1. System Overview
  2. Obtain Equipment
  3. Open Unit
  4. Prepare Panel
  5. Prime the Unit
  1. Position the Transducer
  2. Set Drainage Level
  3. Zero Transducer
  4. Connect to Patient


Nurses may prime and connect the intraventricular drainage system in CCTC.  All CSF draining catheters (intraventricular; lumbar ICP) must be connected to the Codmanä External Drainage System for safety.

Reason for Monitoring Lumbar ICP

During thoracic aneurysm repair, blood flow to the thoracic and lumbar spines can become compromised during aortic crossclamping. Ischemia to the cord can lead to cord edema, which can cause the lumbar ICP to rise and impede normal flow of CSF within the spinal canal. If the lumbar ICP increases, drainage of lumbar CSF can reduce the risk of cord damage by reducing the pressure. Normal ICP is < 10 mmHg.

Thoracic or lumbar spinal cord damage causes paraplegia. In addition to ICP monitoring and prn drainage, hourly spinal cord assessment for changes in sensation and/or movement is essential. Document in the spinal section of CCTC flowsheet.

The CodmanExternal Drainage System is a closed system for drainage and pressure monitoring of intracranial catheters. An antimicrobial filter located at the top of the graduated collecting chamber and bottom of the drainage collecting bag prevents backward flow of fluid or bacteria. 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 panel has a "0" reference point that must be positioned at the level of the catheter (in CCTC, the lumbar spine is approximated as being level with the iliac crest in a patient lying supine). The drip chamber buretrol is then adjusted up or down until it is at a level equal to the maximum desired intracranial pressure.  Lumbar CSF pressure is normally equal to intracranial ICP. 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.

The Codmandrainage unit uses 3-way stopcocks. . The stopcock can be opened in 3 directions simultaneously. The direction the prong points represents the "off" position. This system may be utilized for continuous pressure monitoring alone, continuous drainage alone or continuous drainage and pressure monitoring. 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.

The Unit

The panel (left) must be positioned in an upright position, with the "0" reference point on the panel level with the patient's catheter. In CCTC, we use the iliac crest as the lumbar ICP reference. 

The drip chamber is then adjusted to a level equal to the maximum desired lumbar CSF pressure (in cmH20 or mmHg).

The mounting panel stopcock is at the "0" level.

icp buretrol

Buretrol Close-up (left)

  • Roller to adjust drip chamber up and down
  • Drainage tubing
  • Filter
  • Level of drainage (drip point)
  • Fluid collection
  • Arrow for alignment of drip chamber with level of desired pressure in cm H20 is the column to the right (red on panel) and mmHg is the column to the left (black on panel).

stopcock picture

3-Way Stopcock (left)

The prong is pointing to pathways that are closed. This picture on the left displays the stopcock "open" to the patient, the drainage system and pressure monitoring.






Obtain Equipment

1.  Codman External Drainage System
2.  500 ml bag of 0.9% NaCl
3.  1 single transducer kit for arterial line
4.  IV pole
5.  Laser level (in CN cupboard)
or lasel level pen at CN desk.

6.Obtain PPE



Open Unit

Open package with Codman External Drainage Unit, being careful not to drop extension pieces out; extension pieces are loosely connected in package.


The connections are loosely attached to facilitate gas sterilization.


Prepare Panel

  1. Replace the vented white cap located on the mounting panel stopcock (at the "0" reference mark) with a dead-end luer lock cap (provided in kit).
  2. Turn the mounting panel stopcock with the flat side (off) toward the cap.

    Always leave the mounting panel stopcock in this position; if you wish to turn the stopcock open or closed to drainage, use the stopcock closest to the lumbar catheter.


This opens the system between the drainage tubing and drip chamber in preparation for flushing. 

By only adjusting one stopcock during use, the risk of accidental closure/opening of the system is reduced.


Prime the Unit

  1. Perform hand hygiene.
  2. Hang a bag of normal saline. 
  3. Using the normal saline, prime the pressure tubing as per setting up a hemodynamic system.
  4. Remove the extension piece at the distal end of the pressure tubing. 
  5. Remove the cap from the stopcock located at the end of the drainage tubing (this will be referred to as the "patient stopcock").
  6. Connect the distal end of the pressure tubing to the stopcock where the cap has been removed.  Be careful not to contaminate the connections.
  7. Turn the patient stopcock with flat side (off) towards the patient connection end of the circuit.
  8. Pull the flush device until the all air bubbles have been eliminated and fluid drips readily into the drip chamber.
  9. Turn the patient stopcock with the flat side (off) towards the drip chamber.
  10. Remove the unvented cap at the tip of the drainage tubing, being careful not to contaminate the end.
  11. Flush the circuit until all air has been expelled between the patient stopcock and end of drainage tubing. 
  12. Replace the unvented cap at the end of tubing and tighten. 
  13. Turn the patient stopcock to a 45 degree angle from the tip.


