External validation of the PC-ECMO score in postcardiotomy veno-arterial extracorporeal membrane oxygenation

Reliable stratification of the risk of early mortality after postcardiotomy veno-arterial extracorporeal membrane oxygenation (V-A-ECMO) remains elusive. In this study, we externally validated the PC-ECMO score, a specific risk scoring method for prediction of in-hospital mortality after postcardiotomy V-A-ECMO. Overall, 614 patients who required V-A-ECMO after adult cardiac surgery were gathered from an individual patient data meta-analysis of nine studies on this topic. The AUC of the logistic PC-ECMO score in predicting in-hospital mortality was 0.678 (95%CI 0.630-0.726; p < 0.0001). The AUC of the logistic PC-ECMO score in predicting on V-A-ECMO mortality was 0.652 (95%CI 0.609-0.695; p < 0.0001). The Brier score of the logistic PC-ECMO score for in-hospital mortality was 0.193, the slope 0.909, the calibration-in-the-large 0.074 and the expected/observed mortality ratio 0.979. 95%CIs of the calibration belt of fit relationship between observed and predicted in-hospital mortality were never above or below the bisector (p = 0.072). The present findings suggest that the PC-ECMO score may be a valuable tool in clinical research for stratification of the risk of patients requiring postcardiotomy V-A-ECMO.

Inter-institutional analysis of the outcome after postcardiotomy veno-arterial extracorporeal membrane oxygenation

INTRODUCTION

Patients requiring postcardiotomy veno-arterial extracorporeal membrane oxygenation (V-A-ECMO) have a high risk of early mortality. In this analysis, we evaluated whether any interinstitutional difference exists in the results of postcardiotomy V-A-ECMO.

METHODS

Studies on postcardiotomy V-A-ECMO were identified through a systematic review for individual patient data (IPD) meta-analysis. Analysis of interinstitutional results was performed using direct standardization, estimation of observed/expected in-hospital mortality ratio and propensity score matching.

RESULTS

Systematic review of the literature yielded 31 studies. Data from 10 studies on 1269 patients treated at 25 hospitals were available for the present analysis. In-hospital mortality was 66.7%. The relative risk of in-hospital mortality was significantly higher in six hospitals. Observed versus expected in-hospital mortality ratio showed that four hospitals were outliers with significantly increased mortality rates, and one hospital had significantly lower in-hospital mortality rate. Participating hospitals were classified as underperforming and overperforming hospitals if their observed/expected in-hospital mortality was higher or lower than 1.0, respectively. Among 395 propensity score matched pairs, the overperforming hospitals had significantly lower in-hospital mortality (60.3% vs 71.4%, p = 0.001) than underperforming hospitals. Low annual volume of postcardiotomy V-A-ECMO tended to be predictive of poor outcome only when adjusted for patients' risk profile.

CONCLUSIONS

In-hospital mortality after postcardiotomy V-A-ECMO differed significantly between participating hospitals. These findings suggest that in many centers there is room for improvement of the results of postcardiotomy V-A-ECMO.

Hyperlactatemia and poor outcome After postcardiotomy veno-arterial extracorporeal membrane oxygenation: An individual patient data meta-Analysis

INTRODUCTION

Postcardiotomy veno-arterial extracorporeal membrane oxygenation (V-A-ECMO) is associated with significant mortality. Identification of patients at very high risk for death is elusive and the decision to initiate V-A-ECMO is based on clinical judgment. The prognostic impact of pre-V-A-ECMO arterial lactate level in these critically ill patients has been herein evaluated.

METHODS

A systematic review was conducted to identify studies on postcardiotomy VA-ECMO for the present individual patient data meta-analysis.

RESULTS

Overall, 1269 patients selected from 10 studies were included in this analysis. Arterial lactate level at V-A-ECMO initiation was increased in patients who died during the index hospitalization compared to those who survived (9.3 vs 6.6 mmol/L, p < 0.0001). Accordingly, in hospital mortality increased along quintiles of pre-V-A-ECMO arterial lactate level (quintiles: 1, 54.9%; 2, 54.9%; 3, 67.3%; 4, 74.2%; 5, 82.2%, p < 0.0001). The best cut-off for arterial lactate was 6.8 mmol/L (in-hospital mortality, 76.7% vs. 55.7%, p < 0.0001). Multivariable multilevel mixed-effect logistic regression model including arterial lactate level significantly increased the area under the receiver operating characteristics curve (0.731, 95% CI 0.702-0.760 vs 0.679, 95% CI 0.648-0.711, DeLong test p < 0.0001). Classification and regression tree analysis showed the in-hospital mortality was 85.2% in patients aged more than 70 years with pre-V-A-ECMO arterial lactate level ≥6.8 mmol/L.

