1) Allocation ratio
Eligible participants will be allocated in a 1:1 ratio into two parallel groups:
Group A: Regional anesthesia alone (RA)
Group B: Combined regional + general anesthesia (RA+GA)
2) Sequence generation (how the random list is created)
An independent person (e.g., a statistician or a researcher not involved in anesthesia delivery or outcome assessment) will generate the randomization sequence.
A computer-generated random sequence will be created using software such as Randomization.com, SPSS, or Microsoft Excel.
To ensure balance between the groups during recruitment, block randomization will be used.
3) Block randomization (to keep groups balanced)
Variable block sizes will be applied to reduce predictability (e.g., block sizes of 4 and 6, randomly mixed).
Within each block, equal numbers of participants will be assigned to each group, but the order will be randomized.
Example:
In a block of 4, 2 patients will be allocated to RA and 2 to RA+GA, but in random order.
4) Allocation concealment (preventing prediction)
To ensure that no one can predict the next assignment, allocation concealment will be performed using the standard SNOSE method:
Sealed, Opaque, Sequentially Numbered Envelopes (SNOSE)
Envelopes will be opaque, light-proof, sealed, and sequentially numbered (001 to 060).
Each envelope will contain a paper indicating the assigned group (RA or RA+GA).
Envelopes will be prepared and sealed by an independent researcher.
The envelopes will be stored securely until use.
5) Implementation (when and who opens the envelope)
After confirming eligibility and obtaining written informed consent, each participant will receive a study ID (e.g., 001, 002, …, 060).
The anesthesia provider (who is not blinded) will open the corresponding envelope immediately before anesthesia induction.
The group allocation will be recorded in a confidential allocation log.
6) Documentation and quality control
The master randomization list will remain with the independent statistician and will not be accessible to assessors.
Used envelopes will be retained for auditing and verification.
Any protocol deviations will be documented.
7) Cross-over management and analysis plan
If a participant allocated to RA alone requires conversion to general anesthesia for clinical reasons:
General anesthesia will be administered as needed (patient safety is the priority).
The case will be recorded as a protocol deviation/crossover.
The participant will remain in the original allocated group for the primary analysis based on the Intention-To-Treat (ITT) principle.
A secondary Per-Protocol (PP) analysis may also be performed.
Because the interventions are anesthesia techniques, full blinding of the anesthesia provider is not possible. However, this study will be implemented as a practical double-blind trial, meaning:
Participants will be blinded
Postoperative outcome assessors will be blinded
Data analysts/statisticians will be blinded
The anesthesia provider delivering anesthesia will not be blinded
1) Participant blinding
Participants will not be informed about their group assignment.
To maintain participant blinding:
Both groups will undergo similar preoperative preparation and operating room workflow.
All patients will receive an ultrasound-guided interscalene block.
To minimize the patient’s ability to identify the anesthetic technique, standardized light sedation may be used when clinically appropriate.
The informed consent will state that the patient will receive one of two standard anesthesia approaches.
2) Outcome assessor blinding
Postoperative delirium and agitation will be assessed by trained personnel (e.g., PACU nurse/research assistant) who:
Are not involved in anesthesia delivery
Do not have access to anesthesia records
Will assess outcomes only using the participant study ID
Assessment tools may include:
Confusion Assessment Method (CAM) / CAM-ICU
Richmond Agitation-Sedation Scale (RASS) or Sedation-Agitation Scale
3) Data analyst blinding
All collected data will be entered into the database using coded group labels (Group A and Group B).
The statistician will receive the dataset without knowing which group corresponds to RA or RA+GA.
Group identity will be revealed only after completion of the primary statistical analysis.
4) Standardization of perioperative care to maintain blinding
To reduce the chance of group disclosure:
Postoperative pain control, antiemetic use, and sedation protocols will be standardized across groups.
The anesthesia record will be kept separate from the outcome assessment forms.
PACU and ward staff will be instructed not to discuss anesthesia type in the presence of the blinded assessor.
5) Prevention and documentation of unblinding
Assessors will not be allowed to review the anesthesia chart.
If unblinding is suspected (e.g., the assessor guesses the group), this will be recorded in a separate form as “assessor guess of allocation” to evaluate blinding quality.
6) Emergency unblinding
Emergency unblinding will be permitted only if knowledge of the anesthetic technique is clinically essential for patient management.
The reason for unblinding will be documented.
The date/time and personnel involved will be recorded.
The participant will still remain in the ITT analysis.