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2002
Spinal Anesthesia for Cesarean Section after Failed Labor Epidural Analgesia: Retrospective Analysis of Two Dosing RegimensRakesh B. Vadhera, M.D.; Falguni J. Siswawala, M.D.; Dmitry Portnoy, M.D.; Aristides P. Koutrouvelis, M.D.
Department of Anesthesiology, The University of Texas Medical Branch, Galveston, Texas
Introduction: The recommendations on the use of spinal anesthesia (SAB) for c-section after failed labor epidural anesthesia have varied, ranging from avoiding SAB completely
1,2 to reducing the dose of local anesthetic (LA) by 20-30%
3 to using a normal dose of LA
4,5. At our institution, we compared the latter two dosing regimens--using the standard amount of LA in SAB vs. using a reduced dose of LA in SAB in situations where the epidural block was inadequate. The outcome measures were the incidence of total SAB and failed or inadequate SAB.
Methods: In a retrospective, non-randomized study analyzing the two different dosing schedules used at our institution, patients who received SAB for c-section after labor epidural analgesia were reviewed for indication for conversion to SAB, documentation of block and efficacy of epidural analgesia before SAB, duration for which the infusion was stopped prior to SAB, level of block, blood pressure changes, treatment of hypotension, and postoperative complications. Patients were separated into 2 groups based on LA dosage: Group A (1.5cc of 0.75% heavy bupivacaine with 20 mcg fentanyl) and Group B (reduced dose of LA with 15 mcg fentanyl for SA). The reduced amount of LA used in Group B was calculated (shown below) using the hypothesis that spinal segments already partially blocked require only half the amount of LA to produce total SAB when compared to segments with no block.
Calculated Dose=
# of segments with no block+ # of segments with some block (0.5) x Dose ÷ 18 (i.e., the total target segments required to achieve a T-4 block)
Results: Forty-seven charts were reviewed where patients underwent c-section under SAB after failed epidural block (Group A=24 patients; Group B=23 patients). Group A accounted for 2 cases of total SAB while Group B had none. Neither group had any failed SAB.
Discussion: The data suggest a possibility of total SAB anesthesia after failed epidural blocks when a standard dose of LA was utilized. The data also showed no failed SAB when a reduced dose of LA was used. The data also suggest that there is a way to calculate the dose of LA for SAB in such circumstances.
References:
1. Int J Obstet Anesth 1994;3:153.
2. J Clin Anesth 1995;7:71.
3. Anesth Analg 1994;78:1029-1035.
4. Anesth Analg 1995;81:654-656.
5. Br J Anaesth 1991;66:596-607.
Anesthesiology 2002; 96: A1021Copyright © 2008,
American Society of Anesthesiologists.
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