CONCLUSIONS

Among patients requiring postcardiotomy V-A-ECMO, hyperlactatemia was associated with a marked increase of in-hospital mortality. Arterial lactate may be useful in guiding the decision-making process and the timing of initiation of postcardiotomy V-A-ECMO.

Veno-Arterial Extracorporeal Membrane Oxygenation in the Adult: A Bridge to the State of the Art

Despite the technological advancements in the last 40 years, conditions such as refractory cardiogenic shock and cardiac arrest still present a very high mortality rate in real-world clinical practice.

In this light, we have reviewed the techniques, indications, contraindications, and results of the so- called Veno-Arterial Extracorporeal Circulatory Membrane Oxygenation (VA-ECMO) in the adult population to evaluate the current results of this temporary cardio-pulmonary support as salvage and/or bridge therapy in the patient suffering from refractory cardiogenic shock or cardio-circulatory arrest.

The results are encouraging, especially in the setting of refractory cardiogenic shock and in-hospital cardiac arrest. Among a selected population, the prompt institution of a VA-ECMO may radically change the prognosis by sustaining vital functions while looking for the leading cause or waiting for the reversal of the temporary cardio-respiratory negative condition.

The future directions aim to standardized and shared protocols, miniaturization of the machines, and possibly the institution of specialized “ECMO teams” for in and the out-of-hospital institution of the tool.

Prevention of Cardiac Surgery-Associated Acute Kidney Injury by Implementing the KDIGO Guidelines in High-Risk Patients Identified by Biomarkers: The PrevAKI-Multicenter Randomized Controlled Trial

BACKGROUND

Prospective, single-center trials have shown that the implementation of the Kidney Disease: Improving Global Outcomes (KDIGO) recommendations in high-risk patients significantly reduced the development of acute kidney injury (AKI) after surgery. We sought to evaluate the feasibility of implementing a bundle of supportive measures based on the KDIGO guideline in high-risk patients undergoing cardiac surgery in a multicenter setting in preparation for a large definitive trial.

METHODS

In this multicenter, multinational, randomized controlled trial, we examined the adherence to the KDIGO bundle consisting of optimization of volume status and hemodynamics, functional hemodynamic monitoring, avoidance of nephrotoxic drugs, and prevention of hyperglycemia in high-risk patients identified by the urinary biomarkers tissue inhibitor of metalloproteinases-2 [TIMP-2] and insulin growth factor-binding protein 7 [IGFBP7] after cardiac surgery. The primary end point was the adherence to the bundle protocol and was evaluated by the percentage of compliant patients with a 95% confidence interval (CI) according to Clopper-Pearson. Secondary end points included the development and severity of AKI.

RESULTS

In total, 278 patients were included in the final analysis. In the intervention group, 65.4% of patients received the complete bundle as compared to 4.2% in the control group (absolute risk reduction [ARR] 61.2 [95% CI, 52.6-69.9]; P < .001). AKI rates were statistically not different in both groups (46.3% intervention versus 41.5% control group; ARR -4.8% [95% CI, -16.4 to 6.9]; P = .423). However, the occurrence of moderate and severe AKI was significantly lower in the intervention group as compared to the control group (14.0% vs 23.9%; ARR 10.0% [95% CI, 0.9-19.1]; P = .034). There were no significant effects on other specified secondary outcomes.

CONCLUSIONS

Implementation of a KDIGO-derived treatment bundle is feasible in a multinational setting. Furthermore, moderate to severe AKI was significantly reduced in the intervention group.

A Multinational Observational Study Exploring Adherence With the Kidney Disease: Improving Global Outcomes Recommendations for Prevention of Acute Kidney Injury After Cardiac Surgery

BACKGROUND

The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend a bundle of different measures for patients at increased risk of acute kidney injury (AKI). Prospective, single-center, randomized controlled trials (RCTs) have shown that management in accordance with the KDIGO recommendations was associated with a significant reduction in the incidence of postoperative AKI in high-risk patients. However, compliance with the KDIGO bundle in routine clinical practice is unknown.

