The platelet in cardiopulmonary bypass

Thrombocytopenia after Aortic Valve Replacement Using Sutureless Valves

Background

Sutureless valves are widely used in aortic valve replacement surgery, with Perceval valves and Intuity valves being particularly prominent. However, concerns have been raised about postoperative thrombocytopenia with Perceval valves (Corcym, UK). We conducted a comparative analysis with the Intuity valve (Edwards Lifesciences, USA), and assessed how thrombocytopenia affected patient and transfusion outcomes.

Methods

Among 595 patients who underwent aortic valve replacement from June 2016 to March 2023, sutureless valves were used in 53 (Perceval: n=23; Intuity: n=30). Platelet counts were monitored during hospitalization and outpatient visits. Daily platelet count changes were compared between groups, and the results from patients who underwent procedures using Carpentier Edwards Perimount Magna valves were used as a reference group.

Results

Compared to the Intuity group, the Perceval group showed a significantly higher amount of platelet transfusion (5.48±1.64 packs vs. 0.60±0.44 packs, p=0.008). During the postoperative period, severe thrombocytopenia (<50,000/μL) was significantly more prevalent in the Perceval group (56.5%, n=13) than in the Intuity group (6.7%, n=2). After initial postoperative depletion, daily platelet counts increased, with significant differences observed in the extent of improvement between the Perceval and Intuity groups (p<0.001). However, there was no significant difference in early mortality or the incidence of neurological complications between the 2 groups.

Conclusion

The severity of postoperative thrombocytopenia differed significantly between the Perceval and Intuity valves. The Perceval group showed a significantly higher prevalence of severe thrombocytopenia and higher platelet transfusion volumes. However, thrombocytopenia gradually recovered during the postoperative period in both groups, and the early outcomes were similar in both groups.

Clinical Midterm Results of Surgical Aortic Valve Replacement with Sutureless Valves

Background

Sutureless aortic valves may enable shorter procedure times, which benefits patients with elevated surgical risk. We describe the outcomes of patients with aortic stenosis who underwent aortic valve replacement (AVR) using the sutureless Perceval aortic bioprosthesis.

Methods

Data from a retrospective cohort were obtained from a clinical database. The study enrolled patients with symptomatic severe aortic stenosis who underwent surgical AVR with a sutureless bioprosthesis between August 2015 and December 2020. In total, 113 patients were included (mean age, 75.3±8.4 years; 57.5% women; median Society of Thoracic Surgeons score, 9.7%; mean follow-up period, 51.19±20.6 months). Of these patients, 41 were octogenarians (36.2%) and 3 were nonagenarians (2.6%). Transthoracic echocardiography was employed to assess changes in ejection fraction (EF), left ventricular mass index (LVMI), and mean pressure gradient (MPG).

Results

The in-hospital mortality rate was 2.6%, and 13 patients developed new-onset atrial fibrillation. A permanent pacemaker was implanted in 3 patients (2.6%). The median intensive care unit stay was 1 day (interquartile range [IQR], 1-2 days), and the median hospital stay was 12 days (IQR, 9.5-15 days). The overall survival rate at 5 years was 95.9%. LVMI and MPG were reduced postoperatively, while EF increased over the follow-up period. No structural valve deterioration was observed, and no meaningful paravalvular leakage developed during follow-up.

Conclusion

The use of a sutureless valve in the aortic position is safe and feasible, even for high-risk elderly patients requiring surgical AVR. LVMI and MPG decreased postoperatively, while EF increased over the follow-up period.

The Association of Oxygen Delivery and Transfusion on Cardiopulmonary Bypass with Acute Kidney Injury

OBJECTIVES

To estimate whether the association of transfusion and acute kidney injury (AKI) has a threshold of oxygen delivery below which transfusion is beneficial but above which it is harmful.

DESIGN

Retrospective study SETTING: Cardiovascular operating room and intensive care unit PARTICIPANTS: Patients undergoing cardiac surgery with continuous oxygen delivery monitoring during cardiopulmonary bypass INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: Logistic regression was used to estimate the associations between oxygen delivery (mean, cumulative deficit, and bands of oxygen delivery), transfusion, and their interaction and AKI. A subgroup analysis of transfused and nontransfused patients with exact matching on cumulative oxygen deficit and time on bypass with adjustment for propensity to receive a transfusion using logistic regression. Nine hundred ninety-one of 4,203 patients developed AKI within 7 days. After adjustment for confounders, lower mean oxygen delivery (odds ratio [OR], 0.968; 95% confidence interval [CI], 0.949-0.988; p = 0.002) and transfusions (OR, 1.442; 95% CI, 1.077, 1.932; p = 0.014) were associated with increased odds of AKI by 7 days. As oxygen delivery decreased, the risk of AKI increased, with the slope of the OR steeper at <160 mL/m2/min. In the subgroup analysis, matched transfused patients were more likely than matched nontransfused patients to develop AKI (45% [n = 145] v 31% [n = 101]; p < 0.001). However, after propensity score adjustment, the difference was nonsignificant (OR, 1.181; 95% CI, 0.796-1.752; p = 0.406).

CONCLUSIONS

We found a nonlinear relationship between oxygen delivery and AKI. We found no level of oxygen delivery at which transfusion was associated with a decreased risk of AKI.

Thrombocytopenia after sutureless and standard stented aortic valve replacement: a retrospective analysis of risk factors, clinical course, and early outcome

OBJECTIVES

Thrombocytopenia following Perceval aortic valve replacement has been described previously with variable outcome. Studies have lacked a robust analysis of platelet fluctuation and factors affecting it. We aimed to statistically describe the trend in thrombocyte variability as compared with conventional aortic valve replacement, and to assess predictors as well as impact on associated outcomes.

METHODS

One hundred consecutive patients with first-time Perceval were retrospectively compared to 219 patients after Perimount Magna Ease valve replacement. The primary outcome was the serial thrombocyte count on day 0-6. Generalized estimating equations were used to analyse the data using fixed-effect models: for the effect of the post-operative day on platelet count, and random-effect models estimating both time-variant (platelets) and time in-variant variables (valve type, age, LV function, pre-op platelet level).

RESULTS

Perceval patients were older (72 ± 1 vs 68 ± 1 years, p < 0.01) with higher NYHA status (3(2-3) vs 2(1-2), p < 0.001). Mean platelet count in the sutureless group was lowest on day 2 (91.9 ± 31.6 vs 121.7 ± 53.8 × 103 µl-1), and lower on day 4 (97.9 ± 44) and 6 (110.6 ± 61) compared to the conventional group (157.2 ± 60 and 181.7 ± 79) but did not result in a higher number of transfusions, bleeding or longer hospital stay (p > 0.05). Reduced platelet count was a strong predictor of red cell transfusion in the conventional (p = 0.016), but not in the sutureless group (p = 0.457). Age (Coef -1.025, 95%CI-1.649--0.401, p < 0.001) and CPB-time (Coef 0.186, 95%CI-0.371--0.001, p = 0.048) were predictors for lower platelet levels.

CONCLUSION

Considering the older patient profile treated with Perceval, postoperative thrombocytopenia does not impact on outcome in terms of transfusions, complications or hospital stay.

