Point-of-care assessment of platelet reactivity in the emergency department may facilitate rapid rule-out of acute coronary syndromes: a prospective cohort pilot feasibility study

Oxygen therapy for sepsis and prevention of complications

Patients with sepsis have a wide range of respiratory disorders that can be treated with oxygen therapy. Experimental data in animal sepsis models show that oxygen therapy significantly increases survival, while clinical data on the use of different oxygen therapy protocols are ambiguous. Oxygen therapy, especially hyperbaric oxygenation, in patients with sepsis can aggravate existing oxidative stress and contribute to the development of disseminated intravascular coagulation. The purpose of this article is to compare experimental and clinical data on oxygen therapy in animals and humans, to discuss factors that can influence the results of oxygen therapy for sepsis treatment in humans, and to provide some recommendations for reducing oxidative stress and preventing disseminated intravascular coagulation during oxygen therapy.

Platelet Dysfunction in Cardiac Surgery: When is the Best Time to Assess It? An Observational Single Center Study

Purpose. Cardiac surgery is characterized by a high risk of complications related to perioperative bleeding. Guidelines suggest the use of local algorithms based on perioperative point-of-care tests to assess and manage potential coagulation abnormalities. We investigated whether heparin reversal administration affects the adenosine-5-diphosphate (ADP) test values, thus identifying the earliest time point following cardio-pulmonary bypass that permits the promptest detection and treatment of potential platelet dysfunctions. Methods. This was a retrospective, single-center, observational study enrolling cardiac surgery patients requiring cardiac bypass. ADP-tests at 4 different time-points during surgery (T0: baseline, T1: at aortic de-clamping, T2: 10 minutes after protamine administration, and T3: at the end of surgery) were performed. Results. 63 patients undergoing elective cardiac surgery were studied. Baseline ADP-test values were almost constantly greater than intraoperative values, and end of surgery values were often greater than previous intraoperative values. The only difference that proved to be not statistically significant was between T1 and T2, with a clinically insignificant mean difference of -.2 U (95%CI of difference: -6.9 - 6.5 U). There was no correlation between the variation in ADP-test values pre- and post-protamine administration and the protamine-to-heparin ratio. Conclusion. The results of the present study support the hypothesis that the ADP-test could be performed early, at aortic de-clamping before protamine administration. This approach allows for the promptest assessment of a potential impairment in platelet function, and its timely correction.

Mean platelet volume and clinical outcomes of patients with chest pain discharged from internal medicine wards

BACKGROUND

Currently, there are no clinical scores for risk stratification of low-risk patients with chest pain. We aimed to examine the association between mean platelet volume (MPV) and risk for adverse clinical outcomes in patients with chest pain discharged from internal medicine wards following acute coronary syndrome (ACS) rule-out.

PATIENTS AND METHODS

Included were patients who were admitted to internal medicine wards and were discharged following an ACS-rule-out during 2010-2016. The primary endpoint was the composite of all-cause mortality and hospital admission due to ACS at 30-days following hospital discharge.

RESULTS

Included in the study were12 440 patients who were divided into three groups according to MPV. The composite endpoint of 30-day all-cause mortality and hospital admission for ACS occurred more frequently among patients with high MPV. Each one-point increase in MPV was associated with an 18% increase in the risk for the composite endpoint (P = 0.02). Considering patients with MPV less than 7.8 fl as the reference group yielded adjusted hazard ratios for the composite endpoint that was significantly higher in patients in the high MPV tertile ( > 8.8 fl) (hazard ratio 1.6; 95% confidence interval = 1.1-2.5; P = 0.04). Each one-point increase in MPV was associated with an 11% increase in the risk for 1-year all-cause mortality (P = 0.01) and a 10% increase in the risk for 1-year ACS (P = 0.04).

CONCLUSION

We found an independent association between high MPV and the risk of death and ACS among patients with chest pain who were discharged from internal medicine wards following an ACS-rule-out. MPV may be combined in the risk stratification of patients with chest pain.

Platelet pathophysiology, pharmacology, and function in coronary artery disease

Platelets play a key role in the pathophysiology of coronary artery disease and acute coronary syndromes. Our understanding of platelet function in thrombus formation has increased considerably, resulting in the development of clinically effective treatment strategies and identification of new targets. An underappreciated platelet function is their contribution toward acute and chronic inflammatory processes including atherogenesis. In this review, we discuss the role of platelets in atherosclerosis and thrombosis, platelet function testing, and the pharmacology of currently available antiplatelet drugs.

Utility of point of care assessment of platelet reactivity (using the PFA-100®) to aid in diagnosis of stroke

BACKGROUND

Rapid and accurate diagnosis of patients presenting with symptoms of stroke is needed to facilitate the timely delivery of proven effective treatment for patients with acute ischemic stroke (AIS). The aim of this study was to determine whether early assessment of platelet reactivity in patients presenting with symptoms of AIS was associated with a diagnosis of AIS, transient ischemic attack (TIA), or stroke mimic.

METHODS

This prospective study included patients with symptoms of AIS treated at an inner-city emergency department (ED). Blood samples were obtained and assayed for platelet reactivity (quantified by closure time). Patients were grouped by discharge diagnosis into: AIS, TIA, or stroke mimic. Binary logistic regression model was used to predict the association of closure time with the final diagnosis of 1) either AIS or TIA or, 2) stroke mimic.

RESULTS

Of 114 patients enrolled, 32 were diagnosed with AIS, 33 TIA, and 49 were diagnosed as a stroke mimic. There was no significant difference in closure times among patients with a diagnosis of AIS or TIA versus stroke mimic. A history of migraines and history of seizures were independently associated with lower odds of an AIS or TIA diagnosis (OR 0.31, 95% CI 0.10 to 0.94 and OR 0.08, 95% CI 0.01 to 0.88, respectively).

CONCLUSION

Closure time was not found to be a clinically reliable differentiator of patients with a diagnosis of AIS, TIA, or stroke mimic in the ED.

Platelet function tests: a comparative review

In physiological hemostasis a prompt recruitment of platelets on the vessel damage prevents the bleeding by the rapid formation of a platelet plug. Qualitative and/or quantitative platelet defects promote bleeding, whereas the high residual reactivity of platelets in patients on antiplatelet therapies moves forward thromboembolic complications. The biochemical mechanisms of the different phases of platelet activation – adhesion, shape change, release reaction, and aggregation – have been well delineated, whereas their complete translation into laboratory assays has not been so fulfilled. Laboratory tests of platelet function, such as bleeding time, light transmission platelet aggregation, lumiaggregometry, impedance aggregometry on whole blood, and platelet activation investigated by flow cytometry, are traditionally utilized for diagnosing hemostatic disorders and managing patients with platelet and hemostatic defects, but their use is still limited to specialized laboratories. To date, a point-of-care testing (POCT) dedicated to platelet function, using pertinent devices much simpler to use, has now become available (ie, PFA-100, VerifyNow System, Multiplate Electrode Aggregometry [MEA]). POCT includes new methodologies which may be used in critical clinical settings and also in general laboratories because they are rapid and easy to use, employing whole blood without the necessity of sample processing. Actually, these different platelet methodologies for the evaluation of inherited and acquired bleeding disorders and/or for monitoring antiplatelet therapies are spreading and the study of platelet function is strengthening. In this review, well-tried and innovative platelet function tests and their methodological features and clinical applications are considered.