SUMMARY: Thrombocytopenia is a frequent finding in hospitalized patients and is one of the most common reasons for inpatient hematology consultations. Thrombocytopenia is usually defined as a platelet count of less than 150,000 per cubic millimeter, whereas severe thrombocytopenia is considered as platelet counts less than 50,000 per cubic millimeter. It is estimated that the prevalence of thrombocytopenia at admission to ICU is around 20-30% of patients, and a similar number of patients develop thrombocytopenia (from a normal platelet count) while being treated in the ICU.
Approximately 18% of hospitalized patients undergo Central Venous Catheter (CVC) placement, an invasive procedure, during admission. Central Venous Catheter facilitates simultaneous infusion of multiple medications, administration of vasoactive drugs, irritating or hypertonic solutions such as TPN, as well as hemodialysis and hemodynamic monitoring. The routine use of ultrasound guided CVC placement has greatly reduced the risk of bleeding complication. In clinical practice, platelet-transfusion thresholds range from 20,000 to 50,000 per cubic millimeter, as there is lack of good-quality evidence. It is however unclear whether the use of prophylactically transfused platelet concentrates is necessary to prevent CVC-related bleeding complications, in patients with severe thrombocytopenia.
The PACER trial is a multicenter, randomized, controlled, noninferiority study of Prophylactic Platelet Transfusion Prior to Central Venous Catheter Placement in Patients with Thrombocytopenia. This trial was conducted on hematology wards and in ICUs at 10 hospitals in the Netherlands, to evaluate whether the omission of prophylactic platelet transfusion before CVC placement in patients with a platelet count of 10,000 to 50,000 per cubic millimeter increased the risk of catheter-related bleeding. This study included 373 patients (N=373) randomized in a 1:1 ratio to receive either one unit of platelet concentrate (N=188) or no platelet transfusion (N=185) before CVC placement. CVC placement was ultrasound guided, performed by an experienced operator, could be of any diameter, could be either tunneled or nontunneled, and could be placed in the internal jugular vein, subclavian vein, or femoral vein. Randomization was stratified according to the trial center and catheter type (large-bore dialysis catheter or regular catheter). Patient characteristics at the time of CVC placement were well balanced between the two trial groups. Exclusion criteria included therapeutically administered anticoagulant, a history of congenital or acquired coagulation factor deficiency or bleeding risk, or a spontaneously prolonged INR of 1.5 or more.
The Primary outcome was the occurrence of catheter-related bleeding of Grade 2-4 within 24 hours after CVC placement. Bleeding was assessed according to the Common Terminology Criteria for Adverse Events. The occurrence of bleeding and any related treatments were recorded by trained staff members at each site immediately after CVC placement, and at 1 hour and 24 hours thereafter. A key Secondary outcome was major bleeding (Grade 3-4).
Grade 2-4 catheter-related bleeding occurred in 4.8% of patients in the platelet transfusion group and in 11.9% of patients in the no-transfusion group. The absolute risk difference was 7.1%, Relative Risk was 2.45, and noninferiority of withholding platelet transfusion was not shown. The risk of Grade 3 or 4 catheter-related bleeding was lower in the platelet transfusion group compared to the no-transfusion group (2.1% versus 4.9%), with Relative Risks consistent with the Primary outcome.
The bleeding risk in the prespecified exploratory subgroup analysis, were similar to the findings of the Primary analysis. The bleeding risk among the patients being treated on the hematology ward was higher than that among patients in the ICU, and the same was true with the use of tunneled catheters as compared with nontunneled catheters. The differences in CVC-related bleeding risk was attributed to patients in the ICU more often having consumptive thrombocytopenia, whereas patients with hematologic problems in the hematology ward more often have hypoproliferative thrombocytopenia.
It was concluded from this study that in patients with severe thrombocytopenia, withholding prophylactic platelet transfusion before Central Venous Catheter placement in those with a platelet count of 10,000 to 50,000 per cubic millimeter resulted in more catheter-related bleeding events, and prophylactic platelet transfusion was associated with a lower risk of bleeding.
Platelet Transfusion before CVC Placement in Patients with Thrombocytopenia. van Baarle FLF, van de Weerdt EK, van der Velden WJFM, et al. N Engl J Med 2023; 388:1956-1965.
