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Sub-Tenon’s injection for posterior segment surgery

2001; Elsevier BV; Volume: 108; Issue: 6 Linguagem: Inglês

10.1016/s0161-6420(00)00448-6

1549-4713

Alvin K.H. Kwok, Timothy Y. Y. Lai, Eng-Leong Neoh, Rupert W.H Lee, Dennis S.C. Lam,

Anesthesia and Pain Management

The article by Li and coauthors on demonstrating the safety and efficacy of sub-Tenon’s injection for local anesthesia in vitreoretinal surgery was of particular interest to us. In their series of 200 patients who received sub-Tenon’s anesthesia containing an 11-ml mixture of 5 ml 2% lidocaine (Xylocaine), 5 ml 0.5% bupivacaine (Marcaine), and 1 ml of 150 hyaluronidase (Wydase) units as primary anesthesia, only 31 (15.5%) patients required additional preoperative or intraoperative sub-Tenon’s local anesthesia supplementation. No associated ocular or systemic complications were observed.We have also demonstrated similar results in a prospective study of 50 patients using the same technique.1Kwok A.K.H. Van Newkirk M.R. Lam D.S.C. Fan D.S.P. Sub-Tenon’s anesthesia in vitreoretinal surgery a needleless technique.Retina. 1999; 19: 291-296Crossref PubMed Google Scholar The similarities of the two studies include the prospective nature, a single quadrant injection of sub-Tenon’s anesthesia, and without the use of a separate transcutaneous lid nerve or subconjunctival injection. However, we used a simple, readily available curved 19-gauge blunt irrigating cannula, instead of their use of the Greenbaum cannula. Most importantly, our initial volume of local anesthetic solution injected was 4 ml rather than their use of 11 ml. The potential advantage of injecting a larger volume of anesthetic solution is to prolong the anesthetic effect, so that supplementation later can be avoided or minimized. This may be accountable for the higher supplementation rate of more than 50% in our series compared with their rate of 15.5%. The main potential concern of injection of a large volume of anesthetic solution into the retrobulbar space is a severe rise of intraocular pressure (IOP). We encountered difficulty in giving the whole 11 ml of sub-Tenon’s injection in many patients. In one particular woman with relatively narrow interpalpebral fissure, there was persistent elevation of IOP of more than 50 mmHg for 15 minutes, measured by three reliable readings using Tonopen intraoperatively. Lateral canthotomy and intravenous mannitol had to be administered to control the dangerous level of elevated IOP. Similar complications after giving 6 ml of sub-Tenon’s anesthesia have also been reported.2Mein C.E. Woodcock M.G. Local anesthesia for vitreoretinal surgery.Retina. 1990; 10: 47-49Crossref PubMed Scopus (70) Google ScholarIn summary, sub-Tenon’s anesthesia is an effective means of regional anesthesia for vitreoretinal surgery. A prospective study is warranted and is already underway in our institute to determine the optimal volume of sub-Tenon’s anesthesia that provides safe and adequate anesthesia. The article by Li and coauthors on demonstrating the safety and efficacy of sub-Tenon’s injection for local anesthesia in vitreoretinal surgery was of particular interest to us. In their series of 200 patients who received sub-Tenon’s anesthesia containing an 11-ml mixture of 5 ml 2% lidocaine (Xylocaine), 5 ml 0.5% bupivacaine (Marcaine), and 1 ml of 150 hyaluronidase (Wydase) units as primary anesthesia, only 31 (15.5%) patients required additional preoperative or intraoperative sub-Tenon’s local anesthesia supplementation. No associated ocular or systemic complications were observed. We have also demonstrated similar results in a prospective study of 50 patients using the same technique.1Kwok A.K.H. Van Newkirk M.R. Lam D.S.C. Fan D.S.P. Sub-Tenon’s anesthesia in vitreoretinal surgery a needleless technique.Retina. 1999; 19: 291-296Crossref PubMed Google Scholar The similarities of the two studies include the prospective nature, a single quadrant injection of sub-Tenon’s anesthesia, and without the use of a separate transcutaneous lid nerve or subconjunctival injection. However, we used a simple, readily available curved 19-gauge blunt irrigating cannula, instead of their use of the Greenbaum cannula. Most importantly, our initial volume of local anesthetic solution injected was 4 ml rather than their use of 11 ml. The potential advantage of injecting a larger volume of anesthetic solution is to prolong the anesthetic effect, so that supplementation later can be avoided or minimized. This may be accountable for the higher supplementation rate of more than 50% in our series compared with their rate of 15.5%. The main potential concern of injection of a large volume of anesthetic solution into the retrobulbar space is a severe rise of intraocular pressure (IOP). We encountered difficulty in giving the whole 11 ml of sub-Tenon’s injection in many patients. In one particular woman with relatively narrow interpalpebral fissure, there was persistent elevation of IOP of more than 50 mmHg for 15 minutes, measured by three reliable readings using Tonopen intraoperatively. Lateral canthotomy and intravenous mannitol had to be administered to control the dangerous level of elevated IOP. Similar complications after giving 6 ml of sub-Tenon’s anesthesia have also been reported.2Mein C.E. Woodcock M.G. Local anesthesia for vitreoretinal surgery.Retina. 1990; 10: 47-49Crossref PubMed Scopus (70) Google Scholar In summary, sub-Tenon’s anesthesia is an effective means of regional anesthesia for vitreoretinal surgery. A prospective study is warranted and is already underway in our institute to determine the optimal volume of sub-Tenon’s anesthesia that provides safe and adequate anesthesia. Sub-Tenon’s injection for posterior segment surgery: author’s replyOphthalmologyVol. 108Issue 6Preview Full-Text PDF