Platelet function after cardiac surgery and its association with severe postoperative bleeding: the PLATFORM study

Platelet transfusion enhances pro-aggregatory status shortly after coronary artery bypass grafting (CABG while modulating platelet pro-inflammatory state 1-week post-surgery

During coronary artery bypass grafting (CABG), the surgical procedure, particularly the manipulation of the major arteries of the heart, induces a significant inflammatory state that may compromise platelet function to the extent that platelet transfusion is required. Given stored platelets as a major source of biological mediators, this study investigates the effects of platelet transfusion on the major pro-aggregatory, pro-inflammatory and immunomodulatory markers of platelets. Platelets from 20 patients, 10 who received platelet transfusion and 10 without, were subjected to flow cytometery where P-selectin and CD40 ligand (CD40L) expressions and PAC-1 binding (activation-specific anti GPIIb/GPIIIa antibody) analysed at five-time points of 24 h before surgery, immediately, 2 h, 24 h and 1 week after surgery. Analysis of intra-platelet transforming growth factor-beta-1 (TGF-β1) was also conducted using western blotting. Patients with platelet transfusion showed increased levels of P-selectin, CD40L and intra-platelet TGF-β1 2-h after surgery compared to those without transfusion (p < 0.05). PAC-1 binding was increased 24 h after surgery in transfused patients (p < 0.05). Given the significant post-transfusion elevation of platelet TGF-β1, P-sel/CD40L reduction in transfused patients a week after was of much interest. This study showed for the first time the significant effects of platelet transfusion on the pro-inflammatory, pro-aggeregatory and immunomodulatory state of platelets in CABG patients, which manifested with immediate, midterm and delayed consequences. While the increased pro-inflammatory conditions manifested as an immediate effect of platelet transfusion, the pro-aggregatory circumstances emerged 24 h post-transfusion. A week after surgery, attenuations of pro-inflammatory markers of platelets in transfused patients were shown, which might be due to the immunomodulatory effects of TGF-β1.

The evolving knowledge on primary hemostasis in patients with cirrhosis: A comprehensive review

Patients with cirrhosis develop complex alterations in primary hemostasis that include both hypocoagulable and hypercoagulable features. This includes thrombocytopenia, multiple alterations of platelet function, and increased plasma levels of von Willebrand factor. Contrary to the historical view that platelet dysfunction in cirrhosis might be responsible for an increased bleeding tendency, the current theory posits a rebalanced hemostasis in patients with cirrhosis. Severe thrombocytopenia is not indicative of the bleeding risk in patients undergoing invasive procedures and does not dictate per se the need for pre-procedural prophylaxis. A more comprehensive and individualized risk assessment should combine hemostatic impairment, the severity of decompensation and systemic inflammation, and the presence of additional factors that may impair platelet function, such as acute kidney injury and bacterial infections. Although there are multiple, complex alterations of platelet function in cirrhosis, their net effect is not yet fully understood. More investigations evaluating the association between alterations of platelet function and bleeding/thrombosis may improve risk stratification in patients with decompensated cirrhosis. Besides hemostasis, the assessment of von Willebrand factor Ag and ADP-induced, whole-blood platelet aggregation normalized by platelet count (VITRO score and PLT ratio) are promising biomarkers to predict the risk of hepatic decompensation and survival in both compensated and decompensated patients. Further investigations into the in vivo interplay between platelets, circulating blood elements, and endothelial cells may help advance our understanding of cirrhotic coagulopathy. Here, we review the complex changes in platelets and primary hemostasis in cirrhosis and their potential clinical implications.

Detection of cellular traction forces via the force-triggered Cas12a-mediated catalytic cleavage of a fluorogenic reporter strand

Molecular forces generated by cell receptors are infrequent and transient, and hence difficult to detect. Here we report an assay that leverages the CRISPR-associated protein 12a (Cas12a) to amplify the detection of cellular traction forces generated by as few as 50 adherent cells. The assay involves the immobilization of a DNA duplex modified with a ligand specific for a cell receptor. Traction forces of tens of piconewtons trigger the dehybridization of the duplex, exposing a cryptic Cas12-activating strand that sets off the indiscriminate Cas12-mediated cleavage of a fluorogenic reporter strand. We used the assay to perform hundreds of force measurements using human platelets from a single blood draw to extract individualized dose-response curves and half-maximal inhibitory concentrations for a panel of antiplatelet drugs. For seven patients who had undergone cardiopulmonary bypass, platelet dysfunction strongly correlated with the need for platelet transfusion to limit bleeding. The Cas12a-mediated detection of cellular traction forces may be used to assess cell state, and to screen for genes, cell-adhesion ligands, drugs or metabolites that modulate cell mechanics.

