Original ContributionBlood ammonia is a predictive biomarker of neurologic outcome in cardiac arrest patients treated with therapeutic hypothermia
Introduction
Out-of-hospital cardiac arrest (OHCA) occurs in about 1 in 2500 adults in the developed world each year [1]. However, despite advances in postcardiac arrest care, the survival rate to hospital discharge with good neurologic outcome after OHCA remains low [2], [3].
Therapeutic hypothermia (TH) is a proven standard therapy used to reduce brain injury in comatose survivors with cardiopulmonary arrest (CPA). Recently, the use of mild therapeutic hypothermia (MTH) in comatose survivors with CPA, which is commonly used worldwide, was evaluated as part of the chain for cardiopulmonary resuscitation (CPR) and emergency cardiac care [4].
Although early and accurate prognostication of neurologic outcome is important and an essential component of postcardiac arrest care, it is difficult and challenging. Therefore, many investigators have previously evaluated predictive biomarkers, including brain-specific biomarkers, such as S-100 protein and neuron-specific enolase in survivors with CPA [5], [6]. However, most studies were performed in patients who were not treated with TH, and most general hospitals are not able examine biomarkers.
Recently, 2 studies revealed that laboratory findings including serum ammonia and lactate levels were predictors of neurologic outcome in postcardiac arrest patients [7], [8]. However, in those studies, only a small proportion of patients received TH, which is one of standard therapy, and the number of patients who had good neurologic outcome was relatively small.
Thus, the aim of this study was to investigate the association between neurologic outcome and common laboratory measurements, including ammonia and lactate level on arrival in the emergency department (ED) and the value of these measurements as predictive factors of neurologic outcome in OHCA patients treated with TH.
Section snippets
Study population
The setting of the study was university hospital ED with an annual patient volume of 90 000. We conducted a single-center and retrospective cohort study between February 2007 and July 2010 at a tertiary hospital located in Incheon city, South Korea. This study was approved by the institutional review board of our hospital.
The subjects of the present study consisted of patients aged 18 years or older who were successfully resuscitated after nontraumatic OHCA and then treated with TH. We excluded
Basal characteristics of study patients
We have tried TH in 140 patients during the study period, and TH was discontinued because of hemodynamic instability and refractory arrhythmias despite treatment in 3 patients. So, 137 patients have reached at the target temperature and finished TH protocol. Two patients who were already diagnosed with chronic renal failure and 18 patients who were referred from another hospital after ROSC were excluded. Finally, the remaining 117 patients were enrolled in this study. Thirty-four patients
Discussion
The patients who achieve ROSC after OHCA had neurologic injury, cardiovascular dysfunction, and multiple organ failure because of whole body ischemia-reperfusion injury called “postcardiac arrest syndrome (PACS)” [10]. Whole body ischemia-reperfusion causes multiorgan damage and results in changes in various laboratory measurements. However, studies concerning the changes and mechanism of the underlying laboratory measurements and influence of these in the neurologic outcome of postcardiac
Conclusions
Among the blood laboratory measurements on ED arrival, blood ammonia levels greater than 96 mg/dL were only independent predictive biomarker of poor neurologic outcome for OHCA patients treated with MTH. Thus, higher blood ammonia levels on ED arrival was associated with poor neurologic outcome in OHCA patients who were treated with TH.
However, further prospective and multicenter studies are needed to evaluate the exact mechanisms and determine the cutoff values.
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Cited by (21)
Long-Term Neurological Outcome of Extracorporeal Cardiopulmonary Resuscitation for Out-of-Hospital Cardiac Arrest Patients With Nonshockable Rhythms: A Single-Center, Consecutive, Retrospective Observational Study
2022, Journal of Emergency MedicineCitation Excerpt :In our study, low ammonia level at arrival was associated with good neurological outcomes. Other studies pointed out the association between ammonia level at arrival and neurological outcomes, consistent with our results (11–13). Short door-to-on-pump interval was also associated with good neurological outcomes (p = 0.04).
Ion shift index as a promising prognostic indicator in adult patients resuscitated from cardiac arrest
2019, ResuscitationCitation Excerpt :In fact, a number of studies have reported changes in serum electrolyte levels following cardiac arrest in the same direction as the changes in extracellular ion concentrations following ischaemia (reported in previous experimental studies).9–17 A few studies have examined the associations between serum electrolyte levels and outcomes in cardiac arrest patients,18–22 but yielded conflicting results. These conflicting results may be due, in part, to the fact that only minor changes in serum electrolyte levels occur following ischaemia compared with those that occur in the ECF.2
Severe acidemia on arrival not predictive of neurologic outcomes in post-cardiac arrest patients
2016, American Journal of Emergency MedicineCitation Excerpt :Lower arterial pH in post–cardiac arrest patients upon intensive care unit (ICU) admission is associated with poor neurologic outcomes [8]. The association between arterial pH at the time of arrival at the emergency department (ED) and neurologic outcomes has seldom been reported [9]. Targeted temperature management is the recommended treatment for comatose post–cardiac arrest patients [2].
Correlation between initial serum levels of lactate after return of spontaneous circulation and survival and neurological outcomes in patients who undergo therapeutic hypothermia after cardiac arrest
2015, ResuscitationCitation Excerpt :Early and effective clearance of serum lactate (i.e., lower levels) are associated with lower mortality in patients with many critical illnesses, including sepsis and severe trauma 13–18. For cardiac arrest survivors, the relationships between clearance of serum lactate and neurological and survival outcomes have been studied 19–23. However, few studies have addressed the potential relationship between initial serum levels of lactate and outcomes in patients who have been treated with TH.