Cardiopulmonary bypass parameters improve the prediction of 30-day mortality following cardiac surgery

Currently 30-day mortality is commonly used as a quality indicator for cardiac surgery; however, prediction models have not included the role of cardiopulmonary bypass (CPB). We hypothesized that reproducing currently utilised prediction model methods of 30-day mortality using the Australian and New Zealand Collaborative Perfusion Registry (ANZCPR) would identify relevant CPB predictors. Nine centers in Australia and New Zealand collected data using the ANZCPR between 2011-2020. CPB parameter selection was determined by evaluating association with 30-day mortality. Data were divided into model creation (n = 15,073) and validation sets (n = 15,072). Bootstrap sampling and automated variable selection methods were used to develop candidate models. The final model was selected using prediction mean square error and Bayesian Information Criteria. The average receiver operating characteristic (ROC), p-value for Hosmer-Lemeshow chi-squared test and MSE were obtained from multifold validation. In total, 30,145 patients were included, of which 735 (2.4%) died within 30 day of surgery. The area under the ROC curve for the model including CPB parameters was significantly greater than preoperative risk factors only (0.829 vs 0.783, p < 0.001). CPB parameters included in the predictive model were CPB time, red blood cell transfusion, mean arterial pressure <50 mmHg, minimum oxygen delivery, cardiac index <1.6 L/min/m2. CPB parameters improve the prediction of 30-day mortality. Randomised trials designed to evaluate modifiable CPB parameters will determine their impact on mortality.

Real-Time Detection of Circulating Thrombi in an Extracorporeal Circuit Using Doppler Ultrasound: In-Vitro Proof of Concept Study

BACKGROUND

Thromboembolic stroke continues to be by far the most common severe adverse event in patients supported with mechanical circulatory assist devices. Feasibility of using Doppler ultrasound to detect circulating thrombi in an extracorporeal circuit was investigated.

METHODS

A mock extracorporeal circulatory loop of uncoated cardiopulmonary bypass tubing and a roller pump was setup. A Doppler bubble counter was used to monitor the mean ultrasound backscatter signal (MUBS). The study involved two sets of experiments. In Scenario 1, the circuit was sequentially primed with human blood components, and the MUBS was measured. In Scenario 2, the circuit was primed with heparinized fresh porcine blood, and the MUBS was measured. Fresh blood clots (diameter <1,000 microns, 1,000-5,000 microns, >5,000 microns) were injected into the circuit followed by protamine administration.

RESULTS

In Scenario 1 (n = 3), human platelets produced a baseline MUBS of 1.5 to 3.5 volts/s. Addition of packed human red blood cells increased the baseline backscatter to 17 to 21 volts/s. Addition of fresh frozen plasma did not change the baseline backscatter. In Scenario 2 (n = 5), the blood-primed circuit produced a steady baseline MUBS. Injection of the clots resulted in abrupt and transient increase (range: 3-30 volts/s) of the baseline MUBS. Protamine administration resulted in a sustained increase of MUBS followed by circuit thrombosis.

CONCLUSIONS

Doppler ultrasound may be used for real-time detection of circulating solid microemboli in the extracorporeal circuit. This technology could potentially be used to design safety systems that can reduce the risk of thromboembolic stroke associated with mechanical circulatory support therapy.

Activity of anticoagulant proteins on the polymer-coated and heparin-coated membranes in an extracorporeal circulation circuit

INTRODUCTION

We performed in vitro experiments using whole human blood without anticoagulants to clarify the activity of anticoagulant proteins on membranes coated with acrylate-copolymer (ACP) with a hydrophilic blood-contacting layer compared to those coated by immobilizing heparin (IHP) in extracorporeal circulation.

METHODS

Whole human blood from healthy volunteers was recirculated in two types of experimental circuits with an ACP-coated reservoir and tubes and an ACP-coated or IHP-coated membrane. To compare the fluctuation of anticoagulant proteins, the circuit pressure at the inlet and outlet of the membrane was measured every 5 min; antithrombin antigen (ATQ), antithrombin activity, protein-C quantitation (PCQ), protein-C activity, protein-S free antigen (PSQ), and protein-S activity were measured at 0, 30, 60, 120, and 180 min in each experiment (n = 5).

RESULTS

The time taken to achieve high circuit pressure (> 300 mmHg) at the inlet of the membrane was significantly shorter in the ACP-coated membrane circuit (28 ± 2.7 min) than in the IHP-coated membrane circuit (54 ± 24 min); however, the ATQ, PCQ, and PSQ at 180 min of recirculation were significantly higher in the former than in the latter (all p < .05).

CONCLUSIONS

ACP-coated membranes can prevent the consumption of anticoagulant proteins but cannot delay circuit thrombogenicity compared to IHP-coated membranes. Considering patient care during the post-extracorporeal circulation period, the use of ACP coating, which can preserve anticoagulant protein, is better in extracorporeal circulation circuits.

Inflammation and Oxidative Stress in the Context of Extracorporeal Cardiac and Pulmonary Support

Extracorporeal circulation (ECC) systems, including cardiopulmonary bypass, and extracorporeal membrane oxygenation have been an irreplaceable part of the cardiothoracic surgeries, and treatment of critically ill patients with respiratory and/or cardiac failure for more than half a century. During the recent decades, the concept of extracorporeal circulation has been extended to isolated machine perfusion of the donor organ including thoracic organs (ex-situ organ perfusion, ESOP) as a method for dynamic, semi-physiologic preservation, and potential improvement of the donor organs. The extracorporeal life support systems (ECLS) have been lifesaving and facilitating complex cardiothoracic surgeries, and the ESOP technology has the potential to increase the number of the transplantable donor organs, and to improve the outcomes of transplantation. However, these artificial circulation systems in general have been associated with activation of the inflammatory and oxidative stress responses in patients and/or in the exposed tissues and organs. The activation of these responses can negatively affect patient outcomes in ECLS, and may as well jeopardize the reliability of the organ viability assessment, and the outcomes of thoracic organ preservation and transplantation in ESOP. Both ECLS and ESOP consist of artificial circuit materials and components, which play a key role in the induction of these responses. However, while ECLS can lead to systemic inflammatory and oxidative stress responses negatively affecting various organs/systems of the body, in ESOP, the absence of the organs that play an important role in oxidant scavenging/antioxidative replenishment of the body, such as liver, may make the perfused organ more susceptible to inflammation and oxidative stress during extracorporeal circulation. In the present manuscript, we will review the activation of the inflammatory and oxidative stress responses during ECLP and ESOP, mechanisms involved, clinical implications, and the interventions for attenuating these responses in ECC.

Renal and Cerebral Hypoxia and Inflammation During Cardiopulmonary Bypass

Cardiac surgery-associated acute kidney injury and brain injury remain common despite ongoing efforts to improve both the equipment and procedures deployed during cardiopulmonary bypass (CPB). The pathophysiology of injury of the kidney and brain during CPB is not completely understood. Nevertheless, renal (particularly in the medulla) and cerebral hypoxia and inflammation likely play critical roles. Multiple practical factors, including depth and mode of anesthesia, hemodilution, pump flow, and arterial pressure can influence oxygenation of the brain and kidney during CPB. Critically, these factors may have differential effects on these two vital organs. Systemic inflammatory pathways are activated during CPB through activation of the complement system, coagulation pathways, leukocytes, and the release of inflammatory cytokines. Local inflammation in the brain and kidney may be aggravated by ischemia (and thus hypoxia) and reperfusion (and thus oxidative stress) and activation of resident and infiltrating inflammatory cells. Various strategies, including manipulating perfusion conditions and administration of pharmacotherapies, could potentially be deployed to avoid or attenuate hypoxia and inflammation during CPB. Regarding manipulating perfusion conditions, based on experimental and clinical data, increasing standard pump flow and arterial pressure during CPB appears to offer the best hope to avoid hypoxia and injury, at least in the kidney. Pharmacological approaches, including use of anti-inflammatory agents such as dexmedetomidine and erythropoietin, have shown promise in preclinical models but have not been adequately tested in human trials. However, evidence for beneficial effects of corticosteroids on renal and neurological outcomes is lacking. © 2021 American Physiological Society. Compr Physiol 11:1-36, 2021.

