Arterial ammonia levels: Prognostic marker in traumatic hemorrhage

In blunt trauma, extent of hemorrhage cannot be determined by physical examination, and vital signs may also not give clear picture in all the patients, especially young healthy ones. Hemorrhagic shock has been reported to increase blood ammonia levels. Arterial ammonia was analyzed in blunt trauma abdomen patients and correlated with shock index (SI). Its predictive value was determined for timely decision of intervention.

Hundred blunt trauma abdomen patients presented in the emergency ward of tertiary care hospital were included in the study. Group I comprised 62 patients requiring either blood transfusion ≥2 units and/or intervention to control bleeding within 24 h following admission. Group II had 38 patients: Not requiring transfusion/intervention during hospital stay. Arterial blood sample was taken immediately after admission; ammonia was analyzed within 20 min of sampling on Cobas 6000 (Roche). SI was calculated. Predictive value of ammonia was determined using receiver operating characteristic curve.

Ammonia levels and SI were significantly (P < 0.001) higher in Group I compared to Group II patients (68.55 ± 14.36 umol/L vs. 37.55 ± 7.41 umol/L and 1.28 ± 0.5 vs. 0.74 ± 0.12, respectively). Significantly higher number of patients in Group I (88.7% vs. 13%) had SI > 0.9. Ammonia levels were significantly higher in patients with complications and in those expired.

Ammonia levels were significantly higher in patients requiring blood transfusion/intervention in 24 h of admission. The best cutoff value to maximize sensitivity and specificity was ammonia >58.85 μmol/L. Ammonia estimation at admission can be clinically significant indicator of traumatic hemorrhage needing intervention.