Moderator's View: Buttonhole cannulation of arteriovenous fistulae: great caution is warranted.

Potential advantages of buttonhole (BH) cannulation over the standard rope-ladder technique have been claimed on the basis of small sized, potentially biased observational studies with a relatively short follow-up. On the contrary, randomized controlled trials (RCTs) show inconclusive or conflicting results. The uncertain benefit must thus be weighed against a definite increase in the infectious risk with the BH technique, which may not be completely abolished by preventative strategies. Awaiting the results of long-term studies (>2-3 years follow-up), the widespread use of the BH technique is not warranted, especially in busy in-centre haemodialysis (HD) settings with many rotating nurses. In our experience, the BH technique has been implemented safely in a self-care HD unit, presumably because of the limited number of cannulators and, in the case of self-cannulating patients, direct supervision by a small team of nurses. Units (and patients) willing to use the BH technique should be aware that BH is an extremely demanding technique and requires constant and strict adherence to the protocol. Regular monitoring of infection rates is recommended. Additional RCTs are clearly warranted, together with large-sized observational studies with multivariable adjustment.