Prospective observational study at a level one trauma centre. Inclusion criteria: Patients with suspected major injury. Exclusion criteria: Patients who received blood trans
fusion in the
first 4 h, and those who deceased or were trans
ferred to other units be
fore the completion o
f the observation period (4 h). We measured IVF and ΔHct at 4 h a
fter triage. We classi
fied patients as having minor or major injury on the basis o
f injury severity score ≥15. Receiver Operating Characteristic (ROC) curve was used to test the diagnostic per
formance o
f ΔHct in identi
fying major injury. We tested the operating characteristics o
f ΔHct cut-o
ff values o
f 5 and 10 in detecting major injury. We also measured the correlation o
f IVF and ΔHct in a subgroup o
f patients with low potential
for blood loss (ISS < 3) to account
for possibility o
f haemodilution.
Results
Four hundred and ninety-four patients (convenience sample) were enrolled (age 36 ± 17 years, 82%male, 57%blunt trauma). Sixty-three patients (13%) had major injury. The area under the ROC curve for ΔHct was not significantly different from the unity line (p = 0.20). ΔHct-4 h > 5 points had a sensitivity of 40%(95%CI, 29–52%), specificity of 94%(95%CI, 92–96%), likelihood ratio for a positive test (LR+) of 7.1 (95%CI, 4.4–11.7), and likelihood ratio for a negative test (−LR) of 0.64 (95%CI, 0.52–0.78) in identifying major trauma. ΔHct-4 h > 10 points had sensitivity of 16%(95%CI, 9–27%), specificity of 95%(95%CI, 92–0.96%), +LR of 3.0 (95%CI, 1.5–5.9), and –LR of 0.89 (95%CI, 0.80–0.99). In our subgroup analysis, we detected no significant correlation (p = 0.09) between the IVF and ΔHct-4 h.
Conclusions
ΔHct-4 h > 5 or 10 points is suggestive of major injury (high specificity and +LR). However, the failure to drop the Hct cannot be used to rule out major injury (low sensitivity and −LR).
