Thursday, December 14, 2006

debunking the myths, revealing the truth

In my position I’m frequently asked how to perform procedures and I’m especially asked how to perform procedures that aren’t found in the Nursing Practice Standards & Guidelines. One such procedure is the removal of CVCs.

Each time somebody asks me how to remove a CVC I run through the same process:

· Ask the patient to lie on the bed
· Wash your hands using the ‘asceptic hand wash’ procedure
· Remove the dressing
· Cleanse the site as per the Guideline for changing a CVC dressing
· Remove the sutures
· Ask the patient to take a deep breath and hold it
· Gently remove the CVC, checking that the tip is intact
· Place pressure on the site for at least a minute (the patient can breath again now)
· Cover the site with an occlusive dressing
· Dispose of your sharp appropriately
· Place rubbish in correct receptacles
· No, we don’t routinely culture the tip in this institution

Easy, except that every time I got to ‘ask the patient to take a deep breath and hold it’ and explaining the rationale of intrathoracic pressure preventing an air embolus I was plagued by the niggling doubt that this could just be an urban myth. One of those nursing traditions passed along by word of mouth for time immemorial. I had never seen this written down anywhere – I was just going by what I was taught 10 years ago when I was a novice nurse.

Yesterday another person approached me. “I can’t find a protocol – how do you remove a CVC?” I ran through my spiel and decided I couldn’t do this one more time without knowing for sure if the deep breath was really, really necessary. After I’d supervised this CVCs final moments of usefulness I did a search and – hey presto… the deep breath is REALLY, REALLY necessary!

Dong et al (1998) report that “after the removal of CVCs, a short track between the skin and the vein, about 2.5cm, may be formed and stay open for a brief moment. This track, formed with a 14-gauge catheter, can transmit about 200ml of air in a second…”

Yes I typed that correctly! 200ml air in a second. Woah.

Further digging revealed that it is the intrathoracic pressures on inspiration that make this most likely to occur. By having the patient take a deep breath and hold it (Valsalva manoeuvre) the pressures are greater in the intrathoracic space than in the atmosphere, so air is less likely to enter the vein and cause an air embolus. If a patient cannot hold their breath, the safest way to remove the CVC is on expiration (Peter and Saxman, 2003).

I discovered that not only is holding the breath during the removal of the CVC important, it is also helpful if the patient holds their breath between releasing the pressure and applying the occlusive dressing, betadine ointment provides a seal that prevents air entry through the CVC track, and the patient should lie in bed for at least 30 minutes post removal.

All that for one procedure we perform all the time with little thought! I’ll be giving a copy of these articles to everyone who asks me for advice on CVC removal!

This has been a positive experience for me. Not just because I found good information that helped me sort myth from truth but because it’s opened my eyes to all the other simple, frequently performed nursing procedures that are shrouded in myth and tradition. Is there a good reason for all of them too?

I’m on a mission to debunk the myths and reveal the truth in order to provide evidence based practice whenever possible!

Dong et al (1998) “The CVC removal distress syndrome: An unappreciated complication of Central Venous Catheter removal” in American Surgeon 64(4), April, p344

Peter and Saxman (2003) “Preventing Air Embolism When Removing CVCs: An Evidenced-Based Approach to Changing Practice” in MEDSURG Nursing 12(4), August, 223 – 228.