Lumbar Drain (Codman External Drainage system)

• 0.15% risk of spinal cord injury with unruptured AAA

• artery of Adamkiewicz arises from above L3 in most people

  • clamping at or above this level increases risk of spinal cord injury​

• ICP in the lumbar space may become higher if there is a flow obstruction due to cord edema (no CSF may drain)

• Normal lumbar CSF pressure is < 10 mmHg

• preservative free saline is used to flush the system

• the "0" reference point is at the level of the patient's catheter (some places use iliac crest)

  • a drainage level of 10 cmH20 above the lumbar space provides automatic "venting" of CSF if the pressure rises above 10 cmH20

  • if the "0" reference and the drip chamber are both positioned level with the catheter, drainage would occur the moment the lumbar CSF pressure > 0.  This could lead to over drainage and potential for cerebral bleeding

• the blue column and green column are different units

• the unit must hang upright at all times. If it is placed flat in a horizontal position, the filter at the top of the drip chamber can become wet, preventing the system from draining properly

• The drip chamber buretrol is then adjusted up or down until it is at a level equal to the maximum desired intracranial pressure

• If the system is open to drainage, CSF will drain as soon as the pressure in the lumbar space exceeds the pressure determined by the height of the drip chamber above the catheter

• ​To obtain an accurate pressure measurement, the stopcock should be turned "off" to drainage and "open" to the patient catheter and pressure monitoring system  

  • If pressure is measured when the drainage unit is open in all 3 directions, the pressure measured will be a reflection of the patient and drainage bag

• Excessive fluid removal or reduction in the intracranial pressure can increase the risk for intracranial bleeding

• Turn stopcock off temporarily when repositioning patient to prevent over-drainage. Recheck drain level and return to drainage position once patient's position has been stabilized

• A minimum ICP should be identified to prevent intracranial dehydration which may increase risk for bleeding

• Turn drain off to drainage if output exceeds ordered maximum (usually 10-20 ml/hr).If pressure is low, an order to raise the drain level pr switch to intermittent drainage may be indicated.

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Cord Perfusion Pressure

• MAP - lumbar ICP