Coagulopathic-induced membrane dysfunction during extracorporeal membrane oxygenation: a case report

Comparative analysis of oxygenator dysfunction in polymethylpentene oxygenators: A pilot study

INTRODUCTION

Polymethylpentene (PMP) oxygenators serve as the primary oxygenator type utilized for ECMO. With the number of PMP oxygenators available, it has become increasingly important to determine differences among each oxygenator type that can lead to varying metrics of oxygenator dysfunction.

METHODS

This study was a retrospective, single-center analysis of adult patients supported on ECMO between December 2020 to December 2021 with varying PMP oxygenators including the Medtronic Nautilus Smart (Minneapolis, MA), the Eurosets AMG PMP (Medolla, Italy) and Getinge Quadrox-iD and the Getinge Cardiohelp HLS Module Advanced System (Gothenberg, Sweden).

RESULTS

A total of 19 patients were included in our study. 10 patients (52.6%) were supported with a Medtronic Nautilus Smart oxygenator, 5 patients (26.3%) were supported with an Eurosets AMG PMP Oxygenator, and 4 patients (21.1%) were supported with either a Getinge Quadrox-iD oxygenator or Getinge Cardiohelp HLS system. Patients supported with Eurosets AMG PMP oxygenators experienced higher resistance and lower post-oxygenator PaO2 in comparison to other cohorts (p < .02 and < .002 respectively). There was no difference in measured oxygen transfer between cohorts (p = .667). Two patients, both supported by Eurosets AMG PMP, experienced oxygenator failure (p = .094).

CONCLUSION

Radial flow oxygenators are prone to higher resistance and lower post-oxygenator PaO2when compared to transverse flow oxygenators. Future larger multicenter studies are required to fully discern the differences between flow-varying polymethylpentene oxygenators and their appropriate cutoffs for oxygenator dysfunction.

Impact of thrombelastography in paediatric intensive care

We assessed the clinical impact of thrombelastography (TEG®) results (TEG® 5000, Haemonetics Corporation, Braintree, MA, USA) by measuring their ability to cause changes in a theoretical treatment plan and contribute to the understanding of haemostasis. We prospectively included paediatric intensive care unit (PICU) patients who had standard tests of haemostasis and TEG ordered and had an arterial catheter or extracorporeal access port in situ. Blood for standard tests and TEG was taken simultaneously. Independent of patient care, general patient information and results of standard laboratory tests were presented to five clinicians who were asked to document their theoretical treatment plan. Clinicians were then shown TEG results and asked if they caused a change in their plan, if they confirmed initial standard laboratory test results, if they enabled a better understanding of haemostasis and if they provided additional information. Inter-rater agreement between the clinicians was determined. Forty-two TEG results were obtained from 34 patients. Overall, the inclusion of TEG results led to a change in treatment plan in 97 of 207 occasions (47%), confirmed standard laboratory test results in 177 of 204 occasions (87%), enabled a better understanding of haemostasis in 140 of 204 occasions (69%) and provided additional information in 131 of 204 occasions (64%). Variation existed between clinicians, seemingly due to individual differences, with poor inter-rater agreement. We conclude that TEG results led to changes in treatment plans almost half the time, confirmed findings of standard tests and provided a better understanding of haemostasis, but randomised controlled trials are required to determine the role and influence of TEG results on patient outcome.

Antithrombin Concentrate Use in Pediatric Extracorporeal Membrane Oxygenation: A Multicenter Cohort Study

OBJECTIVE

To describe antithrombin concentrate use and to compare thrombotic and hemorrhagic outcomes throughout the hospital stay in pediatric subjects who received extracorporeal membrane oxygenation in a Pediatric Health Information System-participating children's hospital.

DESIGN

Retrospective, multi-center, cohort study.

SETTING

Forty-three free-standing children's hospitals participating in Pediatric Health Information System.

SUBJECTS

Children older than or equal to 18 years of age who underwent extracorporeal membrane oxygenation between 2003 and 2012.

INTERVENTIONS

Subjects were classified as receiving antithrombin if they received at least one dose of antithrombin while on extracorporeal membrane oxygenation.

MEASUREMENTS AND MAIN RESULTS

International Classification of Diseases, Ninth Revision, Clinical Modification codes codes were used to identify hemorrhagic and thrombotic complications during their hospitalization. Pediatric Health Information System data were analyzed to determine hospital-length of stay and in-hospital mortality. A total of 1,931 of 8,601 eligible subjects (21.5%) received at least one dose of antithrombin during their extracorporeal membrane oxygenation course. Antithrombin use during extracorporeal membrane oxygenation increased from 2.4% to 51.9% (p < 0.001) over the 10-year study period. Subjects who received antithrombin while on extracorporeal membrane oxygenation were younger (p = 0.02), had more chronic conditions (p < 0.001), and longer hospital stays (p < 0.001). On multivariate analysis, antithrombin use was associated with thrombotic events (odds ratio, 1.55; 95% CI, 1.36-1.77; p < 0.001), hemorrhagic events (odds ratio, 1.27; 95% CI, 1.14-1.42; p < 0.001), and longer hospital length of stays (slope coefficient, 1.05 d; 95% CI, 1.04-1.06; p < 0.001). No difference was observed in mortality (odds ratio, 0.99; 95% CI, 0.89-1.11; p = 0.90).

