Should I have found the signal before I put on the MARC 600?
How do I know if the headframe is tight enough?
Can I put the headframe on too tightly?
How long can I leave the headframe on?
When is the best time to apply the headframe when monitoring intra-operatively?
What is the best position for the patient to be in when applying the headframe?
Why am I having trouble keeping the headframe in place?

Should I have found the signal before I put on the MARC 600?
It is not necessary, but it is preferred to first find a signal and assess the temporal window with a hand held probe.  Once you have initially found the signal, you know where you want the MARC 600 probe(s) positioned, making application of the headframe easier.

How do I know if the headframe is tight enough?
The goal is to prevent movement of the probes.  The MARC 600 is correctly tightened if you can not dislodge the probes by moving the headframe.  The easiest way to do this is by holding the front strap with one hand and the back strap with the other and trying to move the headframe up and down or from side to side.  You want the headframe to be on only as tightly as needed to maintain a good signal.

Can I put the headframe on too tightly?
No.  The MARC 600 is designed with a tension knob.  If it is tightened too much, it will 'click back'.  However, it is important to realize that you want the headframe to be as comfortable as possible.  If the patient is conscious, communicate with them as to their comfort level.  If the patient is unconscious, only tighten the headframe to the extent necessary to maintain a good signal.

How long can I leave the headframe on?
For continuous monitoring, the MARC 600 can be used for up to 6-8 hours for a single monitoring.   It is important to realize that the neoprene pads do not allow the skin to breathe.   Therefore, if  monitoring is required for an extended period of time, it is recommended to completely loosen or remove the headframe for 30-60 minutes every 3 hours of monitoring.

When is the best time to apply the headframe when monitoring intra-operatively?
If at all possible, apply the MARC 600 pre-operatively with the patient still awake.   With the patient awake and cooperative, applying the headframe and finding a signal is much easier.  Also, the patient can communicate any discomfort the headframe may be causing which would indicate incorrect application.

What is the best position for the patient to be in when applying the headframe?
When you first apply the headframe, have the patient sit up if possible.  After ensuring a proper fit, position the patient to the expected intra-operative position after intubation.  Make final signal adjustment here so as to prevent the need to readjust during surgery.

Why am I having trouble keeping the headframe in place?
One of the most important things to remember when applying the headframe is to use the hairtool to lift hair up from underneath the neoprene pads.  If you do not do this, the neoprene pads slide on the hair which will not give you a secure and proper fit.  Also, it is important to wipe the forehead with alcohol to remove any oils which may cause the neoprene pads to slip and to position the front strap just above the bony ridge of the eyebrows.

If you have any questions, comments, or specific problems, please email marc@spencertechnologies.com.