Vascular access cannulation and the end of religion: is it time or our own human variables that determine success?

Sir,

We would like to extend our congratulations to Dr Saran [1] and Dr Brunori [2] for their attempts to determine the optimal timing of the initial cannulation of haemodialysis fistulae according to rigorous scientific data. When we first reported our study on that topic, there were no data and the opinions regarding the length of time delay after surgery before cannulation varied considerably [3]. Yet those opinions had developed into almost a religion that would hold firm to tradition, often resistant to logic, at each different institution. For many months after its publication, we received postcards (since email was not yet popular) from physicians from many different countries distressed that we had challenged their firmly held belief that ‘x (fill in a number from 2–16, depending upon the institution) weeks are necessary for access maturation before cannulation.

Even before it became outdated, out humble work contained too many unredeemable flaws and therefore we are grateful for the work of both Dr Saran and Dr Brunori. Nevertheless, our study was more in agreement with the results of Dr Saran than Dr Brunori and it did not contain the flaws about which Dr Brunori complains of the recent DOPPS study [4]. Our work was not based upon a questionnaire to different centres, but was actually compiled by the nephrologists treating 644 patients who underwent 1137 operations for haemodialysis access. Our study was not just a report of ‘intention to treat’ nor of a routine facility practice, but an actual analysis (to the very day) of the survival of each patient's access compared to the length of cannulation delay (also to the very day) after surgery for that access. Like Dr Saran, we found no survival benefit to any delay in cannulation of either fistulae or grafts. Therefore, we would also agree with Dr Saran that to place an artificial length of time to delay cannulation sentences the patient to the use of a dialysis catheter, which is associated with considerable morbidity and mortality. Yet we would also have to agree with Dr Brunori that early cannulation is not for every access. At the time we performed our study, we were very fortunate to have had available haemodialysis nurses with over a quarter of a century of dialysis experience. They could distinguish between those fistulae that could be could be safely cannulated and those which could not. Of course, the quality of the blood vessel was important as was the acumen of the nurses. The vessels that could not be safely be cannulated at an earlier date were more likely to be vessels of poor quality that were destined to an eventual failure without ever developing or being cannulated. Since many of our patients were referred after the onset of ESRD, those with the longest cannulation delays were therefore often the patients with the slowest fistula maturation, thus skewing our data to a survival advantage for early cannulation (Figures 1 and 2). Nevertheless, we experienced more thrombosis in fistulae that were never cannulated or cannulated at dates greater than 1 month after surgery those that were cannulated early.



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Fig. 1. Survival patterns for early vs late cannulation of fistulae.

 


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Fig. 2. Hazard function for patterns for early vs late cannulation of fistulae.

 
It would appear to us that there is probably no physiologic lower limit to the time in which a fistula can be safely cannulated, but rather the success of cannulation and of access survival depends upon the experience of the nurse and the quality of the blood vessel. We wonder if perhaps it is such differences in those variables that actually determined the contrasting results of Dr Saran's and Dr Brunori's studies rather than, or in addition to, any methodological differences. We would suggest therefore that the timing of access cannulation should probably be individualized and not placed under any strict guidelines of some old-time religion, whether those guidelines are according to the either the opinions or the experience of other centres. Instead access cannulation should be based upon the skill of the nurse and the quality of the blood vessel of the individual patient.

Conflict of interest statement. None declared.

Charles J. Diskin and Thomas J. Stokes

Hypertension, Nephrology, Dialysis and Transplantation Medical Arts Complex Building No. 21 121 N. 20th Street Opelika AL 36801, USA Email: HNDTS12{at}bellsouth.net

References

  1. Saran R, Pisoni RL, Young EW. Timing of first cannulation of arteriovenous fistula: are we waiting too long? Nephrol Dial Transplant 2005; 20: 688–690[Free Full Text]
  2. Brunori G, Ravani P, Mandolfo S, Imbasciati E, Malberti F, Cancarini G. Fistula maturation: doesn't time matter at all? Nephrol Dial Transplant 2005; 20: 684–687[Free Full Text]
  3. Diskin CJ, Stokes TJ, Panus LW. The importance of delay in cannulation after hemodialysis vascular access surgery. Nephron 1996; 74: 245–249[ISI][Medline]
  4. Saran R, Dykstra DM, Pisoni RL et al. Timing of first cannulation and vascular access failure in haemodialysis: an analysis of practice patterns at dialysis facilities in the DOPPS. Nephrol Dial Transplant 2004; 19: 2334–2340[Abstract/Free Full Text]




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