METHODS

This observational prevalence study was performed in conjunction with a prospective RCT investigating the role of the KDIGO bundle in high-risk patients undergoing cardiac surgery. A 2-day observational prevalence study was performed in all participating centers before the RCT to explore routine clinical practice. The participating hospitals provided the following data: demographics and surgical characteristics, AKI rates, and compliance rates with the individual components of the bundle.

RESULTS

Ninety-five patients were enrolled in 12 participating hospitals. The incidence of AKI within 72 hours after cardiac surgery was 24.2%. In 5.3% of all patients, clinical management was fully compliant with all 6 components of the bundle. Nephrotoxic drugs were discontinued in 52.6% of patients, volume optimization was performed in 70.5%, 52.6% of the patients underwent functional hemodynamic monitoring, close monitoring of serum creatinine and urine output was undertaken in 24.2% of patients, hyperglycemia was avoided in 41.1% of patients, and no patient received radiocontrast agents. The patients received on average 3.4 (standard deviation [SD] ±1.1) of 6 supportive measures as recommended by the KDIGO guidelines. There was no significant difference in the number of applied measures between AKI and non-AKI patients (3.2 [SD ±1.1] vs 3.5 [SD ±1.1]; P = .347).

CONCLUSIONS

In patients after cardiac surgery, compliance with the KDIGO recommendations was low in routine clinical practice.

CPAP Effects on Oxygen Delivery in One-Lung Ventilation During Minimally Invasive Surgical Ablation for Atrial Fibrillation in The Supine Position

OBJECTIVE

In minimally invasive surgical ablation for atrial fibrillation during video-assisted thoracoscopy surgery, one-lung ventilation (OLV) with a double- lumen tube is commonly employed. In contrast with the majority of thoracic procedures, the patient lies supine; thus, the protective effect of gravity is lost and intrapulmonary shunt remains high. To decrease intrapulmonary shunt and to increase oxygenation, many strategies are utilized: high inspiratory fraction of oxygen (F_IO₂), positive end-expiratory pressure on the ventilated lung, and continuous positive airway pressure (CPAP) on the deflated lung.

DESIGN

The authors performed a prospective, single- center, randomized study to evaluate the effect of additional CPAP in the nonventilated lung on oxygen delivery during surgical ablation for atrial fibrillation via video-assisted thoracoscopy in the supine position.

SETTING

University hospital Centro Cardiologico Monzino IRCCS, Milano, Italy.

PARTICIPANTS

Twenty-two patients scheduled for minimally invasive surgical ablation for atrial fibrillation.

INTERVENTIONS

The patients underwent pressure-controlled ventilation, adjusting inspiratory pressure to obtain a tidal volume of 7 mL/kg while keeping F_IO₂ constantly 1.0, a respiratory rate to maintain arterial partial pressure of carbon dioxide (PaCO₂) between 35 and 40 mmHg, and positive end-expiratory pressure of 5 cmH₂O. During OLV, inspiratory pressure was reduced to obtain a tidal volume of 5 mL/kg, maintaining F_IO₂ of 1.0, a respiratory rate to maintain PaCO₂ between 35 and 40 mmHg with capnothorax of 10 cmH₂O. The patients were then randomized into the CPAP group (CPAP 10 cmH₂0 on deflated lung) and NO CPAP group. Inotropic agents (dopamine or dobutamine) were used if cardiac index fell below 1.5 L/min/m².

MEASUREMENTS AND MAIN RESULTS

Twenty-two patients were enrolled, randomized, and completed the study. Median age was 62 years. The difference in arterial partial pressure of oxygen between the 2 groups was shy of significance, p = 0.16. Cardiac index progressively increased during OLV until the end of the procedure in both groups (p < 0.01) and was maintained above 1.5 mL/min/m² during the whole study time. Arterial oxygen content remained stable during the entire procedure in both groups (p = 0.27). Oxygen delivery index (DO₂I) increased significantly during the procedure (p < 0.01); nevertheless, the difference in DO₂I between the CPAP and NO CPAP group was nonsignificant (p = 0.61). Intrapulmonary shunt (Q_s/Q_t) increased during OLV (p < 0.01 for the time effect) and remained high until total lung ventilation was reintroduced. No difference in Q_s/Q_t was observed between the CPAP and NO CPAP groups (p = 0.98). Similarly, mean pulmonary artery pressure increased significantly during OLV and remained high at the end of the procedure in both groups (time effect p < 0.01).

