Article, Emergency Medicine

Etiologies of altered mental status in patients with presumed ethanol intoxication

a b s t r a c t

Background: Altered mental status is a commonly evaluated problem in the ED. ethanol intoxication is common, and prehospital history may bias emergency physicians to suspect this as the cause of altered mental status. Quantitative ethanol measurement can rapidly confirm the diagnosis, or if negative, prompt further evaluation. Our objective was to identify the etiologies of altered mental status in ED patients initially presumed to be intox- icated with ethanol but found to have negative quantitative ethanol levels.

Methods: This was a 5-year (2012-2016) electronic medical record review of ED patients presenting with altered mental status. Patients were included if they presented with presumed ethanol intoxication and had an initial ethanol concentration of zero. Etiologies of altered mental status were categorized into medical, traumatic, psy- chiatric, and drug-related causes.

Results: 29,322 patients presented during the study period with presumed alcohol intoxication, 1875 patients had negative ethanol levels. The etiology of altered mental status was due to illicit substances in 1337 patients (71%), psychiatric causes in 354 patients (19%), medical causes in 166 patients (9%) and trauma in 18 patients

(1%). A total of 179 patients (10%) were admitted to the hospital; 19 patients (1%) to the ICU.

Conclusions: The presumptive diagnosis of ethanol intoxication in patients presenting to the ED with altered mental status was inaccurate in 5% of patients. The etiology of altered mental status was serious and required hospitalization in 10% of the cohort. Rapid assessment of quantitative ethanol levels should be performed, breath- alyzers may be preferred over serum testing.

(C) 2018


Altered mental status is a nonspecific diagnostic phrase com- monly used in the emergency department (ED) [1]. The term describes the undifferentiated presentation of abnormal mentation, and includes some degree of Altered level of consciousness, impaired cognition and decreased awareness or attention. Commonly encountered in the ED [2], “AMS presents a formidable challenge to the (emergency) physician because it does not suggest a discrete diagnosis but may be the Primary presentation for a variety of medical conditions” [1].

As far back as the 1930’s, acute ethanol intoxication was noted to be the most common cause of coma in a public hospital [3]. Although coma is the most Severe form of AMS, the diagnostic term can present with a

? Sources of support: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.Presentations: Society for Academic Emergency Medicine, Annual Meeting, Orlando, Florida. May 2017.

* Corresponding author at: Hennepin County Medical Center, Department of Emergency Medicine – EMS-825, Minneapolis, MN 55415, United States.

E-mail address: [email protected] (M.L. Martel).

wide spectrum of altered mentation. Sedation, lethargy and confusion may be seen, but agitation and bizarre behaviors are also encountered. By definition, patients with AMS are unable to provide any meaningful history. In ideal circumstances, family or friends are available to provide details of the patient’s baseline, past medical history, timeline of the ill- ness and any additional, relevant information. In lieu of these alternate historians, first-responders and emergency medical service (EMS) per- sonnel are the only source of clinical information. Much of the initial ED evaluation is often based on this limited history, and a subset of these pa- tients is presumed to be acutely intoxicated with ethanol. Breath or serum ethanol levels can rapidly confirm the diagnosis, and if negative, prompt further evaluation. Our objective was to identify the etiologies of altered mental status in ED patients initially presumed to be intoxicated with eth-

anol, but were found to have negative ethanol concentrations.


This was a retrospective, observational cohort study of ED patients presenting with AMS and presumed ethanol intoxication between

0735-6757/(C) 2018

1058 M.L. Martel et al. / American Journal of Emergency Medicine 36 (2018) 10571059

January 1, 2012 and December 31, 2016. This study was approved by the institutional review board.

