Antithrombin Levels Predict Ischemic Trouble in ECMO Patients

When someone's lungs or heart need a break, a machine called venovenous ECMO can take over oxygen exchange. But the machine's tubes can trigger clotting and inflammation. A protein called antithrombin helps control blood clotting. In critical illness, antithrombin often drops. Whether that drop predicts trouble during ECMO has been unclear.

A team looked back at records from one medical center. They studied 734 adults who received VV ECMO between 2013 and 2023. The team checked antithrombin levels before treatment started. They also tracked CT-confirmed ischemic, thrombotic, and bleeding complications, plus death during ECMO. They used logistic regression, cause-specific Cox models, and unsupervised methods.

About 64% of patients had antithrombin deficiency, defined as below 77%. Lower antithrombin lined up with higher inflammatory markers. Ischemic complications showed up in 7.6% of deficient patients, compared with 1.9% of others. That difference was significant. Thrombotic and bleeding rates were similar between groups.

Each 1% increase in antithrombin activity lowered the odds of ischemic events by 3%. The odds ratio was 0.97, with a 95% confidence interval from 0.95 to 0.98. The best cutoff for predicting ischemia was 49. That gave an area under the curve of 0.74. The analysis also found three subphenotypes. One looked like a consumptive state, with very low antithrombin. That group had the most ischemic complications and the highest death rate.

These results point to a simple blood test clue. Baseline antithrombin activity and inflammation may help identify VV ECMO patients at higher risk of ischemia and death. The consumptive profile may be especially dangerous. Doctors may use this information to spot high-risk patients early.