Title:
Intradialytic hemodynamic instability: effects of cool temperature dialysate, citrate and platelet activity

M. Gritters¹ ;M. Gritters² ;M. Gritters³ ;M. Gritters³ ;M. Gritters⁴ ;M. Gritters³ ;M. Gritters² ;M. Gritters¹

1. Nephrology Amsterdam' ne '' ; 3. Biochemistry Amsterdam' ne ''

E-mail address corresponding author:
mareillegritters@hotmail.com

Background:
Intradialytic hypotension (IDH) is a disabling complication and may contribute to an increased morbidity and mortality. The application of `cold` dialysate (35 C) substantially reduces IDH. Relevant literature: (1)In rats, shear stress induced platelet aggregation and subsequent serotonin release induces hypotension in roller pump perfused extracorporeal circulations.(ref 1)(2)A reduction in platelet activity at lower core temperatures was suggested from studies in cardiopulmonary bypass surgery. (3)Citrate reduces platelet activation during HD to a considerable extent. (ref 2) Therefore, in the present study, blood pressure (BP) and platelet activation were measured during three modes of HD: (1)standard, [HD dal, 37]:dalteparin, dialysate T 37, (2)cool T, [HD dal, 35]:dalteparin, dialysate T 35 3) citrate, [HD cit, 37]: citrate, dialysate T 37

Methods:
Ten stable chronic HD patients were studied during [HD dal, 37], [HD dal, 35] and [HD cit, 37] in a randomized, cross-over fashion. BP was measured (Dinamap) every 15 minutes during three consecutive HD sessions on each modality. Hypotensive episodes were scored according to selected criteria.(ref 3) Blood samples were taken at the third HD session from the efferent line at t0, t5, t30, t60 and t150. Platelet activation, degranulation, aggregation and serotonin release were studied by measuring platelet CD62p expression, platelet factor 4 (PF4), platelet aggregates (number/ 250 platelets), platelet serotonin content (platelet rich plasma) and plasma serotonin (platelet poor plasma), respectively.

Results:
Mean systolic and diastolic BP were significantly higher during [HD dal, 35] than during [HD dal, 37] (p < 0.01). Moreover, a tendency to less hypotensive episodes during [HD dal, 35] was seen. Neither a higher mean BP, nor less hemodynamic instability was found during [HD cit, 37]. As expected, citrate [HD cit, 37] markedly reduced platelet activation and degranulation. Interestingly, platelet activation and degranulation during [HD dal, 35] were not lower, but on some occasions even higher than during [HD dal, 37]. Concerning platelet aggregate formation and serotonin release, no differences were seen between the three modalities.

Conclusion:
1. Hemodynamic stability is optimal during cool dialysate temperature dialysis, whereas citrate shows no beneficial effects 2. Platelet activation (CD62) and degranulation (PF4) are markedly reduced during citrate HD and are, on the contrary, more pronounced during cool dialysate temperature 3. No differences in serotonin release are seen 4. The beneficial effects of cool dialysate temperature can not be explained by a reduction in platelet activation and serotonin release 5. Whereas serotonin plays a key role in hypotension during extracorporeal circulation in rats, this could not be demonstrated in humans

Subject:
Hemodialysis

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