Ophthalmic regional anesthesia: medial canthus episcleral (sub-tenon) anesthesia is more efficient than peribulbar anesthesia: A double-blind randomized study.

BACKGROUND: Regional anesthesia and especially peribulbar anesthesia commonly is used for cataract surgery. Failure rates and need for reinjection remains high, however, with peribulbar anesthesia. Single-injection high-volume medial canthus episcleral (sub-Tenon's) anesthesia has proven to be an efficient and safe alternative to peribulbar anesthesia. METHODS: The authors, in a blind study, compared the effectiveness of both techniques in 66 patients randomly assigned to episcleral anesthesia or single-injection peribulbar anesthesia. Motor blockade (akinesia) was used as the main index of anesthesia effectiveness. It was assessed using an 18-point scale (0-3 for each of the four directions of the gaze, lid opening, and lid closing, the total being from 0 = normal mobility to 18 = no movement at all). This score was compared between the groups 1, 5, 10, and 15 min after injection and at the end of the surgical procedures. Time to onset of the blockade also was compared between the two groups, as was the incidence of incomplete blockade with a need for supplemental injection and the satisfaction of the surgeon, patient, and anesthesiologist. RESULTS: Episcleral anesthesia provided a quicker onset of anesthesia, a better akinesia score, and a lower rate of incomplete blockade necessitating reinjection (0 vs. 39%; P < 0.0001) than peribulbar anesthesia. Even after supplemental injection, peribulbar anesthesia had a lower akinesia score than did episcleral anesthesia. Peribulbar anesthesia began to wear off during surgery, whereas episcleral anesthesia did not. CONCLUSION: Medial canthus single-injection episcleral anesthesia is a suitable alternative to peribulbar anesthesia. It provides better akinesia, with a quicker onset and more constancy in effectiveness.

Medial canthus episcleral (sub-Tenon) anesthesia imaging.

Medial canthus single injection periocular anesthesia is an alternative technique to classical regional anesthesia techniques for cataract surgery. The occurrence of a chemosis at the end of this injection has made us question ourselves about the real site of injection. The purpose of this anatomic study was to identify this site with precision, and to describe the spreading of the injected solution. Various volumes of colored liquid latex were injected when using this technique on 10 human orbits. They were deeply frozen and sectioned in thin slices. The site of injection is clearly the episceral (sub-Tenon) space. This is a gliding space through which pass the ciliary nerves supplying the globe sensitivity. This could explain the high quality of the analgesia of the globe. With the larger volumes injected, spreading of the latex was detected in the orbicularis palpebra. This probably explains the good akinesia of the lids obtained without any facial block. Spreading of the latex to the rectus muscles sheaths should explain the good akinesia of the globe, but was only partially proved in this study. We conclude that the medial canthus single injection periocular anesthesia is an episcleral (sub-Tenon) injection which may explain good anesthesia.

Medial canthus (caruncle) single injection periocular anesthesia.

We studied 151 consecutive patients scheduled for elective short-duration ophthalmic procedures to assess the efficacy of an alternative approach to periocular anesthesia. Single injection at the medial canthus was performed with a 25-gauge needle. The studied variables were: injected volume, onset time of the block, akinesia (scored on a 12-point scale), adequate surgical anesthesia (scored on a 5-point scale), and need for reinjection. The injected volume of local anesthetic solution was 8.6 +/- 1.7 mL. The onset time of anesthesia was 6.9 +/- 3.0 min, with an akinesia score of 11.6 +/- 1.1 (maximum 12). Additional reinjections were necessary in 14 cases (9.2%). There was a learning curve for the technique, with 8 of the additional injections being performed in the first 30 patients (26.6%), and 6 in the last 121 (4.9%). The surgical score recorded after surgery was 4.8 +/- 0.6 (maximum 5). There were no complications, including injury to the globe, optic nerve, or retina or orbital hematoma. Medial canthus single injection periocular anesthesia appears to be a promising alternative to the usual double injection peribulbar block.

Brachial plexus block with bupivacaine: effects of added alpha-adrenergic agonists: comparison between clonidine and epinephrine.

The effects of clonidine and epinephrine, administered into the brachial plexus sheath, were evaluated in 60 patients who underwent surgery of the upper limb. All patients received 40 to 50 ml of 0.25% bupivacaine, injected into the brachial plexus sheath, using the supraclavicular technique. The patients were randomly allocated to two groups so that 30 patients received 150 micrograms clonidine hydrochloride (Group I), and 30 received 200 micrograms epinephrine (Group II). The quality and the duration of analgesia were assessed as well as the possible side-effects. The block produced with the addition of clonidine was longer (994.2 +/- 34.2 vs 728.3 +/- 35.8 min) and superior to that with epinephrine (P less than 0.001). No major side-effects were recorded. We conclude that the injection of clonidine into the brachial plexus sheath is an attractive alternative to epinephrine to prolong the duration of analgesia following upper limb surgery under conduction anaesthesia.