealing which is the intervention or control group. The code will be broken only after the final statistical report is prepared. How blinding is achieved: The randomization sequence and capsule codes are generated and maintained by an independent researcher who is not involved in patient recruitment, care, or outcome assessment. Opaque, sealed, sequentially numbered envelopes containing the allocation are opened only after patient enrollment, and the corresponding coded capsule is administered. The placebo capsule is identical to the caffeine capsule in appearance (size, color, weight) and administration method. Outcome assessors and data collectors are not present during the randomization process and do not have access to the allocation envelopes or codes. Thus, all key personnel (participants, investigators, care providers, and outcome assessors) are masked, ensuring a double‑blind design. The data analyst will also be blinded if feasible.

Due to the limited sample size (68 participants) and the single‑center nature of this investigator‑initiated trial, the data are collected solely for the predefined statistical analysis outlined in the protocol. There is no current plan or funding to prepare a deidentified dataset for public sharing. However, if a reasonable request is made by other researchers after publication, the corresponding author will consider sharing aggregated data or summary statistics upon request, subject to institutional and ethical approvals.