Cold-stored platelets for acute bleeding in cardiac surgical patients: a narrative review

PURPOSE

Cold-stored platelets (CSP) are an increasingly active topic of international research. They are maintained at 1-6 °C, in contrast to standard room-temperature platelets (RTP) kept at 20-24 °C. Recent evidence suggests that CSP have superior hemostatic properties compared with RTP. This narrative review explores the application of CSP in adult cardiac surgery, summarizes the preclinical and clinical evidence for their use, and highlights recent research.

SOURCE

A targeted search of MEDLINE and other databases up to 24 February 2022 was conducted. Search terms combined concepts such as cardiac surgery, blood, platelet, and cold-stored. Searches of trial registries ClinicalTrials.gov and WHO International Clinical Trials Registry Platform were included. Articles were included if they described adult surgical patients as their population of interest and an association between CSP and clinical outcomes. References of included articles were hand searched.

PRINCIPAL FINDINGS

When platelets are stored at 1-6 °C, their metabolic rate is slowed, preserving hemostatic function for increased storage duration. Cold-stored platelets have superior adhesion characteristics under physiologic shear conditions, and similar or superior aggregation responses to physiologic agonists. Cold-stored platelets undergo structural, metabolic, and molecular changes which appear to "prime" them for hemostatic activity. While preliminary, clinical evidence supports the conduct of trials comparing CSP with RTP for patients with platelet-related bleeding, such as those undergoing cardiac surgery.

CONCLUSION

Cold-stored platelets may have several advantages over RTP, including increased hemostatic capacity, extended shelf-life, and reduced risk of bacterial contamination. Large clinical trials are needed to establish their potential role in the treatment of acutely bleeding patients.

Supplemental fibrinogen restores thrombus formation in cardiopulmonary bypass-induced platelet dysfunction ex vivo

BACKGROUND

Major cardiac surgery related blood loss is associated with increased postoperative morbidity and mortality. Platelet dysfunction is believed to contribute to post-cardiopulmonary bypass (CPB)-induced microvascular bleeding. We hypothesised that moderately hypothermic CPB induces platelet dysfunction and that supplemental fibrinogen can restore in vitro thrombus formation.

METHODS

Blood from 18 patients, undergoing first-time elective isolated aortic valve surgery was drawn before CPB, 30 min after initiation of CPB, and after CPB and protamine administration, respectively. Platelet aggregation was quantified by optical aggregometry, platelet activation by flow-cytometric detection of platelet surface expression of P-selectin, annexin V, and activated glycoprotein IIb/IIIa, thrombus formation under flow and effect of supplemental fibrinogen (4 mg ml-1) on in vitro thrombogenesis.

RESULTS

Post-CPB adenosine-diphosphate and TRAP-6-induced aggregation decreased by 40% and 10% of pre-CPB levels, respectively (P<0.0001). Although CPB did not change glycoprotein IIb/IIIa receptor expression, it increased the percentage of unstimulated P-selectin (1.2% vs 7%, P<0.01) positive cells and annexin V mean fluorescence intensity (15.5 vs 17.2, P<0.05), but decreased percentage of stimulated P-selectin (52% vs 26%, P<0.01) positive cells and annexin V mean fluorescence intensity (508 vs 325, P<0.05). Thrombus area decreased from 6820 before CPB to 5230 after CPB (P<0.05, arbitrary units [a.u.]). Supplemental fibrinogen increased thrombus formation to 20 324 and 11 367 a.u. before CPB and after CPB, respectively (P<0.001), thereby restoring post-CPB thrombus area to levels comparable with or higher than pre-CPB baseline.

CONCLUSIONS

Single valve surgery using moderately hypothermic CPB induces partial platelet dysfunction. Thrombus formation was restored in an experimental study design by ex vivo supplementation of fibrinogen.

Effect of Desmopressin on Bleeding After Heart Surgeries: A Narrative Review

Desmopressin is an analog of the antidiuretic hormone (vasopressin), which causes anticoagulant activity by increasing plasma factor 8. The use of desmopressin dates back to 1977, when this hormone was used to prevent bleeding during tooth extraction and surgery in patients with hemophilia A and von Willebrand disease. After that, this hormone was expanded to prevent bleeding in congenital defects and conditions such as chronic kidney and liver failure. Also, this hormone is used to prevent bleeding in major surgeries such as heart surgery, where the patient loses much blood and needs a blood transfusion. Considering the importance of desmopressin in bleeding control, the present study was conducted to investigate the possible effect of this hormone in heart surgery.

Are Viscoelastic Tests Clinically Useful to Identify Platelet-Dependent Bleeding in High-Risk Cardiac Surgery Patients?

