Hello, my son has a CVC for PN and we use an ethanol lock 3x's per week. I have used a 3mL syringe to aspirate the lock for the past couple of years bc I could not get blood return with a larger syringe. His Dr at the time was the one to suggest the smaller syringe. We have recently changed infusion providers as well as ordering physician for his PN and are now being told it isn't safe to use anything smaller than a 10mL syringe bc of risk of catheter collapse. Bard's procedure manual states that syringes smaller than 10mL create more pressure and should not be used for INFUSION but that a LARGER syringe for aspiration creates MORE pressure. Am I reading that correctly? Wouldn't it actually then be safer to aspirate with the smaller syringe? There seem to be so many inconsistencies and I just want to make sure I'm doing what is safest for his catheter. I can't seem to find any definitive recommendations besides from Bard and theirs isn't even clear. Thanks!
I too use a smaller syringe on central line draws as it creates less pressure within the catheter and the catheter is less likely to collapse with aspiration as it will with a larger syringe. Larger syringes have "too much pulling" power if you will.
Though it is true, that one should not be ascertaining the patency of a line with anything less than a 10 cc syringe barrell, after you assess that the line is open, and there is no resistance to your flush/infusion, then use the appropriate syringe to give the medication.
So, flushing a line should be with a 10 cc syringe barrell or larger. Aspirating from a central line should be done with syringes smaller than 10 cc.
You go Nurse Mom.
I am still a bit baffled as to why Bard would suggest using a larger syringe with aspiration difficulties, even in the context of a potentially occluded CVC. I realize that some doctors are educated on the specifics of syringe size safety, but unfortunately not all are. This is frustrating. I felt (although likely unintentionally) as if my concern for my son's safety was being questioned by requesting that his doctors order smaller syringes specifically for this purpose. They were very adamant that it would place the catheter at greater risk and suggested that we either stop using the ethanol locks altogether or flush them through. Good to know neither of those is necessary.
I saw somewhere reference to a publication that explains the physics behind why size safety is opposite for infusion and aspiration. Anybody know where I could find that?
A Review of the Physical Principles of Fluid Administration
www.journals.elsevierhealth.com/periodicals/jvad/article/.../abstract
Journal of Vascular Access Devices, Volume 4, Issue 2, Pages 7-11, 1999,
Authors:Denise Macklin, BSN, RNC, CRNI.
Infusion therapy has grown into a Specialty requiring exacting knowledge and has moved from the periphery of medical care to its very core. In order to achieve an optimal outcome while caring for a patient receiving
intravenous therapy, a nurse needs to have a basic understanding of some of the physical principles that affect flow rates. Troubleshooting problems with intravenous systems can be a frustrating and time consuming
aspect of a nurse’s practice. This article will review some basic principles that will enhance any nurse’s ability to assess, develop an individualized plan of and intervene when problems arise.
When my 13 yr old daughter had a central line I walked the hospital floors distributing this article. Nurses saw improved ASPIRATION success by using a smaller syringe (diameter). Hope this easy to understand article helps.
The 10ml syringe is used for flushing because of its diameter and the pressure associated with it. If you are familiar with the BD PosiFlush saline syringe, they all have a 10ml syringe diameter with various fill volumes.
Do you have to create an account to view this? It keeps saying Forbidden when I try to open it. I seriously scoured the internet lastnight for this exact article because I found reference to it in another thread on here. But the only place I found it was asking $27.95 for the download. My son's Dr did agree to let me try a 5mL syringe but was still pretty insistent that based on their research, it could break the catheter.
In discussions with many biomedical engineers that design all types of catheters, I have always been told that smaller syringes create more pressure on ASPIRATION. During injection smaller syringes create MORE pressure. So when injecting, a 10 mL syringe should always be used to flush, aspirate to check for a blood return, and assess catheter patency be checking for resistance. Following that step, when patency has been established, the syringe size is NOT a factor because you have established that the catheter is open and patent. Catheter rupture could happen when excessive force is applied when you also meet some type of resistance. Once patency has been established, the chance of catheter damage are greatly reduced. So you can use a syringe size that is appropirate for the medication being given.
On aspiration, a larger syringe will provide greater surface area so that you can pull harder and faster. This could cause the catheter walls to collapse and occlude the backflow of blood. BUT this does not generally lead to permanent catheter damage. Once the force on the syringe plunger has been released, the catheter returns to its normal size and shape. A smaller syringe will allow for more success with obtaining a blood sample because you do not have as much surface area of the syringe and can not pull as hard and fast.
Lynn
Lynn Hadaway, M.Ed., RN, NPD-BC, CRNI
Lynn Hadaway Associates, Inc.
PO Box 10
Milner, GA 30257
Website http://www.hadawayassociates.com
Office Phone 770-358-7861
Thank you for your reply Lynn! The problem that we are having is that for some reason we cannot aspirate anything from the catheter with a 10mL syringe following the ethanol lock dwell time. This is only a problem after the ethanol locks and blood return is otherwise good with a 10mL syringe. So the safety of using the smaller syringe at all is what is in question since we know (although we don't know why) the larger syringe will not withdraw the ethanol lock.
This is part of what is confusing me...Pg 42 from the Bard Nursing Procedure Manual under their Troubleshooting Aspiration Difficulties section says, "Attempt to aspirate with a 20cc syringe (creates greater vacuum)". Sounds consistent with what Lynn is saying but it confuses me because it seems like a greater vacuum would create more intraluminal pressure, meaning a smaller syringe would create less.
I agree that the Bard language is confusing and wrong as a larger syringe would cause more difficulty on aspiration.
The ethanol lock does not contain any type of anticoagulant usually. So there could be thrombus or clot accummulating at or near the catheter tip. This is a normal process around a catheter which the body is perceiving to be a foreign object. The more you try to aspirate, the more the fibrin/thrombus is pulled over the catheter lumen. I understand the need for the ethanol lock to reduce the risk of bloodstream infection but it does not address the issue of an anticoagulant to prevent this problem of fibrin/thrombus. Lynn
Lynn Hadaway, M.Ed., RN, NPD-BC, CRNI
Lynn Hadaway Associates, Inc.
PO Box 10
Milner, GA 30257
Website http://www.hadawayassociates.com
Office Phone 770-358-7861