TABLE 1.
Comparison of Platelet Function, Physiologic Markers of Perfusion, and CCTs Between TBI Patients and Controls
| N | % ADP Inhibition, Median (IQR) |
% AA Inhibition, Median (IQR) |
BD, mean ± SEM |
SBP, Median (IQR) |
Platelet Count, Mean ± SEM |
INR Median (IQR) |
PTT, Median (IQR) |
RValue Median (IQR) |
MA Median (IQR) |
|
|---|---|---|---|---|---|---|---|---|---|---|
| Controls | 10 | 15.5 (13.2–29.1) | 2.2 (0–5.8) | NA | NA | 229 ± 28 | 0.81 (0.74–0.98) | 33.0 (29.9–36.6) | 7.5 (6.15–8.2) | 63.3 (60.8–65) |
| All TBI | 70 | 64.5 (39.3–95.1) | 25.6 (3.1–76.7) | −0.6 ± 0.36 | 132 (119.5–150) | 204 ± 8.9 | 1.1 (1–1.2) | 29.3 (26.6–32.4) | 5.75 (4.7–6.7) | 61.5 (55.8–65.4) |
| GCS score > 8 | 41 | 56.5 (35–79.1) | 40.4 (12.9–78.9) | −1.1 ±0.47 | 140 (122–152) | 181 ± 11.1 | 1(1–1.2) | 29.2 (27.7–32) | 6.2 (5–7.4) | 61.6 (57.6–64.4) |
| GCS score ≤ 8 | 29 | 93.1 (44.8–98.3) | 14.4 (0–62.2) | 0.10 ± 0.56 | 128 (119–147) | 236 ± 12.7 | 1.1 (1–1.2) | 29.4 (25.4–32.6) | 5.4 (4.2–6) | 61.1 (55.2–66.2) |
Patients with any degree of TBI (defined as head AIS score >3) have a marked inhibition of platelet stimulation by both the ADP and AA pathways, compared with the uninjured controls. Moreover, the degree of ADP pathway inhibition is significantly higher in the subgroup of TBI patients with a GCS score of 8 or lower, the standard clinical cutoff for GCS at which patients are considered to have a “severe” TBI and are prophylactically intubated. Conversely, there is no correlation between BD, SBP, INR, PTT, platelet count, TEG R-time, or MA with the severity of TBI as measured by GCS. Although the INR shows a slight prolongation in the group of all TBI, compared with controls, both cohorts are within the reference range. Reference ranges: BD, −2 mEq/L to 2 mEq/L; platelet count, 150 × 103/μL to 400 × 103/μL; INR, 0.8 to 1.2; PTT, 23 seconds to 37 seconds; TEG R-time, 4 minutes to 8 minutes; TEG MA, 54 mm to 72 mm.