BACKGROUND

Postoperative use of platelet function testing to rule out microvascular bleeding due to platelet dysfunction after cardiac surgery still lacks strong reference data and reliable cutoff values, yielding a clinically adequate sensitivity and specificity. The present study aims to investigate the performance of two different point-of-care viscoelastic devices and platelet aggregometry in expressing surgery-dependent platelet dysfunction and anticipating postoperative major bleeding in a cohort of high-risk patients.

METHODS

Prospective cohort study of 50 adult patients who were on antiplatelet drugs discontinued for no more than 7 days (clopidogrel and prasugrel) or 5 days (ticagrelor) undergoing cardiac surgery with cardiopulmonary bypass (CPB). Coagulation and platelet function testing, including QUANTRA, ROTEM, and Multiplate, were assessed preoperatively and postoperatively. Chest drain blood loss was measured in the first 12 postoperative hours. Perioperative bleeding was assessed using a modified version of the Universal Definition of Perioperative Bleeding (UDPB) in cardiac surgery, modified to not consider anemia-correcting packed red cells transfusions in the absence of bleeding >600 mL/12 h. Major bleeding was identified as UDPB class II or higher.

RESULTS

Multiplate adenosine diphosphate (ADPtest) was significantly ( P = .001) reduced after CPB, whereas TRAPtest was not. The platelet component (PC) as extrapolated by ROTEM data (EXTEM MCF-FIBTEM MCF) was unchanged after CPB, while the A10 PC (PC at 10 minutes) was significantly ( P = .001) reduced. The QUANTRA platelet contribution to clot stiffness (PCS) was significantly ( P = .001) reduced, as well. At the ROC analysis for the predictive ability of the post-CPB platelet function testing, the best discrimination was obtained by the QUANTRA PCS, with an area under the curve (AUC) (95% confidence interval [CI]) of 0.80 (0.66-0.91), P = .001, followed by the ROTEM A10 PC with AUC (95% CI) of 0.75 (0.51-0.99), P = .004, and PC with AUC (95% CI) of 0.74 (0.50-0.99), P = .009. The Multiplate ADPtest had an AUC (95% CI) of 0.67 (0.42-0.91), and the TRAPtest had an AUC (95% CI) of 0.62 (0.37-0.86). The cutoff values identified were 13 hPa for the QUANTRA PCS, 40 mm for the ROTEM A10, and 48.5 mm for the ROTEM PC, with negative predictive values of 84%, 81%, and 86%, respectively, and positive predictive values of 55%, 53%, and 69%, respectively.

CONCLUSIONS

QUANTRA PCS, ROTEM A10 PC, and Multiplate ADPtest showed a significant decrease after CPB, whereas ROTEM PC and Multiplate TRAPtest did not. Major bleeding was predicted with a moderate to good discrimination by the post-CPB viscoelastic tests (PCS, PC, and A10 PC).

Is the platelet function test effective in predicting blood loss in patients undergoing hepatic resection?

Purpose

The platelet function analyzer (PFA)-100/200 is widely used to assess platelet function. However, its role in predicting the perioperative risk of bleeding in patients undergoing liver resection remains controversial. Therefore, we aimed to ascertain whether the platelet function test could be useful in predicting bleeding risk in patients undergoing hepatic surgery.

Methods

The study participants were patients who underwent hepatectomy for hepatocellular carcinoma at our hospital over a period of 10 years from January 1, 2010 to May 31, 2020. PFA-200 values of these patients were divided into 2 groups; normal (n = 333) and prolonged (n = 39).

Results

There were no significant differences regarding the volumes of calculated blood loss during surgery between the normal and prolonged PFA groups (879.55 ± 1,046.50 mL vs. 819.74 ± 912.64 mL, respectively; P = 0.733); intraoperative RBC transfusion (0.52 ± 2.02 units vs. 0.26 ± 1.02 units, P = 0.419) and postoperative RBC transfusion (0.24 ± 1.17 units vs. 0.46 ± 1.97 units, P = 0.306) were similar between the 2 groups, respectively. Multivariate analysis revealed no association between PFA closure time and calculated blood loss (hazard ratio, 1.06; P = 0.881). Moreover, there was no association between PFA closure time and preoperative laboratory results or assessment of tool-related liver function in multivariate analysis.

Conclusion

There was no correlation between the amount of blood loss and platelet function in patients who underwent liver resection. In patients undergoing liver resection who are not managed on antiplatelet agents or do not have chronic kidney disease, the use of routine PFA is not recommended.

