Incidence, kinetics, and clinical impact of thrombocytopenia in venovenous ECMO: insights from the multicenter observational PROTECMO study

Critical Care volume 29, Article number: 349, Published: 07 August 2025

Background

Thrombocytopenia is a recognized risk factor for bleeding during extracorporeal membrane oxygenation (ECMO). This study determines the incidence, risk factors, and clinical relevance of thrombocytopenia and platelet transfusions during venovenous (VV) ECMO.

Methods

The multicenter, prospective observational PROTECMO study included 652 adult patients who received VV ECMO for respiratory failure. Thrombocytopenia was classified as mild (100–149·10⁹/L), moderate (50–99·10⁹/L), or severe (< 50·10⁹/L). Bleeding events were evaluated using a modified Bleeding Academy Research Consortium score. Cox proportional hazards and logistic regression analyses were done to identify predictors, and quantify the association between platelet counts and bleeding risk.

Results

A total of 182 patients (27.9%) had thrombocytopenia at baseline (mild in 14.7%, moderate in 8.7%, and severe in 4.4%). Thrombocytopenia during ECMO, at least once in 80.2% of patients, was mild in 21.3% of cases, moderate in 32.2%, and severe in 26.7%. A 10·10⁹/L decrease in platelet count was associated with a 3.7% (95% CI: 2.4–5.0%) increase in risk of bleeding. There was no strong evidence of nonlinear relationship within the platelet count range between 25,000 and 300,000. This relation remained consistent across all ECMO weeks. Mild thrombocytopenia increased the risk of experiencing a bleeding event by 61% (hazard ratio (HR) 1.611, 95% CI 1.230–2.109, p = 0.0005), while moderate and severe thrombocytopenia increased the risk by roughly 90% (moderate: HR 1.944 (CI 1.484–2.545), p < 0.0001; severe: HR 1.876 (CI 1.275–2.7680), p = 0.0014). The risk for thrombocytopenia < 100·10⁹/L during ECMO significantly increased with ICU days prior to ECMO start, postoperative admission, immunocompromised state, renal replacement therapy, septic shock, low hemoglobin, and circuit exchange.

Conclusions

Thrombocytopenia is highly prevalent in VV ECMO, and associated with a significant increase in the risk of bleeding, and a reduction in 6-month survival, particularly at platelet counts below 100·10⁹/L. Further research is needed to better define the outcomes associated with specific thresholds for transfusion of platelets.

 

Blood trauma in veno-venous extracorporeal membrane oxygenation: low pump pressures and low circuit resistance matter

Critical Care volume 28, Article number: 330, Published: 08 October 2024

Background

Veno-venous extracorporeal membrane oxygenation (VV ECMO) has become standard of care in patients with the most severe forms of acute respiratory distress syndrome. However, hemolysis and bleeding are one of the most frequent side effects, affecting mortality. Despite the widespread use of VV ECMO, current protocols lack detailed, in-vivo data-based recommendations for safe ECMO pump operating conditions. This study aims to comprehensively analyze the impact of VV ECMO pump operating conditions on hemolysis by combining in-silico modeling and clinical data analysis.

Methods

We combined data from 580 patients treated with VV ECMO in conjunction with numerical predictions of hemolysis using computational fluid dynamics and reduced order modeling of the Rotaflow (Getinge) and DP3 (Xenios) pumps. Blood trauma parameters across 94,779 pump operating points were associated with numerical predictions of shear induced hemolysis.

Results

Minimal hemolysis was observed at low pump pressures and low circuit resistance across all flow rates, whereas high pump pressures and circuit resistance consistently precipitated substantial hemolysis, irrespective of flow rate. However, the lower the flow rate, the more pronounced the influence of circuit resistance on hemolysis became. Numerical models validated against clinical data demonstrated a strong association (Spearman’s r = 0.8) between simulated and observed hemolysis, irrespective of the pump type.

Conclusions

Integrating in-silico predictions with clinical data provided a novel approach in understanding and potentially reducing blood trauma in VV ECMO. This study further demonstrated that a key factor in lowering side effects of ECMO support is the maintenance of low circuit resistance, including oxygenators with the lowest possible resistance, the shortest feasible circuit tubing, and cannulae with an optimal diameter.