Intrathecal Fentanyl and Dexmedetomidine Added to Bupivacaine for Subarachnoid Anaesthesia for Percutaneous Nephrolithotomy

Spinal anesthesia is a straightforward procedure that acts quickly. However, because of its neurotoxic effects, a common anesthetic like lidocaine has mostly been substituted by alternative substances like bupivacaine. Regular bupivacaine dosages are linked to considerable sympathetic block, as well as persistent and severe sensory and motor block, which may not be desired for certain individuals. Although diluted bupivacaine at low doses restricts the distribution of spinal block and produces a comparatively quick recovery, it might not offer a sufficient degree of sensory block. Bupivacaine's side effects and dosage requirements are lessened by the potentiating effects of the short-acting lipophilic opioid fentanyl and the more selective α2 agonist dexmedetomidine. These spinal adjuncts are used to extend analgesia in addition to lessening the negative effects of local anesthetics.

The danger of respiratory depression for lipophilic opioids, such as fentanyl and sufentanil, is primarily restricted to the first two hours following intrathecal injection. Because fentanyl is more lipid soluble than morphine, there is a significantly lower chance of delayed respiratory depression brought on by the rostral distribution of an intrathecal injected drug to respiratory centers.

Both visceral and somatic pain can be reduced by intrathecal α2 receptor agonists. Compared to clonidine (α2/α1 200:1), dexmedetomidine has greater selectivity for the α2 receptor (α2/α1 1600:1). According to a number of studies, when given intrathecally, α2 receptor agonists will increase the analgesia that subtherapeutic doses of local anesthetics like bupivacaine deliver because of their synergistic effects with little hemodynamic effects. The goal will be to determine if bupivacaine and fentanyl or bupivacaine and dexmedetomidine produced higher-quality anesthesia.

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Methods and patients:

After obtaining Institutional Ethical Committee approval, this prospective randomised double-blinded study was carried out in a tertiary health care centre on 60 patients After obtaining Institutional Ethical Committee approval, this prospective randomised double-blinded study will be carried out in a tertiary health care centre on 60 patients of

Intervention:

Spinal anaesthesia will be performed in all patients in the sitting position. Under strict aseptic precautions, using 25G Quincke needle mid-line spinal puncture was performed at L2-L3 level.

In Group fentanyl (F), an injection of bupivacaine 0.5% (3.5 ml) + fentanyl 0.5 ml (25 μg) was administered intrathecally.

In Group dexmedetomidine( D), dexmedetomidine will be first diluted in normal saline to obtain a dose of 5 μg in 0.5 ml. Then, an injection of bupivacaine 0.5% (3.5 ml) + dexmedetomidine 0.5 ml (5 μg) will be administered intrathecally. Drug will be administered over 10 seconds (s) using 5 cc syringes with cephalad orientation of the spinal needle bevel. The patients were turned supine immediately after the injection of the drug.

Midazolame and fentanyle will be administered on request as rescue analgesic and for sedation if needed . post-operatively and side-effects such as hypotension, bradycardia, pruritus, vomiting, shivering, respiratory depression were also monitored. Pruritus was managed with i.v chlorpheniramine maleate.

Inclusion criteria

• both sex aged between 18 and 60 years,
• belonging to American Society of Anaesthesiologists (ASA) physical status Grade I and II undergoing PCNL under spinal anaesthesia.

Exclusion criteria

• Patients with a history of spine surgery,
• infection at the injection site,
• coagulopathy,
• hypovolemia,
• increased intracranial pressure,
• indeterminate neurologic disease,
• spinal deformities,
• communication problems,
• known hypersensitivity to local anaesthetics, opioids or dexmedetomidine