The incidence of thrombocytopenia associated with continuous renal replacement therapy in critically ill patients

Introduction: Thrombocytopenia in the intensive care unit (ICU) is a commonly experienced complication; the pathology is not always easily understood. Continuous renal replacement therapy (CRRT) provides a method to dialyze unstable critically ill patients. We hypothesized that CRRT may precipitate a form of thrombocytopenia. In trials thrombocytopenia occurred at rates as high as 70%. The etiology remains unknown and results in additional diagnostic workup, as well as possible drug therapy. The extent, duration and temporal relation of thrombocytopenia remain to be determined. Objectives: Identify a pattern in platelet fluctuations after the initiation of CRRT and its impact on health care. Methods: A retrospective study was conducted in patients receiving CRRT for >24 h with no pre-existing thrombocytopenia. Patients initiated on CRRT had daily platelet counts monitored, and CRRT attributes and therapeutic interventions were collected. Platelets were assessed for time to nadir, degree of decline and time to return to baseline after discontinuation of CRRT. Results: Forty-nine patients met inclusion criteria. Thirty-seven percent of patients receiving heparinoids were tested for heparin-induced thrombocytopenia (HIT), during CRRT, with 39% of these patients having therapy changed to non-heparinoid agents due to suspected HIT; no HIT antibodies were positive. Eleven patients (22%) receiving anticoagulants, prophylactically or therapeutically had them held for a drop in platelets. There was a mean decline in platelets of 48% with a mean of 4.6 days to the nadir. An average 2.48 days were observed until rebound to >150 x 10(3)/mm(3). Statistical analysis failed to identify any patient attributes that correlated with the probability of thrombocytopenia. Conclusion: CRRT appears to be associated with a drop in platelets within the first 5 days of therapy with an average decline of 48%. However, platelets appear to return to >150 x 10(3)/mm(3) after cessation of CRRT. This fluctuation should be considered in the setting of patients developing thrombocytopenia after initiation of CRRT.