Coagulation and Transfusion Updates From 2021

2021 and the COVID 19 pandemic have brought unprecedented blood shortages worldwide. These deficits have propelled national efforts to reduce blood usage, including limiting elective services and accelerating Patient Blood Management (PBM) initiatives. A host of research dedicated to blood usage and management within cardiac surgery has continued to emerge. The intent of this review is to highlight this past year's research pertaining to PBM and COVID-19-related coagulation changes.

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.

Platelet function assessed by ROTEM® platelet in patients receiving antiplatelet therapy during cardiac and vascular surgery

Patients undergoing coronary artery bypass graft (CABG) surgery or carotid endarterectomy (CEA) continue antiplatelet therapy perioperatively, which may increase bleeding risk. We aimed to investigate whether Rotational thromboelastometry (ROTEM^®) platelet, a newly marketed platelet function analysis, would detect antiplatelet therapy in CABG and CEA patients; whether detection of reduced platelet function was associated with increased bleeding; and whether ex vivo desmopressin increased platelet function. We included 20 CABG patients continuing aspirin and 20 CEA patients continuing clopidogrel (n = 1) or clopidogrel and aspirin (n = 19). Platelet function was analyzed with ROTEM^® platelet and light transmission aggregometry (LTA). According to the lower reference limit, ROTEM^® platelet managed to detect aspirin, but clopidogrel detection was inadequate compared to LTA. Using a previously published cut-off for bleeding risk, 6 (30%) patients receiving aspirin and 4 (21%) patients receiving both clopidogrel and aspirin demonstrated platelet function below this cut-off. One of the four CEA patients below the cut-off died from intracerebral hemorrhage postoperatively. CABG patients below (n = 6) and above (n = 14) the cut-off did not differ in chest tube output (median [range]: 373 ml [250-900] vs. 368 ml [195-820]). Ex vivo addition of desmopressin did not increase platelet function. In conclusion, ROTEM^® platelet does reveal aspirin treatment whereas clopidogrel treatment is most often overlooked. Due to low bleeding in the study population, it was not possible to conclude on the association with bleeding risk.

A Comparative Study of Multiple Electrode Aggregometry Technologies in Cardiac Surgery: Different Values, Same Clinical Relevance

OBJECTIVES

The assessment of platelet function in cardiac surgery patients who recently received dual-antiplatelet therapy is considered in the existing guidelines. Among available devices, Multiplate (MP) and ROTEM Platelet (RP) are both based on electrical impedance. This study aimed to determine the agreement between MP and RP in cardiac surgery patients under dual-antiplatelet therapy discontinued before surgery. Secondarily, it compared the ability of the MP and RP in predicting postoperative bleeding and the need for platelet transfusion.

DESIGN

A prospective cohort study.

SETTING

A hospital in Milan, Italy.

PARTICIPANTS

Fifty adult patients preoperatively and postoperatively tested.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were studied with adenosine diphosphate (ADP) and thrombin receptor-activating peptide (TRAP) testing on both of the devices. The mean preoperative ADP tests were below the respective lower limit of the reference value, thus reflecting a good ability of these tests to detect the residual or ongoing effects of antiplatelet drugs acting on the P2Y₁₂ receptor. The agreement between the 2 methodologies was very poor for both the ADP and TRAP tests, with a percentage error of 80%. The preoperative ADP tests were predictive for the need of platelet concentrate transfusion, with cut-off values at 35 U for the ADP-MP and 60 Ω/min for the ADP-RP. No correlation was found for postoperative bleeding.

CONCLUSION

Both technologies seemed to offer potential benefits in the surgical approach to patients who preoperatively received antiplatelet drugs. However, the results of these tests are not interchangeable, and different cut-off values should be applied.

Low postoperative blood platelet count may be a risk factor for 3-year mortality in patients with acute type A aortic dissection

Background

Mortality and complications remain high after acute type A aortic dissection (ATAAD) open surgery and are associated with coagulation dysfunction. Platelets play an important role in the process of coagulation. This study explored the relationship between postoperative platelet counts and 3-year mortality after operation in patients with ATAAD undergoing open aortic repair surgery.

Methods

Patients with ATAAD who underwent Total Arch Replacement and Frozen Elephant Trunk in Fuwai Hospital from 2011 to 2015 were selected for this study. The perioperative data were collected and sorted through the electronic clinical case system. Multivariate Logistic regression was used to analyze the risk factors for death within three years after surgery.

Results

A total of 495 patients were included in the analysis. After correction for confounding factors, decreased postoperative platelet count remained an independent factor that was associated with lower mortality (OR = 0.918, 95% CI 0.853–0.988, P = 0.023).

Conclusions

The study indicated that decreased postoperative platelet count may lead to increased 3-year mortality, in patients with ATAAD who underwent open aortic repair surgery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-021-01623-7.

