Original Basic Science Article
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Multiple Electrode Aggregometry for the Assessment of Acquired Platelet Dysfunctions during Extracorporeal Circulation
1 Department of Anesthesiology, Intensive Care Medicine and Pain
Therapy, University Hospital Frankfurt, Frankfurt, Germany 2 Department of Thoracic and Cardiovascular Surgery, University Hospital Frankfurt, Frankfurt, Germany 3 Department of Anesthesiology and Intensive Care Medicine, Hannover Medical School, Hannover, Germany
Address for correspondence Priv.-Doz. Dr. Christian Friedrich Weber, Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Theodor Stern Kai 7, Frankfurt 60590, Germany (e-mail: [email protected]).
Thorac Cardiovasc Surg 2015;63:21–27.
Abstract
Keywords
► extracorporeal circulation ► hemostasis ► aggregometry ► Multiplate ► platelet dysfunction
received April 2, 2014 accepted after revision May 6, 2014 published online August 1, 2014
Background There have been many reports on how the usage of extracorporeal circulation (ECC) is independently associated with the induction of platelet dysfunctions. The aim of the present investigation was to study the capability of the multiple electrode aggregometry (MEA) using the Multiplate (Roche AG, Grenzach, Germany) device to reflect the extent of ECC-associated platelet dysfunctions. Patients and Methods The study population consisted of patients who were treated with either hypothermic (cardiopulmonary bypass [CPB]) or normothermic (extracorporeal membrane oxygenation) ECC. Hemostatic analyses included conventional laboratory coagulation tests and aggregometric measures following stimulation with different agonists using MEA. The area under the aggregation curve in the ADPtest (ex vivo adenosine diphosphate induced platelet aggregation) of the MEA was defined as the primary end point. The analyses were performed before the usage of ECC (baseline) and 90 minutes (T1), 120 minutes (T2), 150 minutes (T3), and 180 minutes (T4) after the usage of ECC. In the hypothermic ECC group, additional hemostatic analyses were performed after the patient’s postoperative admission to the intensive care unit (T5). Periprocedural data and results of other hemostatic testing were defined as secondary end points. Results A total of n ¼ 40 patients were assessed for eligibility and n ¼ 25 patients were finally enrolled into the study (hypothermic ECC group: n ¼ 20; normothermic ECC group: n ¼ 5). The extent of ADP-induced platelet aggregation decreased significantly between baseline and consecutive measuring points during hypothermic ECC and remained unchanged between T4 and T5. In the normothermic ECC group, ADP-induced aggregability was significantly lower at T1 compared with baseline and remained unchanged from T1 onward. Conclusion Data from the present study indicate that ex vivo ADP-induced platelet aggregation in MEA reflects the time-dependent extent of ECC-induced platelet dysfunction.
© 2015 Georg Thieme Verlag KG Stuttgart · New York
DOI http://dx.doi.org/ 10.1055/s-0034-1383817. ISSN 0171-6425.
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Haitham Mutlak1 Christian Reyher1 Patrick Meybohm1 Nestoras Papadopoulos2 Alexander Alfons Hanke3 Kai Zacharowski1 Christian Friedrich Weber1
MEA for the Assessment of Acquired Platelet Dysfunctions
Weber et al. Hypothermic Extracorporeal Circulation Group
Introduction Patients undergoing extracorporeal circulation (ECC) are at an increased risk for the development of coagulopathy and hemorrhage. Bleeding disorders often necessitate the transfusion of allogenic blood products, which have been shown to be independently associated with the development of cardiac and noncardiac adverse events as well as increased morbidity and mortality.1–3 In addition to the deficiencies of the plasmatic coagulation system due to the dilution, activation, and consumption of coagulation factors,4,5 disturbances in primary hemostasis in terms of platelet dysfunctions also contribute to coagulopathy.6,7 The etiology of platelet dysfunctions is multifactorial; its spectrum is composed of impaired platelet aggregability associated with the periprocedural continuation of antiaggregatory medication and the development of unspecific platelet dysfunctions during ECC. In addition to platelet activation, degranulation and mechanical defragmentation following exposure to foreign surfaces from the circuit and unfractionated heparin8,9 also hypothermia negatively affects platelet aggregability.10,11 Data from a pilot study indicate that the duration of ECC is correlated with the extent of ECC-induced platelet dysfunctions.12 A method that enables the rapid, reliable, and sensitive assessment of the hemostatic potential of primary hemostasis would be of clinical relevance because it may facilitate goal-directed and efficient hemotherapy. Multiple electrode aggregometry (MEA) using the Multiplate device (Roche AG, Grenzach, Germany) analyzes platelet function in response to different agonists at the bedside.13 MEA was used in a variety of studies to study the effects of temperature, acidosis, ultrafiltration, colloids, anticoagulants, and antifibrinolytics on platelet aggregation. Furthermore, MEA is increasingly used for the perioperative monitoring of platelet function, especially in cardiac surgery.14 The aim of the present investigation was to study whether MEA is feasible to reflect the time-dependent extent of ECCinduced platelet dysfunction. Aiming to differentiate ECC from potentially hypothermia-associated disturbances of primary hemostasis, we enrolled patients who were treated with either hypothermic or normothermic ECC.
Patients and Methods Trial Design This prospective cohort, single-center study complies with the declaration of Helsinki and was approved by the local Scientific and Ethics Review Board (filed with the reference number 18911). The study was registered with ClinicalTrials. gov (Identifier NCT01354847).
Step 1. Patients scheduled for elective, complex cardiac surgery (double and triple valve procedures or redo surgery) with ECC were preoperatively screened for eligibility, and written consent was obtained. Patients were eligible if ex vivo arachidonic acid and ADP-induced platelet aggregation were within normal reference values after the induction of anesthesia (T0). Step 2. Patients were enrolled in the study if the duration of ECC exceeded 180 minutes.
Normothermic Extracorporeal Circulation group Step 1. Patients requiring extracorporeal membrane oxygenation (ECMO) for the treatment of acute respiratory distress syndrome were screened for eligibility. Step 2. Patients were enrolled into the study if (1) ex vivo arachidonic acid and ADP-induced platelet aggregation were within normal reference values following implantation of ECMO cannulas (T0) and (2) written consent was obtained from a juridical legitimated representative of the patient.
Anesthetic Management Anesthetic management was performed in accordance to institutional standards. In the hypothermic ECC group, periprocedural anesthesia was maintained using 1 to 2 vol% sevoflurane (Sevoran, Abbott, Wiesbaden, Germany) and intermittent boluses of sufentanil. In the normothermic ECC group, general anesthesia was maintained using continuous infusion of 3 to 5 mg/kg/h propofol (Disoprivan, AstraZeneca GmbH, Wedel, Germany) and 0.1 to 0.3 µg/kg/min remifentanil (Remifentanil, B Braun AG, Melsungen, Germany). Muscle relaxation was not performed routinely.
Management of Extracorporeal Circulation Hypothermic Extracorporeal Circulation Group Our institutional standards concerning methodology of hypothermic ECC have comprehensively been published elsewhere.14,15 The ECC circuit consisted of a membrane oxygenator (Quadrox oxygenator, Maquet Cardiopulmonary AG, Hirrlingen, Germany) equipped with a heat exchanger and a centrifugal pump system (Rotaflow, Maquet Cardiopulmonary AG). Priming volume consisted of 1,200 mL of crystalloid solution (Sterofundin, B. Braun Melsungen AG). Unfractionated heparin (Heparin-Natrium Braun, B. Braun Melsungen AG) was used to achieve an activated clotting time (ACT) of > 400 seconds. For heparin reversal at the end of ECC (performed in mild hypothermia), protamine sulfate (Protaminsulfat, Novo Nordisk Pharma GmbH, Vienna, Austria) was administered, guided by the ACT. No procoagulatory therapy was performed before the administration of protamine at the end of ECC.
