We can extract two important findings from this observational study: (a) major bleeding complications were not detected in the entire population studied, which reinforces the idea of ultrasound guidance as a safe procedure; (b) prophylactic platelet transfusions were not associated with a reduction of bleeding complications in patients with severe thrombocytopenia subjected to central venous catheterization under ultrasound guidance.
Current guidelines recommend prophylactic platelet transfusion for central venous access in patients with platelet counts < 20 x103/µL [6, 14] or 50 x103/µL [15–16]; however, the strength of such recommendations is weak and are largely based on small observational studies including a limited number of patients with very low platelet counts. Previous studies have reported a low rate of bleeding complications in patients with thrombocytopenia undergoing central venous cannulation . Nevertheless, the number of patients with severe thrombocytopenia (platelet counts < 20 x103/µL) included in these studies was extremely low [18–22] and a high proportion of such patients received a prophylactic platelet transfusion prior to the procedure [17, 20–22]. In the largest systematic review of central venous access in patients with severe coagulopathy, Van de Weerdt et al.  found no difference in bleeding complications associated with prophylactic platelet transfusions. Remarkably, most patients were subjected to central venous catheterization under ultrasound guidance.
Ultrasound guidance for venous catheter placement has shown to reduce the incidence of bleeding complications [2, 5, 25, 33–37] and it is considered a standard of care in clinical practice today . In agreement with this, our study included 221 acutely ill patients with severe thrombocytopenia requiring central venous access for any cause (hemodynamic monitoring, medication infusion, renal replacement therapy, etc.), under ultrasound guidance. Remarkably, no major bleeding complications were detected in the entire cohort and the total number of minor bleeding events was quite similar to the previously reported in the literature, which highlights the role of ultrasound as a tool to increase safety in these clinical conditions. These findings were consistent even in the subgroup of patients with platelet counts below 10 x103/µL. In addition, subclavian access was not associated with an increased rate of bleeding complications compared to the jugular site. Interestingly, procedures without prophylactic platelet transfusion were most commonly performed by emergency medicine physicians, which probably reflects a higher frequency of emergent central venous cannulations in this setting.
This study has several limitations. First, its retrospective nature and, therefore, the lack of control by randomization and blinding might limit the external validity of conclusions. Admittedly, although propensity scores were constructed incorporating baseline characteristics likely influencing the decision for prophylactic platelet transfusions (other than thrombocytopenia itself), other non-identifiable factors might not have been included. In addition, the relatively small sample size of this cohort might introduce a risk of missing important differences at the baseline which might contribute to the absence of difference between the P-PPLT and N-PPLT groups. Second, we were not able to identify if the decision on “non-transfusion” relied on some particular attending physicians, which could constitute a potential factor of confusion. Nevertheless, we speculate that the lower occurrence of prophylactic transfusions ordered by emergency physicians respond to a higher frequency of emergency situations not captured by the retrospective nature of our observation. Third, although ultrasound-guided catheterization is an apparently safe procedure in severe thrombocytopenic patients, appropriate training and developed skills are fundamental to reproduce good results. In our hospital, there is an established ultrasound training program for emergency department and critical care staff, so these findings may not be replicable in other environments.
Fourth, even though our results suggest the apparent safety of non-routine prophylactic transfusion in severe thrombocytopenic patients subjected to venous catheterization under ultrasound guidance, future prospective research efforts are necessary to confirm such results.