Dexamethasone and Duration of Spinal Anesthesia

This study will evaluate the effect of intravenous dexamethasone on the duration of hyperbaric bupivacaine spinal anesthesia in patients undergoing lower abdominal surgery.

Eligible patients will be adults classified as American Society of Anesthesiologists (ASA) physical status I or II and meeting the predefined inclusion and exclusion criteria. All patients will undergo a preoperative assessment by a consultant anesthetist and will be deemed fit for anesthesia and surgery before enrollment.

After establishment of standard monitoring in the operating theatre, an 18-gauge peripheral intravenous cannula will be secured. Patients will receive either 8 mg of dexamethasone diluted in 100 mL of normal saline or 100 mL of normal saline alone, according to the study protocol. The administration will be performed in a manner intended to maintain blinding of the personnel responsible for subsequent assessment of block regression.

Following the intravenous intervention, spinal anesthesia will be performed using a 25-gauge spinal needle with the patient in the sitting position. A dose of 12-15 mg of 0.75% hyperbaric bupivacaine will be administered intrathecally at the L3-L4 or L4-L5 intervertebral space. Correct intrathecal placement will be confirmed by free flow of cerebrospinal fluid through the spinal needle. The patient will subsequently be positioned supine.

The sensory block will be assessed by testing the response to pinprick at the relevant dermatomes, while the degree of motor blockade will be assessed using the Modified Bromage Scale. Surgery will commence after an adequate sensory block extending to the T4 dermatome and a Modified Bromage score of 1 have been achieved.

Following establishment of spinal anesthesia, serial assessments of sensory and motor blockade will be performed at 15-minute intervals by a member of the anesthesia team who was not involved in administration of the spinal anesthetic, in order to minimize assessment bias. Sensory block regression will be assessed sequentially at the dermatomes from T4 toward the lower thoracic levels. The primary outcome will be the duration from establishment of the sensory block until regression to the T10-T12 dermatome level.

Following surgery, patients will be transferred to the Post-Anesthesia Care Unit (PACU), where continued assessment of the sensory and motor blockade will be performed. The total duration of sensory blockade and motor blockade will be recorded. Postoperative pain intensity will be assessed using the Visual Analogue Scale (VAS) at 4 hours after surgery.

The study will collect demographic and clinical variables, including age, sex, primary diagnosis, and type of surgical procedure. Quantitative outcome measures will include the time required for sensory block regression to the T10-T12 level, total duration of sensory blockade, total duration of motor blockade, and postoperative pain intensity at 4 hours. These outcomes will be compared to determine whether intravenous dexamethasone prolongs the duration of hyperbaric bupivacaine spinal anesthesia and influences postoperative analgesic outcomes.

Inclusion criteria

• Patients undergoing lower abdominal surgeries and orthopaedic surgeries including pelvic and lower extremity surgeries
• Patients classified as American Society of Anesthesiologists (ASA) physical status I or II

Exclusion criteria

• Patients with a history of spinal surgery, spinal instrumentation, or previous failed spinal anaesthesia
• Patients with pre-existing neurological disorders, peripheral neuropathy, or sensory/motor deficits
• Patients with known hypersensitivity or allergy to local anaesthetic agents or dexamethasone
• Patients with congenital spinal deformities or acquired spinal conditions such as advanced spondylosis or kyphoscoliosis that may interfere with neuraxial block
• Patients with contraindications to spinal anaesthesia, including coagulopathy, local infection at the injection site, or raised intracranial pressure
• Patients with diabetes mellitus, chronic steroid therapy, immunosuppression, or systemic infection (due to steroid use)
• Pregnant patients or those undergoing emergency surgeries