A Phase 4 interventional study of Dexmedetomidine 5 micrograms (intrathecal) and Dexmedetomidine 10 micrograms (intrathecal) in Spinal Anesthesia, Intraoperative Hypotension and Bradycardia, sponsored by Hussain Aziz Bhatti. Completed at 1 site in Pakistan. Open to participants aged 18 Years to 80 Years. Per ClinicalTrials.gov, last updated 2026-11-10.
Sponsored by Hussain Aziz Bhatti · Phase 4, Interventional, and Treatment
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.
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.
317 studies on the registry are indexed under Bradycardia; 71 are open to participants now.
This study's enrollment of 544 is above the median of 100 across 187 interventional studies indexed under Bradycardia.
Browse Bradycardia studies →This is the only study on the registry with Hussain Aziz Bhatti as lead sponsor.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
ASA physical status
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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%
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 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 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.
12.5 mg (2.5 ml) of 0.5% hyperbaric bupivacaine given intrathecally in both groups.
Incidence of intraoperative hypotension
Proportion of patients with a fall in mean arterial pressure of more than 20% from the pre-spinal baseline at any time during surgery.
Time frame: During surgery: from intrathecal injection to the end of surgery (up to 3 hours)
Incidence of intraoperative bradycardia
Proportion of patients with heart rate below 60 beats per minute at any time during surgery.
Time frame: During surgery: from intrathecal injection to the end of surgery (up to 3 hours)
Number of intraoperative hypotensive episodes
Total count of separate episodes of mean arterial pressure fall of more than 20% from baseline per patient.
Time frame: During surgery: from intrathecal injection to the end of surgery (up to 3 hours)
Number of intraoperative bradycardic episodes
Total count of separate episodes of heart rate below 60 beats per minute per patient.
Time frame: During surgery: from intrathecal injection to the end of surgery (up to 3 hours)
Total intraoperative phenylephrine and atropine dose
Cumulative intravenous phenylephrine (micrograms) given for hypotension and atropine (mg) given for bradycardia.
Time frame: During surgery: from intrathecal injection to the end of surgery (up to 3 hours)
Time to two-segment regression of sensory block
Time in minutes from intrathecal injection until the highest sensory level (pinprick) regresses by two dermatomes.
Time frame: From intrathecal injection until regression of the highest sensory level by two dermatomes, assessed every 15 minutes up to 8 hours
Plan to share: Undecided
No publications or documents are linked to this record.
Ran from Aug 2025 to primary completion in Oct 2026, 14 months.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Nov 2026. You cannot join it, but the record below documents what was studied.
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