Hypobaric Spinal Anesthesia Consideration

1. Hypobaric Spinal AnesthesiaConsideration Presented By R3 顏郁軒2004/11/01

2. Question • Marcain choice : heavy , plain , or hypobaric • Volume and Concentration VS Sensory block level & Duration • Hemodynamic change • Lateral decubitus VS supine

3. Miller • the mass of drug (mg dose) injected is more important in determining the eventual block height than the volume of isobaric drug administered • the mean value of CSF specific gravity :1.0069

4. Cerebrospinal Fluid Density Influences Extent of PlainBupivacaine Spinal Anesthesia • Anesthesiology 2002; 96:1325–30 • Hyperbaric solution : position dependentplain solution : not or less position dependent • Lateral decubitus  collect CSF 2 ml & 3 ml(15mg) plain Marcaine was injected  supine

5. Cerebrospinal Fluid Density Influences Extent of PlainBupivacaine Spinal Anesthesia

6. Cerebrospinal Fluid Density Influences Extent of PlainBupivacaine Spinal Anesthesia

7. Cerebrospinal Fluid Density Influences Extent of PlainBupivacaine Spinal Anesthesia • The higher the CSF density, the higher the maximal level of block observed for plain bupivacaine solutions. • CSF density is significantly different between some subgroup populations (higher in men than in women, higher in postmenopausal than premenopausal women, higher in nonpregnant than in pregnant women)

9. Low-dose bupivacaine: a comparison of hypobaric and near isobaric solutions for arthroscopic surgery of the knee • Anaesthesia, 1999, 54, pages 540–545 • I (n=30): 1.2 ml 0.5% plain MarcaineII (n=30): 3.4 ml 0.18 % Marcaine • Lateral decubitus for 20 mins post spinal anesthesia and slight head –down(10o)

10. Low-dose bupivacaine: a comparison of hypobaric and near isobaric solutions for arthroscopic surgery of the knee

11. Low-dose bupivacaine: a comparison of hypobaric and near isobaric solutions for arthroscopic surgery of the knee • the hypobaric solution spread one dermatome higher than the plain solution • The motor block between operated and nonoperated sides was significantly different at all testing times irrespective of the solution used

12. Low-dose bupivacaine: a comparison of hypobaric and near isobaric solutions for arthroscopic surgery of the knee • Our results indicate that a mainly unilateral motor and sensory block can also be obtained with the less hypobaric solution when the patients remain in the lateral position 20 min after the injection of the local anaesthetic. • This finding suggests that total dosage is more important than the volume used even when using low doses of local anaesthetic

13. Low-dose bupivacaine: a comparison of hypobaric and near isobaric solutions for arthroscopic surgery of the knee • Hemodynamic status Group I: 2 p’t with hypotensionGroup II : 1 p’t with hypotension No bradycardia was seen

14. Isobaric Versus Hypobaric Spinal Bupivacaine for Total HipArthroplasty in the Lateral Position • Anesth Analg 2003;97:589 –94 • Group I (n=20) : 3.5 ml plain Marcaine (17.5mg) + 1.5ml normal saline • Group II (n=20) : 3.5 ml plain Marcaine (17.5mg) + 1.5ml distilled water

15. Isobaric Versus Hypobaric Spinal Bupivacaine for Total HipArthroplasty in the Lateral Position • Patients remained in the lateral position until the end of surgery • Evolution of upper sensory block level & motor function on nondependent (operative) and dependent sides • Mean arterial blood pressure (MAP) and heart rate (HR) were recorded

16. Isobaric Versus Hypobaric Spinal Bupivacaine for Total HipArthroplasty in the Lateral Position

17. Isobaric Versus Hypobaric Spinal Bupivacaine for Total HipArthroplasty in the Lateral Position

18. Isobaric Versus Hypobaric Spinal Bupivacaine for Total HipArthroplasty in the Lateral Position • hypobaric bupivacaine showed a significantly delayed sensory regression to L2 on the nondependent side of 45 minutes

19. A Low-Dose Bupivacaine: A Comparison ofHyperbaric and Hypobaric Solutions forUnilateral Spinal Anesthesia • Regional Anesthesia and Pain Medicine, Vol 29, No 1 (January–February), 2004: pp 17–22 • Group I (n=25) : 7.5 mg (1.5 ml , 0.5% heavy Marcaine ) • Group II (n=25) : 7.5 mg (4.2 ml , 0.18% plain Marcaine) • Lateral position for 15 mins

20. A Low-Dose Bupivacaine: A Comparison ofHyperbaric and Hypobaric Solutions forUnilateral Spinal Anesthesia

21. A Low-Dose Bupivacaine: A Comparison ofHyperbaric and Hypobaric Solutions forUnilateral Spinal Anesthesia

22. A Low-Dose Bupivacaine: A Comparison ofHyperbaric and Hypobaric Solutions forUnilateral Spinal Anesthesia • the total amount of local anesthetic molecules injected into the spinal canal appears to be the more important factor • In patients for whom lying on the operative site is impossible, using a hypobaric solution would be preferable.

23. Conclusion • Heavy & Hypobaric : 也許比plain更好預測麻醉的高度 • 側躺的方式可減少一些CV 方面的變化 • 考慮用Hypobaric , dose 要減低 • 用Hypobaric 的方式 , 可能可延長麻醉的時間

24. THANKS FOR YOUR ATTENTION !!!