Perioperative outcomes of combined heart surgery and lung tumor resection: a systematic review and meta-analysis

Objective

The prevalence of patients with concomitant heart and lung lesions requiring surgical intervention is increasing. Simultaneous cardiac surgery and pulmonary resection avoids the need for a second operation. However, there are concerns regarding the potentially increased mortality and complication rates of simultaneous surgery and the adequacy of lung exposure during heart surgery. Therefore, we performed a meta-analysis to evaluate the perioperative mortality and complication rates of combined heart surgery and lung tumor resection.

Methods

A comprehensive literature search was performed in July 2020. The PubMed, Embase, and Web of Science databases were searched to identify studies that reported the perioperative outcomes of combined heart surgery and lung tumor resection. Two reviewers independently screened the studies, extracted data, and assessed the risk of bias of included studies. Pooled proportions and 95% confidence intervals (95% CI) were calculated by R version 3.6.1 using the meta package.

Results

A total of 536 patients from 29 studies were included. Overall, the pooled proportion of operative mortality was 0.01 (95% CI: 0.00, 0.03) and the pooled proportion of postoperative complications was 0.40 (95% CI: 0.24, 0.57) for patients who underwent combined cardiothoracic surgery. Subgroup analysis by lung pathology revealed that, for patients with lung cancer, the pooled proportion of anatomical lung resection was 0.99 (95% CI: 0.95, 1.00) and the pooled proportion of systematic lymph node dissection or sampling was 1.00 (95% CI: 1.00, 1.00). Subgroup analysis by heart surgery procedure found that the pooled proportion of postoperative complications of patients who underwent coronary artery bypass grafting (CABG) patients using the off-pump method was 0.17 (95% CI: 0.01, 0.43), while the pooled proportion of complications after CABG using the on-pump method was 0.61 (95% CI: 0.38, 0.82).

Conclusion

Combined heart surgery and lung tumor resection had a low mortality rate and an acceptable complication rate. Subgroup analyses revealed that most patients with lung cancer underwent uncompromised anatomical resection and mediastinal lymph node sampling or dissection during combined cardiothoracic surgery, and showed off-pump CABG may reduce the complication rate compared with on-pump CABG. Further researches are still needed to verify these findings.

Rotational thromboelastometry and conventional coagulation tests in patients undergoing major cardiac or aortic surgery: a retrospective single-center cohort study

Algorithms for treatment of diffuse bleeding in cardiac surgery are based on intervention thresholds of coagulation tests, such as rotational thromboelastometry (ROTEM) or conventional laboratory tests. The relationship between these two approaches is unclear in patients with increased risk of coagulation abnormalities. We retrospectively analyzed the data of 248 patients undergoing major cardiac and/or aortic surgery. ROTEM and conventional laboratory tests were performed simultaneously after termination of cardiopulmonary bypass and protamine administration to investigate the extrinsic and intrinsic system, and to determine deficiencies in platelets and fibrinogen. We evaluated the association between ROTEM and conventional tests by linear regression analysis and compared the frequency of exceeding established thresholds for clinical intervention. Significant linear associations between ROTEM 10 min after the start of coagulation, and plasma fibrinogen concentration or platelet count (FIBTEM A10, R² = 0.67, p < 0.001; EXTEM A10, R² = 0.47, p < 0.001) were obtained. However, the 95% prediction intervals exceeded clinically useful ranges (92–233 mg/dL fibrinogen at the intervention threshold of FIBTEM A10 = 10 mm; 14 × 10³–122 × 10³/µL platelets at the intervention threshold of EXTEM A10 = 40 mm). The association between EXTEM and INR (R² = 0.23), and INTEM and aPTT (R² = 0.095) was poor. The frequency of exceeding intervention thresholds and, consequently, of triggering treatment, varied markedly between ROTEM and conventional tests (p < 0.001 for all comparisons). The predictability of conventional coagulation test results by ROTEM is limited, thus hampering the interchangeability of methods in clinical practice.

Effect of Prolonged Hypothermic Cardiopulmonary Bypass, Heparin, and Protamine on Platelet: A Small-Group Study

Cardiopulmonary bypass (CPB) is associated with platelet dysfunction (PD), an important cause of postoperative bleeding. The etiology of PD is not completely understood. We mapped the platelets' function during CPB to determine the etiology of PD. Platelets activation, measured by procaspase activating compound-1 and P-selectin expression (CD62P), after activation by adenosine diphosphate and thrombin receptor activator peptide, were decreased by protamine. Changes during CPB were insignificant. Platelet-leukocyte aggregation was increased by CPB but not by protamine. Platelet apoptosis marker, annexin V, was increased by protamine. Changes during CPB were insignificant. Our findings demonstrate that protamine given after CPB plays a central role in PD and count decrease.

