Suja Ray, T Sivashanmugam, M Ravishankar
Mahatma Gandhi Medical College and Research Institute, Pondicherry, India
Background and Aims: During regional anaesthesia, because of absence of clear cut fascial compartment to consistently separate the neural tissues from the epimysium of the surrounding muscles,the local anaesthetic (LA) tends to easily spread away from the target site leading to complications. The availability of LA at the target site comes down and hence,the efficacy of the LA may also come down. Subepineural deposition of local anaesthetics hastens the onset of blockade and prolongs the duration of analgesia in sciatic nerve block. This study was designed to evaluate the efficacy of U/S guided supraclavicular block when LAs are deposited in the conventional extrafascial (EF) plane and in subfascial (SF) plane.
Methods: 32 consecutive patients posted for emergency or elective elbow and below elbow surgeries were recruited. They were randomly allocated to one of the groups by sealed envelope technique and under U/S guidance supraclavicular brachial plexus block was performed using 23 gauge needle, attached to a 20 ml syringe via a three way by a 100 cm pressure monitoring line. The pressure developed during the conventional EF or SF injection of drug was monitored by a syringe pump (Injectomat MC Agilia® , Fresenius Kabi AG, Bad Homburg, Germany) attached to pressure monitoring line; the LA syringe was attached to remaining port of a three way connector. A mixture of LAs (12.5 ml each of 2% lignocaine with adrenaline and 0.5% bupivacaine) was uniformly used for both approaches. After satisfactory drug deposition under U/S guidance, the final needle removal time was noted as block time. Block characteristics were assessed by a blinded observer every 5 minutes for 30 minutes and at 2, 4, 6, 8, 10, 12, 24 post-operative hours. Readiness for surgery was defined as absence of surgical site pain while attempting motor manoeuvre, atleast scale 1 sensory block (assessed on a 3-point qualitative scale for perseverance of cold) and motor loss (assessed on 3-point qualitative scale) in the four nerve territory.
Results: In the SF group the time to readiness for surgery was significantly shorter (7 ± 3.0 min vs. 20 ± 10.1 min; P = 0.000) and the duration of analgesia was longer (561 ± 89 min vs. 367 ± 89 min; P = 0.000) when compared to EF group [Table 1]. None of the patients registered any persistent neurological changes at the end of 24 hrs. Subfascial deposition of local anaesthetic provided a shorter onset time for surgical anaesthesia due to less intra and extra neural diffusion time for the LA and prolonged analgesia as less surface area is available for systemic absorption of LA when compared to extrafascial deposition.
Table 1.
Block characteristics

Conclusion: Subfascial deposition of LA provides faster onset of surgical anaesthesia and prolonged analgesia without any persistent neurological deficit at 24 hrs.
REFERENCES
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