Perineal Repair

Summary

  • Dose: 1.5 ml 0.5% hyperbaric or isobaric bupivacaine with 15 mcg fentanyl.

  • Position: Sitting, immediately supine and then lithotomy.

  • Expectation: Surgical block for up to 60 minutes (vagina, cervix) or 90 minutes (perineum) post-spinal.

Considerations

  • While repair is likely to require a sacral block, the following factors favour (or forgive) slightly larger doses:

    • An IDC will be placed after surgery;

    • Expeditious ambulation is not required;

    • Occasionally the surgeon may wish to explore deeper structures (e.g. upper vagina, cervix);

    • Uncommonly, if anterior structures are affected, coverage of L1,2 (ilioinguinal & genital branch genitofemoral) may be required.

Evidence

  • Transcutaneous electrical stimulation (TES) evidence [1,2] suggests that 10-15 min of anaesthesia will be achieved at the ankle (L4/L5) per mg of hyperbaric bupivacaine (left lateral & immediately supine). This suggests that 5 mg of hyperbaric bupivacaine will cover L4/L5 for ~ 50 minutes.

  • In a group of young (~25 yr) patients undergoing pilonidal cyst/sinus surgery, 5 mg isobaric bupivacaine (sitting, then immediately prone) was 100% successful [3]. A median level of T12 was achieved and surgery lasted an average of 60 minutes.

  • 5 mg or 10 mg hyperbaric bupivacaine (lateral, immediately supine or lithotomy) was successful in all patients undergoing short (< 60 min) procedures (urology, orthopaedic, anal) [4]. An average level of T11 was achieved. Ambulation, on average, within 3 hours. Void, on average, within 4 hours. Home readiness was achieved in 80% at 6 hours, and 90% at 7 hours.

  • 5 mg hyperbaric bupivacaine with 10 mcg fentanyl (diluted to 3 ml with NaCl 0.9%) provided a block to T8 (T3-T12) for knee arthroscopy [5]. Injection was done in the lateral position (immediately supine). No surgical duration was given but the success rate was 100%. Discharge occurred on average within 3.5 hours.

REFERENCES

  1. Liu et al. Dose-response characteristics of spinal bupivacaine in volunteers. Anesthesiology 1996;85:729-36.

  2. McDonald et al. Hyperbaric spinal ropivacaine. A comparison to bupivacaine in volunteers. Anesthesiology 1999;90:971-7.

  3. Cuvas et al. The use of low dose plain solutions of local anaesthetic agents for spinal anaesthesia in the prone position: bupivacaine compared with levobupivacaine. Anaesthesia 2009;64:14-18.

  4. Tarkkila et al. Home-readiness after spinal anaesthesia with small doses of hyperbaric 0.5% bupivacaine. Anaesthesia 1997;52:1157-1160.

  5. Ben-David et al. Intrathecal fentanyl with small-dose dilute bupivacaine: better anaesthesia without prolonging recovery.  Anesth Analg 1997;85(3):560-5