• Tomoki Nishiyama.
• Department of Anaesthesiology, Harada Hospital, Toyooka, Iruma, Saitama, Japan. nishit-tky@umin.ac.jp.
• Anaesthesiol Intensive Ther. 2017 Jan 1; 49 (1): 53-56.

BackgroundTo know the objective methods of the effects of the brachial plexus block, we studied the changes in percutaneous oxygen pressure (tcPO₂) with the hypothesis that tcPO₂ increases significantly on the blocked arm in comparison with the non-blocked arm, a phenomenon which is connected with vasodilation following the brachial plexus block.MethodsFifteen patients scheduled for upper extremity surgery, aged 20 to 70 years, with ASA physical status I or II were included. Before anaesthesia, the electrodes used to measure tcPO₂ were put on the radial side of the forearm and upper arm of both the right and left sides (a total of 4 electrodes). Oxygen at 6 L min⁻¹ was administered by a facial mask. Once midazolam 1-2 mg and fentanyl 50 μg had been administered intravenously, a propofol infusion was started at a dose of 2 mg kg⁻¹ h⁻¹. The interscalene block was performed by means of a nerve stimulator, using 20 mL of 1% lidocaine solution combined with 20 mL of 0.75% ropivacaine solution. TcPO₂ was measured just before the block and 30 minutes after the block.ResultsTcPO₂ in both forearm and upper arm significantly increased after the block in both sides namely, blocked and non-blocked. No difference was observed in tcPO₂ between the blocked side and non-blocked side.ConclusionChanges of tcPO₂ are not useful in order to assess the effects of the interscalene block under oxygen administration.

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