Perioperative platelet reduction after sutureless or stented valve implantation: results from the PERSIST-AVR controlled randomized trial

OBJECTIVES

Platelet count reduction is a common but not fully understood phenomenon after aortic valve replacement (AVR) with bioprosthesis implantation. The aim of the present study was to investigate the occurrence and the clinical impact of platelet count reduction in patients receiving the Perceval bioprosthesis compared to those receiving standard sutured stented bioprosthetic aortic valve in a randomized, controlled AVR study.

METHODS

PERceval Sutureless Implant versus STandard Aortic Valve Replacement is a prospective, randomized, adaptive, open-label trial. Patients were randomized (March 2016-September 2018) to AVR with a sutureless or stented valve. Ad hoc analyses have been performed to evaluate the occurrence of platelet count reduction and the clinical impact of the platelet variations in the 2 groups.

RESULTS

The Perceval group showed a higher platelet reduction than the control group (46% vs 32%). The phenomenon was transient in both groups, with a slow recovery of the platelet count by hospital discharge. No differences were observed between groups regarding need of transfusions, blood loss, major bleeding and stroke events.

CONCLUSIONS

The Perceval sutureless aortic bioprosthesis implantation is associated with higher rate of transient platelet reduction as compared to stented bioprostheses for AVR. However, the platelet count reduction is transient and the decline does not affect the patient's clinical outcomes. Current explanations for this phenomenon are speculative, and further investigations are required to elucidate it.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02673697-ClinicalTrials.gov-4 February 2016.

Device-Induced Hemostatic Disorders in Mechanically Assisted Circulation

Mechanically assisted circulation (MAC) sustains the blood circulation in the body of a patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) or on ventricular assistance with a ventricular assist device (VAD) or on extracorporeal membrane oxygenation (ECMO) with a pump-oxygenator system. While MAC provides short-term (days to weeks) support and long-term (months to years) for the heart and/or lungs, the blood is inevitably exposed to non-physiological shear stress (NPSS) due to mechanical pumping action and in contact with artificial surfaces. NPSS is well known to cause blood damage and functional alterations of blood cells. In this review, we discussed shear-induced platelet adhesion, platelet aggregation, platelet receptor shedding, and platelet apoptosis, shear-induced acquired von Willebrand syndrome (AVWS), shear-induced hemolysis and microparticle formation during MAC. These alterations are associated with perioperative bleeding and thrombotic events, morbidity and mortality, and quality of life in MCS patients. Understanding the mechanism of shear-induce hemostatic disorders will help us develop low-shear-stress devices and select more effective treatments for better clinical outcomes.

Left ventricular assist device implantation causes platelet dysfunction and proinflammatory platelet-neutrophil interaction

Blood flow through left ventricular assist devices (LVAD) may induce activation and dysfunction of platelets. Dysfunctional platelets cause coagulation disturbances and form platelet-neutrophil conjugates (PNC), which contribute to inflammatory tissue damage. This prospective observational cohort study investigated patients, who underwent implantation of a LVAD (either HeartMate II (HM II) (n = 7) or HeartMate 3 (HM 3) (n = 6)) and as control patients undergoing coronary artery bypass grafting (CABG) and/or aortic valve replacement (AVR) (n = 10). We performed platelet and leukocyte flow cytometry, analysis of platelet activation markers, and platelet aggregometry. Platelet CD42b expression was reduced at baseline and perioperatively in HM II/3 compared to CABG/AVR patients. After surgery the platelet activation marker β-thromboglobulin and platelet microparticles increased in all groups while platelet aggregation decreased. Platelet aggregation was more significantly impaired in LVAD compared to CABG/AVR patients. PNC were higher in HM II compared to HM 3 patients. We conclude that LVAD implantation is associated with platelet dysfunction and proinflammatory platelet-leukocyte binding. These changes are less pronounced in patients treated with the newer generation LVAD HM 3. Future research should identify device-specific LVAD features, which are associated with the least amount of platelet activation to further improve LVAD therapy.

Effects of remote ischemic preconditioning on platelet activation and reactivity in patients undergoing cardiac surgery using cardiopulmonary bypass: a randomized controlled trial

During cardiopulmonary bypass (CPB), platelet activation and dysfunction are associated with adverse outcomes. Remote ischemic preconditioning (RIPC) has been shown to attenuate platelet activation. We evaluated the effects of RIPC on platelet activation during CPB in patients undergoing cardiac surgery. Among 58 randomized patients, 26 in the RIPC group and 28 in the sham-RIPC group were analyzed. RIPC consisted of 4 cycles of 5-min ischemia induced by inflation of pneumatic cuff pressure to 200 mmHg, followed by 5-min reperfusion comprising deflation of the cuff on the upper arm. Platelet activation was assessed using flow cytometry analysis of platelet activation markers. The primary endpoint was the AUC of CD62P expression during the first 3 h after initiation of CPB. Secondary outcomes were the AUC of PAC-1 expression and monocyte-platelet aggregates (MPA) during 3 h of CPB. The AUCs of CD62P expression during 3 h after initiation of CPB were 219.4 ± 43.9 and 211.0 ± 41.2 MFI in the RIPC and sham-RIPC groups, respectively (mean difference, 8.42; 95% CI, -14.8 and 31.7 MFI; p =.471). The AUCs of PAC-1 expression and MPA did not differ between groups. RIPC did not alter platelet activation and reactivity during CPB in patients undergoing cardiac surgery.

Neither Preoperative Pulse Pressure nor Systolic Blood Pressure Is Associated With Cardiac Complications After Coronary Artery Bypass Grafting

BACKGROUND

Increased pulse pressure has been associated with adverse cardiovascular events, cardiac and all-cause mortality in surgical and nonsurgical patients. Whether increased pulse pressure worsens myocardial injury and dysfunction after cardiac surgery, however, has not been fully characterized. We examined whether cardiac surgical patients with elevated pulse pressure are more susceptible to myocardial injury, dysfunction, cardiac-related complications, and mortality. Secondarily, we examined whether pulse pressure was a stronger predictor of the outcomes than systolic blood pressure.

METHODS

This retrospective observational study included adult cardiac surgical patients having elective isolated on-pump coronary artery bypass grafting (CABG) between 2010 and 2017 at the Cleveland Clinic. The association between elevated pulse pressure and (1) perioperative myocardial injury, measured by postoperative troponin-T concentrations, (2) perioperative myocardial dysfunction, assessed by the requirement for perioperative inotropic support using the modified inotropic score (MIS), and (3) cardiovascular complications assessed by the composite outcome of postoperative mechanical circulatory assistance or in-hospital mortality were assessed using multivariable linear regression models. Secondarily, the association between pulse pressure versus systolic blood pressure and the outcomes were compared.