Normothermic Extracorporeal Circulation Group Participants In both groups, patients (age 18 years or older) were suitable for this trial after two inclusion steps. Known hereditary coagulopathies, medications with any antiaggregatory agents (e.g., cyclooxygenase [COX] inhibitors or ADP antagonists) and pregnancy were defined as exclusion criteria. Thoracic and Cardiovascular Surgeon
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In the normothermic ECC group, the Permanent Life Support System (PLS, Maquet Cardiopulmonary AG, Hirrlingen, Germany) was used. The system incorporates a diffusion membrane oxygenator (Quadrox D, Maquet Cardiopulmonary AG) with an integrated heat exchanger and a centrifugal pump system (Rotaflow, Maquet Cardiopulmonary AG). The
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22
MEA for the Assessment of Acquired Platelet Dysfunctions
Hematological Analyses Blood samples for hematological analyses were drawn using an arterial cannula that was routinely implemented in each patient. For MEA analyses, the blood was collected in heparinanticoagulated and calcium-balanced tubes. For conventional laboratory analyses, sodium citrate-anticoagulated as well as EDTA tubes were used. Conventional laboratory coagulation analyses included the assessment of platelet count, hemoglobin concentration, fibrinogen concentration, international normalized ratio (INR), and aPTT. Analyses were performed at the institutional laboratory using fully automated analyzers, STA-R Evolution (Roche AG, Grenzach, Germany) and Sysmex XE 2001 (Sysmex GmbH, Norderstedt, Germany). Standard quality control procedures for each device were routinely performed following the manufacturer’s recommendations.
Multiple Electrode Aggregometry Methodology of MEA with the Multiplate device has comprehensively been described elsewhere.13–15 Its methodical principle is based on impedance aggregometry16 and relies on the proaggregatory properties of activated platelets. The MEA device has five test cells. In each of these singleuse test cells, two metal wires are implemented. Following stimulation of platelets aggregation using different agonists (among others 32 mmol/L thrombin receptor activating peptide in the TRAP test, 0.5 mmol/L arachidonic acid in the ASPI test, and 0.4 mmol/L ADP in the ADP test), platelets aggregation on the surface of the sensor wires induces an increase of the electrical impedance between the wires. The change of impedance as a consequence of platelets attachment to the electrodes is continuously monitored for a period of 6 minutes. Extent of platelets aggregability is expressed by the area under the aggregation curve, which is presented as arbitrary units called “aggregation units” (U). The reference ranges for healthy subjects given by the manufacturer were 87 to 147 U for the TRAP test, 51 to 109 U for the ASPI test, and 61 to 96 U for the ADP test.
Perioperative Hemotherapy Perioperative hemotherapy was based on the institutional hemotherapy algorithm.17
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Data Collection Demographic and clinical characteristics were recorded. Conventional laboratory coagulation analyses were routinely performed at two measuring points in the hypothermic ECC group (after induction of anesthesia and at postoperative admission to intensive care unit [ICU]) and at one measuring point in the normothermic ECC group (before implementation of the cannulas). MEA analyses (ASPI test, ADP test, and TRAP test) were performed after the induction of anesthesia in the hypothermic group and before the implementation of the cannulas in the normothermic group (baseline, T0) as well as 90 minutes (T1), 120 minutes (T2), 150 minutes (T3), and 180 minutes (T4) after beginning ECC in both groups. In the hypothermic group, additional MEA analyses were performed after the patient’s postoperative admission to the ICU (T5). At each MEA measuring point, blood gas analyses were performed to assess physiologic preconditions for hemostasis (pH, temperature, plasma concentration of ionized calcium, and hemoglobin).
End Points Primary End Point Extent of ADP-induced platelet aggregation in the MEA (ADP test) was defined as the primary end point.
Secondary End Points These variables are listed as follows: • Ex vivo induced platelet aggregation in the TRAP test and ASPI test of MEA • Duration of ECC, clamping time of the aorta • Physiologic basic conditions for hemostasis (temperature, pH, ionized calcium, hemoglobin concentration) at each measuring point • Results of routinely performed conventional laboratory coagulation testing (platelet count, fibrinogen, INR, and aPTT) • The number of transfused allogenic blood products and administered coagulation factor concentrates and any other hemotherapy during the study period.
Sample Size Analyses and Statistical Methods Previous studies hypothesized that ADP-induced platelet aggregation is most likely the most sensitive test to indicate perioperatively acquired platelet dysfunctions.12 For that reason, the sample size analysis of the present study was based on the expected differences in the ADP test of the MEA between baseline and T1 (90 minutes after beginning ECC). In the absence of published data regarding ECC-induced changes in ex vivo induced platelet aggregability, the sample size calculation was based on the analysis of our previous pilot experiment, which was collected in 10 subjects undergoing cardiac surgery with ECC (change to be detected 10 U, expected standard deviation of 12 U, desired power of 0.8, and an α of 0.01) and revealed a required sample size of at least n ¼ 19 patients to detect statistically significant differences. Thoracic and Cardiovascular Surgeon
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heparin-coated circuit was primed with 600 mL of a crystalloid solution (Sterofundin, B. Braun Melsungen AG). Guided by repetitively activated partial thromboplastin time (aPTT) analyses, anticoagulation was maintained by the continuous infusion of unfractionated heparin (Heparin-Natrium Braun, B. Braun; target: 45–55 seconds; initial dosage: 600–1,200 IU/ kg/h). If the targeted aPTT was not obtained despite repeated heparin administrations, 500 to 1,000 IU of antithrombin was infused. ECC was performed in normothermia (36–37°C). Patients were weaned from ECC following clinical discretion based on institutional standards.
Weber et al.
MEA for the Assessment of Acquired Platelet Dysfunctions
Weber et al.
Fig. 1 Flow chart showing the number of patients at each phase of the trial.
The one-way repeated measures ANOVA on ranks and the Wilcoxon signed rank test were used to analyze differences between the measuring points. Depending on the distribution of the data (Kolmogorov–Smirnov test), the results are given as the mean standard deviation or median (25th/ 75th percentiles). The statistical analyses were performed using SigmaStat 3.5 and SigmaPlot 11 (Systat Software GmbH, Erkrath, Germany) software.
