IVC compression and hyperventilation decrease lumbar CSF volume Tom Archer, MD.
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Transcript of IVC compression and hyperventilation decrease lumbar CSF volume Tom Archer, MD.
http://www.manbit.com/OA/f28-1.htm
Supine position– IVC is compressed and epidural veins are engorged.
Lee RR et al Spine 2001;26:1172–1178
Abdominal compression narrows the IVC in non-pregnant volunteers.
Lee RR et al Spine 2001;26:1172–1178
Hyperventilation alone decreases lumbar CSF volume by 10%, abdominal compression alone decreases it by 28 %. Both together decrease CSF volume by 41%.
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.
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.