RESULTS

Of 2704 patients who met the inclusion/exclusion criteria, complete data were available for 2003 patients. Increased pulse pressure over 40 mm Hg was associated with elevated postoperative troponin-T level, estimated to be 1.05 (97.5% confidence interval [CI], 1.02-1.09; P < .001) times higher per 10 mm Hg increase in pulse pressure. The association between pulse pressure and myocardial dysfunction and the composite outcome of cardiovascular complications and death were not significant. There was no difference in the association with pulse pressure versus systolic blood pressure and troponin-T concentrations.

CONCLUSIONS

Elevated preoperative pulse pressure was associated with a modest increase in postoperative troponin-T concentrations, but not postoperative cardiovascular complications or in-hospital mortality in patients having CABG. Pulse pressure was not a better predictor than systolic blood pressure.

Partial upper sternotomy for concomitant left atrial ablation and aortic valve replacement

BACKGROUND

Minimally invasive access via partial sternotomy has been established for aortic valve surgery in the past years. But concomitant procedures like atrial ablation and aortic valve replacement via partial upper sternotomy have not been investigated so far. We therefore present our operative technique and results in terms of safety and efficacy, including follow-up and quality of life.

METHODS

Between February 2007 and March 2014 a total of 67 patients undergoing isolated minimally invasive aortic valve replacement received concomitant left atrial ablation at our centre. Operative technique and short- and midterm results are described, including quality of life assessment using the SF-36 questionnaire.

RESULTS

Operative techniqual success rate was 98.5%. We observed only one (1.5%) ablation-related conversion to full sternotomy. Operative times, reexploration and stroke rates as well as 30-day mortality are comparable to open procedures. Efficacy: The proportions of patients in sinus rhythm at discharge was 54.5% for paroxysmal AF patients and 27.7% overall. After a mean follow-up time of 38.0±22.6 months the cardiac related mortality rate was 4.5%, the rate of sinus rhythm was 72.7% for paroxysmal AF patients and 36.8% overall. Of survivors, overall mean quality of life was 7.3±2.1 as measured by SF-36.

CONCLUSIONS

Concomitant left atrial ablation and aortic valve replacement can safely be performed via partial sternotomy and results are non-inferior to open surgery.

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.

The blood protective effect of autologous platelet separation in aortic dissection

OBJECTIVE

This study aimed to retrospectively analyze the blood protective effect of autologous platelet separation in operations for acute aortic dissection.

METHODS

A total of 130 patients with acute aortic dissection were enrolled into the present study. The average age of these patients was 52.962±10.5061 years old. These patients underwent the modified aortic arch replacement with the elephant trunk technique or endovascular aortic exclusion with covered stent. Among these patients, 68 patients who underwent autologous platelet separation were assigned to the platelet separation group, while the remaining patients were assigned to the control group. All operations were performed under deep hypothermic circulatory arrest. After anesthesia, 1-2 therapeutic doses of autologous platelets were isolated from patients in the platelet separation group, and these platelets were quickly infused back to these patients after heparin was neutralized by protamine at the end of the cardiopulmonary bypass. The preoperative and postoperative indexes in these two groups were compared.

RESULTS

There were no statistically significant differences in age, gender, smoking history, drinking history and hypertension history between these two groups. Compared with controls, the transfusion volume of allogeneic platelets in the perioperative period significantly decreased in the platelet separation group (1.919±1.6226 vs. 0.794±1.1789, P < #x003C;< #x200A;0.05), and the use rate of allogeneic platelets also significantly decreased (74.19% vs. 45.59%, P < #x003C;< #x200A;0.05).

CONCLUSION

The intraoperative auto transfusion of platelets significantly reduced the volume of allogeneic platelet transfusion after the operation for aortic dissection, which has a significant blood protective effect.

Therapeutic potential of fibrinogen γ-chain peptide-coated, ADP-encapsulated liposomes as a haemostatic adjuvant for post-cardiopulmonary bypass coagulopathy

Fibrinogen γ-chain peptide-coated, adenosine 5'-diphosphate (ADP)-encapsulated liposomes (H12-ADP-liposomes) are a potent haemostatic adjuvant to promote platelet thrombi. These liposomes are lipid particles coated with specific binding sites for platelet GPIIb/IIIa and encapsulating ADP. They work at bleeding sites, facilitating haemostasis by promoting aggregation of activated platelets and releasing ADP to strongly activate platelets. In this study, we investigated the therapeutic potential of H12-ADP-liposomes on post-cardiopulmonary bypass (CPB) coagulopathy in a preclinical setting. We created a post-CPB coagulopathy model using male New Zealand White rabbits (body weight, 3 kg). One hour after CPB, subject rabbits were intravenously administered H12-ADP-liposomes with platelet-rich plasma (PRP) collected from donor rabbits (H12-ADP-liposome/PRP group, n = 8) or PRP alone (PRP group, n = 8). Ear bleeding time was greatly reduced for the H12-ADP-liposome/PRP group (263 ± 111 s) compared with the PRP group (441 ± 108 s, p < 0.001). Electron microscopy showed platelet thrombus containing liposomes at the bleeding site in the H12-ADP-liposome/PRP group. However, such liposome-involved platelet thrombi were not observed in the end organs after H12-ADP-liposome administration. These findings suggest that H12-ADP-liposomes could help effectively and safely consolidate platelet haemostasis in post-CPB coagulopathy and may have potential for reducing bleeding complications after cardiovascular surgery with CPB.

Prolonged Cardiopulmonary Bypass is Associated With Endothelial Glycocalyx Degradation

BACKGROUND

The endothelial glycocalyx (EG) is involved in critical regulatory mechanisms that maintain endothelial vascular integrity. We hypothesized that prolonged cardiopulmonary bypass (CPB) may be associated with EG degradation. We performed an analysis of soluble syndecan-1 levels in relation to duration of CPB, as well as factors associated with cell stress and damage, such as mitochondrial DNA (mtDNA) and inflammation.

METHODS

Blood samples from subjects undergoing cardiac surgery with CPB (n = 54) were obtained before and during surgery, 4-8 h and 24 h after completion of CPB, and on postoperative day 4. Flow cytometry was used to determine subpopulations of white blood cells. Plasma levels of mtDNA were determined using quantitative polymerase chain reaction and plasma content of shed syndecan-1 was measured. To determine whether syndecan-1 was signaling white blood cells, the effect of recombinant syndecan-1 on mobilization of neutrophils from bone marrow was tested in mice.

RESULTS

CPB is associated with increased mtDNA during surgery, increased syndecan-1 blood levels at 4-8 h, and increased white blood cell count at 4-8 h and 24 h. Correlation analysis revealed significant positive associations between time on CPB and syndecan-1 (r_s = 0.488, P < 0.001) and level of syndecan-1 and neutrophil count (r_s = 0.351, P = 0.038) at 4-8 h. Intravenous administration of recombinant syndecan-1 in mice resulted in a 2.5-fold increase in the number of circulating neutrophils, concurrent with decreased bone marrow neutrophil number.

CONCLUSIONS

Longer duration of CPB is associated with increased plasma levels of soluble syndecan-1, a signal for EG degradation, which can induce neutrophil egress from the bone marrow. Development of therapy targeting EG shedding may be beneficial in patients with prolonged CPB.