Results A total of n ¼ 40 patients were assessed for eligibility. Of those, n ¼ 15 did not fulfill the inclusion criteria, and n ¼ 25 patients were finally enrolled into the study (►Fig. 1). The hypothermic and normothermic ECC groups consisted of n ¼ 20 and n ¼ 5 patients, respectively. ►Table 1 shows demographic and clinical characteristics. ►Fig. 2 shows the MEA results of patients in the hypothermic ECC group. Compared with baseline at T0, platelet aggregation in the TRAP test remained unchanged until T2 and was significantly lower at T3 and T4. There were no significant differences between the MEA results obtained at the baseline and T5. Compared with baseline, ex vivo arachidonic acid–induced platelet aggregation in the ASPI test was significantly lower at each consecutive measuring point. Platelet aggregation did not change significantly after the beginning of ECC at T1. Compared with baseline, ADP-induced platelet aggregation was significantly decreased at each of the consecutive measuring points. ADP-induced aggregability in platelets decreased continuously during ECC and remained unchanged between the last intraoperative measuring point (T4) and postoperative admission to the ICU (T5). ►Fig. 3 shows the MEA results of patients in the normothermic ECC group. Platelet aggregation in the TRAP test and ASPI test remained unchanged during the study period. Compared with baseline, ADP-induced platelet aggregation was significantly decreased at T1 and at every consecutive measuring point. From T1 onward, ADP-induced platelet aggregation did not change significantly. ►Table 2 shows physiological basic conditions for hemostasis at each measuring point. ►Table 3 shows the results of routinely performed conventional laboratory coagulation testing in both the hypothermic and normothermic ECC groups. Thoracic and Cardiovascular Surgeon
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Discussion The aim of the present study was to investigate whether MEA is a feasible method to reflect ECC-induced platelet dysfunctions. The main result of the study showed that ex vivo ADPinduced platelet aggregation in MEA (ADP test) decreased the dependency of ECC duration. However, thrombin-induced platelet aggregation (TRAP test) remained unchanged during the whole study period, and arachidonic acid–induced platelet aggregation (ASPI test) decreased between baseline and T1 but did not change between T1 and the subsequent measuring points. Thus, we hypothesized that the ADP test might be the most sensitive test to reflect ECC-induced disturbances of platelet aggregability. The results of our study agreed with those obtained from Velik-Salchner et al, who showed in their pilot study that the ADP-induced platelet aggregation of patients undergoing cardiac surgery was markedly decreased 15 minutes after CPB compared with baseline values obtained
Table 1 Baseline demographic and clinical characteristics Hypothermic ECC group (n ¼ 20)
Normothermic ECC group (n ¼ 5)
Sex (male)
15 (75)
5 (100)
Age (y)
76 9
53 þ 11
BMI (kg/m )
27 5
35 þ 8
ASA score
3 (3/4)
4 (4/4)
EuroSCORE
7.1 3.1
Double valve surgery
14 (70)
2
Triple valve surgery
4 (20)
Redo surgery
2 (10)
ECC time (min)
216 26
Clamping time (min)
147 33
Crystalloids (mL)
2,475 875
Colloids (mL)
1025 112
Abbreviations: ASA, American Society for Anesthesiology; BMI, body mass index; ECC, extracorporeal circulation. Note: The data are presented as numbers (%) or the mean standard deviation.
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Fig. 2 Hypothermic ECC group: Ex vivo induced platelet aggregation was assessed at baseline (T0) and 90 minutes (T1), 120 minutes (T2), 150 minutes (T3), 180 minutes (T4) after beginning ECC, and postoperative admission to the ICU (T5), respectively. # indicates the significant difference (p < 0.05) in comparison to baseline.
before induction of anesthesia. The authors stated that ADPinduced assays are preferable for detecting the CPB-induced impairment of platelet aggregation.12 However, the assessment of arachidonic acid and thrombin-induced platelet aggregation are also integral parts of several aggregometry-based hemotherapy algorithms.14,18,19 Apart from the assessment of the effectiveness of antiaggregatory medication, the ASPI test is routinely used to monitor alterations of platelet function resulting from unspecific impairments of platelet COX I pathway due to acidosis, hypothermia, and colloids.20,21 Thus, the observed significant decrease in arachidonic acid–induced platelet aggregation between baseline and T1 is comprehensible. In contrast to the
Weber et al.
Fig. 3 Normothermic ECC group: Ex vivo induced platelet aggregation was assessed at baseline (T0) and at 90 minutes (T1), 120 minutes (T2), 150 minutes (T3), and 180 minutes (T4) after beginning ECC. # indicates the significant difference (p < 0.05) in comparison to baseline.
ADP test, platelet aggregation in the ASPI test remained unchanged from T1 onward; we attribute this observance to an assumed stronger stimulation of platelet aggregation following exposure to arachidonic acid compared with ADP. However, the strongest activation of platelet aggregation in MEA results from the stimulation of the thrombin receptor (TRAP test). Therefore, it was unsurprising to find that ex vivo induced aggregation in the TRAP test remained unchanged during the study period in both groups. Thus, our data indicate that the TRAP test was not sensitive enough to reflect unspecific ECC-induced disturbances in platelet aggregability. The observed changes in ex vivo induced platelet aggregation may be of a multifactorial cause and cannot be Thoracic and Cardiovascular Surgeon
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MEA for the Assessment of Acquired Platelet Dysfunctions
MEA for the Assessment of Acquired Platelet Dysfunctions
Weber et al.
Table 2 Physiologic basic conditions for hemostasis at different time points T0 T (°C) pH Cai (mmol/L) Hb (g/dL)
T1
T2
T3
T4
T5 36.9 0.6
Hypothermic ECC
36.4 0.4
32.7 0.7
32.8 0.6
32.9 0.7
32.9 0.9
Normothermic ECC
36.5 1.1
36.5 1.2
37.1 0.7
37.1 0.9
37.1 0.6
Hypothermic ECC
7.41 0.1
7.39 0.05
7.36 0.06
7.38 0.04
7.38 0.05
Normothermic ECC
7.38 0.1
7.38 0.1
7.36 0.08
7.42 0.02
7.39 0.03
Hypothermic ECC
1.2 0.04
1.20 0.05
1.20 0.05
1.19 0.04
1.20 0.06
Normothermic ECC
1.2 0.01
1.16 0.1
1.2 0.06
1.19 0.1
1.2 0.1
Hypothermic ECC
12.5 2.2
9.2 1.6
9.2 1.4
9.2 1.3
8.9 1.2
Normothermic ECC
8.8 0.9
8.9 0.8
8.7 1.2
8.6 0.8
9.2 0.9
7.36 0.05 1.22 0.17 9.0 1.0
Abbreviations: Cai,, ionized calcium; ECC, extracorporeal circulation; Hb, hemoglobin; T, temperature. Note: The data are presented as the mean standard deviation.
Table 3 Results of routine clinical chemistry analyses at baseline Hypothermic ECC
Normothermic ECC
T0
T5
T0
210 72
165 48
136 30
Fibrinogen (mg/dL)
370 95
172 31
258 44
INR
1.34 0.15
1.51 0.11
1.23 0.23
aPTT (s)
42 5
45 5
48 4
Platelet count (/nL)
Abbreviations: aPTT, activated partial thromboplastin time; ECC, extracorporeal circulation; INR, international normalized ratio. Note: The data are presented as the mean standard deviation.
