Role of Platelet Transfusion in the Reversal of Anti-Platelet Therapy

Emergency Neurosurgery in a Patient With Pacemaker: The Double Trouble

Perioperative management of a patient with multiple comorbidities, being taken up for an emergency neurosurgical procedure presents a unique set of challenges to the anesthetist as it requires quick preoperative evaluation in order to avoid any delay in the surgery and limit the extent of cerebral injury. This case report highlights the perioperative management of a 55-year-old obese male patient, with a history of hypertension and coronary artery disease with a permanent pacemaker presenting to the emergency with weakness of right upper and lower limbs, suggestive of an acute stroke due to intracerebral hemorrhage. The patient was taken up for emergency decompressive craniectomy in view of increasing intracranial pressure and deteriorating consciousness. The pacemaker could not be changed to asynchronous mode in the preoperative period due to the non-availability of a magnet and trained personnel from the company of the pacemaker to change the settings immediately. Intraoperatively, all the necessary precautions for the prevention of pacemaker-related complications were followed. After the completion of the surgery, the patient was shifted to the neuro-intensive care unit for postoperative management.

Perioperative Management of Anticoagulant and Antiplatelet Therapy

Anticoagulant and Antiplatelet Drug ManagementManagement of patients on an anticoagulant or antiplatelet drug who require surgery or an invasive procedure is a common clinical problem. Douketis and Spyropoulos provide an evidence-based but practical approach to managing anticoagulants and antiplatelet drugs in the perioperative setting.

Aspirin use and bleeding events during thrombocytopenia after autologous stem-cell transplantation for multiple myeloma

Background

In patients with cardiovascular (CV) comorbidities that necessitate antiplatelet therapy (APT), its optimal management during chemotherapy-induced thrombocytopenia remains elusive, as the risk of bleeding has to be balanced against the risk of CV events. The purpose of this study was to assess the risk for bleeding with APT during thrombocytopenia in patients with multiple myeloma undergoing high-dose chemotherapy and subsequent autologous stem-cell transplantation (ASCT) with and without acetylsalicylic acid (ASA) as comedication.

Methods

We assessed patients who underwent ASCT at the Heidelberg University Hospital between 2011 and 2020 for bleeding events, management strategies for ASA intake during thrombocytopenia, transfusion requirements, and the occurrence of CV events.

Results

There were 57/1,113 patients who continued ASA until at least 1 day after ASCT; thus, a continuous platelet inhibition during thrombocytopenia was assumed. Most of the patients (41/57) continued ASA until they had a platelet count of 20-50/nl. This range reflects the kinetics of thrombocytopenia and nondaily measurements of platelets during ASCT. A tendency toward a higher risk for bleeding events in the ASA group was demonstrated (1.9% (control group) vs. 5.3% (ASA), p = 0.082). The risk factors for bleeding in multivariate analysis were the duration of thrombocytopenia < 50/nl, a history of gastrointestinal bleeding, and diarrhea. The factors predicting the duration of thrombocytopenia were age >60 years, a hematopoietic stem-cell transplantation comorbidity index ≥3, and an impaired bone marrow reserve at admission. CV events occurred in three patients; none of them took ASA or had an indication for APT.

Conclusions

The intake of ASA until thrombocytopenia with a platelet count of 20-50/nl appears safe, although an elevated risk cannot be excluded. If ASA is indicated for the secondary prevention of CV events, the evaluation of risk factors for bleeding and a prolonged time of thrombocytopenia before conditioning is crucial to adapt the strategy for ASA intake during thrombocytopenia.

Challenges and opportunities in the care of chronic subdural haematoma: perspectives from a multi-disciplinary working group on the need for change

INTRODUCTION

A chronic subdural haematoma (cSDH) is a collection of altered blood products between the dura and brain resulting in a slowly evolving neurological deficit. It is increasingly common and, in high income countries, affects an older, multimorbid population. With changing demographics improving the care of this cohort is of increasing importance.

