1. How I do infusion test. Dr Zofia H. Czosnyka
University of Cambridge, UK
Infusion test: procedure to identify model of CSF compensatory reserve introduced in 1973 by Anthony Marmarou. Essential parameters: Resistance to CSF outflow and compliance of CSF space
ICP
Infusion 1 ml/min
TIME ~30 minutes

2. What we need? Hardware Pressure transducer, tubing, needles
Essential: sterile preparation of transducer and tubings

4. If pulse waveform of ICP is small or noisy,
ABP (Finapress) pulse is helpful.
See spectra,
check peaks associated to heart rate in ABP and ICP

5. ICP HR
AMP
RAP
Real time observation of trends of mean ICP, heart rate, pulse amplitude of ICP and RAP index during the study. Always mark start, end of infusion!

6. ICP
AMP
RESP RR
Slow SD
AMP/RESP
‘Waveforms trends’ – pulse amplitude, respiratory amplitude, respiratory rate (RR), power of SLOW ICP waves

7. ICP
AMP
AMP
ICP
Pulse amplitude/pressure line. Slope is usually positive.
Higher slope (according to Professor Anile, J Neurosurg Jul;113(1):64-73)
=> indicates better chance to respond to shunting: Slope above 0.15.

8. Lower breakpoint of AMP-P line- is it ‘optimal pressure?
ICP
AMP
AMP
ICP

9. ICP
AMP
After study is finished: Analysis of the model of Professor Marmarou:
First: mark baseline, transition and end-plateau periods.
Introduce infusion rate and press ‘calculate’

10. Click ‘more’ and you see:
Interpolation of ICP trend
with modelling
curve
Exponential pressure-volume curve
Amplitude –pressure line
Trend of amplitude in time
I use this screen to assess visually quality of identification of the model

11. If everything looks OK,
you can display report
and
copy/ paste it to WORD

12. Test ‘unfinished’- if pressure increases to 40 mm Hg without reaching plateau
ICP HR
AMP
RAP

13. ‘Dynamic’ analysis may predict plateau
R= 77 mmHg/(ml/min)
‘Dynamic’ analysis may predict plateau

14. ICP
AMP
One needle test: we usually observe rapid increase of ICP just after start of infusion, not reflected by increase in AMP. Tick in ‘Parameters’ -> ‘one needle’ option and problem of higher resistance of the needle may be solved automatically...

15. Step-rise of ICP is accounted for and eliminated from its potential influence on CSF compensatory parameters

16. Now in situ: VP stratas @ 0.5 in line with Ommaya.
ICP HR
AMP
RAP
Hydrocephalus post SAH in Shunted - revisions. Last revision (09/10/12).
Now in situ: VP 0.5 in line with Ommaya.
Headaches, tenderness over the tubing and the valve.

17. ICM+ has a database of shunt parameters from Cambridge Shunt Lab
ICM+ has a database of shunt parameters from Cambridge Shunt Lab. Every shunt at given performance level has a limit above which pressure should not rise during infusion of given rate
( 1ml/min or 1.5 ml/min). If pressure exceeds this limit (blue horizontal line), it indicates that shunt underdrains.
Shunt underdrains

18. If blue line is not crossed, shunt probably works properly

19. Final report sent to consultant neurosurgeon
John John HospitalNo XXXXXXXX 28/10/2013
DateOfBirth XXXXXXXX Sex Male
DateOfIctus 28/10/2013 DateOfAdmission
SAH, delayed hydrocephalus, low OP in LP. Increase in ventricle size in CT. Low GCS (9). LP
study on A5
ICP baseline [mmHg] 4.39 ICP plateau [mmHg] 25.52
AMP baseline [mmHg] 0.94 AMP plateau [mmHg] 2.79
Rcsf [mmHg*min/ml] Elastance [1/ml] 0.14
PVI [ml] Pss [mmHg] 0.00
CSF production rate [ml/min] 0.27 Volume infused [ml] 29.48
Infusion duration [min] Normalised Error [%] 1.351
Final report sent to consultant neurosurgeon
Normal baseline pressure with increased resistance to CSF outflow. Strong regular vasogenic waves recorded during the study. Overall: Disturbed CSF dynamics.
Dr. Czosnyka
CSF sample sent to bacteriology Y
 CSF withdrawn at end of study as therapeutic test: N
Should you require any assistance with these results, Professor Pickard, Dr’s Zofia or Marek Czosnyka will be happy to assist.  Contact details are: Dr Zofia Czosnyka – ; Dr Marek Czosnyka – 3932; Professor Pickard – 6858 (Maria, secretary)

20. Happy infusion studies!