CONCLUSIONS

In this multicenter retrospective cohort study, subjects who received antithrombin during extracorporeal membrane oxygenation had a higher number of thrombotic and hemorrhagic events throughout the hospitalization and longer length of stays without an associated difference in mortality. While limitations exist with this analysis and results should be interpreted with caution, the fact remains that over half of pediatric patients on extracorporeal membrane oxygenation are currently receiving antithrombin without clear benefit, with extra cost, and potential harms, there needs to be strong consideration for a clinical trial.

Antithrombin concentrates use in children on extracorporeal membrane oxygenation: a retrospective cohort study

OBJECTIVE

To investigate whether receipt of any antithrombin concentrate improves laboratory and clinical outcomes in children undergoing extracorporeal membrane oxygenation for respiratory failure during their hospitalization compared with those who did not receive antithrombin.

DESIGN

Retrospective cohort study.

SETTING

Single, tertiary-care pediatric hospital.

PATIENTS

Sixty-four neonatal and pediatric patients who underwent extracorporeal membrane oxygenation for respiratory failure between January 2007 and September 2011.

INTERVENTION

Exposure to any antithrombin concentrate during their extracorporeal membrane oxygenation course compared with similar children who never received antithrombin concentrate.

MEASUREMENTS AND MAIN RESULTS

Thirty patients received at least one dose of antithrombin during their extracorporeal membrane oxygenation course and 34 patients did not receive any. The median age at admission was less than 1-month old. Age, duration of extracorporeal membrane oxygenation, or first antithrombin level did not differ significantly between the two cohorts. The mean plasma antithrombin level in those who never received antithrombin was 42.2% compared with 66% in those who received it. However, few levels reached the targeted antithrombin level of 120% and those who did fell back to deficient levels within an average of 6.8 hours. For those who received antithrombin concentrate, heparin infusion rates decreased by an average of 10.2 U/kg/hr for at least 12 hours following administration. No statistical differences were noted in the number of extracorporeal membrane oxygenation circuit changes, in vivo clots or hemorrhages, transfusion requirements, hospital or ICU length of stay, or in-hospital mortality.

CONCLUSIONS

Intermittent, on-demand dosing of antithrombin concentrate in pediatric patients on extracorporeal membrane oxygenation for respiratory failure increased antithrombin levels, but not typically to the targeted level. Patients who received antithrombin concentrate also had decreased heparin requirements for at least 12 hours after dosing. However, no differences were noted in the measured clinical endpoints. A prospective, randomized study of this intervention may require different dosing strategies; such a study is warranted given the unproven efficacy of this costly product.

Unfractionated heparin activity measured by anti-factor Xa levels is associated with the need for extracorporeal membrane oxygenation circuit/membrane oxygenator change: a retrospective pediatric study

OBJECTIVE

Investigate whether anti-Factor Xa levels are associated with the need for change of circuit/membrane oxygenator secondary to thrombus formation in pediatric patients.

DESIGN AND SETTINGS

Retrospective single institution study.

PATIENTS

Retrospective record review of 62 pediatric patients supported with extracorporeal membrane oxygenation from 2009 to 2011.

INTERVENTIONS

Data on standard demographic characteristics, indications for extracorporeal membrane oxygenation, duration of extracorporeal membrane oxygenation, activated clotting time measurements, anti-Factor Xa measurements, and heparin infusion rate were collected. Generalized linear models were used to associate anti-Factor Xa concentrations and need for change of either entire circuit/membrane oxygenator secondary to thrombus formation.

MEASUREMENTS AND MAIN RESULTS

Sixty-two patients met study inclusion criteria. No-circuit change was required in 45 of 62 patients. Of 62 patients, 17 required change of circuit/membrane oxygenator due to thrombus formation. Multivariate analysis of daily anti-Factor Xa measurements throughout duration of extracorporeal membrane oxygenation support estimated a mean anti-Factor Xa concentration of 0.20 IU/mL (95% CI, 0.16, 0.24) in no-complete-circuit group that was significantly higher than the estimated concentration of 0.13 IU/mL (95% CI, 0.12, 0.14) in complete-circuit group (p = 0.001). A 0.01 IU/mL decrease in anti-Factor Xa increased odds of need for circuit/membrane oxygenator change by 5% (odds ratio = 1.105; 95% CI, 1.00, 1.10; p = 0.044). Based on the observed anti-Factor Xa concentrations, complete-circuit group had 41% increased odds for requiring circuit/membrane oxygenator change compared with no-complete-circuit group (odds ratio = 1.41; 95% CI, 1.01, 1.96; p = 0.044). Mean daily activated clotting time measurement (p = 0.192) was not different between groups, but mean daily heparin infusion rate (p < 0.001) was significantly different between the two groups.

