External Ventricular Drain
OVERVIEW
- ICP monitor than allows CSF drainage
USES
- measurement and treatment of raised ICP
- hydrocephalus of at risk of hydrocephalus following TBI
DESCRIPTION
- gold standard of ICP measurement
- catheter inserted in lateral ventricle at operation via a burr hole
— passes through brain tissue
— transducer is usually remote but catheter tip transducer also available
— zero level is the external auditory meatus
Components
- Sampling port
- Connector for transducer cable
- Safety pin to attach to pillow
- Filter
- Transducer
- Collection tubing
- Collecting chamber
- Level marker connected to chamber
- Measuring column (in centimetres)
- Collecting bag
METHOD OF USE
- Attach flushed transducer to fluid-filled catheter – do not inject
- Set transducer to reference level (EAM or aortic root)
- Attach drainage manometer and set at 10-20 cm H2O at level of EAM
- Monitor ICP continuously with intermittent drainage (hourly) unless clinically indicated, for which drainage may be increased in frequency or continuously
- Septic surveillance of CSF daily ( or as per protocol)
OTHER INFORMATION
Interpretation of Waveforms
- High amplitude of 50-100mmHg sustained for 15 min (‘A waves’) – raised ICP
- Saw tooth with small changes in pressure every 0.5-2 minutes (‘B waves’) – poor intracranial compliance
- Low amplitude oscillations up to 20mmHg for 1 min (‘C waves’) – normal
- Flat ICP trace – compression or kinking of transducer
- Rounded appearance of the waveform – raised ICP
ADVANTAGES
- gold standard
- ventricular pressure considered more reflective of global ICP than subdural, extradural or subarachnoid pressure
- less prone to occlusion
- allows therapeutic withdrawal of CSF
- compliance can be measured
- zero calibration
- cheap
- new devices are antibiotic impregnated to reduce the risk of infection (e.g. Clindamycin/Rifampicin)
DISADVANTAGES/ COMPLICATIONS
- more difficult to insert than a Codman
- infection (ventriculitis)
- haemorrhage
- damage to brain
- accidental venting of CSF
- cannot be inserted in coagulopathy
- no RCT evidence of benefit
Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.
After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.
He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.
His one great achievement is being the father of three amazing children.
On Twitter, he is @precordialthump.
| INTENSIVE | RAGE | Resuscitology | SMACC