Use of alkaline rinsing solution to prevent hypersensitivity reactions during hemodialysis: data from a multicentre retrospective analysis

Background: Hypersensitivity reactions (HSRs) can be enhanced by contact ph ase system activation leading to bradykinin (BK) generation. In patients tr eated with angiotensin converting enzyme inhibitors (ACE-I), an impaired ki nin degradation can magnify the phenomenon. We have previously demonstrated that the electronegative charge of the dialysis membrane (e.g, AN69(R)) an d other cofactors including diluted blood buffer power promote BK generatio n, and that kallikrein synthesis on diluted plasma may be inhibited by keep ing the pH value above 7.4, Our in vitro and ex vivo studies have demonstra ted that the use of an alkaline solution to rinse both filter fluid compart ments before their clinical use can inhibit the activation of mediators tha t are likely to be involved in HSRs. Methods: The present study was aimed at gathering data from a multicenter r etrospective analysis of HSRs in 15 Italian centers, with special attention to the precautions chosen to avoid recurrence, and at evaluating whether a rinsing procedure maintaining the pH of the diluted blood above 7.4 may pr event further HSRs. Results: HSRs were reported in 54 patients on dialysis treatment between Ja nuary 1995 and June 1997, 39/54 HSRs occurred when AN69(R) was used. In 44. 4% of cases, HSRs were associated with ACE-I treatments. The HSR prevention modalities varied considerably among the centers. Two thirds of the nephro logists did not change their dialysis prescription but tried to modify the acidic environment of the patient's diluted blood at the first contact with the dialysis device using an alkaline rinsing procedure (BioPrime(R) with alkaline solution). In other cases ACE-I withdrawal or a change of dialysis membrane was adopted. Thirty-six patients who received alkaline rinsing of the filters were monitored for a total of 686 months (median 17.6 months/p atient) to control HSR recurrences. None of the patients enrolled in this s tudy developed new episodes of HSRs. Conclusions: Even if considered with the caution called for by this kind of study, which was retrospective and uncontrolled, our data suggest a protec tive effect of the alkaline rinsing procedure with buffered solutions in th e development of HSRs.