CONCLUSIONS

Higher anti-Factor Xa concentrations were associated with freedom from circuit/membrane oxygenator change due to thrombus formation in pediatric patients during extracorporeal membrane oxygenation support. Activated clotting time measurements did not differ significantly between groups with or without circuit/membrane oxygenator change. This is the first study to link anti-Factor Xa concentrations with a clinically relevant measure of thrombosis in pediatric patients during extracorporeal membrane oxygenation support. Further prospective study is warranted.

Inhibition of thrombocyte aggregation during extracorporeal lung assist: a case report

In extracorporeal lung assist, membrane oxygenators are used to improve gas exchange. Accumulations on the membranes of coagulation end products can increase resistance to blood flow and diffusion distance. Thus, functioning of the system can be impaired and, in extreme cases, lead to malfunction which may necessitate change out of the oxygenator. We describe a method that complements conventional continuous heparinisation with the administration of acetylsalicylic acid to inhibit thrombocyte aggregation.

Effect of heparin, platelets, activated platelets, platelet fragments, and hematocrit on activated clotting time

Activated clotting time (ACT) is the most commonly used laboratory test to control the heparin effect during extracorporeal techniques. The study was undertaken in order to test in vitro the influence of heparin, platelet count, hematocrit, platelet fragmentation, and platelet activation on ACT. Blood was drawn from volunteer donors into syringes containing citrate. Platelet counts and hematocrit were modified. Platelets were fragmented by sonifier or activated by collagen and adenosine diphosphate (ADP). Different heparin final concentrations were created. Increasing concentrations of heparin had a significant effect on ACT. However, it was not predictable in every case in concentrations lower than 1.0 U/ml. Platelet count generally had no significant effect on ACT. The effect of hematocrit was detectable in a group but not in single cases. Fragmented platelets significantly shortened ACT only without addition of heparin, and the effect was only partly predictable. Activation of platelets by collagen and ADP induced no significant changes. Our results show that heparin is reflected by ACT but that effect is not predictable in every specific patient. Our results also show that other variables that may be altered during extracorporeal techniques such as platelet count, hematocrit, activation, and fragmentation of platelets do not severely influence the ACT.

Pre-operative coagulopathy management of a neonate with complex congenital heart disease: a case study

Severe coagulation defects often develop in neonates undergoing cardiac surgery, both as a result of the surgical intervention, and as pre-existing defects in the hemostatic mechanisms. The following case report describes a newborn patient with complex congenital heart disease and respiratory failure whose pre-operative coagulopathy was aggressively managed prior to surgical correction. A 5-day-old, 2.5 kg child presented with interrupted aortic arch, ventricular septal defect, atrial septal defect, and patent ductus arteriosus. On admission, he was in respiratory arrest suffering from profound acidemia. In addition, the child was hypothermic (30.1 degrees C), septic (Streptococcus viridans), and coagulopathic (disseminated intravascular coagulation-DIC). The patient was immediately intubated and initial coagulation assessment revealed the following: prothrombin time (PT) 48.9 s (international normalized ratio (INR) 15.7), activated partial thromboplastin time (aPTT) >106 s, platelet count 30,000 mm(3), fibrinogen 15 mg dL(-1) and antithrombin III (AT-III) 10%. Before cardiac surgery could be performed, the patient's DIC was corrected with the administration of cryoprecipitate (15 ml), fresh frozen plasma (300 ml), and platelets (195 ml). In spite of the large transfusion of fresh frozen plasma, the AT-III activity, measured as a percentage, remained depressed at 33. Initial thromboelastographic (TEG) determination revealed an index of +2.02, and following 100 IU administration of an AT-III concentrate, declined to -2.32. Sequential TEG profiles were performed over several days, with the results used to guide both transfusion and medical therapy. The congenital heart defect correction was subsequently performed with satisfactory initial results, but the patient developed a fungal infection and expired on the 16th post-operative day. The present case describes techniques of coagulation management for a newborn with both a severe hemostatic defect and congenital heart disease.

Coagulation and anticoagulation in extracorporeal membrane oxygenation

The hemostatic system poses a major problem in extracorporeal membrane oxygenation (ECMO). The foreign surface in the extracorporeal circuit activates platelets and the clotting system. To avoid loss of platelets and activation of the clotting system, anticoagulation is necessary. In addition, in many patients on ECMO, preexisting clotting disorders are present. Therefore, bleeding and/or thrombosis are frequent complications in ECMO patients that require specific treatment and may even necessitate termination of ECMO. Most ECMO centers use heparin for anticoagulation and the activated clotting time (ACT) for monitoring. Reduction of problems with hemostasis may be obtained with less thrombogenic surfaces, new anticoagulants with a short half-life, platelet inhibitors, protease inhibitors, or selective anticoagulation in the extracorporeal circuit. While there will probably never be a complete nonthrombogenic surface available and all anticoagulants will have some risk of bleeding, improvement can be obtained by a combination of measures including better surfaces, more sophisticated anticoagulation regimens, and close laboratory monitoring.