Perioperative care in cardiac surgery

As mortality is now low for many cardiac surgical procedures, there has been an increasing focus on patient centered outcomes such as recovery and quality of life. The Enhanced Recovery After Surgery (ERAS) cardiac society recently published the first set of guidelines for cardiac surgery which will be useful as a starting point to help translate this philosophy for the benefit of those undergoing cardiac surgery. At the same time there are many advances in other areas such as mechanical circulation, diagnostics and quality metrics. We intend here to present a balanced and evidenced based review of selected aspects of current practice, encompassing both UK and international perioperative care with a focus on recent advances. For the convenience of the reader we will adopt the conventional perioperative preoperative, intraoperative and postoperative phases of care. The focus of cardiac surgical practice needs to evolve from mortality to recovery. Those specialists who work in cardiac anaesthesia and critical care are well placed to contribute to these changes. Accompanying this work is the development of technologies to improve recognition of and intervention to prevent early organ dysfunction. Measuring, benchmarking and publishing quality outcomes from cardiac surgical centres is likely to improve services and benefit our patients.

Multiple Electrode Aggregometry After Cardiopulmonary Bypass to Assess Platelet (Dys)-Function and Transfusion Threshold: A Concordance Study

OBJECTIVE

Cardiac surgery patients have a high risk of postoperative bleeding. Historically, the platelet count has been one of the main parameters used to establish the need for platelet transfusions, and the recent introduction of point-of-care tests for platelet function has allowed clinicians to rationalize platelet transfusion needs by assessing the platelet (dys-)function of the patient. For the present study, the authors evaluated how the introduction of one of these systems-the adenosine diphosphate (ADP) test, performed using a Multiplate electrode analyzer (Roche Diagnostics, Basel, Switzerland)-into their clinical practice had modified their platelet transfusion practice. The relationship between the platelet count and the functional evaluation of platelet aggregation (via the ADP test) also was examined.

DESIGN

This was a retrospective, single-center, observational study.

SETTING

Cardiac surgery department of a tertiary care center in North-east Italy.

PARTICIPANTS

Cardiac surgery patients requiring cardiac bypass in 2017 and 2019.

INTERVENTIONS

The primary outcome was to compare platelet transfusion practice before and after the implementation of a platelet function test (the ADP test) into the institution's transfusion algorithm, which replaced the platelet count as the trigger. Secondary outcomes were assessing whether the incorporation of the ADP test into their transfusion algorithm brought about a reduction in the frequency of platelet transfusions compared with previous rates (when only platelets counts were used); assessing patient blood loss in the first 12 postoperative hours; and ascertaining the percentage of patients requiring surgical reexplorations.

MEASUREMENTS AND MAIN RESULTS

The study comprised 110 patients undergoing cardiac surgery from the platelet count period (2017) and 110 patients from the ADP test period (2019). Agreement between platelet counts versus ADP tests in determining the need for platelet transfusion was moderate (κ = 0.483; 95% confidence interval [CI] 0.239-0.728), and the general linear regression relationship between platelet counts and the ADP test (Akaike information criterion = 2536; p < 0.001) was determined. Since the introduction of ADP testing, a highly significant reduction in platelet transfusions has occurred: 41.82% (platelet count period) versus 13.64% (ADP test period) (p < 0.001); average blood loss in the 12 hours postsurgery also was less in the ADP test period (p < 0.001) at 300 mL (95% CI 150-730) compared with 440 mL in the platelet count period (95% CI 135-900). Furthermore, a decreasing trend was observed in the number of patients requiring reexploration to optimize hemostasis in the first 12 hours postsurgery (6.36% v 2.73%); however, this trend did not achieve statistical significance (p = 0.195).

CONCLUSION

The application of new Multiplate analyzer technologies, like the ADP test, have the potential to reduce platelet transfusion rates in cardiac surgery patients compared with the use of platelet counts alone; this point-of-care test may constitute an important strategy to help spare the use of allogeneic blood products. Additional studies are needed to confirm this trend and establish the best cutoff values to apply.

Effects of cardiopulmonary bypass with low-priming volume on clinical outcomes in children undergoing congenital heart disease surgery

Background

Cardiopulmonary bypass (CPB) with high-priming volume can significantly activate the inflammatory response and increse the usage of packed red blood cells (PRBCs). As risks and complications related to transfusions are increasing, many cardiac centers are focusing on reducing the priming volume of CPB. In our center, efforts have also been made to reduce the priming volume, and the effects of CPB with low-priming volume on clinical outcomes in children undergoing congenital heart disease (CHD) surgery were investigated in this study to provide referential experiences for pediatric CPB.