exclusively attributed to the use of ECC. Several factors, such as pH,21 hemoglobin concentration,22 platelet count,23 and hypothermia,24 have been shown to influence platelet aggregability. Intending to register reversible and therefore potentially irrelevant hemostatic effects of hypothermia on MEA results, we enrolled patients treated with either hypothermic or normothermic ECC. The observed significant reduction in ADP-induced platelet aggregation between baseline and T1, and the trend of the consecutive reduction of the median values from T1 onward led to the assumption that the observed changes in MEA results are independent from hypothermia and can be attributed to the use of ECC. An enrollment of a larger study population, particularly in the normothermic ECC group, would have led to an improvement of validity and informative value of our data. However, the inclusion and exclusion criteria of the present study focus on patients with initially unaffected platelet function, and this collective of patients is extremely rare. In the present study, we assessed the type and amount of hemotherapy that was administered during the study period. However, the study collective of the present descriptive study was too small and too inhomogeneous, and the study period was too short to allow the identification of specific cutoff values by conducting multivariate analyses or receiving operating characteristic curves. The results of our investigation indicate that ADP-induced platelet aggregation may be used to monitor the effects of ECC. Therefore, further studies Thoracic and Cardiovascular Surgeon
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should be conducted to analyze the cutoff values of the ADP test that may indicate an increased risk for the development of perioperative hemorrhage and the consecutive need for optimizing primary hemostasis through the administration of 1-deamino-8-d-arginine vasopressin (DDAVP) and/or the transfusion of platelet concentrates (PCs). We focused on the relatively rare collective of patients with initially unaffected platelet function. This allowed us to investigate the effects of ECC on platelet function that was not affected by drugs such as arachidonic acid or clopidogrel. On account of this, the conclusions of the present study cannot be uncritically transferred to daily practice. There were some limitations in our study. It would have been of clinical interest if we had been able to draw conclusions concerning potential correlations between laboratory results and clinical outcome parameters, such as blood loss and the need for hemotherapy. However, this was not the aim of the present study, and the study collective was too small and too inhomogeneous with a study period that was too short to allow for accurate and well-founded analyses concerning this matter. The interpretation of our study results, particularly of the arachidonic acid–induced platelet aggregation in the ASPI test, may be afflicted with α and β errors. Some patients from the hypothermic ECC group received hemotherapy after weaning from ECC that may have affected platelet function and MEA results. On the basis of our institutional hemotherapy algorithm for the treatment of coagulopathic patients, n ¼ 12 patients received DDAVP,
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MEA for the Assessment of Acquired Platelet Dysfunctions
9 Griffin MJ, Rinder HM, Smith BR, et al. The effects of heparin,
10
11
12
13
Conclusion In patients with initially unaffected platelet function, ex vivo ADP-induced platelet aggregation in MEA decreases in dependency of the ECC duration. Data from the present study indicate that the ADP test of MEA is feasible to reflect the extent of ECC-associated acquired platelet dysfunctions during both normothermic and hypothermic ECC.
14
15
16 17
References 1 Paone G, Likosky DS, Brewer R, et al; Membership of the Michigan
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Society of Thoracic and Cardiovascular Surgeons. Transfusion of 1 and 2 units of red blood cells is associated with increased morbidity and mortality. Ann Thorac Surg 2014;97(1):87–93, discussion 93–94 Watson GA, Sperry JL, Rosengart MR, et al; Inflammation and Host Response to Injury Investigators. Fresh frozen plasma is independently associated with a higher risk of multiple organ failure and acute respiratory distress syndrome. J Trauma 2009;67(2): 221–227, discussion 228–230 Vivacqua A, Koch CG, Yousuf AM, et al. Morbidity of bleeding after cardiac surgery: is it blood transfusion, reoperation for bleeding, or both? Ann Thorac Surg 2011;91(6):1780–1790 Davidson SJ, Burman JF, Philips SM, et al. Correlation between thrombin potential and bleeding after cardiac surgery in adults. Blood Coagul Fibrinolysis 2003;14(2):175–179 Chandler WL. Effects of hemodilution, blood loss, and consumption on hemostatic factor levels during cardiopulmonary bypass. J Cardiothorac Vasc Anesth 2005;19(4):459–467 Sniecinski RM, Levy JH. Bleeding and management of coagulopathy. J Thorac Cardiovasc Surg 2011;142(3):662–667 Beurling-Harbury C, Galvan CA. Acquired decrease in platelet secretory ADP associated with increased postoperative bleeding in post-cardiopulmonary bypass patients and in patients with severe valvular heart disease. Blood 1978;52(1):13–23 Hofmann B, Bushnaq H, Kraus FB, et al. Immediate effects of individualized heparin and protamine management on hemostatic activation and platelet function in adult patients undergoing cardiac surgery with tranexamic acid antifibrinolytic therapy. Perfusion 2013;28(5):412–418
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protamine, and heparin/protamine reversal on platelet function under conditions of arterial shear stress. Anesth Analg 2001;93(1): 20–27 Wolberg AS, Meng ZH, Monroe DM III, Hoffman M. A systematic evaluation of the effect of temperature on coagulation enzyme activity and platelet function. J Trauma 2004;56(6):1221–1228 Slaughter TF, Sreeram G, Sharma AD, El-Moalem H, East CJ, Greenberg CS. Reversible shear-mediated platelet dysfunction during cardiac surgery as assessed by the PFA-100 platelet function analyzer. Blood Coagul Fibrinolysis 2001;12(2):85–93 Velik-Salchner C, Maier S, Innerhofer P, et al. An assessment of cardiopulmonary bypass-induced changes in platelet function using whole blood and classical light transmission aggregometry: the results of a pilot study. Anesth Analg 2009;108(6):1747–1754 Tóth O, Calatzis A, Penz S, Losonczy H, Siess W. Multiple electrode aggregometry: a new device to measure platelet aggregation in whole blood. Thromb Haemost 2006;96(6):781–788 Weber CF, Görlinger K, Meininger D, et al. Point-of-care testing: a prospective, randomized clinical trial of efficacy in coagulopathic cardiac surgery patients. Anesthesiology 2012;117(3):531–547 Mutlak H, Rehse C, Scheller B, et al. Comparison of heparin vs. lepirudin anticoagulated tubes for the assessment of ASS-induced platelet dysfunction using the Multiplate device. Appl Cardiopulm Pathophysiol 2013;17:275–283 Cardinal DC, Flower RJ. The study of platelet aggregation in whole blood [proceedings]. Br J Pharmacol 1979;66(1):94P–95P Weber CF, Zacharowski K, Brün K, et al. [Basic algorithm for Pointof-Care based hemotherapy: perioperative treatment of coagulopathic patients]. Anaesthesist 2013;62(6):464–472 Görlinger K, Dirkmann D, Hanke AA, et al. First-line therapy with coagulation factor concentrates combined with point-of-care coagulation testing is associated with decreased allogeneic blood transfusion in cardiovascular surgery: a retrospective, singlecenter cohort study. Anesthesiology 2011;115(6):1179–1191 Görlinger K, Dirkmann D, Weber CF, Rahe-Meyer N, Hanke AA. Algorithms for transfusion and coagulation management in massive haemorrhage. Anästh Intensivmed 2011;52:145–159 Scharbert G, Kalb M, Marschalek C, Kozek-Langenecker SA. The effects of test temperature and storage temperature on platelet aggregation: a whole blood in vitro study. Anesth Analg 2006; 102(4):1280–1284 Hanke AA, Dellweg C, Kienbaum P, Weber CF, Görlinger K, RaheMeyer N. Effects of desmopressin on platelet function under conditions of hypothermia and acidosis: an in vitro study using multiple electrode aggregometry. Anaesthesia 2010;65(7): 688–691 Bochsen L, Johansson PI, Kristensen AT, Daugaard G, Ostrowski SR. The influence of platelets, plasma and red blood cells on functional haemostatic assays. Blood Coagul Fibrinolysis 2011;22(3): 167–175 Hanke AA, Roberg K, Monaca E, et al. Impact of platelet count on results obtained from multiple electrode platelet aggregometry (Multiplate). Eur J Med Res 2010;15(5):214–219 Ortmann E, Klein AA, Sharples LD, et al. Point-of-care assessment of hypothermia and protamine-induced platelet dysfunction with multiple electrode aggregometry (Multiplate®) in patients undergoing cardiopulmonary bypass. Anesth Analg 2013;116(3): 533–540
Thoracic and Cardiovascular Surgeon
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and n ¼ 4 patients were transfused with PC after neutralization of heparin (between T4 and T5). This was unavoidable for ethical reasons and most likely explains the observed phenomenon that ADP-induced platelet aggregation remained unchanged between T4 and T5. To assess the potential effect of DDAVP on platelets aggregability, we compared MEA results obtained from patients who received (n ¼ 12) or did not receive (n ¼ 8) DDAVP between T4 and T5. There were no significant group differences neither in the ADP test (29 [16/66] U, median [25th/75th] percentile, vs. 26 [17/47] U, p ¼ 0.787), nor in the ASPI test (30 [18/53] vs. 20 [13/39] U, p ¼ 0.44) or in the TRAP test (116 [81/147] vs. 82 [72/115] U, p ¼ 0.263).
