PFO Testing
PFO EVALUATION WITH Power
M-Mode TCD
Power M-Mode (PM)-TCD
machine is used to monitor the anterior circulation of the brain through
the temporal bones or by interrogating the cervical internal carotid
arteries. A right or left upper extremity vein (the antecubital
site is optimal and preferred) is accessed using a 21, 22 or 23 gauge
butterfly infusion set or an IV catheter set. Three syringes are
prepared with 9cc’s of saline and 1 cc of air. Intravenous
injections are made using agitated saline during normal respiration and
with a 10-second 40 mmHg calibrated Valsalva strain and a 10-second
non-calibrated Valsalva strain. Injections may be confirmed by
Doppler monitoring the pulmonary artery or by echocardiography of the
right atrium.*
PROTOCOL
1. Check to ensure
you have the following for the Power M-Mode TCD machine.
- Hand held probe
- Two Ball probes
- Two cables
- Head frame with pads
- Ultrasound gel
2. Check to
ensure you have the following for the intravenous injections.
- One unit of 30 ml
bacteriostatic sodium chloride 0.9% solution (aka saline).
- Four 10 cc syringes
- One needle for drawing
solution into the syringes
- Alcohol swabs (2-3)
- One of the following:
butterfly infusion set or IV catheter with 6-inch extension set
- One 3-way stopcock with
rotating male luer lock adaptor
- Surgical tape and/or 3M
Tegaderm
- Cotton ball
- Gloves
- Valsalva meter
- Tubing
- Pulmonary Artery
Monitoring Device or transthoracic echo monitoring*
*To avoid false
negatives and to time the Valsalva, we monitor the pulmonary artery with
a Doppler probe (2-5 MHz) placed along the left mid-sternum border.
Here we detect the “bubble cloud” that produces a loud noise when it
impacts the right side of the heart.
3. Turn on pm-TCD
machine and enter patient data.
4.
Place head frame on patient, being sure the frame is snug, but not
painful for the patient.
5. Plug
in hand held probe. Find the
best temporal window and mark and/or note location of the window and
attach ball probe to the head frame so that the probe aligns in the area
the windows was found.
6. Plug
cable that is connected to the ball probe into one of the two ports on
the pm-TCD (note: use the top port for the left probe and the
lower port for the right probe).
7.
Annotate/label the vessel on the pm-TCD accordingly.
8.
Optimize signal and then tighten probe to the head frame. Lock the
desired angle of the probe by tightening the lever. Proceed to the
contralateral side and repeat steps # 5, 6 and 7.
Intravenous injection preparation and procedure using butterfly infusion
set:
1. Determine which arm
and vein will be used for venous access (antecubital access is
preferred).
2. Prep
the arm by applying a tourniquet and prep site of venous entry with an
alcohol swab.
3. Open
the butterfly needle package, straighten out the tubing of the set and
attach the three-way stopcock to the end of the tubing.
4.
Attach one of the prepared saline syringes to one of the two available
ports on the stopcock.
(Saline syringe should be on the port that aligns with the tubing).
5.
If gloves are not already on, put gloves on now.
6.
Advise the patient you are ready to proceed with the “stick” just before
you do so.
7.
Insert needle into the vein.
8.
Remove tourniquet.
9. Attach the
second (1 cc of air) syringe to the stopcock.
Intravenous injection preparation and procedure using an IV catheter
1. Determine which arm
and vein will be used for venous access (antecubital access is
preferred).
2. Prep
the arm by applying a tourniquet and prep site of venous entry with an
alcohol swab.
3. Open
6” tubing extension kit
4. Open the
stopcock package and attach stopcock to the tubing.
5. Open
the IV catheter needle.
6.
If gloves are not already on, put gloves on now.
7.
Advise the patient you are ready to proceed with the “stick” just before
you do so.
8.
Insert needle in the vein. Advance canula and remove the
needle by pulling the needle out while advancing the canula.
9.
Remove tourniquet.
10. Remove
needle and dispose of in a Sharps Container.
11. Quickly
attach the 6” tubing extension set to the IV.
12.
With the stopcock lever in the off position connect the saline syringe
and the 1 cc of air syringe to the stopcock.
BUBBLE STUDY
Intravenous
injection at rest and with normal respiration – first injection
- Place CW probe slightly
left to the left of the mid chest to monitor the pulmonary artery to
confirm arrival and timing of micro bubbles after the injection.
- Press “Record” and then
“Save” on the pm-TCD.
- Draw a small amount (~.5
cc) of blood (if possible) from the vein into the syringe with the
saline solution and then proceed to agitate the saline solution to
create micro bubbles for the injection.
- After approximately 10
agitations, rapidly inject the solution into the access site.
Announce when you start the injection and press “Save” on the
pm-TCD.
Note the number of cardiac
cycles/seconds it takes for the bubbles to reach the pulmonary
artery (this information will be used for the timing of the Valsalva
strain(s) during the calibrated and non-calibrated injections.
- Observe the pm-TCD screen
for micro embolic tracks (bubbles) for a period of one minute post
injection.
VALSALVA STRAIN INJECTIONS
The
patient will be instructed when to perform the Valsalva maneuver
based on the number of cardiac
cycles determined from pulmonary artery monitoring or visualization of
the bubble bolus in the right atrium utilizing echocardiography during
the first injection. A brief
explanation of how to perform both the calibrated and non-calibrated
Valsalva maneuver should precede the second and third injections.
For the second injection the patient will be advised to take a
deep breath, bare down and blow on the tubing connected to a
syphgmometer for a count of 10 seconds.
For the non-calibrated Valsalva, advise the patient to hold their
breath while bearing down for a count of 10-seconds.
Intravenous injection – 40 mmHg calibrated
Valsalva strain
- Connect tubing to the syphgmometer.
- Hand tubing to patient and discuss what they will need to do
in order to adequately perform the Valsalva maneuver portion of
the exam.
- Repeat steps #2, 3 and 4 (from the “at rest” injection
description above); advise the patient to begin the
Valsalva maneuver at the appropriate time post iniation of the
injection and to then blow into the tubing.
Press “Save” when the patient starts to bare down and
blows on the tubing.
- After 10-seconds advise the patient to breathe normally and to
remain still and quiet.
Press “Save” on the pm-TCD at this time.
- Observe the pm-TCD screen for micro embolic tracks (bubbles)
for a period of one minute post injection.
Intravenous injection – non-calibrated
Valsalva strain
- Repeat steps #2, 3 and 4 (from the “at rest” injection
description above); advise the patient to begin the
Valsalva maneuver at the appropriate time (i.e. the number of
cardiac cycles/seconds) after the iniation of the injection and
to hold their breath for a count of 10 seconds.
Press “Save” when the patient starts to bare down.
- After 10-seconds advise the patient to breathe normally and to
remain still and quiet.
Press “Save” on the pm-TCD at this time.
-
Observe the pm-TCD
screen for micro embolic tracks (bubbles) for a period of one
minute post injection.
