Thromboelastographic profiles of healthy very low birthweight infants serially during their first month

Objective: We determined thromboelastographic (TEG) profiles of healthy very low birthweight infants (VLBWIs) of the day of birth and at set intervals during their first month.

Design: Prospective observational study with blinded clinical and laboratory follow-up.

Setting: Level III neonatal intensive care unit (June 2015 to June 2018).

Patients: Consecutive qualifying VLBWIs were enrolled at birth and followed up for 30 days.

Interventions and main outcomes measures: Laboratory (citrated-native TEG, prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, blood count) and clinical variables were retrieved at birth, 3rd-5th, 10th and 30th day of life. Blood samples temporally related to events with a potential hemostatic impact (sepsis, bleeding, platelets/plasma transfusions, ibuprofen/indomethacin administration) were excluded from analysis.

Results: We enrolled 201 VLBWIs and 72 full-term neonates. Sixty-seven of the healthy VLBWIs completed the 30-day follow-up. 541 TEG traces were analysed.On day 1, the median (minimum-maximum) TEG values were as follows: reaction time (R), 8.2 min (1-21.8); kinetics (K), 2.8 min (0.8-16); α angle, 51° (14.2-80.6); maximum amplitude (MA), 54.9 mm (23.9-76.8). PT and APTT were 15.9 s (11.7-51.2) and 59 s (37.8-97.5), respectively. The above parameters suggest minor hypocoagulability compared with term infants. On day 30, the median (minimum-maximum) R was 5 (1-16.9), K 1 (0.8-4.1), α 74.7 (41.1-86.7) and MA 70.2 (35.8-79.7). PT and APTT were 12.1 (10.4-16.6) and 38.8 (29.6-51.4), respectively. Those parameters are consistent with a relatively hypercoagulable phenotype, compared with term infants.

Conclusions: Healthy VLBWIs have a prolonged PT and APTT, but their TEG profiles suggest a relatively balanced hemostatic system, with slight hypocoagulability initially (compared with term neonates), gradually evolving to a somewhat more procoagulant phenotype over the first month.