S.P.A.N.C.

This blog is meant to be a place for Sunnybrook Peri-Anesthesia Nurses (Pre-Admission Centre, Same Day Surgery, Post Anesthetic Are Unit and Surgical Short Stay Unit) to stay in communication with each other and to be up-to-date with concerns regarding the Peri-Anesthesia Department. The Purpose of S.P.A.N.C is •To re-implement a unit based council •to identify the unique role of the Peri-anesthesia nurse and to help staff from other areas understand what it is that we do •to create a collegial atmosphere for sharing our professional experiences within the subgroups of Peri-anesthesia •to facilitate open discussion and priority of issues relating to professional practice, education and research that impact on the quality of our work life and thereby affect positive outcomes for our patients and their families.

Wednesday, April 16, 2008

ICP Waveform

Question: On the ICP waveform, what exactly do P1,P2 and P3 waveforms represent?
Answer:
This is what a normal ICP waveform looks like:
The ICP waveform results from transmission of arterial and venous pressure through CSF and parenchyma.
The ICP waves correlate with each cardiac systole and diastole, and therefore mimics an arterial waveform. Each individual wave has three peaks. They are fairly flat with little variation in amplitude when the ICP is low.
There are 3 distinct pressure oscillations:

P1 (percussion wave) and reflects cardiac systole
P2 (tidal wave) reflects cardiac diastole
P3 (dicrotic wave) is located immediately after the dicrotic notch and sloped into the diastolic baseline portion

Analysis of the ICP waveform should include an assessment of the wave amplitude and the configuration of the wave (P1, P2, P3,).
As the ICP rises, so does the amplitude of the three wave components. Persistent elevations usually cause P2 to increase more than the P1 or P3 components, resulting in a rounded appearance of the pressure wave.


See how P2 is higher than the other waves? P1 is supposed to be the highest. Not a good thing – this means that overall the ICP is rising – higher wave, higher pressure.
the elevated P2 means that the intracranial compliance is probably decreasing, as the pressure is rising. Makes sense – pressure rises, things get less compliant, more rigid.
Monroe-Kellie Hypothesis!

Hopes this helps clarify the question, Sandi. Thanks for asking!

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