CompletedNCT07929818ClinicalTrials.gov record

Intrathecal Dexmedetomidine 5 mcg Versus 10 mcg With Bupivacaine for Infra-umbilical Surgery

Spinal Anesthesia · Intraoperative Hypotension · Bradycardia

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What this study involves

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Study type: Interventional
Phase: Phase 4
Age range: 18 years - 80 years
Sex eligible: All sexes
Healthy volunteers: Not accepted
Participants: 544 Actual

These are starting points, not an eligibility decision. The research team must review the full requirements.

About the research

This randomized controlled trial compares two isovolumetric intrathecal doses of dexmedetomidine (5 micrograms and 10 micrograms) added to 12.5 mg hyperbaric bupivacaine for spinal anaesthesia in adults undergoing elective infra-umbilical surgery. A total of 544 patients are randomly allocated into two groups of 272 each. The incidence of intraoperative hypotension is the primary outcome. Intraoperative bradycardia, number of hypotensive and bradycardic episodes, rescue drug use and time to two-segment regression of the sensory block are secondary outcomes.

Read the full description

Subarachnoid block is a single-shot technique with a limited duration of anaesthesia and analgesia. Dexmedetomidine, a selective alpha-2 adrenergic agonist, prolongs the sensory and motor block when added to intrathecal local anaesthetic without causing respiratory depression, but it may cause dose-dependent bradycardia and hypotension. Published trials comparing 5 micrograms and 10 micrograms intrathecal dexmedetomidine report conflicting rates of hypotension and bradycardia, so the lowest effective dose that keeps haemodynamics stable remains unclear.

After approval from the Ethics Research Review Committee of PIMS and written informed consent, 544 ASA I-II adults aged 18-80 years scheduled for elective infra-umbilical surgery under spinal anaesthesia are randomly allocated by computer-generated random numbers into two groups of 272 each. Group L receives 5 micrograms dexmedetomidine and Group H receives 10 micrograms dexmedetomidine; each dose is diluted with normal saline to 1 ml and added to 12.5 mg of 0.5% hyperbaric bupivacaine, so that both injectates have the same volume. Patients are blinded to group allocation.

Heart rate and mean arterial pressure are recorded at baseline and throughout surgery. Intraoperative hypotension is defined as a fall in mean arterial pressure of more than 20% from baseline and is treated with intravenous phenylephrine. Intraoperative bradycardia is defined as a heart rate below 60 beats per minute and is treated with intravenous atropine. The number of hypotensive and bradycardic episodes, total phenylephrine and atropine doses, highest level of sensory block and time to two-dermatome regression of the sensory block are recorded.

Data are analysed in SPSS version 26.0. Normality of quantitative data is checked by the Shapiro-Wilk test. Categorical outcomes are compared by the chi-square test and quantitative outcomes by the independent sample t-test. Effect modifiers (age, gender, ASA class, type of surgery and level of sensory block) are controlled by stratification and multivariable logistic regression. A p-value of less than 0.05 is taken as significant.

Who may be able to participate?

The list below is the sponsor’s full registry wording. It can include conditions, prior treatment, test results and other requirements. A match in search does not mean you qualify.

Inclusion Criteria:

Age 18 to 80 years
ASA physical status I or II
Elective infra-umbilical surgery under spinal anaesthesia
Body mass index 18 to 30 kg/m2
Willing to give written informed consent

Exclusion Criteria:

Known allergy or hypersensitivity to dexmedetomidine or local anaesthetics
Cardiovascular instability (arrhythmia, severe hypertension or hypotension)
Significant hepatic, renal or neurological disease
Contraindication to spinal anaesthesia (coagulopathy, infection at the puncture site)
Pregnancy or lactation
Current use of alpha-2 agonists or antagonists
History of substance abuse or chronic pain

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Treatment, groups and participation

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Assignment: Random assignment
Masking: Single masked

Group L: Dexmedetomidine 5 mcg

Spinal anaesthesia with 12.5 mg of 0.5% hyperbaric bupivacaine plus dexmedetomidine 5 micrograms diluted to 1 ml with normal saline.

Drug: Dexmedetomidine 5 micrograms (intrathecal) · Drug: Hyperbaric bupivacaine 0.5%

Group H: Dexmedetomidine 10 mcg

Spinal anaesthesia with 12.5 mg of 0.5% hyperbaric bupivacaine plus dexmedetomidine 10 micrograms diluted to 1 ml with normal saline.

Drug: Dexmedetomidine 10 micrograms (intrathecal) · Drug: Hyperbaric bupivacaine 0.5%

Dexmedetomidine 5 micrograms (intrathecal) DRUG

Dexmedetomidine 5 micrograms diluted with normal saline to 1 ml and added to 12.5 mg hyperbaric bupivacaine, injected intrathecally at L3-L4 or L4-L5 in the sitting position.

Dexmedetomidine 10 micrograms (intrathecal) DRUG

Dexmedetomidine 10 micrograms diluted with normal saline to 1 ml and added to 12.5 mg hyperbaric bupivacaine, injected intrathecally at L3-L4 or L4-L5 in the sitting position.

Hyperbaric bupivacaine 0.5% DRUG

12.5 mg (2.5 ml) of 0.5% hyperbaric bupivacaine given intrathecally in both groups.

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