CONCLUSIONS

During OLV for atrial fibrillation surgical ablation in the supine position, CPAP on the deflated lung seemed to be ineffective to reduce Q_s/Q_t or to increase arterial partial pressure of oxygen and DO₂I, provided cardiac output was maintained above 1.5 L/min/m².

Biomarker-guided implementation of the KDIGO guidelines to reduce the occurrence of acute kidney injury in patients after cardiac surgery (PrevAKI-multicentre): protocol for a multicentre, observational study followed by randomised controlled feasibility trial

INTRODUCTION

Acute kidney injury (AKI) is a frequent complication after cardiac surgery with adverse short-term and long-term outcomes. Although prevention of AKI (PrevAKI) is strongly recommended, the optimal strategy is uncertain. The Kidney Disease: Improving Global Outcomes (KDIGO) guideline recommended a bundle of supportive measures in high-risk patients. In a single-centre trial, we recently demonstrated that the strict implementation of the KDIGO bundle significantly reduced the occurrence of AKI after cardiac surgery. In this feasibility study, we aim to evaluate whether the study protocol can be implemented in a multicentre setting in preparation for a large multicentre trial.

METHODS AND ANALYSIS

We plan to conduct a prospective, observational survey followed by a randomised controlled, multicentre, multinational clinical trial including 280 patients undergoing cardiac surgery with cardiopulmonary bypass. The purpose of the observational survey is to explore the adherence to the KDIGO recommendations in routine clinical practice. The second phase is a randomised controlled trial. The objective is to investigate whether the trial protocol is implementable in a large multicentre, multinational setting. The primary endpoint of the interventional part is the compliance rate with the protocol. Secondary endpoints include the occurrence of any AKI and moderate/severe AKI as defined by the KDIGO criteria within 72 hours after surgery, renal recovery at day 90, use of renal replacement therapy (RRT) and mortality at days 30, 60 and 90, the combined endpoint major adverse kidney events consisting of persistent renal dysfunction, RRT and mortality at day 90 and safety outcomes.

ETHICS AND DISSEMINATION

The PrevAKI multicentre study has been approved by the leading Research Ethics Committee of the University of Münster and the respective Research Ethics Committee at each participating site. The results will be used to design a large, definitive trial.

TRIAL REGISTRATION NUMBER

NCT03244514.

Improvement of neutrophil gelatinase-associated lipocalin sensitivity and specificity by two plasma measurements in predicting acute kidney injury after cardiac surgery

Introduction

Acute kidney injury (AKI) remains among the most severe complication after cardiac surgery. The aim of this study was to evaluate the neutrophil gelatinase-associated lipocalin (NGAL) as possible biomarker for the prediction of AKI in an adult cardiac population.

Materials and methods

Sixty-nine consecutive patients who underwent cardiac surgeries in our hospital were prospectively evaluated. In the intensive care unit (ICU) NGAL was measured as a new biomarker of AKI besides serum creatinine (sCrea). Patients with at least two factors of AKI risk were selected and samples collected before the intervention and soon after the patient's arrival in ICU. As reference standard, sCrea measurements and urine outputs were evaluated to define the clinical AKI. A Triage Meter for plasma NGAL fluorescence immunoassay was used.

Results

Acute kidney injury occurred in 24 of the 69 patients (35%). Analysis of post-operative NGAL values demonstrated an AUC of 0.71, 95% CI (0.60 - 0.82) with a cut-off = 154 ng/mL (sensitivity = 76%, specificity = 59%). Moreover, NGAL after surgery had a good correlation with the AKI stage severity (P ≤ 0.001). Better diagnostic results were obtained with two consecutive tests: sensitivity 86% with a negative predictive value (NPV) of 87%. At 10-18 h after surgery sCrea measurement, as confirmatory test, allowed to reach a more sensitivity and specificity with a NPV of 96%.

Conclusions

The assay results showed an improvement of NGAL diagnostic accuracy evaluating two tests. Consequently, NGAL may be useful for a timely treatment or for the AKI rule out in ICU patients.

A Morphological and Quantitative Analysis of Lung CT Scan in Patients With Acute Respiratory Distress Syndrome and in Cardiogenic Pulmonary Edema

BACKGROUND

The acute respiratory distress syndrome (ARDS) and cardiogenic pulmonary edema (CPE) are both characterized by an increase in lung edema that can be measured by computed tomography (CT). The aim of this study was to compare possible differences between patients with ARDS and CPE in the morphologic pattern, the aeration, and the amount and distribution of edema within the lung.

