Hematological complications in children subjected to extracorporeal membrane oxygenation

OBJECTIVES

To analyze the hematological complications and need for transfusions in children receiving extracorporeal life support (ECLS).

DESIGN

A retrospective study was carried out.

SETTING

A pediatric intensive care unit.

PATIENTS

Children under 18 years of age subjected to ECLS between September 2006 and November 2015.

INTERVENTIONS

None.

VARIABLES OF INTEREST

Patient and ECLS characteristics, anticoagulation, hematological and coagulation parameters, transfusions and clinical course.

RESULTS

A total of 100 patients (94 with heart disease) with a median age of 11 months were studied. Seventy-six patients presented bleeding. The most frequent bleeding point was the mediastinum and 39 patients required revision surgery. In the first 3days, 97% of the patients required blood transfusion (34.4ml/kg per day), 94% platelets (21.1ml/kg per day) and 90% plasma (26.6ml/kg per day). Patients who were in the postoperative period, those who were bleeding at the start of ECLS, those requiring revision surgery, those who could not suspend extracorporeal circulation, and those subjected to transthoracic cannulation required a greater volume of transfusions than the rest of the patients. Thromboembolism occurred in 14 patients and hemolysis in 33 patients. Mortality among the children who were bleeding at the start of ECLS (57.6%) was significantly higher than in the rest of the patients (37.5%) (P=.048).

CONCLUSIONS

Children subjected to ECLS present high blood product needs. The main factors related to transfusions were the postoperative period, bleeding at the start of ECLS, revision surgery, transthoracic cannulation, and the impossibility of suspending extracorporeal circulation. Children with bleeding suffered greater mortality than the rest of the patients.

Acquired von Willebrand syndrome and impaired platelet function during venovenous extracorporeal membrane oxygenation: Rapid onset and fast recovery

BACKGROUND

Bleeding contributes to the high mortality of venovenous extracorporeal membrane oxygenation (vvECMO). The development of acquired von Willebrand syndrome (AVWS) has been identified as relevant pathology during ECMO. This study was performed to determine the onset of AVWS after implantation and the recovery of von Willebrand factor (VWF) parameters after explantation of ECMO in a large cohort of patients.

METHODS

VWF parameters of 59 patients treated with vvECMO at a university ECMO center were obtained before ECMO implantation, during therapy, and after explantation. In a subgroup of patients, light transmission aggregometry of platelets and flow-cytometric quantification of platelet granule secretion were performed.

RESULTS

All patients developed severe AVWS hours after implantation of vvECMO. After explantation, AVWS recovered within 3 hours in 60%, within 6 hours in 86%, and in all patients within 1 day. Aggregometry showed hypoaggregability of platelets after stimulation with ADP, ristocetin, collagen, and epinephrine. Flow-cytometric platelet analyses revealed severely reduced expression of CD62 and CD63.

CONCLUSIONS

All patients during vvECMO support rapidly develop AVWS and platelet dysfunction, resulting in severe impairment of coagulation. After explantation, AVWS overwhelmingly recovers within hours, resulting in a hypercoagulative state. These findings augment the need for novel extracorporeal technologies with reduced shear stress, and shift the emphasis for intense anti-coagulation during ECMO instead to a time-point after explantation.

Bleeding during veno-venous ECMO cannot reliably be predicted by rotational thrombelastometry (ROTEM™)

Introduction:

Veno-venous extracorporeal membrane oxygenation (vvECMO) used for respiratory support is associated with clinical bleeding in at least one third of patients. Mechanisms promoting bleeding, like acquired von Willebrand syndrome, cannot be identified by routine coagulation tests. This study was performed to evaluate rotational Thrombelastography (ROTEM™) for specific results predicting bleeding events during vvECMO.

Methods:

Five hundred and thirty-four ROTEM™ analyses of 57 patients over 574 days have been evaluated. Patients were graded into three groups according to the severity of bleeding, following the Freiburg ECMO bleeding assessment. ROTEM™ results and basic as well as comprehensive laboratory coagulation tests have been compared among the three groups and overall between defined time points.