Weber et al.
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Multiple Electrode Aggregometry for the Assessment of Acquired Platelet Dysfunctions during Extracorporeal Circulation
1 Department of Anesthesiology, Intensive Care Medicine and Pain
Therapy, University Hospital Frankfurt, Frankfurt, Germany 2 Department of Thoracic and Cardiovascular Surgery, University Hospital Frankfurt, Frankfurt, Germany 3 Department of Anesthesiology and Intensive Care Medicine, Hannover Medical School, Hannover, Germany
Address for correspondence Priv.-Doz. Dr. Christian Friedrich Weber, Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Theodor Stern Kai 7, Frankfurt 60590, Germany (e-mail: [email protected]).
Thorac Cardiovasc Surg 2015;63:21–27.
Abstract
Keywords
► extracorporeal circulation ► hemostasis ► aggregometry ► Multiplate ► platelet dysfunction
received April 2, 2014 accepted after revision May 6, 2014 published online August 1, 2014
Background There have been many reports on how the usage of extracorporeal circulation (ECC) is independently associated with the induction of platelet dysfunctions. The aim of the present investigation was to study the capability of the multiple electrode aggregometry (MEA) using the Multiplate (Roche AG, Grenzach, Germany) device to reflect the extent of ECC-associated platelet dysfunctions. Patients and Methods The study population consisted of patients who were treated with either hypothermic (cardiopulmonary bypass [CPB]) or normothermic (extracorporeal membrane oxygenation) ECC. Hemostatic analyses included conventional laboratory coagulation tests and aggregometric measures following stimulation with different agonists using MEA. The area under the aggregation curve in the ADPtest (ex vivo adenosine diphosphate induced platelet aggregation) of the MEA was defined as the primary end point. The analyses were performed before the usage of ECC (baseline) and 90 minutes (T1), 120 minutes (T2), 150 minutes (T3), and 180 minutes (T4) after the usage of ECC. In the hypothermic ECC group, additional hemostatic analyses were performed after the patient’s postoperative admission to the intensive care unit (T5). Periprocedural data and results of other hemostatic testing were defined as secondary end points. Results A total of n ¼ 40 patients were assessed for eligibility and n ¼ 25 patients were finally enrolled into the study (hypothermic ECC group: n ¼ 20; normothermic ECC group: n ¼ 5). The extent of ADP-induced platelet aggregation decreased significantly between baseline and consecutive measuring points during hypothermic ECC and remained unchanged between T4 and T5. In the normothermic ECC group, ADP-induced aggregability was significantly lower at T1 compared with baseline and remained unchanged from T1 onward. Conclusion Data from the present study indicate that ex vivo ADP-induced platelet aggregation in MEA reflects the time-dependent extent of ECC-induced platelet dysfunction.
© 2015 Georg Thieme Verlag KG Stuttgart · New York
DOI http://dx.doi.org/ 10.1055/s-0034-1383817. ISSN 0171-6425.
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Haitham Mutlak1 Christian Reyher1 Patrick Meybohm1 Nestoras Papadopoulos2 Alexander Alfons Hanke3 Kai Zacharowski1 Christian Friedrich Weber1
MEA for the Assessment of Acquired Platelet Dysfunctions
Weber et al. Hypothermic Extracorporeal Circulation Group
Introduction Patients undergoing extracorporeal circulation (ECC) are at an increased risk for the development of coagulopathy and hemorrhage. Bleeding disorders often necessitate the transfusion of allogenic blood products, which have been shown to be independently associated with the development of cardiac and noncardiac adverse events as well as increased morbidity and mortality.1–3 In addition to the deficiencies of the plasmatic coagulation system due to the dilution, activation, and consumption of coagulation factors,4,5 disturbances in primary hemostasis in terms of platelet dysfunctions also contribute to coagulopathy.6,7 The etiology of platelet dysfunctions is multifactorial; its spectrum is composed of impaired platelet aggregability associated with the periprocedural continuation of antiaggregatory medication and the development of unspecific platelet dysfunctions during ECC. In addition to platelet activation, degranulation and mechanical defragmentation following exposure to foreign surfaces from the circuit and unfractionated heparin8,9 also hypothermia negatively affects platelet aggregability.10,11 Data from a pilot study indicate that the duration of ECC is correlated with the extent of ECC-induced platelet dysfunctions.12 A method that enables the rapid, reliable, and sensitive assessment of the hemostatic potential of primary hemostasis would be of clinical relevance because it may facilitate goal-directed and efficient hemotherapy. Multiple electrode aggregometry (MEA) using the Multiplate device (Roche AG, Grenzach, Germany) analyzes platelet function in response to different agonists at the bedside.13 MEA was used in a variety of studies to study the effects of temperature, acidosis, ultrafiltration, colloids, anticoagulants, and antifibrinolytics on platelet aggregation. Furthermore, MEA is increasingly used for the perioperative monitoring of platelet function, especially in cardiac surgery.14 The aim of the present investigation was to study whether MEA is feasible to reflect the time-dependent extent of ECCinduced platelet dysfunction. Aiming to differentiate ECC from potentially hypothermia-associated disturbances of primary hemostasis, we enrolled patients who were treated with either hypothermic or normothermic ECC.
Patients and Methods Trial Design This prospective cohort, single-center study complies with the declaration of Helsinki and was approved by the local Scientific and Ethics Review Board (filed with the reference number 18911). The study was registered with ClinicalTrials. gov (Identifier NCT01354847).
Step 1. Patients scheduled for elective, complex cardiac surgery (double and triple valve procedures or redo surgery) with ECC were preoperatively screened for eligibility, and written consent was obtained. Patients were eligible if ex vivo arachidonic acid and ADP-induced platelet aggregation were within normal reference values after the induction of anesthesia (T0). Step 2. Patients were enrolled in the study if the duration of ECC exceeded 180 minutes.
Normothermic Extracorporeal Circulation group Step 1. Patients requiring extracorporeal membrane oxygenation (ECMO) for the treatment of acute respiratory distress syndrome were screened for eligibility. Step 2. Patients were enrolled into the study if (1) ex vivo arachidonic acid and ADP-induced platelet aggregation were within normal reference values following implantation of ECMO cannulas (T0) and (2) written consent was obtained from a juridical legitimated representative of the patient.
Anesthetic Management Anesthetic management was performed in accordance to institutional standards. In the hypothermic ECC group, periprocedural anesthesia was maintained using 1 to 2 vol% sevoflurane (Sevoran, Abbott, Wiesbaden, Germany) and intermittent boluses of sufentanil. In the normothermic ECC group, general anesthesia was maintained using continuous infusion of 3 to 5 mg/kg/h propofol (Disoprivan, AstraZeneca GmbH, Wedel, Germany) and 0.1 to 0.3 µg/kg/min remifentanil (Remifentanil, B Braun AG, Melsungen, Germany). Muscle relaxation was not performed routinely.
