Angiotensin-converting-enzyme inhibitors and anaphylactoid reactions to high-flux membrane dialysis In a retrospective study, 9 of 236 haemodialysis patients treated with high-flux polyacrylonitrile 'AN 69' membranes were found to have had anaphylactoid reactions. Treatment with angiotensin-converting-enzyme (ACE) inhibitors had been recently started in all 9 affected patients; only 5 of 227 unaffected patients had been treated with ACE inhibitors, and anaphylactoid reactions disappeared after discontinuation of ACE inhibitors. 