Two approaches-one phenomenon-thrombocytopenia after surgical and transcatheter aortic valve replacement

BACKGROPUND AND AIM

Postoperative thrombocytopenia after surgical aortic valve replacement (SAVR) or transcatheter aortic valve replacement (TAVR) and aggravating causes were the aim of this retrospective study.

METHODS

Data of all patients treated with SAVR (n = 1068) and TAVR (n = 816) due to severe aortic valve stenosis was collected at our center from 2010 to 2017. Preprocedural and postprocedural values were collected from electronic patient records.

RESULTS

There was a significant drop in platelets in both groups, the TAVR group showed overall superior platelet preservation compared to the AVR group (P < .001). In the SAVR subgroup analysis, a significant difference in platelet preservation was observed between the valve types (P < .001), particularly with the Freedom SOLO valve. In the TAVR subgroup analysis, the valve type did not influence platelet count (PLT) reduction (P = .13). In the SAVR subgroup analyses, PLT was found to be worsened with cardiopulmonary bypass (CPB) duration.

CONCLUSION

Thrombocytopenia frequently occurs after implantation of a biological heart valve prosthesis, with a higher frequency observed in patients after cardiac surgery rather than TAVR. Although some surgical bioprosthetic models are more susceptible to this phenomenon, CPB duration seems to be a major determinant for the development of postoperative thrombocytopenia.

Impact of high mechanical shear stress and oxygenator membrane surface on blood damage relevant to thrombosis and bleeding in a pediatric ECMO circuit

The roles of the large membrane surface of the oxygenator and the high mechanical shear stress (HMSS) of the pump in the extracorporeal membrane oxygenation (ECMO) circuit were examined under a pediatric support setting. A clinical centrifugal pump and a pediatric oxygenator were used to construct the ECMO circuit. An identical circuit without the oxygenator was constructed for comparison. Fresh human blood was circulated in the two circuits for 4 hours under the identical pump speed and flow. Blood samples were collected hourly for blood damage assessment, including platelet activation, generation of platelet-derived microparticles (PDMP), losses of key platelet hemostasis receptors (glycoprotein (GP) Ibα (GPIbα) and GPVI), and high molecular weight multimers (HMWM) of von Willebrand factor (VWF) and plasma free hemoglobin (PFH). Platelet adhesion on fibrinogen, VWF, and collagen was further examined. The levels of platelet activation and generation of PDMP and PFH exhibited an increasing trend with circulation time while the expression levels of GPIbα and GPVI receptors on the platelet surface decreased. Correspondingly, the platelets in the blood samples exhibited increased adhesion capacity to fibrinogen and decreased adhesion capacities on VWF and collagen with circulation time. Loss of HMWM of VWF occurred in both circuits. No statistically significant differences were found in all the measured parameters for blood damage and platelet adhesion function between the two circuits. The results indicate that HMSS from the pump played a dominant role in blood damage associated with ECMO and the impact of the large surface of the oxygenator on blood damage was insignificant.

Effects of Baseline Thrombocytopenia and Platelet Decrease Following Renal Replacement Therapy Initiation in Patients With Severe Acute Kidney Injury

OBJECTIVES

Thrombocytopenia is common in critically ill patients with severe acute kidney injury and may be worsened by the use of renal replacement therapy. In this study, we evaluate the effects of renal replacement therapy on subsequent platelet values, the prognostic significance of a decrease in platelets, and potential risk factors for platelet decreases.

DESIGN

Post hoc analysis of the Acute Renal Failure Trial Network Study.

SETTING

The Acute Renal Failure Trial Network study was a multicenter, prospective, randomized, parallel-group trial of two strategies for renal replacement therapy in critically ill patients with acute kidney injury conducted between November 2003 and July 2007 at 27 Veterans Affairs and university-affiliated medical centers.

SUBJECTS

The Acute Renal Failure Trial Network study evaluated 1,124 patients with severe acute kidney injury requiring renal replacement therapy.

INTERVENTIONS

Predictor variables were thrombocytopenia at initiation of renal replacement therapy and platelet decrease following renal replacement therapy initiation.

MEASUREMENTS AND MAIN RESULTS

Outcomes were mortality at 28 days, 60 days, and 1 year, renal recovery, renal replacement therapy free days, ICU-free days, and hospital-free days. Baseline thrombocytopenia in patients requiring renal replacement therapy was associated with increased mortality and was also associated with lower rates of renal recovery. A decrease in platelet values following renal replacement therapy initiation was associated with increased mortality. Continuous renal replacement therapy was not an independent predictor of worsening thrombocytopenia compared with those treated with intermittent hemodialysis.

CONCLUSIONS

Baseline thrombocytopenia and platelet decrease following renal replacement therapy initiation were associated with increased mortality, and baseline thrombocytopenia was associated with decreased rates of renal recovery. Continuous renal replacement therapy did not decrease platelets compared with hemodialysis.

Platelet Biogenesis in the Lung Circulation

Megakaryocytes are normal cellular components of the blood returning to the heart and entering the lungs, and historical data has pointed to a role of the lungs in platelet production. Recent studies using intravital microscopy have demonstrated that platelet release occurs in the lung from bone marrow megakaryocytes that embolize into the lung circulation.

Extracorporeal life support and systemic inflammation

Extracorporeal life support (ECLS) encompasses a wide range of extracorporeal modalities that offer short- and intermediate-term mechanical support to the failing heart or lung. Apart from the daily use of cardiopulmonary bypass (CPB) in the operating room, there has been a resurgence of interest and utilization of veno-arterial and veno-venous extracorporeal membrane oxygenation (VA- and VV-ECMO, respectively) and extracorporeal carbon dioxide removal (ECCO₂R) in recent years. This might be attributed to the advancement in technology, nonetheless the morbidity and mortality associated with the clinical application of this technology is still significant. The initiation of ECLS triggers a systemic inflammatory response, which involves the activation of the coagulation cascade, complement systems, endothelial cells, leukocytes, and platelets, thus potentially contributing to morbidity and mortality. This is due to the release of cytokines and other biomarkers of inflammation, which have been associated with multiorgan dysfunction. On the other hand, ECLS can be utilized as a therapy to halt the inflammatory response associated with critical illness and ICU therapeutic intervention, such as facilitating ultra-protective mechanical ventilation. In addition to addressing the impact on outcome of the relationship between inflammation and ECLS, two different but complementary pathophysiological perspectives will be developed in this review: ECLS as the cause of inflammation and ECLS as the treatment of inflammation. This framework may be useful in guiding the development of novel therapeutic strategies to improve the outcome of critical illness.

Review and Update: Hematologic Malignancies and Adult Cardiac Surgery

As treatments for hematologic malignancies continue to advance, many patients with active disease and many more in remission will present for cardiac surgical procedures. Radiation and chemotherapeutic therapies for hematologic malignancies often result in cardiopulmonary injury. Evidence demonstrates that patients with hematologic malignancies undergoing cardiac surgery are at risk for perioperative adverse events, including bleeding, clotting, infection, and immunomodulation. However, short- and long-term mortality has been found to be acceptable. This review will distinguish the important points of characterizing, understanding, and managing hematologic malignancies in the cardiac surgical patient.

