Agreement Between the TEG 6s and TEG 5000 Analyzers in Extracorporeal Membrane Oxygenation

Agreement between the thromboelastography reaction time parameter using fresh and citrated whole blood during extracorporeal membrane oxygenation with Teg®5000 and Teg®6s

PURPOSE

We aimed at assessing the correlation between TEG reaction time (TEG-R) in citrated and fresh blood samples with TEG5000 and TEG 6S during heparin administration in patients with and without ECMO support.

MATERIALS AND METHODS

Paired TEG5000 (fresh and citrated whole blood, kaolin and kaolin-heparinase) and TEG6S (citrated whole blood) samples were obtained, together with standard coagulation laboratory tests. Bland-Altman analysis and Lin's concordance correlation coefficient were used to assess agreement.

RESULTS

Thirteen consecutive ECMO patients and eight consecutive non-ECMO patients were enrolled and TEG was performed for a total of 84 paired samples. ECMO patients received 19.2 (12.6-25.8) U/kg/h of heparin. Five of the non-ECMO patients did not receive heparin, two of them received a very low prophylactic dose (1.6 and 2.9 IU/kg/h, respectively), and one of them 13.1 U/kg/h of heparin. Using TEG®5000, TEG-R was 21.0 (-23.4; 65.5) min longer on fresh compared to citrated blood in patients receiving heparin while only 1.58 (-5.5; 8.7) min longer in patients not-receiving heparin. These differences were reverted by heparinase.

CONCLUSIONS

Using citrated-recalcified blood to perform TEG might lead to underestimation of the effect of heparin.

Operability of a Resonance-Based Viscoelastic Haemostatic Analyzer in the High-Vibration Environment of Air Medical Transport

Trauma and bleeding are associated with a high mortality, and most of these deaths occur early after injury. Viscoelastic haemostatic tests have gained increasing importance in goal-directed transfusion and bleeding management. A new generation of small-sized and thus portable ultrasound-based viscoelastic analysers have been introduced in clinical practice. We questioned whether a promising candidate can be used in emergency helicopters, with a focus on the susceptibility to vibration stress. We investigated whether the high vibration environment of an emergency helicopter would affect the operability of an ultrasound-based viscoelastic analyser and would yield reproducible results in flight and on the ground. We drew blood from 27 healthy volunteers and performed simultaneous analyses on two TEG 6s. Each measurement was performed in-flight on board an Airbus H135 emergency helicopter and was repeated on the ground, close to the flight area. Results from both measurements were compared, and the recorded tracings and numeric results were analysed for artifacts. Vibratometric measurements were performed throughout the flight in order to quantify changes in the magnitude and character of vibrations in different phases of helicopter operation. The high vibration environment was associated with the presence of artifacts in all recorded tracings. There were significant differences in citrated Kaolin + Heparinase measurements in-flight and on the ground. All other assays increased in variability but did not show significant differences between the two time points. We observed numerous artifacts in viscoelastic measurements that were performed in flight. Some parameters that were obtained from the same sample showed significant differences between in-flight and on-ground measurements. Performing resonance-based viscoelastic tests in helicopter medical service is prone to artifacts. However, a 10 min delay between initiation of measurement and take-off might produce more reliable results.