First, let me say that it is important to fully understand the ventriculostomy set-up you are working with and what impact your interventions have on the drainage amount and subsequent ICP changes.
If CSF is drained too rapidly, pressure and tissue shifting may occur resulting in increased edema, tears on small veins and increased bleeding. Maintaining controlled, yet effective drainage, helps maintain the intracranial anatomic relationships.
If CSF is not permitted to drain for extended periods of time, this may result in increased edema and ICP. A gradual decrease in CSF drainage may suggest reduced edema, while an abrupt decrease may indicate a dislodged or occluded catheter. If you clamp the catheter for a prolonged transport, you might cause an occlusion - difficult to determine how long this would take to happen.
Ventriculostomies are usually clamped for brief periods of time to perform activities that potentially can increase ICP and result in excessive CSF drainage, such as suctioning, re-positioning patient or trips to CT scan and being placed in a supine position. Ventriculostomies operate on gravity - to control the drainage flow, the system (transducer and CSF drainage system reference point) must be level to the tragius. If you do not level the system correctly, you potentially will either have CSF drainage reduced or rapidly flowing out.
Two things to consider before thinking of clamping:
1. How critical is your patient - some patients might not have a large margin to play with and require continual drainage, while others have minimal drainage and are doing well.
2. Transport time - prolonged clamping might occlude catheter.
Also, you should be familiar with the different types of ventriculostomies and drainage systems so you can properly set up using a Propac or other monitoring equipment. Some have microsensors, others do not.
Have submitted this topic as a lecture for AMTC - perhaps will get to talk more about it - hope this helped you in some way - fly safe.
Lynn Kemp, RN, BSN, CCRN, CFRN, CEN, NREMT-P
Trauma Program Manager
St. Barnabas Hospital
Bronx, New York