KEY POINTS

1. Low neuraxial anesthesia (i.e., T10 or lower sensory level) carries physiologic impact different from a block performed to produce high (T5) neuraxial anesthesia.
2. Neuraxial anesthesia carries more risk with the perioperative introduction of LMWHs and potent (glycoprotein) platelet inhibitors.
3. Many spinal and epidural anesthetics fail because of inadequate intravenous sedation and anxiolysis rather than technically flawed blocks.
4. Bupivacaine, levobupivacaine, and ropivacaine provide excellent quality of anesthesia for neuraxial techniques.
5. It is estimated that CSF volume accounts for 80% of the variability in peak block height and regression of sensory and motor block. Except for body weight, the volume of CSF does not correlate with other anthropomorphic measurements available clinically.
6. The epidural space is more segmented and less uniform than previously believed, and the ligamentum flavum is not uniform from skull to sacrum or even within an intervertebral space.
7. During neuraxial anesthesia, there is venous and arterial vasodilation, but because of the large amount of blood in the venous system (approximately 75% of total blood volume), the venodilation effect predominates.
8. It has long been taught that the decrease in blood pressure after neuraxial block can be minimized by administration of crystalloids intravenously before the block; however, this logic needs rethinking.

---

1679

9. Nausea and vomiting may be associated with neuraxial block in up to 20% of patients, and atropine is almost universally effective in treating the nausea associated with high (T5) neuraxial anesthesia.
10. As facility with spinal anesthesia increases, the use of smaller, similarly tipped needles will decrease headache incidence if the number of dural punctures does not increase.
11. TNS after spinal anesthesia develops most frequently after ambulatory procedures, especially in patients placed in lithotomy or positions for knee arthroscopy.
12. The mechanism of a lower frequency of headache with cone-shaped needle tips may be the result of exposing more inflammatory mediators around the opening, rather than the often-quoted more gentle spreading of the dura at the site of puncture.
13. Epidural blood patches are more than 90% effective in relieving postdural puncture headache headaches.
14. One method of increasing the likelihood of correct caudal needle placement is to inject 5 mL of saline rapidly through the caudal needle while palpating the skin overlying the sacrum. If no midline bulge is detected, the needle is probably correctly positioned. If a midline bulge is detected during saline injection, the needle is incorrectly positioned.
15. Local anesthetic-induced systemic toxicity occurs primarily through the unintentional administration of the drug into an epidural vein.