METHODS

We convened a cross-disciplinary working group (the 'Improving Care in Elderly Neurosurgery Initiative') in October 2020. This comprised experts in neurosurgical care and a range of perioperative stakeholders. An Implementation Science framework was used to structure discussions around the challenges of cSDH care within the United Kingdom. The outcomes of these discussions were recorded and summarised, before being circulated to all attendees for comment and refinement.

RESULTS

The working group identified four key requirements for improving cSDH care: (1) data, audit, and natural history; (2) evidence-based guidelines and pathways; (3) shared decision-making; and (4) an overarching quality improvement strategy. Frequent transfers between care providers were identified as impacting on both perioperative care and presenting a barrier to effective data collection and teamworking. Improvement initiatives must be cognizant of the complex, system-wide nature of the problem, and may require a combination of targeted trials at points of clinical equipoise (such as anesthetic technique or anticoagulant management), evidence-based guideline development, and a cycle of knowledge acquisition and implementation.

CONCLUSION

The care of cSDH is a growing clinical problem. Lessons may be learned from the standardised pathways of care such as those as used in hip fracture and stroke. A defined care pathway for cSDH, encompassing perioperative care and rehabilitation, could plausibly improve patient outcomes but work remains to tailor such a pathway to cSDH care. The development of such a pathway at a national level should be a priority, and the focus of future work.

Spontaneous Coronary Artery Dissection: Rediscovering an Old Cause of Myocardial Infarction

Spontaneous coronary artery dissection is an uncommon, but not insignificant cause of acute coronary syndrome that overwhelmingly affects middle-aged women. The pathophysiology of coronary dissection appears to be an outside-in mechanism, where the initiating event is not an intimal tear but rather the formation of an intramural hematoma, which compromises blood flow by reducing the arterial lumen. Considering this mechanism, it is clear to see how intracoronary imaging techniques, such as optical coherence tomography and intravascular ultrasound, are most accurate in the diagnosis. However, they carry a high rate of complications and are therefore generally avoided when the clinical scenario and angiographic appearance both support the diagnosis of spontaneous coronary artery dissection. The natural history of the disease is toward healing of the vessel wall and restoration of blood flow. Therefore, conservative medical management is the preferred approach unless there are high-risk factors such as hemodynamic instability, signs of ischemia and severe proximal or multivessel lesions, in which percutaneous or surgical revascularization should be considered. Perioperative evaluation of these patients must take into account several aspects of this disease. Most of these patients will be receiving single or dual antiplatelet therapy, so one must consider the timing of the event and the surgical hemorrhagic risk when deciding to stop these therapies. Extracoronary vascular disease also must be assessed because it can have an effect on patient monitoring and risk of postoperative complications.

Antithrombotic and Antiplatelet Drug Toxicity

Anticoagulant and antiplatelet drugs target a specific portion of the coagulation cascade or the platelet activation and aggregation pathway. The primary toxicity associated with these agents is hemorrhage. Understanding the pharmacology of these drugs allows the treating clinician to choose the correct antidotal therapy. Reversal agents exist for some of these drugs; however, not all have proven patient-centered outcomes. The anticoagulants covered in this review are vitamin K antagonists, heparins, fondaparinux, hirudin derivatives, argatroban, oral factor Xa antagonists, and dabigatran. The antiplatelet agents reviewed are aspirin, adenosine diphosphate antagonists, dipyridamole, and glycoprotein IIb/IIIa antagonists. Additional notable toxicities are also reviewed.

Evaluating the appropriateness of platelet transfusions compared with evidence-based platelet guidelines: An audit of platelet transfusions at 57 hospitals

BACKGROUND

Platelet transfusions are used to prevent or control bleeding in patients with thrombocytopenia or platelet dysfunction. The pretransfusion platelet count threshold has been studied extensively in multiple patient settings yielding high-quality evidence that has been summarized in several comprehensive evidence-based platelet guidelines.