METHODS

Lung CT was performed at a mean positive end-expiratory pressure level of 5 cm H₂O in both groups. The morphological evaluation was performed by two radiologists, while the quantitative evaluation was performed by a dedicated software.

RESULTS

A total of 60 patients with ARDS (20 mild, 20 moderate, 20 severe) and 20 patients with CPE were enrolled. The ground-glass attenuation regions were similarly present among the groups, 8 (40%), 8 (40%), 14 (70%), and 10 (50%), while the airspace consolidations were significantly more present in ARDS. The lung gas volume was significantly lower in severe ARDS compared to CPE (830 [462] vs 1120 [832] mL). Moving from the nondependent to the dependent lung regions, the not inflated lung tissue significantly increased, while the well inflated tissue decreased (ρ = 0.96-1.00, P < .0001). Significant differences were found between ARDS and CPE mostly in dependent regions. In severe ARDS, the estimated edema was significantly higher, compared to CPE (757 [740] vs 532 [637] g).

CONCLUSIONS

Both ARDS and CPE are characterized by a similar presence of ground-glass attenuation and different airspace consolidation regions. Acute respiratory distress syndrome has a higher amount of not inflated tissue and lower amount of well inflated tissue. However, the overall regional distribution is similar within the lung.

Prolonged red cell storage before transfusion increases extravascular hemolysis

BACKGROUND

Some countries have limited the maximum allowable storage duration for red cells to 5 weeks before transfusion. In the US, red blood cells can be stored for up to 6 weeks, but randomized trials have not assessed the effects of this final week of storage on clinical outcomes.

METHODS

Sixty healthy adult volunteers were randomized to a single standard, autologous, leukoreduced, packed red cell transfusion after 1, 2, 3, 4, 5, or 6 weeks of storage (n = 10 per group). 51-Chromium posttransfusion red cell recovery studies were performed and laboratory parameters measured before and at defined times after transfusion.

RESULTS

Extravascular hemolysis after transfusion progressively increased with increasing storage time (P < 0.001 for linear trend in the AUC of serum indirect bilirubin and iron levels). Longer storage duration was associated with decreasing posttransfusion red cell recovery (P = 0.002), decreasing elevations in hematocrit (P = 0.02), and increasing serum ferritin (P < 0.0001). After 6 weeks of refrigerated storage, transfusion was followed by increases in AUC for serum iron (P < 0.01), transferrin saturation (P < 0.001), and nontransferrin-bound iron (P < 0.001) as compared with transfusion after 1 to 5 weeks of storage.

CONCLUSIONS

After 6 weeks of refrigerated storage, transfusion of autologous red cells to healthy human volunteers increased extravascular hemolysis, saturated serum transferrin, and produced circulating nontransferrin-bound iron. These outcomes, associated with increased risks of harm, provide evidence that the maximal allowable red cell storage duration should be reduced to the minimum sustainable by the blood supply, with 35 days as an attainable goal.REGISTRATION. ClinicalTrials.gov NCT02087514.

FUNDING

NIH grant HL115557 and UL1 TR000040.

Hemostasis changes during veno-venous extracorporeal membrane oxygenation for respiratory support in adults

BACKGROUND

We investigated the coagulation system in patients during extracorporeal membrane oxygenation (ECMO) initiated for respiratory failure and the influence of the ECMO circuit on coagulation tests; we compared different coagulation tests for monitoring unfractionated heparin (UH) therapy; we investigated whether or not coagulation parameters were predictive of bleeding during ECMO.

METHODS

Pilot study on twelve consecutive adult patients admitted at our general ICU for acute respiratory failure and placed on ECMO from November 2011 to October 2012. Coagulation tests were performed before ECMO start and daily, including day of circuit change and day of circuit removal. UH was monitored with activated partial thromboplastin time (APTT) ratio, at a therapeutic range of 1.5-2.0.

RESULTS

We observed no effect of ECMO circuit on coagulation parameters measured pre- and postlung, but platelet count decreased significantly over time (-82x10(3)/mmc, 95%CI 40-123). APTT showed a correlation with antifactor Xa activity, whereas other global coagulation tests such as activated clotting time, thromboelastography and endogenous thrombin potential did not. Major bleeding occurred in three patients but no difference in any coagulation parameter was observed between them and those who did not bleed.

