title: Hypotension in spinal anesthesia: a comparison of isobaric tetracaine with epinephrine and isobaric bupivacaine without epinephrine.
abstract: Two isobaric spinal anesthetic solutions (bupivacaine 0.5%/20 mg without epinephrine and tetracaine 0.5%/15 mg with 0.2 mg epinephrine) were compared in a double-blind study of 60 patients. Patients were injected while in the lateral recumbent position and were immediately turned supine and horizontal. Up to 30 min after injection, no differences were found between the groups regarding segmental level of analgesia, changes in heart rate, and onset to or maximum decrease in mean arterial pressure (MAP). No correlation was found between maximum decrease in MAP and level of analgesia. At time of maximum decrease in MAP (tetracaine group - 16.7 +/- 12.8% (mean + SEM), bupivacaine group -19.4 + 14.8%) the level of analgesia was significantly higher in the tetracaine group (T5-6) than in the bupivacaine group (T7-8). Hypotension occurred in five patients in the bupivacaine group and in six in the tetracaine group. Two patients in the tetracaine group (but none in the bupivacaine group) had bradycardia. Hypotension together with bradycardia was observed in one patient in the tetracaine group but in no patient in the bupivacaine group. Two patients in each group developed postlumbar puncture headache. The authors conclude that the choice of local anesthetic agent, by itself, is not the sole cause of hypotension seen with spinal anesthesia.
mesh_terms: D000775:Anesthesia, Spinal / Q000379:methods*; D001794:Blood Pressure / Q000187:drug effects; D002045:Bupivacaine; D004311:Double-Blind Method; D004341:Drug Evaluation; D004837:Epinephrine; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007022:Hypotension / Q000139:chemically induced*; D008297:Male; D011897:Random Allocation; D013748:Tetracaine
chemical_list: D013748:Tetracaine; D002045:Bupivacaine; D004837:Epinephrine