Results:

Fourteen patients (25 %) presented without bleeding, 22 patients (39 %) showed mild bleeding and 21 patients (36 %) became evident with relevant clinical bleeding. No bleeding shock and no fatal bleeding event occurred. No case of hyperfibrinolysis was observed. Neither a statistical difference for ECMO blood flow nor duration of therapy among the groups could be shown. The only significant difference was clotting time (CT) in the InTEM analysis, with a median (IQR) of 175 (37.5) seconds in Group 1, 190 (54.5) seconds in Group 2 and 204 (90) seconds in Group 3. When comparing overall ROTEM™ analyses between defined time points, continuous worsening of CT can be found in ExTEM, FibTEM and ApTEM. Reduced A10, A20 and congruently maximum clot firmness, especially, developed in ExTEM and ApTEM and with a minor characteristic in InTEM, but not in FibTEM. ROTEM™ and coagulation-parameter results before 19 clinical relevant bleeding episodes compared to all other results only showed differences in FibTEM.

Conclusion:

ROTEM™ as a functional viscoelastic analysis does not provide additional information to basic and comprehensive laboratory tests during vvECMO. Bleeding events cannot be predicted by the means of specific ROTEM™ results.

[Extracorporeal lung support]

Systems for extracorporeal lung support have recently undergone significant technological improvements leading to more effective and safe treatment. Despite limited scientific evidence these systems are increasingly used in the intensive care unit for treatment of different types of acute respiratory failure. In general two types of systems can be differentiated: devices for extracorporeal carbon dioxide removal (ECCO₂R) for ventilatory insufficiency and devices for extracorporeal membrane oxygenation (ECMO) for severe hypoxemic failure. Despite of all technological developments extracorporeal lung support remains an invasive and a potentially dangerous form of treatment with bleeding and vascular injury being the two main complications. For this reason indications and contraindications should always be critically considered and extracorporeal lung support should only be carried out in centers with appropriate experience and expertise.

Laboratory and clinical predictors of 30-day survival for patients on Extracorporeal Membrane Oxygenation (ECMO): 8-Year experience at Albert Einstein College of Medicine, Montefiore Medical Center

PURPOSE

Survival of patients on ECMO has remained stable in every population. Laboratory values predictors of survival are required to improve patient care.

MATERIALS AND METHODS

Clinical Looking Glass software was used to assess Electronic Medical Records (EMRs) of patients at Albert Einstein College of Medicine, Montefiore Medical Center (2007-2014).

RESULTS

Our population comprises of 166 adults and was divided in survivors and non-survivors, within 30days. Indications for ECMO were cardiac (65%), respiratory (25%) and infectious diseases (<10%). Eighty six patients (51.8%) survived the procedure. Gender, body weight, ejection fraction, diastolic blood pressure, and socio-economic status did not differ among survivors and non-survivors. In contrast, younger patients (45yo vs 55yo, p=0.0001) and higher systolic blood pressure (115mmHg vs 103mmHg, p=0.025) have favorable outcome. Univariate analysis shows that pre-cannulation values for creatinine (p=0.0003), chloride (p=0.009), bicarbonate (p=0.015) and pH (p=0.03) have prognostic value. Post-cannulation aPTT, pH, platelet and lymphocyte counts also have discriminative power. Notably, multiple logistic regressions for Multivariate Analysis identified chloride (OR 1.07; 95% CI 1.02-1.13; p=0.004), pH (OR 3.35; 95% CI 1.89-5.9; p<0.0001) and aPTT (OR 0.98; 95% CI 0.976-0.998; p=0.024) as independent risk factors for 30-day mortality. These results imply that pre-existing renal conditions and hemostatic dysregulation contribute to poor outcome. Finally, patients on VV-ECMO have increase odds of survival (OR 1.88; 95% CI 1.06-3.34; p=0.029).

CONCLUSIONS

Laboratory markers identified herein may guide the management of patients on ECMO.

Predictive factors of bleeding events in adults undergoing extracorporeal membrane oxygenation

Background

Bleeding is the most frequent complication associated with extracorporeal membrane oxygenation (ECMO) support in critically ill patients. Nonetheless, risk factors for bleeding have been poorly described especially those associated with coagulation anomalies and anticoagulant therapy during ECMO support. The aim of this study is to describe bleeding complications in critically ill patients undergoing ECMO and to identify risk factors for bleeding events.

Methods

We retrospectively analysed ICU charts of adults who received either veno-venous (VV) or veno-arterial (VA) ECMO support in two participating ICUs between 2010 and 2013. Characteristics of patients with and without bleeding complications, as per the Extracorporeal Life Support Organisation (ELSO) definition, were compared, and the impact of bleeding complications on patient outcomes was assessed using survival analysis. Variables that were independently associated with bleeding, including daily clinical and biological variables during ECMO courses, were modelled.

