Despite the low reported risk of major bleeding complications from central venous catheter (CVC) placement in severely thrombocytopenic patients, the evidence supporting this is primarily from retrospective studies with no standardized protocols. This inconsistency has led to varied practices regarding platelet transfusion thresholds, ranging from 20,000 to 50,000 per cubic millimeter. Key predictors of bleeding complications include the experience of the operator and the use of ultrasound guidance, with the latter significantly reducing complication rates.
However, there are rising concerns over transfusion side effects such as acute lung injury, infection, and allergic reactions. Moreover, the scarcity and cost of blood products, particularly platelet concentrates, are concerning issues projected to worsen with an aging population.
This situation prompts the question of the necessity of prophylactic platelet transfusions to prevent CVC-related bleeding complications in patients with severe thrombocytopenia (those with platelet counts between 10,000 to 50,000 per cubic millimeter). The PACER trial was conducted due to conflicting guidelines regarding platelet-count thresholds for CVC placement, largely because of the lack of high-quality evidence.
Summary of the PACER Trial
In a multicenter, randomized, controlled, noninferiority trial, patients with severe thrombocytopenia were randomly assigned to either receive one unit of prophylactic platelet transfusion or no platelet transfusion before ultrasound-guided CVC placement. The primary outcome was CVC-related bleeding of grade 2 to 4, and a key secondary outcome was grade 3 or 4 bleeding. The noninferiority margin was defined by an upper boundary of the 90% confidence interval of 3.5 for the relative risk.
The study involved 373 instances of CVC placement in 338 patients. Grade 2 to 4 bleeding occurred in 4.8% of
patients in the transfusion group, and 11.9% in the no-transfusion group, demonstrating a relative risk of 2.45 (95% CI 1.27-4.70). Grade 3 or 4 bleeding occurred in 2.1% of the transfusion group and 4.9% of the no-transfusion group, resulting in a relative risk of 2.43.
In subgroup analysis, patients treated on the hematology ward exhibited a higher risk of bleeding compared to those in the Intensive Care Unit (ICU). Additionally, the risk of bleeding was greater with subclavian catheters relative to other catheter locations. Moreover, the use of tunneled catheters was associated with a higher bleeding risk regardless of platelet transfusion in comparison to nontunneled catheters and
The overall costs were higher in the transfusion group than the no-transfusion group, with a difference of $410 per catheter placement, largely due to the cost of prophylactic platelet transfusion. However, post-CVC placement transfusion costs were higher in the no-transfusion group due to more frequent platelet transfusions and transfusions related to bleeding.
The study concluded that withholding prophylactic platelet transfusion before CVC placement in patients with a platelet count of 10,000 to 50,000 per cubic millimeter did not meet the noninferiority margin and led to more CVC-related bleeding events than the prophylactic platelet transfusion.
The findings from the study advocate for a tailored approach when treating patients with severe thrombocytopenia, where platelet count ranges from 10,000 to 50,000 per cubic millimeter.
For patients outside the Intensive Care Unit (ICU), particularly those on the hematology ward, it is recommended to consider prophylactic platelet transfusions. This is especially pertinent for patients with a platelet count less than 30,000 per cubic millimeter as they are likely to require a platelet transfusion within 24 hours.
For patients located in the ICU, a strategy of no-transfusion is proposed. This involves comprehensive monitoring and a low threshold for the therapeutic administration of blood products. The intensive environment of the ICU, which permits extensive monitoring, supports this approach.
Nontunneled catheters are preferred over tunneled catheters.
If a transfusion isn't given, it is advised to circumvent the subclavian site for catheter insertion due to its heightened risk of bleeding.
Patients whose platelet count falls below 20,000 per cubic millimeter remain at a high risk of bleeding, even after being administered a single unit of platelets. Though the transfusion of multiple units could be considered to mitigate this risk, currently, there's a lack of supportive evidence to firmly endorse this strategy.
Floor L.F et al. Platelet Transfusion before CVC Placement in Patients with Thrombocytopenia. N Engl J Med 2023; 388:1956-1965 DOI: 10.1056/NEJMoa2214322. Link