Acquired platelet function disorders

The possibility of an acquired platelet function disorder should be considered in patients who present with recent onset muco-cutaneous bleeding. Despite the availability of newer and faster platelet function assays, light transmission aggregometry (LTA) remains the preferred diagnostic test. This review examines and discusses the causes of acquired platelet dysfunction; most commonly drugs, dietary factors, medical disorders and procedures. In addition to well-known antiplatelet therapies, clinicians should be alert for newer drugs which can affect platelets, such as ibrutinib. There is little clinical trial evidence to guide the management of acquired platelet function defects, but we summarise commonly employed strategies, which include addressing the underlying cause, antifibrinolytic agents, desmopressin infusions, and in selected patients, platelet transfusions.

The association between platelet dysfunction and adverse outcomes in cardiac surgical patients

Haemostatic activation during cardiopulmonary bypass is associated with prothrombotic complications. Although it is not possible to detect and quantify haemostatic activation directly, platelet dysfunction, as measured with point-of-care-assays, may be a useful surrogate. In this study, we assessed the association between cardiopulmonary bypass-associated platelet dysfunction and adverse outcomes in 3010 cardiac surgical patients. Platelet dysfunction, as measured near the end of the rewarming phase of cardiopulmonary bypass, was calculated as the proportion of non-functional platelets after activation with collagen. Logistic regression and multivariable analyses were applied to assess the relationship between platelet dysfunction and a composite of in-hospital death; myocardial infarction; stroke; deep vein thrombosis or pulmonary embolism; and acute kidney injury (greater than a two-fold increase in creatinine). The outcome occurred in 251 (8%) of 3010 patients. The median (IQR [range]) percentage platelet dysfunction was less for those without the outcome as compared with those with the outcome; 14% (8-28% [1-99%]) vs. 19% (11-45% [2-98%]), p < 0.001. After risk adjustment, platelet dysfunction was independently associated with the composite outcome (p < 0.001), such that for each 1% increase in platelet dysfunction there was an approximately 1% increase in the composite outcome (OR 1.012; 95%CI 1.006-1.018). This exploratory study suggests that cardiopulmonary bypass-associated platelet dysfunction has prognostic value and may be a useful clinical measure of haemostatic activation in cardiac surgery.

Thrombocytopenia After Aortic Valve Replacement: Comparison Between Sutureless Perceval S Valve and Perimount Magna Ease Bioprosthesis

Introduction

The incidence of postoperative thrombocytopenia after aortic valve replacement (AVR) with the Perceval S Sutureless bioprosthesis remains unclear. The aim of this study was to report thrombocytopenia associated with the use of sutureless AVR.

Methods

The data was collected retrospectively for patients who had isolated AVR with sutureless Perceval S valve (Group A: 72 patients) and was compared with patients who underwent isolated sutured AVR with Perimount Magna Ease Bioprosthesis (Group B: 101 patients) in our institution between June 2014 and January 2017.

Results

Cardiopulmonary bypass and cross-clamp time were significantly shorter in group A. Maximum drop in platelet count was 58% mean (day 2.3) in group A versus 44% mean (day 1.7) in group B (P=0.0001). Absolute platelet count on postoperative day 1-6 in group A was significantly less than in group B (P≤0.05). Platelet count recovered to preoperative value in 44% patients in group B versus only in 26% patients in group A at discharge (P=0.018). Moderate thrombocytopenia occurs more often in group A (41% vs. 26%) (P=0.008) while severe thrombocytopenia (<50 x 10⁹) was observed in 6% in group A but never in group B. Platelets (P=0.007) and packed red blood cells (P=0.009) transfusion was significantly higher in the group A.

Conclusion

The implantation of sutureless Perceval aortic valves was associated with a significant drop in platelet count postoperatively with slow recovery and higher platelets and packed red blood cells transfusion requirements. A prospective randomised trial is needed to confirm our findings.

Thrombotic Thrombocytopenic Purpura Following Aortic Valve Replacement with St. Jude Medical Trifecta Bio-Prosthesis

Thrombocytopenia is a recognized complication following aortic valve replacement (AVR). While post-operative thrombotic thrombocytopenic purpura (TTP) is less common than heparin-induced thrombocytopenia (HIT), it is associated with high mortality and morbidity and prompt diagnosis and treatment is vital. In this case report, we describe the first reported case of TTP after AVR using the trifecta bio-prosthesis. We recommend that patients with severe and progressive thrombocytopenia following biological AVR should have early screening for both HIT and TTP, to shorten the decision-making process and provide the appropriate therapy.

Fish Oil and Perioperative Bleeding

Background Fish oil is among the most common natural supplements for treatment of hypertriglyceridemia or prevention of cardiovascular disease. However, concerns about theoretical bleeding risk have led to recommendations that patients should stop taking fish oil before surgery or delay in elective procedures for patients taking fish oil by some health care professionals. Methods and Results We tested the effect of fish oil supplementation on perioperative bleeding in a multinational, placebo-controlled trial involving 1516 patients who were randomized to perioperative fish oil (eicosapentaenoic acid+docosahexaenoic acid; 8-10 g for 2-5 days preoperatively, and then 2 g/d postoperatively) or placebo. Primary outcome was major perioperative bleeding as defined by the Bleeding Academic Research Consortium. Secondary outcomes include perioperative bleeding per thrombolysis in myocardial infarction and International Society on Thrombosis and Hemostasis definitions, chest tube output, and total units of blood transfused. Participants' mean (SD) age was 63 (13) years, and planned surgery included coronary artery bypass graft (52%) and valve surgery (50%). The primary outcome occurred in 92 patients (6.1%). Compared with placebo, risk of Bleeding Academic Research Consortium bleeding was not higher in the fish oil group: odds ratio, 0.81; 95% CI, 0.53-1.24; absolute risk difference, 1.1% lower (95% CI, -3.0% to 1.8%). Similar findings were seen for secondary bleeding definitions. The total units of blood transfused were significantly lower in the fish oil group compared with placebo (mean, 1.61 versus 1.92; P<0.001). Evaluating achieved plasma phospholipid omega-3 polyunsaturated fatty acids levels with supplementation (on the morning of surgery), higher levels were associated with lower risk of Bleeding Academic Research Consortium bleeding, with substantially lower risk in the third (odds ratio, 0.30 [95% CI, 0.11-0.78]) and fourth (0.36 [95% CI, 0.15-0.87]) quartiles, compared with the lowest quartile. Conclusions Fish oil supplementation did not increase perioperative bleeding and reduced the number of blood transfusions. Higher achieved n-3-PUFA levels were associated with lower risk of bleeding. These novel findings support the need for reconsideration of current recommendations to stop fish oil or delay procedures before cardiac surgery. Clinical Trial Registration URL: https://www.clinicaltrials.gov . Unique identifier: NCT00970489.

Genome-Wide Association Study Links Receptor Tyrosine Kinase Inhibitor Sprouty 2 to Thrombocytopenia after Coronary Artery Bypass Surgery

INTRODUCTION

 Thrombocytopenia after cardiac surgery independently predicts stroke, acute kidney injury and death. To understand the underlying risks and mechanisms, we analysed genetic variations associated with thrombocytopenia in patients undergoing coronary artery bypass grafting (CABG) surgery.

MATERIALS AND METHODS

 Study subjects underwent isolated on-pump CABG surgery at Duke University Medical Center. Post-operative thrombocytopenia was defined as platelet count < 100 × 10⁹/L. Using a logistic regression model adjusted for clinical risk factors, we performed a genome-wide association study in a discovery cohort (n = 860) and validated significant findings in a replication cohort (n = 296). Protein expression was assessed in isolated platelets by immunoblot.