The study was performed at our tertiary-care, county ED with an an- nual census of approximately 110,000 annual visits. Our ED cares for more than 7000 patients per year with acute ethanol intoxication. We have a specifically designed, 16-bed clinical area dedicated to care for patients with acute ethanol and drug intoxication. This unit is staffed by an ED health care team, comprised of two registered nurses, a resi- dent physician or physician assistant, and is supervised by an attending emergency physician 24 h per day. All patients placed in this unit have a complete physical examination and breath alcohol concentration ob- tained on arrival. The vast majority of visits for acute intoxication are managed in this clinical area of the ED. If the unit is full, or if patients have comorbid medical or traumatic conditions requiring treatment, patients may be seen in other areas of the ED.

Subjects 18 years or older were identified for inclusion in this study using an electronic medical record query of patients who presented with the chief complaints of “alcohol intoxication” or “altered mental status” and were managed in the designated area of the ED. From this search, patients with an initial breath ethanol concentration of zero (un- detectable) were included in the analysis. Any patient with a detectable ethanol level was excluded.

Demographic and clinical data was obtained by a blinded data ana- lyst directly from the electronic medical record. This included the vari- ables age, gender, mode of arrival, comorbidities, disposition, and testing obtained. Two trained abstractors (AL, AK), using a structured data collection form, reviewed the charts of all patients and categorized the etiology of altered mental status into medical, trauma, psychiatric, or drug related causes. The abstractors also recorded the hospital admis- sion diagnoses for all admitted patients, as well as the confirmed or suspected intoxicating substance for patients classified as altered from drug intoxication. In cases where urine Drug testing was not performed, patient reported, or clinically suspected substances are presented. All analyses were descriptive in nature, including means, standard devia- tions, counts, and proportions when appropriate. Data analysis was con- ducted in Stata (Version 15, College Station, TX).


Patients presenting to the ED with Mental status changes represent a complex Diagnostic dilemma. The evaluation frequently includes exten- sive laboratory testing and medical imaging. It is important consider ethanol and illicit substances before pursuing alternate etiologies, but assuming that AMS is due to acute intoxication may be a dangerous medical decision.


We identified 29,322 patients presenting to the dedicated clinical area during the study period with presumed ethanol intoxication. Of these, 1875 patients had negative ethanol levels and were included in the analysis. The mean age was 41.7 years; 1427 (76%) were male. Ad- ditional patient characteristics are presented in Table 1. In this cohort, AMS was due to drug-related etiologies in 1337 patients (71%), psychi- atric etiologies in 354 patients (19%), medical etiologies in 166 patients (9%) and traumatic etiologies in 18 patients (1%). A total of 179 patients (10%) were admitted to the hospital; 19 patients (1%) were admitted to the ICU. Specific admission diagnoses of interest are displayed in Table 2. Table 3 depicts the known or suspected intoxicating substances for patients with drug intoxication.


Alcohol-related ED visits are common and appear to be on the rise [2]. As these encounters continue to increase, it is crucial for the emer- gency physician to have a standard approach to managing these

Table 1 Characteristics of patients presenting with altered mental status, presumed alcohol intox- ication and an undetectable breath alcohol concentration.

Patient variable

Age (mean years) 41.7 (range 18-93)

Male gender 1427 (76%)

Mode of arrival

Emergency medical services

1024 (55%)

law enforcement

583 (31%)

private vehicle

268 (14%)


Chronic liver disease

219 (12%)

Chronic kidney disease

124 (7%)

Ischemic vascular disease

40 (2%)

Chronic obstructive pulmonary disease

35 (2%)

History of traumatic brain injury

116 (6%)

History of intravenous drug abuse

380 (20%)


311 (17%)

bipolar disorder

401 (21%)

Diagnostic testing obtained Computed tomography

217 (12%)

Laboratory testing

448 (24%)

ED disposition

Discharged from ED

1161 (62%)

Discharged to psychiatric services

535 (29%)

Admitted to hospital

179 (10%)

Admitted to ICU

19 (1%)

Survived to hospital discharge

1875 (100%)

All values are number (%) unless otherwise noted. ED: emergency department; ICU: intensive care unit.

patients that is efficient, respects the fact that concomitant pathology is common, and considers alternate diagnoses for the etiology of AMS.

