Paravertebral brachial plexus block in sheep: a cadaveric and in vivo study

The Objective of the present study was to evaluate paravertebral brachial plexus block in sheep. A group of ۱۳ healthy sheep with ۲۰.۱۰ ± ۲.۲۰ kg weight and five months of age were used. In phase I, in five sheep, an insulated needle attached to a nerve stimulator was directed to the location of C۶, C۷, C۸ and T۱ nerves and a ۱.۵۰ mL of a solution containing ۱:۱ methylene blue ۱.۰۰% and lidocaine ۱.۰۰% was injected at each site. Then, the cervical and thoracic areas were dissected and assessed in the cadavers. In phase II, cervical paravertebral block with ۲.۰۰% lidocaine and subsequent assessments were done in eight live sheep. Cadaveric evaluations revealed dye spread in C۶ to T۱ nerves: ۶۱.۷۵ ± ۵.۵۰, ۷۲.۷۵ ± ۹.۱۸, ۴۰.۷۵ ± ۲.۹۹ and ۱۸.۷۵ ± ۳.۳۰ mm, respectively. In three sheep, dye distribution in the anterior mediastinum was observed. In phase II, the onsets of anesthesia were determined within ۱۰ and ۱۵ min for sensory and motor blocks, respectively. Anesthesia at axillary, musculocutaneous, radial and ulnar skin sites and motor block lasted for ۶۷.۵۰ ± ۱۵.۸۰, ۶۳.۷۰ ± ۱۶.۰۰, ۵۵.۰۰ ± ۲۱.۷۰, ۵۶.۷۰ ± ۱۹.۷۰ and ۷۶.۴۰ ± ۲۴.۳۰ min, respectively. In three sheep, no anesthesia was observed for radial and ulnar skin sites. In conclusion, paravertebral brachial plexus block in sheep provided an acceptable block for the upper parts of the elbow joint, however, it was not effective and reliable for more distal structures.

کلیدواژه ها:

Ewe ، Lidocaine ، Methylene blue ، Nerve stimulation ، Paravertebral block