Results

Of the 149 ECMO episodes (111 VA ECMO and 38 VV ECMO) performed in 147 adults, 89 episodes (60 %) were complicated by at least one bleeding event. The most common bleeding sources were: ECMO cannula (37 %), haemothorax or cardiac tamponade (17 %) and ear–nose and throat (16 %). Intra-cranial haemorrhage occurred in five (2.2 %) patients. Bleeding complications were independently associated with worse survival [adjusted hazard ratio (HR) 2.17, 95 % confidence interval (CI) 1.07–4.41, P = 0.03]. Higher activated partial thromboplastin time (aPTT) [adjusted odds ratio (OR) 3.00, 95 % CI 1.64–5.47, P < 0.01], APACHE III score [adjusted OR 1.01, 95 % CI 1.01–1.02, P = 0.01] and ECMO following surgery [adjusted OR 3.04, 95 % CI 1.62–5.69, P < 0.01] were independently associated with greater risk of bleeding occurrence. A similar association between bleeding and higher aPTT was found when non-post-surgical VA ECMO was considered separately.

Conclusions

Bleeding events based on the ELSO bleeding definition occurred in more than 60 % of ECMO episodes and were associated with hospital mortality. We identified higher aPTT prior bleeding as an independent risk factor for bleeding event, suggesting that better control of the aPTT (through a better control of either coagulopathy or anticoagulation) may improve patients’ outcome.

Dual Antiplatelet Therapy (DAPT) versus No Antiplatelet Therapy and Incidence of Major Bleeding in Patients on Venoarterial Extracorporeal Membrane Oxygenation

Aims

Bleeding is a frequent complication in patients on venoarterial extracorporeal membrane oxygenation (VA-ECMO). An indication for dual antiplatelet therapy due to coronary stent implantation is present in a considerable number of these patients. The objective of this retrospective study was to evaluate if dual antiplatelet therapy (DAPT) significantly increases the high intrinsic bleeding risk in patients on VA-ECMO.

Methods and Results

A total of 93 patients were treated with VA-ECMO between October 2010 and October 2013. Average time on VA-ECMO was 58.9 ± 1.7 hours. Dual antiplatelet therapy was given to 51.6% of all patients. Any bleeding was recorded in 60.2% of all patients. There was no difference in bleeding incidence in patients on DAPT when compared to those without any antiplatelet therapy including any bleeding (66.7% vs. 57.1%, p = 0.35), BARC3 bleeding (43.8% vs. 33.3%, p = 0.31) or pulmonary bleeding (16.7% vs. 19.0%, p = 0.77). This holds true after adjustment for confounders. Rate of transfusion of red blood cells were similar in patients with or without DAPT (35.4% vs. 28.6%, p = 0.488).

Conclusions

Bleeding on VA-ECMO is frequent. This registry recorded no statistical difference in bleeding in patients on dual antiplatelet therapy when compared to no antiplatelet therapy. When indicated, DAPT should not be withheld from VA ECMO patients.

Decreased maximum clot firmness in rotational thromboelastometry (ROTEM®) is associated with bleeding during extracorporeal mechanical circulatory support

BACKGROUND:

We aimed to characterize the coagulation disturbances which may increase the risk of bleeding, thrombosis or death shortly after implantation of an extracorporeal membrane oxygenation (ECMO) or ventricular assist (VAD) device.

METHODS:

Antithrombotic treatment was started in 23 VAD and 24 ECMO patients according to the hospital protocol. Additionally, conventional laboratory testing, rotational thromboelastometry (ROTEM®) and platelet function analysis (Multiplate®) were performed at predetermined intervals.

RESULTS:

Four out of twenty-four (16.7%) of ECMO patients and 6/23 (26.1%) of VAD patients had severe bleeding after the procedure. When all the patients were analyzed together, low maximum clot firmness (MCF) in ExTEM and FibTEM analyses was associated with severe bleeding (p<0.05) and low MCF in FibTEM with 30-day mortality. Low platelet count and hematocrit levels were also associated with severe bleeding. When VAD and ECMO patients were separated into different groups, the association between ROTEM® parameters, bleeding and survival was found only in limited time points. Four patients with VAD had cerebral ischemia indicative of thromboembolism. However, this had no significant correlation with ROTEM® or Multiplate® parameters.

CONCLUSION:

Hypocoagulation shown by ROTEM® was associated with bleeding complications in patients with mechanical circulatory support. In contrast, hypercoagulation did not correlate with clinical thrombosis.