Management of Extracorporeal Circulation Hypothermic Extracorporeal Circulation Group Our institutional standards concerning methodology of hypothermic ECC have comprehensively been published elsewhere.14,15 The ECC circuit consisted of a membrane oxygenator (Quadrox oxygenator, Maquet Cardiopulmonary AG, Hirrlingen, Germany) equipped with a heat exchanger and a centrifugal pump system (Rotaflow, Maquet Cardiopulmonary AG). Priming volume consisted of 1,200 mL of crystalloid solution (Sterofundin, B. Braun Melsungen AG). Unfractionated heparin (Heparin-Natrium Braun, B. Braun Melsungen AG) was used to achieve an activated clotting time (ACT) of > 400 seconds. For heparin reversal at the end of ECC (performed in mild hypothermia), protamine sulfate (Protaminsulfat, Novo Nordisk Pharma GmbH, Vienna, Austria) was administered, guided by the ACT. No procoagulatory therapy was performed before the administration of protamine at the end of ECC.
Normothermic Extracorporeal Circulation Group Participants In both groups, patients (age 18 years or older) were suitable for this trial after two inclusion steps. Known hereditary coagulopathies, medications with any antiaggregatory agents (e.g., cyclooxygenase [COX] inhibitors or ADP antagonists) and pregnancy were defined as exclusion criteria. Thoracic and Cardiovascular Surgeon
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In the normothermic ECC group, the Permanent Life Support System (PLS, Maquet Cardiopulmonary AG, Hirrlingen, Germany) was used. The system incorporates a diffusion membrane oxygenator (Quadrox D, Maquet Cardiopulmonary AG) with an integrated heat exchanger and a centrifugal pump system (Rotaflow, Maquet Cardiopulmonary AG). The
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MEA for the Assessment of Acquired Platelet Dysfunctions
Hematological Analyses Blood samples for hematological analyses were drawn using an arterial cannula that was routinely implemented in each patient. For MEA analyses, the blood was collected in heparinanticoagulated and calcium-balanced tubes. For conventional laboratory analyses, sodium citrate-anticoagulated as well as EDTA tubes were used. Conventional laboratory coagulation analyses included the assessment of platelet count, hemoglobin concentration, fibrinogen concentration, international normalized ratio (INR), and aPTT. Analyses were performed at the institutional laboratory using fully automated analyzers, STA-R Evolution (Roche AG, Grenzach, Germany) and Sysmex XE 2001 (Sysmex GmbH, Norderstedt, Germany). Standard quality control procedures for each device were routinely performed following the manufacturer’s recommendations.
Multiple Electrode Aggregometry Methodology of MEA with the Multiplate device has comprehensively been described elsewhere.13–15 Its methodical principle is based on impedance aggregometry16 and relies on the proaggregatory properties of activated platelets. The MEA device has five test cells. In each of these singleuse test cells, two metal wires are implemented. Following stimulation of platelets aggregation using different agonists (among others 32 mmol/L thrombin receptor activating peptide in the TRAP test, 0.5 mmol/L arachidonic acid in the ASPI test, and 0.4 mmol/L ADP in the ADP test), platelets aggregation on the surface of the sensor wires induces an increase of the electrical impedance between the wires. The change of impedance as a consequence of platelets attachment to the electrodes is continuously monitored for a period of 6 minutes. Extent of platelets aggregability is expressed by the area under the aggregation curve, which is presented as arbitrary units called “aggregation units” (U). The reference ranges for healthy subjects given by the manufacturer were 87 to 147 U for the TRAP test, 51 to 109 U for the ASPI test, and 61 to 96 U for the ADP test.
Perioperative Hemotherapy Perioperative hemotherapy was based on the institutional hemotherapy algorithm.17
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Data Collection Demographic and clinical characteristics were recorded. Conventional laboratory coagulation analyses were routinely performed at two measuring points in the hypothermic ECC group (after induction of anesthesia and at postoperative admission to intensive care unit [ICU]) and at one measuring point in the normothermic ECC group (before implementation of the cannulas). MEA analyses (ASPI test, ADP test, and TRAP test) were performed after the induction of anesthesia in the hypothermic group and before the implementation of the cannulas in the normothermic group (baseline, T0) as well as 90 minutes (T1), 120 minutes (T2), 150 minutes (T3), and 180 minutes (T4) after beginning ECC in both groups. In the hypothermic group, additional MEA analyses were performed after the patient’s postoperative admission to the ICU (T5). At each MEA measuring point, blood gas analyses were performed to assess physiologic preconditions for hemostasis (pH, temperature, plasma concentration of ionized calcium, and hemoglobin).
End Points Primary End Point Extent of ADP-induced platelet aggregation in the MEA (ADP test) was defined as the primary end point.
Secondary End Points These variables are listed as follows: • Ex vivo induced platelet aggregation in the TRAP test and ASPI test of MEA • Duration of ECC, clamping time of the aorta • Physiologic basic conditions for hemostasis (temperature, pH, ionized calcium, hemoglobin concentration) at each measuring point • Results of routinely performed conventional laboratory coagulation testing (platelet count, fibrinogen, INR, and aPTT) • The number of transfused allogenic blood products and administered coagulation factor concentrates and any other hemotherapy during the study period.
Sample Size Analyses and Statistical Methods Previous studies hypothesized that ADP-induced platelet aggregation is most likely the most sensitive test to indicate perioperatively acquired platelet dysfunctions.12 For that reason, the sample size analysis of the present study was based on the expected differences in the ADP test of the MEA between baseline and T1 (90 minutes after beginning ECC). In the absence of published data regarding ECC-induced changes in ex vivo induced platelet aggregability, the sample size calculation was based on the analysis of our previous pilot experiment, which was collected in 10 subjects undergoing cardiac surgery with ECC (change to be detected 10 U, expected standard deviation of 12 U, desired power of 0.8, and an α of 0.01) and revealed a required sample size of at least n ¼ 19 patients to detect statistically significant differences. Thoracic and Cardiovascular Surgeon
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heparin-coated circuit was primed with 600 mL of a crystalloid solution (Sterofundin, B. Braun Melsungen AG). Guided by repetitively activated partial thromboplastin time (aPTT) analyses, anticoagulation was maintained by the continuous infusion of unfractionated heparin (Heparin-Natrium Braun, B. Braun; target: 45–55 seconds; initial dosage: 600–1,200 IU/ kg/h). If the targeted aPTT was not obtained despite repeated heparin administrations, 500 to 1,000 IU of antithrombin was infused. ECC was performed in normothermia (36–37°C). Patients were weaned from ECC following clinical discretion based on institutional standards.
Weber et al.
MEA for the Assessment of Acquired Platelet Dysfunctions
Weber et al.
Fig. 1 Flow chart showing the number of patients at each phase of the trial.
The one-way repeated measures ANOVA on ranks and the Wilcoxon signed rank test were used to analyze differences between the measuring points. Depending on the distribution of the data (Kolmogorov–Smirnov test), the results are given as the mean standard deviation or median (25th/ 75th percentiles). The statistical analyses were performed using SigmaStat 3.5 and SigmaPlot 11 (Systat Software GmbH, Erkrath, Germany) software.