RESULTS

 A total of 63 single-nucleotide polymorphisms met a priori discovery thresholds for replication, but only 1 (rs9574547) in the intergenic region upstream of sprouty 2 (SPRY2) met nominal significance in the replication cohort. The minor allele of rs9574547 was associated with a lower risk for thrombocytopenia (discovery cohort, odds ratio, 0.45, 95% confidence interval, 0.30-0.67, p = 9.76 × 10^-5) with the overall association confirmed by meta-analysis (meta-p = 7.88 × 10^-6). Immunoblotting demonstrated expression of SPRY2 and its dynamic regulation during platelet activation. Treatment with a functional SPRY2 peptide blunted platelet extracellular signal-regulated kinase (ERK) phosphorylation after agonist stimulation.

CONCLUSION

 We identified the association of a genetic polymorphism in the intergenic region of SPRY2 with a decreased incidence of thrombocytopenia after CABG surgery. Because SPRY2-an endogenous receptor tyrosine kinase inhibitor-is present in platelets and modulates essential signalling pathways, these findings support a role for SPRY2 as a novel modulator of platelet responses after cardiac surgery.

Use of aspirin and bleeding-related complications after hepatic resection

Background

The operative risk of hepatectomy under antiplatelet therapy is unknown. This study sought to assess the outcomes of elective hepatectomy performed with or without aspirin continuation in a well balanced matched cohort.

Methods

Data were retrieved from a multicentre prospective observational study. Aspirin and control groups were compared by non-standardized methods and by propensity score (PS) matching analysis. The main outcome was severe (Dindo–Clavien grade IIIa or more) haemorrhage. Other outcomes analysed were intraoperative transfusion, overall haemorrhage, major morbidity, comprehensive complication index (CCI) score, thromboembolic complications, ischaemic complications and mortality.

Results

Before matching, there were 118 patients in the aspirin group and 1685 in the control group. ASA fitness grade, cardiovascular disease, previous history of angina pectoris, angioplasty, diabetes, use of vitamin K antagonists, cirrhosis and type of hepatectomy were significantly different between the groups. After PS matching, 108 patients were included in each group. There were no statistically significant differences between the aspirin and control groups in severe haemorrhage (6·5 versus 5·6 per cent respectively; odds ratio (OR) 1·18, 95 per cent c.i. 0·38 to 3·62), intraoperative transfusion (23·4 versus 23·7 per cent; OR 0·98, 0·51 to 1·87), overall haemorrhage (10·2 versus 12·0 per cent; OR 0·83, 0·35 to 1·94), CCI score (24 versus 28; P = 0·520), major complications (23·1 versus 13·9 per cent; OR 1·82, 0·92 to 3·79) and 90-day mortality (5·6 versus 4·6 per cent; OR 1·21, 0·36 to 4·09).

Conclusion

This observational study suggested that aspirin continuation is not associated with a higher rate of bleeding-related complications after elective hepatic surgery.

Diagnostic and therapeutic medical devices for safer blood management in cardiac surgery: systematic reviews, observational studies and randomised controlled trials

Background

Anaemia, coagulopathic bleeding and transfusion are strongly associated with organ failure, sepsis and death following cardiac surgery.

Objective

To evaluate the clinical effectiveness and cost-effectiveness of medical devices used as diagnostic and therapeutic tools for the management of anaemia and bleeding in cardiac surgery.

Methods and results

Workstream 1 – in the COagulation and Platelet laboratory Testing in Cardiac surgery (COPTIC) study we demonstrated that risk assessment using baseline clinical factors predicted bleeding with a high degree of accuracy. The results from point-of-care (POC) platelet aggregometry or viscoelastometry tests or an expanded range of laboratory reference tests for coagulopathy did not improve predictive accuracy beyond that achieved with the clinical risk score alone. The routine use of POC tests was not cost-effective. A systematic review concluded that POC-based algorithms are not clinically effective. We developed two new clinical risk prediction scores for transfusion and bleeding that are available as e-calculators. Workstream 2 – in the PAtient-SPecific Oxygen monitoring to Reduce blood Transfusion during heart surgery (PASPORT) trial and a systematic review we demonstrated that personalised near-infrared spectroscopy-based algorithms for the optimisation of tissue oxygenation, or as indicators for red cell transfusion, were neither clinically effective nor cost-effective. Workstream 3 – in the REDWASH trial we failed to demonstrate a reduction in inflammation or organ injury in recipients of mechanically washed red cells compared with standard (unwashed) red cells.

Limitations

Existing studies evaluating the predictive accuracy or effectiveness of POC tests of coagulopathy or near-infrared spectroscopy were at high risk of bias. Interventions that alter red cell transfusion exposure, a common surrogate outcome in most trials, were not found to be clinically effective.

Conclusions

A systematic assessment of devices in clinical use as blood management adjuncts in cardiac surgery did not demonstrate clinical effectiveness or cost-effectiveness. The contribution of anaemia and coagulopathy to adverse clinical outcomes following cardiac surgery remains poorly understood. Further research to define the pathogenesis of these conditions may lead to more accurate diagnoses, more effective treatments and potentially improved clinical outcomes.

Study registration

Current Controlled Trials ISRCTN20778544 (COPTIC study) and PROSPERO CRD42016033831 (systematic review) (workstream 1); Current Controlled Trials ISRCTN23557269 (PASPORT trial) and PROSPERO CRD4201502769 (systematic review) (workstream 2); and Current Controlled Trials ISRCTN27076315 (REDWASH trial) (workstream 3).

Funding

This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full inProgramme Grants for Applied Research; Vol. 5, No. 17. See the NIHR Journals Library website for further project information.

Does the Roller Pump Adjustment in Cardiopulmonary Bypass Settings Influence Hemolysis?

Introduction

Roller pumps are widely used in procedures involving cardiopulmonary bypass (CPB) due to their ease of operation and maintenance, safety, and cost. Several studies in the literature have compared the use of roller pumps with centrifugal pumps, but the influence of the roller pump adjustment on hemolysis has been poorly explored.

Methods

Measurements of hemolysis rates were carried out in 86 patients. The pump was adjusted by the dynamic calibration method, which was performed by an auxiliary device, and the patients were grouped according to the pump calibration: Group 1 (n = 20) 75 mmHg; Group 2 (n = 24) 150 mmHg; Group 3 (n = 22) 300 mmHg and Group 4 (n = 21) 450 mmHg. The hemolysis rates were measured at 4 different times during CPB (TO: before the surgical procedure; T1: 5 minutes after the start of CPB; T2: 30 minutes of CPB; and T3: 5 minutes after the CPB procedure). Hemolysis rates were calculated between the time intervals T0–T1, T1–T2, and T0–T3.

Results

No difference in hemolysis rates was observed between the groups (p>0.31). During the first 5 minutes of CPB, hemolysis represented 35.5% of the total hemolysis and no significant difference was found between groups (p>0.60).

Conclusions

Calibration of roller pumps by the dynamic method did not influence the hemolysis rates. Additionally, the hemolysis during the first 5 minutes of CPB accounted for ∼1/3 of the total hemolysis.