Methods

The clinical case data of 158 children undergoing CHD surgery with CPB were collected. The children were divided into the low-priming-volume group (group A, n = 79) and the traditional group (group B, n = 79) according to the priming volume. The amount of PRBCs transfused, the postoperative hematological test results and the clinical outcomes of the two groups were compared by the independent sample t-test or the chi-square test.

Results

The amount of PRBCs transfused during CPB and during the whole operation were significantly lower in group A than in group B (p < 0.01), but the hemoglobin (Hb) concentration was higher in group A on the first day after surgery (p < 0.01) and before hospital discharge. However, the latter showed no statistical significant difference. The lowest postoperative platelet count was higher in group A than in group B (p < 0.05). There was no statistical difference in the postoperative inflammatory markers and the main clinical outcomes between the two groups.

Conclusions

The usage of PRBCs in CPB with low-priming volume decreased significantly, but the postoperative Hb concentration and platelet count could still be maintained at a high level, improving the use efficiency of PRBCs. CPB with low-priming volume did not affect the postoperative recovery of patients, so it is worthy of continuous promotion and optimization.

Assessment of hemostatic profile in patients with mild to advanced liver cirrhosis

BACKGROUND

Hemostasis of patients suffering from liver cirrhosis is challenging due to both, pro- and anticoagulatory disorders leading to hemostatic alterations with distinct abnormalities of coagulation. Pathological changes in conventional coagulation analysis and platelet count are common manifestations of decreased liver synthesis of coagulation factors and reduced platelet count in these patients. However, conventional coagulation analysis and platelet count do not reflect in-vivo coagulation status or platelet function. The purpose of this present observational study was therefore to assess the haemostatic profile including plasmatic coagulation using thrombelastometry and impedance aggregometry for platelet function in patients suffering from liver cirrhosis.

AIM

To assess the hemostatic profile of cirrhotic patients according to model for end-stage liver disease (MELD) score.

METHODS

Our study included both in- and outpatients suffering from liver cirrhosis attending the out- and inpatient care of the department of hepatology. Demographic and biochemical data as well as medical history including cause of liver cirrhosis, end stage kidney failure and medication with anticoagulants were recorded. To assess the hemostatic profile, platelet function was analyzed by multiple electrode aggregometry (MEA) using Multiplate^® (ADP-, ASPI- and TRAP-test) and thrombelastometry using ROTEM^® (EXTEM, INTEM, FIBTEM). Data were compared using Mann-Whitney U- or χ²-test. Spearman correlation was performed to analyze the association between MELD Score and results of thrombelastometry and MEA.

RESULTS

A total of 68 patients attending the out- and inpatient care suffering from liver cirrhosis were screened. Of these, 50 patients were included and assigned to groups according to MELD score 6 to 11 (n = 25) or ≥ 17 (n = 25). Baseline patient characteristics revealed significant differences for MELD score (8 vs 22, P < 0.0001) and underlying laboratory parameters (international normalized ratio, bilirubine, creatinine) as well as fibrinogen level (275 mg/dL vs 209 mg/dL, P = 0.006) and aPTT (30 s vs 35 s, P = 0.047). MEA showed a moderately impaired platelet function (medians: AUC_ADP = 43U, AUC_ASPI = 71U, AUC_TRAP = 92U) but no significant differences between both groups. Thrombelastometry using ROTEM^® (EXTEM, INTEM, FIBTEM) revealed values within normal range in both groups. No significant correlation was observed between MELD score and results of MEA/thrombelastometry.

CONCLUSION

Our data demonstrate a partially impaired hemostatic profile in liver cirrhosis patients unrelated to MELD score. An individual assessment of a potential coagulopathy should therefore be considered.

Platelet Transfusion Practice and Related Outcomes in Pediatric Extracorporeal Membrane Oxygenation

OBJECTIVE

To describe factors associated with platelet transfusion during pediatric extracorporeal membrane oxygenation and the relationships among platelet transfusion, complications, and mortality.

DESIGN

Secondary analysis of data collected prospectively by the Collaborative Pediatric Critical Care Research Network between December 2012 and September 2014.

SETTING

Eight Collaborative Pediatric Critical Care Research Network-affiliated hospitals.

