title: Influence of volume on the spread of local anesthetic-methylene blue solution after injection for intercostal block.
abstract: The purpose of this study was to evaluate the influence of the volume of methylene blue-local anesthetic on the spread of the injectate along the costal pleura. Twenty patients undergoing elective thoracotomy were studied. Twelve patients received intercostal nerve injection with 10 mL of 0.5% bupivacaine with methylene blue (10-mL group), and eight patients received 5 mL of 0.5% bupivacaine with methylene blue (5-mL group). The area of spread of the methylene blue was measured after the pleural cavity was incised. The 10-mL group had a mean area of spread of 51.1 cm2 as opposed to 17.6 cm2 for the 5-mL group (P less than 0.05). In the 10-mL group, eight patients had bupivacaine-methylene blue spread to two intercostal spaces, three patients to three intercostal spaces, and one patient to four intercostal spaces. In the 5-mL group, seven patients had bupivacaine methylene blue spread confined to one intercostal space and one patient to two intercostal spaces. We conclude that a potential anatomic space exists between the costal pleura and the internal intercostal muscle and that the spread of local anesthetic after intercostal nerve block injection is volume dependent.
authors.affiliation: Department of Anesthesia, Indiana University School of Medicine, Indianapolis 46202-5115.
authors.forename: S S
authors.initials: SS
authors.lastname: Moorthy
authors.forename: S F
authors.initials: SF
authors.lastname: Dierdorf
authors.forename: P B
authors.initials: PB
authors.lastname: Yaw
mesh_terms: D000772:Anesthesia, Local / Q000379:methods; D000777:Anesthetics / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics*; D002045:Bupivacaine / Q000008:administration & dosage / Q000493:pharmacokinetics; D002626:Chemistry, Pharmaceutical; D004334:Drug Administration Schedule; D006801:Humans; D007273:Injections, Intramuscular; D007366:Intercostal Muscles / Q000033:anatomy & histology / Q000378:metabolism*; D007367:Intercostal Nerves; D008751:Methylene Blue / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics*; D009407:Nerve Block / Q000379:methods*; D010994:Pleura / Q000033:anatomy & histology / Q000378:metabolism
chemical_list: D000777:Anesthetics; D008751:Methylene Blue; D002045:Bupivacaine