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IVC compression and hyperventilation decrease lumbar CSF volume

IVC compression and hyperventilation decrease lumbar CSF volume. Tom Archer, MD. Lateral position– IVC is not compressed. http://www.manbit.com/OA/f28-1.htm. Manbit images. Supine position– IVC is compressed and epidural veins are engorged. http://www.manbit.com/OA/f28-1.htm.

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IVC compression and hyperventilation decrease lumbar CSF volume

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  1. IVC compression and hyperventilation decrease lumbar CSF volume Tom Archer, MD

  2. Lateral position– IVC is not compressed. http://www.manbit.com/OA/f28-1.htm Manbit images

  3. Supine position– IVC is compressed and epidural veins are engorged. http://www.manbit.com/OA/f28-1.htm

  4. Abdominal compression narrows the IVC in non-pregnant volunteers. Lee RR et al Spine 2001;26:1172–1178

  5. Hyperventilation (B) decreases lumbar CSF volume. Lee RR et al Spine 2001;26:1172–1178

  6. Hyperventilation (B) decreases lumbar CSF volume. Lee RR et al Spine 2001;26:1172–1178

  7. Hyperventilation alone decreases lumbar CSF volume by 10%, abdominal compression alone decreases it by 28 %. Both together decrease CSF volume by 41%. Lee RR et al Spine 2001;26:1172–1178

  8. Summary • Volume of lumbar thecal sac and lumbar epidural blood is dynamic and respond to: • 1) IVC compression and • 2) hyperventilation– perhaps d/t decrease in intracranial blood volume with shift of CSF into the head.

  9. Summary • IVC compression in pregnancy, with engorgement of epidural veins and decrease in lumbar CSF volume, probably explains 30% decrease in local anesthetic required for spinal anesthesia in pregnancy. • Rare instances may occur, as in this case, of a “tight” lumbar epidural space with nerve compression and ischemia with epidural medication injection.

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