RESEARCH REPORTS Critical Care TlffiOMBOCYTOPENIA IN INTENSIVE CARE PATIENTS: A COMPREHENSIVE ANALYSIS OF RISKFACTORS IN 314 PATIENTS Mark F Bonfiglio, Sheldon MTraeger, Karen L Kier, Bradley R Martin, Darrell T Hulisz,and Stephen R Verbeck OB,JECI1VE: To define the incidence and severity of thrombocytopenia in a mixedmedical-surgical population of critically ill patients and to examinefactors that may berelated to the development of thrombocytopenia. DESIGN: Retrospective chartreviewof314 critically ill patients requiring at least3 days of critical care. SETfING: A 17-bed combined medical-surgical intensive care unit (ICU)in a 560-bed tertiary care community hospital. PATIENTS: Medical and surgical patients admitted to the ICU. INfERVENTIONS: All medical records overthe duration of the ICU stay were reviewed, All scheduled medications, including dosage and start/stop dates,were recorded. All platelet counts, placement of pulmonary arterycatheters, liver function test results, and admission serumcreatinine concentrations were collected. MEASUREMENT ANDMAINRESULTS: Thrombocytopenia (platelet count less than 200 x IQ9!L) was observed frequently, but rarelyreacheda severestage(7 patients). No singlediagnostic category was significantly associated with thrombocytopenia alone, although the combination of sepsis syndrome/septic shockand respiratory failure was strongly correlated (p < 0.00(1) with thrombocytopenia. Liver function abnormalities were correlated strongly with thrombocyto- penia,and the majority of patients (5 of 7) with severethrombo- cytopenia (lessthan 20 x IQ9!L) werefoundto have concurrent severealterations in liver function test results. Pulmonary artery catheter placement and heparin exposure were associated strongly with thrombocytopenia (p < 0.00(1). Drug therapies that were correlated with thrombocytopenia included heparin and vancomycin Mark F BonfiglioPharmD, Phannacotherapy Specialist. CriticalCare,SummaHealth System, Akron,OH; at the time of the study, he was also an AssistantClinical Professor,Ohio NorthernUniversity,Ada, OH Sheldon M Traeger MD FCCM, Director of Intensive Care Services, Department of InternalMedicine,Summa Health System, Akron, OH, and AssociatePro- fessorof InternalMedicine,NortheastOhioUniversities Collegeof Medicine, Rootstown,OH Karen L K1erMS, Associate Professor of Clinical Pharmacy, Ohio Northern Uni- versity Bradley R Martin MD, AssociateDirectorof IntensiveCareServices,Department of Internal Medicine,Summa Health System, Akron, OH, and Assistant Pro- fessor of InternalMedicine,NortheastOhio UniversitiesCollegeof Medicine Darrell T HuUszPhannD,AssistantProfessor, Department of FamilyMedicine, Case WesternReserveUniversity, Cleveland, OH, and AssociateClinicalProfessor. Ohio Northern University;at the time of this study, he was a Clinical Coordi- nator, Departmentof PharmacyServices, AkronCity Hospital,Akron,OH Stephen R Verbeck MD,lnternal Medicine,Divisionof Gastroenterology, Summa Health System,and AssistantProfessorof Internal Medicine,NortheastOhio UniversitiesCollegeof Medicine Reprints: Mark F Bonfiglio PharmD, PharmacotherapySpecialist, Critical Care, Departmentof PharmacyServices,SummaHealthSystem,Akron,OH 44309, FAX2161375-7622 This study was supported by a grant from Merck. (p < 0.05). Hemodynamic instability was correlated strongly with the presence and severity of thrombocytopenia. In a stepwise linear regression model, the admission platelet count accounted for the largest proportion of the variance (43%), followed by hemodynamic instability (8%)and the requirement for inotropic agents (2%). CONCLUSIONS: Thrombocytopenia in the critically ill occurs frequently, rarely reaches severely depressed concentrations, and primarily represents a manifestation of disease processes initiated priorto admission. Hemodynamic instability and/orheparin exposure appearto bethe strongest identifiable correlates with thrombocytopenia. Although these maycause infrequent isolated cases, other specific drugcausesof thrombocytopenia are not responsible for the majority of casesof thrombocytopenia in the critically ill. Ann Phannacother 1995;29:835-42. lHROMBOCYTOPENlA in the critically ill population is com- monlyassociated with a longer hospital stay and increased mortality.' A variety of medical conditions that often re- quire intensive care unit (ICU) hospitalizations are known to be associated with thrombocytopenia, including hyper- splenism, thermal injury, adult respiratory distress syn- drome (ARDS), disseminated intravascular coagulation (DIe), liver disease, certain nutritionaldeficiencies, and sepsissyndrome/septic shock.' In addition, some common- ly used ICU monitoring procedures, such as pulmonary arterycatheterization, have been correlated with the devel- opmentof thrombocytopenia.v' Although drug-induced thrombocytopeniais reported infrequently in the general population," there may be a high- er potential for this to occur in critically ill patients, The large number of medications received by an individual patient results in a broad exposure and potential for drug interactions,'which may contribute to a higher frequency of hematologic effects. In addition, major organ dysfunc- tion may alter the normalelimination kineticsof medica- tions, resulting in concentration-related toxicities.' It has been difficult to identifythe relative contribution of independent factors in the development of thrombocy- topenia in broad critical care populations. This study at- temptsto define the frequency and factors responsible for thrombocytopenia in a mixed medical-surgical critically ill population, The objective was to identifyindividual sub- groupspredisposed to the development of thrombocytope- The Annalsof Pharmacotherapy • 1995 September, Volume 29 • 835·