Are you getting confused between setting the rate of infusion and
setting the maximum pressure? If the rate is set (e.g., 3 to 5 mL per
second) and the machine's psi can not be limited, then the machine
will keep pumping the set rate and the internal pressure inside the
catheter will increase, possible to a level great enough to cause
catheter rupture. Think of it this way:
Force applied to the syringe meets resistance inside the catheter
and/or vein which then causes the pressure in the catheter lumen to
increase.
Force applied would be the pump or the hand on the syringe for manual
injection.
Resistance is caused by all the things you mentioned plus partial
lumen occlusion from clot or drug precipitate, fibrin/thrombus at the
catheter tip, pinch-off syndrome for subclavian sites, etc.
Sounds like they need a pressure injector with the ability to adjust
the maximum pressure. I am not sure which brands those are. Lynn
At 8:29 AM -0400 7/31/06, Lawler, Maureen C. wrote:
We routinely do CT power injection. The question has arisen re MRI power
injector. Our MRI group uses an injector made by MEDRAD. I'm told that it can
reach 350 psi but it is set much lower. The MRI manager states that "MEDRAD
power injectors are internally programmed to deliver 350 psi and
that parameter
cannot be changed even though we routinely inject at much lower
rates. Psi can
vary depending on a variety of factors such as temp, viscosity,length of
catheter,etc" If you set your power injector to deliver a specific
psi would it
actually be capable of going higher just because it has the potential to go to
350 psi? This doesn't make sense to me. Someone out ther able to shed some
light on this? We currently are using power piccs that can handle 300psi
--
Lynn Hadaway, M.Ed., RNC, CRNI
Lynn Hadaway Associates, Inc.
126 Main Street, PO Box 10
Milner, GA 30257
http://www.hadawayassociates.com
office 770-358-7861