PATIENTS

Age less than 19 years old and treated with extracorporeal membrane oxygenation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 511 children, 496 (97.1%) received at least one platelet transfusion during extracorporeal membrane oxygenation. Neonatal age, venoarterial extracorporeal membrane oxygenation, and various acute and chronic diagnoses were associated with increased average daily platelet transfusion volume (milliliters per kilogram body weight). On multivariable analysis, average daily platelet transfusion volume was independently associated with mortality (per 1 mL/kg; odds ratio, 1.05; CI, 1.03-1.08; p < 0.001), whereas average daily platelet count was not (per 1 × 10/L up to 115 × 10/L; odds ratio, 1.00; CI, 0.98-1.01; p = 0.49). Variables independently associated with increased daily bleeding risk included increased platelet transfusion volume on the previous extracorporeal membrane oxygenation day, a primary cardiac indication for extracorporeal membrane oxygenation, adolescent age, and an acute diagnosis of congenital cardiovascular disease. Variables independently associated with increased daily thrombotic risk included increased platelet transfusion volume on the previous extracorporeal membrane oxygenation day and venoarterial extracorporeal membrane oxygenation. Variables independently associated with decreased daily thrombotic risk included full-term neonatal age and an acute diagnosis of airway abnormality.

CONCLUSIONS

Platelet transfusion was common in this multisite pediatric extracorporeal membrane oxygenation cohort. Platelet transfusion volume was associated with increased risk of mortality, bleeding, and thrombosis.

Gender-based differences in platelet function and platelet reactivity to P2Y12 inhibitors

Background

Gender influences platelet biology. Women have a larger platelet count, but gender-based differences in platelet function remain debated. We performed a study addressing gender-based differences in platelet function using point-of-care platelet function tests (PFT).

Methods

The patient population consisted of 760 cardiac surgery patients where preoperative PFT (multiple-electrode aggregometry [MEA]) were available. Platelet count and function at the ADPtest and TRAPtest were compared in the overall population and separately in patients with or without residual effects of P2Y₁₂ inhibitors.

Results

Women had a significantly (P = 0.001) higher platelet count but a non-significantly higher platelet reactivity to ADP. In clopidogrel-treated patients, the platelets ADP reactivity was significantly (P = 0.031) higher in women, and platelet count was the main determinant of platelet hyper-reactivity. Within patients under full clopidogrel effects, women with a platelet count ≥ 200,000 cells/μL had a significantly (P = 0.023) higher rate of high-on-treatment platelet reactivity (HTPR, 45.5%) with respect to males with a platelet count < 200,000 cells/μL (11.9%), with a relative risk of 6.2 (95% confidence interval 1.4–29).

Conclusions

Our findings confirm that women have a larger platelet count than men, and that this is associated to a trend towards a higher platelet reactivity. HTPR is largely represented in women with a high platelet count. This generates the hypothesis that women requiring P2Y₁₂ inhibitors could potentially benefit from larger doses of drug or should be treated with anti-platelet agents with a low rate of HTPR.

Minimal invasive extracorporeal circulation preserves platelet function after cardiac surgery: a prospective observational study

Introduction:

Cardiac surgery on conventional cardiopulmonary bypass induces a combination of thrombocytopenia and platelet dysfunction which is strongly related to postoperative bleeding. Minimal invasive extracorporeal circulation has been shown to preserve coagulation integrity, though effect on platelet function remains unclear. We aimed to prospectively investigate perioperative platelet function in a series of patients undergoing cardiac surgery on minimal invasive extracorporeal circulation using point-of-care testing.

Methods:

A total of 57 patients undergoing elective cardiac surgery on minimal invasive extracorporeal circulation were prospectively recruited. Anticoagulation strategy was based on individualized heparin management and heparin level–guided protamine titration performed in all patients with a specialized point-of-care device (Hemostasis Management System – HMS Plus; Medtronic, Minneapolis, MN, USA). Platelet function was evaluated with impedance aggregometry using the ROTEM platelet (TEM International GmbH, Munich, Germany). ADPtest and TRAPtest values were assessed before surgery and after cardiopulmonary bypass.

Results:

ADPtest value was preserved during surgery on minimal invasive extracorporeal circulation (58.2 ± 20 U vs. 53.6 ± 21 U; p = 0.1), while TRAPtest was found significantly increased (90 ± 27 U vs. 103 ± 38 U; p = 0.03). Postoperative ADPtest and TRAPtest values were inversely related to postoperative bleeding (correlation coefficient: −0.29; p = 0.03 for ADPtest and correlation coefficient: −0.28; p = 0.04 for TRAPtest). The preoperative use of P2Y12 inhibitors was identified as the only independent predictor of a low postoperative ADPtest value (OR = 15.3; p = 0.02).

Conclusion:

Cardiac surgery on minimal invasive extracorporeal circulation is a platelet preservation strategy, which contributes to the beneficial effect of minimal invasive extracorporeal circulation in coagulation integrity.