Adenosine Receptor Adora2b Plays a Mechanistic Role in the Protective Effect of the Volatile Anesthetic Sevoflurane during Liver Ischemia/Reperfusion

Background

Liver ischemia/reperfusion (IR) injury is characterized by hepatic tissue damage and an inflammatory response. This is accompanied by the formation and vascular sequestration of platelet–neutrophil conjugates (PNCs). Signaling through Adora2b adenosine receptors can provide liver protection. Volatile anesthetics may interact with adenosine receptors. This study investigates potential antiinflammatory effects of the volatile anesthetic sevoflurane during liver IR.

Methods

Experiments were performed ex vivo with human blood and in a liver IR model with wild-type, Adora2a−/−, and Adora2b−/− mice. The effect of sevoflurane on platelet activation, PNC formation and sequestration, cytokine release, and liver damage (alanine aminotransferase release) was analyzed using flow cytometry, luminometry, and immunofluorescence. Adenosine receptor expression in liver tissue was analyzed using immunohistochemistry and real-time polymerase chain reaction.

Results

Ex vivo experiments indicate that sevoflurane inhibits platelet and leukocyte activation (n = 5). During liver IR, sevoflurane (2 Vol%) decreased PNC formation 2.4-fold in wild-type (P &lt; 0.05) but not in Adora2b−/− mice (n ≥ 5). Sevoflurane reduced PNC sequestration 1.9-fold (P &lt; 0.05) and alanine aminotransferase release 3.5-fold (P &lt; 0.05) in wild-type but not in Adora2b−/− mice (n = 5). In Adora2a−/− mice, sevoflurane also inhibited PNC formation and cytokine release. Sevoflurane diminished cytokine release (n ≥ 3) and increased Adora2b transcription and expression in liver tissue of wild-types (n = 4).

Conclusions

Our experiments highlight antiinflammatory and tissue-protective properties of sevoflurane during liver IR and reveal a mechanistic role of Adora2b in sevoflurane-associated effects. The targeted use of sevoflurane not only as an anesthetic but also to prevent IR damage is a promising approach in the treatment of critically ill patients.

Thrombocytopenia in Critical Care Patients

Thrombocytopenia is a common laboratory finding in the intensive care unit (ICU) patient. Because the causes can range from laboratory artifact to life-threatening processes such as thrombotic thrombocytopenic purpura (TTP), identifying the cause of thrombocytopenia is important. In the evaluation of the thrombocytopenia patient, one should incorporate all clinical clues such as why the patient is in the hospital, medications the patient is on, and other abnormal laboratory findings. One should ensure that the patient does not suffer from heparin-induced thrombocytopenia (HIT) or one of the thrombotic microangiopathies (TMs). HIT can present in any patient on heparin and requires specific testing and antithrombotic therapy. TMs cover a spectrum of disease ranging from TTP to pregnancy complications and can have a variety of presentations. Management of disseminated intravascular coagulation depends on the patient’s condition and complication. Other causes of ICU thrombocytopenia include sepsis, medication side effects, post-transfusion purpura, catastrophic anti phospholipid antibody disease, and immune thrombocytopenia.

Using Cone and Plate(let) Analyzer to Predict Bleeding in Cardiac Surgery

The cone and plate(let) analyzer is an established method for assessing platelet function. It evaluates adherence of platelets on an extracellular matrix, expressed as a percentage of surface coverage and the average size of the aggregates. The purpose of this study was to determine the applicability of the cone and plate(let) analyzer in monitoring platelet function and predicting postoperative bleeding. The relationship between postoperative bleeding, perioperative platelet function, and other parameters was studied. A significant decrease in surface coverage was detected upon establishment of cardiopulmonary bypass (from 6.9% ± 3.9% to 4.7% ± 1.7%) with a return to preoperative values at the end of surgery. Preoperative average size and surface coverage were the only parameters that significantly and linearly correlated with postoperative bleeding. Patients with an aggregate average size < 20 μm2 had a significantly higher incidence of severe bleeding (> 965 mL) than those with a size > 20 μm2 (44% vs. 0%), and a higher mean blood loss (908 ± 322 mL vs. 337 ± 78 mL). Similar results were obtained for surface coverage < 5%, indicating the predictive value of these parameters. Preoperative platelet function as evaluated by the cone and plate(let) analyzer is an independent risk factor determining postoperative bleeding.

Thrombocytopenia and extracorporeal membrane oxygenation in adults with acute respiratory failure: a cohort study

PURPOSE

The association between extracorporeal membrane oxygenation (ECMO) use and the development of thrombocytopenia is widely presumed yet weakly demonstrated. We hypothesized that longer duration of ECMO support would be independently associated with worsened thrombocytopenia.

METHODS

We performed a single-center retrospective cohort study of 100 adults who received ECMO for acute respiratory failure. We used generalized estimating equations to test the association between days on ECMO and daily percentage of platelets compared to the first post-cannulation platelet count. We constructed a multivariable logistic regression model with backwards stepwise elimination to identify clinical predictors of severe thrombocytopenia (≤50,000/μL) while on ECMO.

RESULTS

Days on ECMO was not associated with a decrease in platelet count in the unadjusted analysis (β -0.85, 95 % CI -2.05 to 0.36), nor after considering and controlling for days hospitalized prior to ECMO, APACHE II score, platelet transfusions, and potential thrombocytopenia-inducing medications (β -0.83, 95 % CI -1.9 to 0.25). Twenty-two subjects (22 %) developed severe thrombocytopenia. The APACHE II score and platelet count at the time of cannulation predicted the development of severe thrombocytopenia. The odds of developing severe thrombocytopenia increased 35 % for every 5-point increase in APACHE II score (OR 1.35, 95 % CI 0.94-1.94) and increased 35 % for every 25,000/μL platelets below a mean at cannulation of 188,000/μL (OR 1.35, 95 % CI 1.10-1.64).

CONCLUSIONS

Duration of ECMO is not associated with the development of thrombocytopenia. The severity of critical illness and platelet count at the time of cannulation predict the development of severe thrombocytopenia while receiving ECMO for respiratory failure. Future studies should validate these findings, especially in cohorts with more venoarterial ECMO patients, and should characterize the association between thrombocytopenia and bleeding events while on ECMO.

Effect of cardiopulmonary bypass on platelet mitochondrial respiration and correlation with aggregation and bleeding: a pilot study

BACKGROUND

Cardiopulmonary bypass (CPB) may cause platelet dysfunction, contributing to bleeding. There are no investigations of how CPB affects platelet mitochondrial respiration and what correlation this has with platelet aggregation and bleeding.

METHODS

We studied platelet mitochondrial respiration and aggregation in eighteen adult cardiac surgery patients having CPB. The relationships between respiration, aggregation and postoperative bleeding were analyzed.

RESULTS

Platelet respiration, reflected by the respiratory control ratio (RCR), was unchanged after CPB (mean difference in RCR= -0.02 (95% CI=-1.45 to 1.42), p=0.98). Further, there were no significant relationships between indexed adenosine diphosphate (ADP) or thrombin receptor-activating peptide (TRAP)-induced aggregation and the RCR (p=0.12 and p=0.41). Only post-CPB ADP - induced aggregation correlated with 24-hr chest tube output (p=0.04), but indexing for platelet count attenuated the effect (p=0.07).

CONCLUSION

Platelet mitochondrial respiration is preserved after CPB and is not correlated with aggregation or bleeding. Only post-CPB, ADP-induced aggregation correlates with postoperative bleeding.