STUDY DESIGN AND METHODS

A prospective 12-week audit of consecutive platelet transfusions using validated and evidence-based adjudication criteria was conducted. Patient demographic, laboratory, and transfusion details were collected with an electronic audit tool. Each order was adjudicated either electronically or independently by two transfusion medicine physicians. The aim was to determine platelet transfusion appropriateness and common scenarios with deviations from guidelines.

RESULTS

Fifty-seven (38%) of 150 hospitals provided data on 1903 platelet orders, representing 90% of platelet usage in the region during the time period. Overall, 702 of 1693 adult (41.5%) and 133 of 210 pediatric orders (63.3%) were deemed inappropriate. The most common inappropriate platelet order was for prophylaxis in the absence of bleeding or planned procedure in patients with hypoproliferative thrombocytopenia and a platelet count over 10 x 10⁹ /L (53% of inappropriate orders in adults and 45% in pediatrics). Platelet transfusions ordered with either a preprinted transfusion order set (odds ratio [OR], 1.97; 95% confidence interval [CI], 1.44-2.73) or technologist prospective screening (OR, 1.40; 95% CI, 1.10-1.78) were more likely to be appropriate.

CONCLUSION

There is a discrepancy between clinical practice and evidence-based platelet guidelines. Broad educational and system changes will be needed to align platelet transfusion practice with guideline recommendations.

Therapeutic strategies for thrombosis: new targets and approaches

Antiplatelet agents and anticoagulants are a mainstay for the prevention and treatment of thrombosis. However, despite advances in antithrombotic therapy, a fundamental challenge is the side effect of bleeding. Improved understanding of the mechanisms of haemostasis and thrombosis has revealed new targets for attenuating thrombosis with the potential for less bleeding, including glycoprotein VI on platelets and factor XIa of the coagulation system. The efficacy and safety of new agents are currently being evaluated in phase III trials. This Review provides an overview of haemostasis and thrombosis, details the current landscape of antithrombotic agents, addresses challenges with preventing thromboembolic events in patients at high risk and describes the emerging therapeutic strategies that may break the inexorable link between antithrombotic therapy and bleeding risk.

Impaired hemostatic activity of healthy transfused platelets in inherited and acquired platelet disorders: Mechanisms and implications

Platelet transfusions can fail to prevent bleeding in patients with inherited platelet function disorders (IPDs), such as Glanzmann's thrombasthenia (GT; integrin αIIbβ3 dysfunction), Bernard-Soulier syndrome [BSS; glycoprotein (GP) Ib/V/IX dysfunction], and the more recently identified nonsyndromic RASGRP2 variants. Here, we used IPD mouse models and real-time imaging of hemostatic plug formation to investigate whether dysfunctional platelets impair the hemostatic function of healthy donor [wild-type (WT)] platelets. In Rasgrp2-/- mice or mice with platelet-specific deficiency in the integrin adaptor protein TALIN1 ("GT-like"), WT platelet transfusion was ineffective unless the ratio between mutant and WT platelets was ~2:1. In contrast, thrombocytopenic mice or mice lacking the extracellular domain of GPIbα ("BSS-like") required very few transfused WT platelets to normalize hemostasis. Both Rasgrp2-/- and GT-like, but not BSS-like, platelets effectively localized to the injury site. Mechanistic studies identified at least two mechanisms of interference by dysfunctional platelets in IPDs: (i) delayed adhesion of WT donor platelets due to reduced access to GPIbα ligands exposed at sites of vascular injury and (ii) impaired consolidation of the hemostatic plug. We also investigated the hemostatic activity of transfused platelets in the setting of dual antiplatelet therapy (DAPT), an acquired platelet function disorder (APD). "DAPT" platelets did not prolong the time to initial hemostasis, but plugs were unstable and frequent rebleeding was observed. Thus, we propose that the endogenous platelet count and the ratio of transfused versus endogenous platelets should be considered when treating select IPD and APD patients with platelet transfusions.