In accordance with the MoHLTC 4 moments of hand hygiene and LHSC infection control policies in an effort to reduce risk of transmission of microorganisms and secretions.

Heparin is not used due to risk of intracranial bleeding.  The system is not pressurized to avoid introducing fluid into the spinal fluid.

Once primed, the pressure tubing will be used to measure lumbar ICP.

The pressure tubing is connected to the stopcock closest to the patient to minimize the length of tubing that the pressure wave must travel. CSF drainage often contains blood and debris; adding the flush system at the patient stopcock allows the circuit to be flushed between the patient stopcock and the drip chamber as required to maintain patency and pressure transmission.


The entire circuit must be primed to facilitate drainage. Be careful to maintain aseptic technique; CSF contains glucose which promotes bacterial growth that can cause meningitis.

Tightening maintains sterility and prevents loss of priming fluid. A 45 degree angle on any stopcock ensures that it is "off" in all directions.


Position the Transducer

  1. Securely tape the transducer to the side of the mounting panel with the air fluid interface (the air evacuation port of the stopcock above the transducer) at the same horizontal position as the "0" reference on the mounting panel.
  2. Connect the transducer cable to the bedside monitor.
  3. Using the laser level, ensure that the "0" reference on the panel is level with the iliac crest.


Both the transducer and the mounting panel stopcock must be level with the lumbar space.

By securing both stopcocks at the same point, the transducer and mounting panel can be simultaneously referenced by adjustment of the mounting panel.


Set the Drainage Level

  1. Obtain an order for the level of the drainage chamber. 
  2. Loosen the buretrol adjustment screw and move the drip chamber until the small arrow is aligned with the desired height.  
  3. Tighten the screw to secure the buretrol position.

NOTE: A typical order is "10 cmH20" above the lumbar space. The right hand column of numbers (with red writing) is in cmH20.  The column to the left is in mmHg (orders for drip chamber placement are usually in cmH20 - check with the physician to confirm the correct level). 

In the example of "10 cmH20", the system is correctly placed if the "0" reference point is level with the patient's iliac crest and the small arrow is aligned at the 10 cmH20 marking.  


If the "0" reference is level with the patient's catheter, 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.  Normal lumbar CSF pressure is < 10 mmHg.

Weaning of the drainage system can be done by raising the level of the drainage unit. Drainage will only occur if the pressure exceeds this higher pressure. Intermittent drainage may also be initiated, where pressure is monitored and drainage only opened if the pressure exceeds a specific level.

Both the patient and panel stopcocks must be open between the patient's catheter and the drainage chamber for drainage to occur. When the system is left continuously open to drain and the drainage chamber is positioned to initiate drainage at a set level, pressure is maintained at a more consistent level. 

Note that the bedside monitor measures pressure in mmHg; 10 cmH20 is the same as 7.4 mmHg.  Thus, a properly positioned unit with the drip chamber at 10 cmH20 will drain if:

  • the stopcocks are open between the patient's catheter and the drip chamber
  • the pressure in the lumbar space exceeds 10 cmH20 (or exceeds 7.4 mmHg on the bedside monitor).
  • the catheter/circuit is patent (e.g. free of clot or debris)
  • there is fluid in the lumbar space (if the pressure is high due to cord edema, there may not be any CSF to drain)

If the circuit fails to drain despite a pressure on the monitor that is > than the level of the drainage chamber, patency can be assessed by lowering the entire drainage unit to below the head.

Notify Vascular sugery if the unit fails to drain in the presence of an elevated pressure despite troubleshooting efforts.


Zero the Transducer

  1. Select "ICP" as the monitor label.
  2. Open the transducer stopcock to air (taped to the mounting panel).
  3. Press "zero" on the bedside monitor.
  4. If the ICP is > 20, the scale will need to be increased.  


Zeroing and leveling the transducer ensures the bedside monitors reads the ICP accurately.

The ICP default scale is 20.


Connect to Patient

  1. Perfom hand hygiene and don non-sterile gloves.
  2. Connect the lumbar cathter to the drainage unit.


In accordance with the MoHLTC 4 moments of hand hygiene and LHSC infection control policies in an effort to reduce risk of transmission of microorganisms and secretions.

Developed by:
Brenda Morgan
Initial Procedure: November 1988

Last Update:March 29, 2010.

LHSCHealth Professionals

Last Updated December 5, 2014 | © 2007, LHSC, London Ontario Canada