CONCLUSIONS

This pilot study shows that ECMO initiated for respiratory support in adults does not change coagulation parameters. Over time a statistically significant reduction of platelet count was observed, possibly due to consumption within the circuit, consumption microangiopathy or the underlying patients' diseases. Although APTT was appropriate to monitor UH, major bleedings occurred and a lower therapeutic range may be advisable.

Red blood cell transfusion is associated with increased hemolysis and an acute phase response in a subset of critically ill children

In healthy adults, transfusion of older stored red blood cells (RBCs) produces extravascular hemolysis and circulating non-transferrin-bound iron. In a prospective, observational study of critically ill children, we examined the effect of RBC storage duration on the extent of hemolysis by comparing laboratory measurements obtained before, and 4 hr after, RBC transfusion (N = 100) or saline/albumin infusion (N = 20). Transfusion of RBCs stored for longer than 4 weeks significantly increased plasma free hemoglobin (P < 0.05), indirect bilirubin (P < 0.05), serum iron (P < 0.001), and non-transferrin-bound iron (P < 0.01). However, days of storage duration poorly correlated (R(2) <0.10) with all measured indicators of hemolysis and inflammation. These results suggest that, in critically ill children, most effects of RBC storage duration on post-transfusion hemolysis are overwhelmed by recipient and/or donor factors. Nonetheless, we identified a subset of patients (N = 21) with evidence of considerable extravascular hemolysis (i.e., increased indirect bilirubin ≥0.4 mg/dL). In these patients, transfusion-associated hemolysis was accompanied by increases in circulating non-transferrin-bound iron and free hemoglobin and by an acute phase response, as assessed by an increase in median C-reactive protein levels of 21.2 mg/L (P < 0.05). In summary, RBC transfusions were associated with an acute phase response and both extravascular and intravascular hemolysis, which were independent of RBC storage duration. The 21% of transfusions that were associated with substantial hemolysis conferred an increased risk of inducing an acute phase response.

Risk of perioperative seizures in patients undergoing craniotomy with intraoperative brain mapping

BACKGROUND

The identification of risk factors associated with perioperative seizures would be of great benefit to the anesthesiologist in managing brain tumor patients undergoing craniotomy with intraoperative brain mapping.

METHODS

A series of 316 supratentorial craniotomies for tumor resection, in which intraoperative brain mapping was used, were analyzed. From January 2005 to December 2010 the occurrence of intraoperative and immediate postoperative clinical seizures was prospectively recorded into a database. Demographic data, tumor characteristics, preoperative seizure control, intraoperative events and anesthetic management were evaluated as risk factors for intraoperative clinical seizures. Additionally, the association between intraoperative clinical seizures and immediate postoperative seizures was evaluated. In order to determine the best predictors of intraoperative and immediate postoperative clinical seizures, a multivariable analysis by logistic regression was performed.

RESULTS

Younger age, location of the tumor in the frontal and parietal lobe, brain mapping conducted under general anesthesia and non physiologic values of arterial carbon dioxide (PaCO2) during brain mapping were independent positive risk factors for the development of intraoperative clinical seizures. Location of tumor in the frontal lobe, antiepileptic polytherapy, intraoperative seizures requiring pharmacologic treatment during brain mapping, and blood on postoperative CT scan were independent positive risk factors for the development of immediate postoperative seizures.

CONCLUSION

Clinical seizures are common intraoperative and postoperative complications of supratentorial craniotomies with intraoperative brain mapping. The identification of those patients at higher risk of seizures may guide intraoperative and postoperative medical management.

New perspectives on the thrombotic complications of haemolysis

Many clinical settings are associated with haemolysis, from rare conditions, such as paroxysmal nocturnal haemoglobinuria, to common interventions, such as mechanical circulatory support and blood transfusion. The toxic effects of circulating free haemoglobin, haem, and iron are becoming increasingly understood and include an increased risk of thrombotic complications. This review summarizes the epidemiological evidence for an association between haemolysis and thrombosis and explores potential underlying mechanisms. New insights into the role haem plays in inflammatory signalling and in generating neutrophil extracellular traps (NETs) may provide useful strategies for managing pathological states associated with severe haemolysis. A better understanding of the toxic effects of haemolysis will result in better therapies to prevent the side effect of thrombosis.