Results A total of n ¼ 40 patients were assessed for eligibility. Of those, n ¼ 15 did not fulfill the inclusion criteria, and n ¼ 25 patients were finally enrolled into the study (►Fig. 1). The hypothermic and normothermic ECC groups consisted of n ¼ 20 and n ¼ 5 patients, respectively. ►Table 1 shows demographic and clinical characteristics. ►Fig. 2 shows the MEA results of patients in the hypothermic ECC group. Compared with baseline at T0, platelet aggregation in the TRAP test remained unchanged until T2 and was significantly lower at T3 and T4. There were no significant differences between the MEA results obtained at the baseline and T5. Compared with baseline, ex vivo arachidonic acid–induced platelet aggregation in the ASPI test was significantly lower at each consecutive measuring point. Platelet aggregation did not change significantly after the beginning of ECC at T1. Compared with baseline, ADP-induced platelet aggregation was significantly decreased at each of the consecutive measuring points. ADP-induced aggregability in platelets decreased continuously during ECC and remained unchanged between the last intraoperative measuring point (T4) and postoperative admission to the ICU (T5). ►Fig. 3 shows the MEA results of patients in the normothermic ECC group. Platelet aggregation in the TRAP test and ASPI test remained unchanged during the study period. Compared with baseline, ADP-induced platelet aggregation was significantly decreased at T1 and at every consecutive measuring point. From T1 onward, ADP-induced platelet aggregation did not change significantly. ►Table 2 shows physiological basic conditions for hemostasis at each measuring point. ►Table 3 shows the results of routinely performed conventional laboratory coagulation testing in both the hypothermic and normothermic ECC groups. Thoracic and Cardiovascular Surgeon
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Discussion The aim of the present study was to investigate whether MEA is a feasible method to reflect ECC-induced platelet dysfunctions. The main result of the study showed that ex vivo ADPinduced platelet aggregation in MEA (ADP test) decreased the dependency of ECC duration. However, thrombin-induced platelet aggregation (TRAP test) remained unchanged during the whole study period, and arachidonic acid–induced platelet aggregation (ASPI test) decreased between baseline and T1 but did not change between T1 and the subsequent measuring points. Thus, we hypothesized that the ADP test might be the most sensitive test to reflect ECC-induced disturbances of platelet aggregability. The results of our study agreed with those obtained from Velik-Salchner et al, who showed in their pilot study that the ADP-induced platelet aggregation of patients undergoing cardiac surgery was markedly decreased 15 minutes after CPB compared with baseline values obtained
Table 1 Baseline demographic and clinical characteristics Hypothermic ECC group (n ¼ 20)
Normothermic ECC group (n ¼ 5)
Sex (male)
15 (75)
5 (100)
Age (y)
76 9
53 þ 11
BMI (kg/m )
27 5
35 þ 8
ASA score
3 (3/4)
4 (4/4)
EuroSCORE
7.1 3.1
Double valve surgery
14 (70)
2
Triple valve surgery
4 (20)
Redo surgery
2 (10)
ECC time (min)
216 26
Clamping time (min)
147 33
Crystalloids (mL)
2,475 875
Colloids (mL)
1025 112
Abbreviations: ASA, American Society for Anesthesiology; BMI, body mass index; ECC, extracorporeal circulation. Note: The data are presented as numbers (%) or the mean standard deviation.
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Fig. 2 Hypothermic ECC group: Ex vivo induced platelet aggregation was assessed at baseline (T0) and 90 minutes (T1), 120 minutes (T2), 150 minutes (T3), 180 minutes (T4) after beginning ECC, and postoperative admission to the ICU (T5), respectively. # indicates the significant difference (p < 0.05) in comparison to baseline.
before induction of anesthesia. The authors stated that ADPinduced assays are preferable for detecting the CPB-induced impairment of platelet aggregation.12 However, the assessment of arachidonic acid and thrombin-induced platelet aggregation are also integral parts of several aggregometry-based hemotherapy algorithms.14,18,19 Apart from the assessment of the effectiveness of antiaggregatory medication, the ASPI test is routinely used to monitor alterations of platelet function resulting from unspecific impairments of platelet COX I pathway due to acidosis, hypothermia, and colloids.20,21 Thus, the observed significant decrease in arachidonic acid–induced platelet aggregation between baseline and T1 is comprehensible. In contrast to the
Weber et al.
Fig. 3 Normothermic ECC group: Ex vivo induced platelet aggregation was assessed at baseline (T0) and at 90 minutes (T1), 120 minutes (T2), 150 minutes (T3), and 180 minutes (T4) after beginning ECC. # indicates the significant difference (p < 0.05) in comparison to baseline.
ADP test, platelet aggregation in the ASPI test remained unchanged from T1 onward; we attribute this observance to an assumed stronger stimulation of platelet aggregation following exposure to arachidonic acid compared with ADP. However, the strongest activation of platelet aggregation in MEA results from the stimulation of the thrombin receptor (TRAP test). Therefore, it was unsurprising to find that ex vivo induced aggregation in the TRAP test remained unchanged during the study period in both groups. Thus, our data indicate that the TRAP test was not sensitive enough to reflect unspecific ECC-induced disturbances in platelet aggregability. The observed changes in ex vivo induced platelet aggregation may be of a multifactorial cause and cannot be Thoracic and Cardiovascular Surgeon
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MEA for the Assessment of Acquired Platelet Dysfunctions
MEA for the Assessment of Acquired Platelet Dysfunctions
Weber et al.
Table 2 Physiologic basic conditions for hemostasis at different time points T0 T (°C) pH Cai (mmol/L) Hb (g/dL)
T1
T2
T3
T4
T5 36.9 0.6
Hypothermic ECC
36.4 0.4
32.7 0.7
32.8 0.6
32.9 0.7
32.9 0.9
Normothermic ECC
36.5 1.1
36.5 1.2
37.1 0.7
37.1 0.9
37.1 0.6
Hypothermic ECC
7.41 0.1
7.39 0.05
7.36 0.06
7.38 0.04
7.38 0.05
Normothermic ECC
7.38 0.1
7.38 0.1
7.36 0.08
7.42 0.02
7.39 0.03
Hypothermic ECC
1.2 0.04
1.20 0.05
1.20 0.05
1.19 0.04
1.20 0.06
Normothermic ECC
1.2 0.01
1.16 0.1
1.2 0.06
1.19 0.1
1.2 0.1
Hypothermic ECC
12.5 2.2
9.2 1.6
9.2 1.4
9.2 1.3
8.9 1.2
Normothermic ECC
8.8 0.9
8.9 0.8
8.7 1.2
8.6 0.8
9.2 0.9
7.36 0.05 1.22 0.17 9.0 1.0
Abbreviations: Cai,, ionized calcium; ECC, extracorporeal circulation; Hb, hemoglobin; T, temperature. Note: The data are presented as the mean standard deviation.
