Blood ammonia is a predictive biomarker of neurologic outcome in cardiac arrest patients treated with therapeutic hypothermia.
OBJECTIVE
The aim of this study was to investigate the value of commonly examined laboratory measurements, including ammonia and lactate, in predicting neurologic outcome of out-of-hospital cardiac arrest (OHCA) patients treated with therapeutic hypothermia (TH).


METHODS
This was a retrospective cohort study of patients with a return of spontaneous circulation after OHCA who were treated with TH between February 2007 and July 2010. We measured typical blood measurements on arrival at the emergency department. The subjects were classified into 2 groups: the good neurologic outcome group (Cerebral Performance Category [CPC] 1-2 at 1 month) and the poor neurologic outcome group (Cerebral Performance Category 3-5). We compared blood biomarker levels and basal characteristics between the 2 groups. Logistic regression analyses were performed to determine independent biomarkers that predict poor neurologic outcome.


RESULTS
A total of 117 patients were included. Between the 2 groups, significantly different levels of blood measurements included hemoglobin level, pH, Pao(2), Paco(2), base excess, albumin, glucose, potassium, chloride, bilirubin, phosphorous, and ammonia. In multivariate analyses, blood ammonia level (>96 mg/dL; odds ratio [OR], 7.240; 95% confidence interval [CI], 1.718-30.512), noncardiac causes (OR, 46.215; 95% CI, 9.670-220.873), and time interval from collapse to return of spontaneous circulation (>33 min; OR, 5.943; 95% CI, 1.543-22.886) were significantly related to poor neurologic outcome.


CONCLUSIONS
Among the blood measurements on emergency department arrival, blood ammonia (>96 mg/dL) was the only independent predictive biomarker of poor neurologic outcome. Thus, higher blood ammonia level was associated with poor neurologic outcome in OHCA patients treated with TH.
Department of Emergency Medicine, Gachon University Gil Hospital, Incheon 405-760, South Korea. speialkey7@naver.com
Young Mo
YM
Cho
Yong Su
YS
Lim
Hyuk Jun
HJ
Yang
Won Bin
WB
Park
Jin Seong
JS
Cho
Jin Joo
JJ
Kim
Sung Youl
SY
Hyun
Mi Jin
MJ
Lee
Young Joon
YJ
Kang
Gun
G
Lee
D000328:Adult; D000641:Ammonia / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced; D002534:Hypoxia, Brain / Q000097:blood*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D058687:Out-of-Hospital Cardiac Arrest / Q000097:blood* / Q000628:therapy; D012189:Retrospective Studies; D013997:Time Factors
D015415:Biomarkers; D000641:Ammonia