In the ED, we have had some difficulty determining how and when to perform CT scans for those who may have pulmonary embolism, but who are critically ill, requiring multiple drips, and/or have difficult access.
The following email and memo will, we hope, help in this process.
> -----Original Message-----
> From: Keith Conover, M.D.,
FACEP > Sent: Friday, February 21, 2003 2:56 PM
> To: emap@list.pitt.edu
> Cc: Bea Carlin, M.D.
> Subject: CT for PE in critical patients
>
> Had a patient a week or so ago who was critically ill, required
> multiple IV medications, and PE was up there in the differential
> diagnosis. Mulitiple attempts at peripheral IV access were
> unsuccessful, and so I stuck in a triple lumen catheter.
>
> But then, talking with both the CT tech and the radiology resident on
> call, I got some somewhat confusing and changing answers to my
> questions about doing a CT for PE on this woman. But yesterday, I
> spoke with Dilip Shindei, one of the radiology attendings, about an
> unrelated matter, and we got to discussing CT for PE in such settings.
>
> Here is a summary of what I got from him, which seems to make sense
> (more so than what I got that night); I wanted to share this with
> others as the situation is likely to occur again.
>
> 0. Sending critical patients to nuclear medicine for a VQ scan is a
> nonstarter unless you really want to (a) let the patient die, and (b)
> create grief for the radiology resident and nurse.
>
> 1. Standard protocol for infusing dye for a CT for PE is to infuse dye
> rapidly through an 18 ga or larger peripheral IV that is running well.
>
> 2. You simply can't give the dye fast enough through a triple lumen
> catheter, the resistance is too high and as John (CT tech) said, "it
> would explode."
>
> 3. Standard protocol is to NOT give pressure-infuser dye through a
> central line of any sort, due to the danger of the catheter coming
> loose and becoming embolic in the vascular system. However, if a \
> patient really, really doesn't have any peripheral IV access that is
> adequate, there are two options.
>
> a. Place an EJ line with a standard IV catheter, 18 Ga or bigger. OR,
> if can't get an EJ:
>
> b. Go ahead and place an introducer, and give dye through this (not
> standard, but if the study really needs to be done, Dilip suggested
> this was probably better than simply refusing to do it).
>
> c. If the patient requires multiple IV drips, as do many critical
> patients, it may make sense to place a triple lumen for drips, and then
> temporarily place an introducer for the CT (placing in the groin might
> make sense as it's compressible).
>
> Bea, please look this over and see if it makes sense; it would be great
> if we could come up with something before the next time this is needed.
>
> Thanks very much.
>
> --Keith Conover, M.D., FACEP
Dear Keith,
Attached is the memo put out last spring regarding injecting through central catheters. I think the important thing to remember is that if longer or smaller catheters are used you run the risk of not being able to deliver a good bolus resulting in a non-diagnostic study, and the risk of ruining the catheter. None of the catheters are approved for use with a power injector and none ever will be as the manufacturers will not go through the cost fo the process. When these catheters fracture they typically split lengthwise, usually at the skin entry site, due to repeated flexing at that site causing a relative point of weakness. It is unlikely that a fragment will go flying off the end and embolize. there is a risk of extravasation in the subcutaneous tissue. I do not think these catheters should be used for diagnostic studies unless everyone--patent and the MD's taking care of the pt. long-term, and who will have to replace the catheter, are in agreement that this is the right way to proceed.
I hope this answers your questions. If not, you should contact Dr. Bansal who is extremely knowledgeable about catheters.
To: Staff Radiologists
Radiology Residents
Radiology Nurses
CT Technologists
From: Beatrice Carlin, M.D.
Date: May 29, 2002
Re: Intravenous Access Requirements for CT Pulmonary Angiography
There have been several situations over the last year or two when we had difficulty attaining appropriate IV access for CT pulmonary angiograms. Multiple questions have arisen as to which catheters can be used. Recently, Drs. Bansal, Greer and Emch met and have come up with the following recommendations:
1) 18 or 20-gauge angiocath in the antecubital fossa.
2) Central venous catheter using a minimum 7-French cordis/introducer/sheath.
3) Central venous catheter using a minimum 6-French single lumen venous catheter, no longer than 15 cm.
4) 18 or 20-gauge catheter in arm or hand can be utilized. More peripheral access will require a decrease in flow rates, which will affect the quality of the study (see protocol), and has an increased risk of extravasation. These should be avoided if possible.
If you anticipate difficulty with venous access on patients, please clearly communicate our requirements before the patient comes to the CT scanner. This should minimize wasted time and catheter changes.
BC/ns
Copy: Dr. Kenneth Greer
Critical Care Medicine