Dexmedetomidine versus magnesium in a modified Bier’s block for diagnostic knee arthroscopy

الملخص EN

Introduction Modified Bier’s block, the intercuff technique, has successfully been used recently in the lower limb.

The aim of this study is to compare the analgesic efficacy of magnesium and dexmedetomidine when added to lidocaine in a modified Bier’s block in diagnostic knee arthroscopy.

Patients and methods Sixty adult ASA I and II patients were randomly divided into three groups: group I received docaine 2% at a dose of 3 mg/kg diluted by isotonic saline to a total volume 0.5 ml/kg.

Group II received lidocaine 2% at a dose of 3 mg/kg+ 15 ml magnesium sulfate 10% diluted by isotonic saline to a total volume 0.5 ml/kg.

Group III received lidocaine 2% at a dose of 3 mg/kg, 0.5 mg/kg dexmedetomidine diluted by isotonic saline to a total volume 0.5 ml/kg.

Onset and recovery of sensory block were detected.

Intraoperative analgesic consumption (intravenous fentanyl), and the mean arterial blood pressure, heart rate, respiratory rate, and SpO2 were recorded.

Intraoperative side effects (hypotension, bradycardic, nausea and vomiting, skin rash, and local anesthetic toxicity) were observed and managed.

Postoperative mean arterial blood pressure, heart rate, Visual Analogue Scale (VAS), and the time to first analgesic requirement were recorded as well as total analgesic (dictofen intramuscularly) consumption within the first 24 postoperative hours.

Results There was no significant difference between the three groups in terms of intraoperative blood pressure, pulse rate, oxygen saturation, and respiratory rate (P40.05).

There was no significant difference between the three groups in the postoperative average mean blood pressure and pulse rate (P40.05).

In terms of onset time, recovery time, and time to first analgesic dose, there was a highly significant difference between groups I and II (Po0.001) and groups I and III (Po0.001).

Patients in group II required less intraoperative fentanyl than those in group I (Po0.037) and patients in group III also required less IV fentanyl in comparison with the patients in group I (P40.024).

Intraoperative VAS was significantly higher in group I compared with groups II and III (Po0.001).

VAS was significantly higher in the patients in group III compared with the patients in group II at 30 min after distal above-knee tourniquet infection (P=0.018).

There was a significant difference between groups I and II (P=0.0001) and groups I and III (P=0.045) in the postoperative analgesic requirements.

Postoperative VAS was significantly high in group I compared with groups II and III in the first 24 h postoperatively (Po0.001).

There was so statistical difference in the side effects apart from sedation in group III and pain on injection in group II.

Conclusion The addition of dexmetetomidine or magnesium to lidocaine in a modified Bier’s block equally shortened the onset time of the block, prolonged the recovery time, and prolonged the time to the first analgesic dose.

It also improved the tourniquet pain, decreasing the intraoperative analgesic requirements and improving postoperative VAS and analgesic requirements, with no major side effects