IVC compression and hyperventilation decrease lumbar CSF volume
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Transcript of IVC compression and hyperventilation decrease lumbar CSF volume
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IVC compression and hyperventilation decrease lumbar CSF volume
Tom Archer, MD
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Lateral position– IVC is not compressed.
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Supine position– IVC is compressed and epidural veins are engorged.
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Lee RR et al Spine 2001;26:1172–1178
Abdominal compression narrows the IVC in non-pregnant volunteers.
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Lee RR et al Spine 2001;26:1172–1178
Hyperventilation (B) decreases lumbar CSF volume.
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Lee RR et al Spine 2001;26:1172–1178
Hyperventilation (B) decreases lumbar CSF volume.
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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%.
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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.
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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.