Table 3 Results of routine clinical chemistry analyses at baseline Hypothermic ECC
Normothermic ECC
T0
T5
T0
210 72
165 48
136 30
Fibrinogen (mg/dL)
370 95
172 31
258 44
INR
1.34 0.15
1.51 0.11
1.23 0.23
aPTT (s)
42 5
45 5
48 4
Platelet count (/nL)
Abbreviations: aPTT, activated partial thromboplastin time; ECC, extracorporeal circulation; INR, international normalized ratio. Note: The data are presented as the mean standard deviation.
exclusively attributed to the use of ECC. Several factors, such as pH,21 hemoglobin concentration,22 platelet count,23 and hypothermia,24 have been shown to influence platelet aggregability. Intending to register reversible and therefore potentially irrelevant hemostatic effects of hypothermia on MEA results, we enrolled patients treated with either hypothermic or normothermic ECC. The observed significant reduction in ADP-induced platelet aggregation between baseline and T1, and the trend of the consecutive reduction of the median values from T1 onward led to the assumption that the observed changes in MEA results are independent from hypothermia and can be attributed to the use of ECC. An enrollment of a larger study population, particularly in the normothermic ECC group, would have led to an improvement of validity and informative value of our data. However, the inclusion and exclusion criteria of the present study focus on patients with initially unaffected platelet function, and this collective of patients is extremely rare. In the present study, we assessed the type and amount of hemotherapy that was administered during the study period. However, the study collective of the present descriptive study was too small and too inhomogeneous, and the study period was too short to allow the identification of specific cutoff values by conducting multivariate analyses or receiving operating characteristic curves. The results of our investigation indicate that ADP-induced platelet aggregation may be used to monitor the effects of ECC. Therefore, further studies Thoracic and Cardiovascular Surgeon
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should be conducted to analyze the cutoff values of the ADP test that may indicate an increased risk for the development of perioperative hemorrhage and the consecutive need for optimizing primary hemostasis through the administration of 1-deamino-8-d-arginine vasopressin (DDAVP) and/or the transfusion of platelet concentrates (PCs). We focused on the relatively rare collective of patients with initially unaffected platelet function. This allowed us to investigate the effects of ECC on platelet function that was not affected by drugs such as arachidonic acid or clopidogrel. On account of this, the conclusions of the present study cannot be uncritically transferred to daily practice. There were some limitations in our study. It would have been of clinical interest if we had been able to draw conclusions concerning potential correlations between laboratory results and clinical outcome parameters, such as blood loss and the need for hemotherapy. However, this was not the aim of the present study, and the study collective was too small and too inhomogeneous with a study period that was too short to allow for accurate and well-founded analyses concerning this matter. The interpretation of our study results, particularly of the arachidonic acid–induced platelet aggregation in the ASPI test, may be afflicted with α and β errors. Some patients from the hypothermic ECC group received hemotherapy after weaning from ECC that may have affected platelet function and MEA results. On the basis of our institutional hemotherapy algorithm for the treatment of coagulopathic patients, n ¼ 12 patients received DDAVP,
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MEA for the Assessment of Acquired Platelet Dysfunctions
9 Griffin MJ, Rinder HM, Smith BR, et al. The effects of heparin,
10
11
12
13
Conclusion In patients with initially unaffected platelet function, ex vivo ADP-induced platelet aggregation in MEA decreases in dependency of the ECC duration. Data from the present study indicate that the ADP test of MEA is feasible to reflect the extent of ECC-associated acquired platelet dysfunctions during both normothermic and hypothermic ECC.
14
15
16 17
References 1 Paone G, Likosky DS, Brewer R, et al; Membership of the Michigan
2
3
4
5
6 7
8
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protamine, and heparin/protamine reversal on platelet function under conditions of arterial shear stress. Anesth Analg 2001;93(1): 20–27 Wolberg AS, Meng ZH, Monroe DM III, Hoffman M. A systematic evaluation of the effect of temperature on coagulation enzyme activity and platelet function. J Trauma 2004;56(6):1221–1228 Slaughter TF, Sreeram G, Sharma AD, El-Moalem H, East CJ, Greenberg CS. Reversible shear-mediated platelet dysfunction during cardiac surgery as assessed by the PFA-100 platelet function analyzer. Blood Coagul Fibrinolysis 2001;12(2):85–93 Velik-Salchner C, Maier S, Innerhofer P, et al. An assessment of cardiopulmonary bypass-induced changes in platelet function using whole blood and classical light transmission aggregometry: the results of a pilot study. Anesth Analg 2009;108(6):1747–1754 Tóth O, Calatzis A, Penz S, Losonczy H, Siess W. Multiple electrode aggregometry: a new device to measure platelet aggregation in whole blood. Thromb Haemost 2006;96(6):781–788 Weber CF, Görlinger K, Meininger D, et al. Point-of-care testing: a prospective, randomized clinical trial of efficacy in coagulopathic cardiac surgery patients. Anesthesiology 2012;117(3):531–547 Mutlak H, Rehse C, Scheller B, et al. Comparison of heparin vs. lepirudin anticoagulated tubes for the assessment of ASS-induced platelet dysfunction using the Multiplate device. Appl Cardiopulm Pathophysiol 2013;17:275–283 Cardinal DC, Flower RJ. The study of platelet aggregation in whole blood [proceedings]. Br J Pharmacol 1979;66(1):94P–95P Weber CF, Zacharowski K, Brün K, et al. [Basic algorithm for Pointof-Care based hemotherapy: perioperative treatment of coagulopathic patients]. Anaesthesist 2013;62(6):464–472 Görlinger K, Dirkmann D, Hanke AA, et al. First-line therapy with coagulation factor concentrates combined with point-of-care coagulation testing is associated with decreased allogeneic blood transfusion in cardiovascular surgery: a retrospective, singlecenter cohort study. Anesthesiology 2011;115(6):1179–1191 Görlinger K, Dirkmann D, Weber CF, Rahe-Meyer N, Hanke AA. Algorithms for transfusion and coagulation management in massive haemorrhage. Anästh Intensivmed 2011;52:145–159 Scharbert G, Kalb M, Marschalek C, Kozek-Langenecker SA. The effects of test temperature and storage temperature on platelet aggregation: a whole blood in vitro study. Anesth Analg 2006; 102(4):1280–1284 Hanke AA, Dellweg C, Kienbaum P, Weber CF, Görlinger K, RaheMeyer N. Effects of desmopressin on platelet function under conditions of hypothermia and acidosis: an in vitro study using multiple electrode aggregometry. Anaesthesia 2010;65(7): 688–691 Bochsen L, Johansson PI, Kristensen AT, Daugaard G, Ostrowski SR. The influence of platelets, plasma and red blood cells on functional haemostatic assays. Blood Coagul Fibrinolysis 2011;22(3): 167–175 Hanke AA, Roberg K, Monaca E, et al. Impact of platelet count on results obtained from multiple electrode platelet aggregometry (Multiplate). Eur J Med Res 2010;15(5):214–219 Ortmann E, Klein AA, Sharples LD, et al. Point-of-care assessment of hypothermia and protamine-induced platelet dysfunction with multiple electrode aggregometry (Multiplate®) in patients undergoing cardiopulmonary bypass. Anesth Analg 2013;116(3): 533–540
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and n ¼ 4 patients were transfused with PC after neutralization of heparin (between T4 and T5). This was unavoidable for ethical reasons and most likely explains the observed phenomenon that ADP-induced platelet aggregation remained unchanged between T4 and T5. To assess the potential effect of DDAVP on platelets aggregability, we compared MEA results obtained from patients who received (n ¼ 12) or did not receive (n ¼ 8) DDAVP between T4 and T5. There were no significant group differences neither in the ADP test (29 [16/66] U, median [25th/75th] percentile, vs. 26 [17/47] U, p ¼ 0.787), nor in the ASPI test (30 [18/53] vs. 20 [13/39] U, p ¼ 0.44) or in the TRAP test (116 [81/147] vs. 82 [72/115] U, p ¼ 0.263).
Weber et al.
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