By Peter Laird, MD
Buttonhole cannulation, also known as constant site cannulation , is a technique for accessing dialysis fistulas utilizing dull needles in an established tract. However, there are very few studies available on how well it compares to standard techniques such as the "rope ladder" technique that moves up and down the fistula. A recent study on 70 patients randomized to either rope ladder or buttonhole technique revealed higher complication rates in the buttonhole cohort:
Method: 70 subjects were recruited for this study. Subjects randomised to the buttonhole group had their fistula cannulated by the same staff member for two to four weeks at the same angle and direction with sharp needles. Once the tunnel was developed, blunt needles were used. The control group continued with usual practice (rope ladder rotation technique).
Results: Infection at the cannulation site occurred in four patients in the buttonhole group and one in the rope ladder rotation group (p= 0.11). Haematomas at the cannulation site and site pain experienced during the dialysis session were more often recorded for the buttonhole group (p< 0.05).
Conclusions: This study showed that buttonhole cannulation resulted more infections, haematoma formation, and site pain during dialysis than with the rope ladder rotation group. A further larger scale longitudinal study is recommended.
It is unclear at this time what the advantages of Buttonhole cannulation serves in the incenter population where nurses may not have the necessary time to adequately prepare the buttonhole before cannulation. Removing the scab prior to cannulation takes me several minutes, something that most dialysis technicians and nurses don't have in abundance. The finding of increased pain in this study is also interesting and I wonder if that was in relation to the process of scab removal by the nurses or the actual needle insertion. I greatly appreciate my own gentle hand when it comes to removing my scabs , but in the beginning before I acquired that task, the nurses removing the scab often hurt me more than the actual cannulation.
I would also like to see the same study in self care dialysis patients at home to see how well the incenter results compare to home patients. The issue of increased infections is a serious issue that in my opinion is related to individual preparation techniques more so than the buttonhole constant site technique itself since I have utilized buttonhole cannulation for four years without a single infection to date. Likewise, I know Bill Peckham has also avoided access infections while utilizing constant site cannulation for several years.
In addition to proper preparation and scab removal, I take great care with my fistula after dialysis, changing my band aids soaked with blood when I remove the pressure dressing in two hours, first cleaning around the site with alcohol pads. I only use a sterile needle for each site to pick the scabs as well as sterile disposable plastic tweezers to help clean the scab, never using the same needle or tweezer for both. For my own care, the pain of inserting needles in an established buttonhole is greatly diminished. Adding to that, I have never had a hematoma formation. Buttonhole cannulation in the hands of a self care patient is still a consideration in my opinion based on my own experiences. I believe it simply takes dedication to the fundamental principles of infection control before, during and after dialysis as well as a willing patient to learn self cannulation.
I would hope that this study does not diminish the utilization of the only proven method of decreasing aneurysm formation that thousands of patients worldwide utilize on a daily basis. Further studies are warranted but I would suggest comparing self care buttonhole cannulation at home to that of in-center care where the technicians and nurses perform the cannulation. For myself, I am grateful for this useful technique and that I further have not had any of these complications listed in this study. Longitudinal studies employing self cannulation hopefully will improve upon the results in this study as some smaller studies already show:
According to the nurses, in 26 cases (79%) the use of the buttonhole method was considered a success, especially because of easier cannulation with less pain. The cosmetic effects of the buttonhole method, compared with the rope-ladder method, were considered favourable in 12 patients: less haematomas and less scar tissue were present compared with the rope-ladder technique; none of the patients suffered from negative cosmetic effects (Table 2).
The paradoxical findings between the prior observational studies conducted over several months and years and this randomized and controlled trial needs further explanation before application in the clinical setting. Certainly we do know that adherence to proper buttonhole technique including complete scab removal and infection control is the key to success for many dialysis patients who continue to note the benefits of buttonhole cannulation. Regardless of the disappointing results of this RCT on buttonhole cannulation, it remains in my opinion a useful technique especially in the home hemodialysis population.