Critical Care Trauma Centre


Question of the Week: March 24, 2000

An intraventricular drainage unit is positioned at 15 cm above the external auditory canal.  The bedside monitor reveals a pressure of 35 mmHg, however, there is no drainage of CSF from the catheter.  Identify 2 possible reasons for the absence of drainage.
trr the absence of drainage.

1. The catheter may be blocked.

  • To check for catheter patency, lower the drainage chamber below the patient's head.  If the catheter is patent, CSF drainage should occur.
  • Evaluate the ICP waveform.  Ensure that an appropriate scale is selected to ensure good visibiltiy of the waveform.   If the catheter is patent, a crisp waveform should be present; the waveform should demonstrate pressure changes that correspond to the heart rhythm.
  • When evaluating the intracranial pressure, be sure to have the system open to the intraventricular catheter and closed to the drainage unit.  Pressure measurements that are obtained with the stopcock opened to both the patient catheter and drainage unit can produce inaccurate readings (reflecting a blended pressure from the patient catheter AND the drainage bag versus exclusively from the patient catheter alone).
2. The ventricles do not have CSF to drain; the cause for the elevated ICP is cerebral edema.

Medical intervention is needed in either situation.

Brenda Morgan
Clinical Educator,CCTC
March 24, 2000
Return to Main Page