The generic clinical finding of “altered mental status” truly repre- sents a broad differential diagnosis for the emergency physician to con- sider and evaluate. Both primary neurologic processes and secondary responses to Disease states can result in a depressed mental state. There is a paucity of evidence-based data to guide the EP as they assess patients with AMS but published studies would suggest that in patients with coma, substance abuse, head trauma, and Neurologic events are common [3-5]. In one review of ED patients specifically with the pre- senting problem of AMS, in descending order of frequency; neurologic events, intoxication (ethanol and illicit substances), head trauma and psychiatric syndromes were identified as the principal considerations [4]. To our knowledge this is the first study to specifically evaluate the etiology of AMS in patients who were initially believed to be intoxicated but tested negative for ethanol.

Table 2 Hospital admission diagnoses in ED patients presumed to be intoxicated but had negative ethanol concentrations.

admission diagnosisa N (%)

Drug intoxication/overdose (illicit drug)

67 (3.6)

Drug intoxication/overdose (prescription drug)

51 (2.7)


29 (1.5)


23 (1.2)

Hepatic encephalopathy

17 (0.9)


16 (0.9)

alcohol withdrawal

16 (0.9)

Agitation/excited delirium

15 (0.8)

Acute renal failure

14 (0.7)

Intracranial hemorrhage

8 (0.4)

Other electrolyte problem

6 (0.3)


4 (0.2)


4 (0.2)


2 (0.1)


2 (0.1)

Cerebrovascular accident/transient ischemic attack

2 (0.1)

gastrointestinal hemorrhage

2 (0.1)

a Patients may have had more than one admission diagnosis.

M.L. Martel et al. / American Journal of Emergency Medicine 36 (2018) 10571059 1059

Table 3

Known or clinically suspected intoxicating substance for patients with drug intoxication.

Substance N (%)

Methamphetamine 322 (24.1)

Opioids 294 (22)

THC (includes K2) 218 (16.3)

Benzodiazepines 164 (12.3)

Cocaine 144 (10.8)

Hallucinogens (PCP, LSD, mushrooms) 93 (7)

Inhalants 42 (3.1)

MDMA/Ecstacy 18 (1.3)

Other Substances (includes bath salts) 22 (1.6)

Unknown 20 (1.5)

With this in mind, when patients present to the ED with a report of intoxication with ethanol, some clinicians may forgo additional testing or diagnostics based on the prevalence of intoxication as the etiology of AMS. Our findings would suggest that these reports must be distin- guished from primary history obtained from a patient, and history ob- tained in lieu of primary data. Our study highlights the inherent risk associated with the ED evaluation of AMS, and supports the practice of vigilance when these patients arrive in the ED. A significant number of patients (5%) who were presumed to be under the influence of ethanol, in fact had another clinically significant etiology for their AMS.

Arguably, our findings support confirming ethanol levels even in pa-

tients where a primary history is suggestive of ethanol intoxication. Ex- perienced EPs are likely to appreciate the pitfalls associated with assuming a patient is acutely intoxicated with ethanol, and our study highlights the importance of rapidly confirming this on arrival in the ED. The use of breathalyzers over serum testing may be more valuable in these time sensitive assessments, or at a minimum as a first line test, in cases of AMS where ethanol use is suspected. Fortunately, breath alcohol analyzers are readily available in the US and frequently employed in the ED. [6,7]

Anecdotally, EPs may avoid ethanol testing in patients with AMS who are presumed to be intoxicated. The belief is that formal testing may impair the EPs ability to coordinate a disposition, particularly if the ethanol level is “too high”. If ethanol intoxication is suspected and not confirmed, based on our findings, one in 20 patients would be erro- neously managed and 1-2% of these patients would be critically ill.

To our knowledge, this is the first study to assess the etiology of pa- tients presenting to the ED with AMS who are presumed to be acutely intoxicated with ethanol but are found to have negative ethanol levels. This is a particularly at-risk group of patients, as it is plausible that the ED evaluation could be delayed or performed in a less complete manner simply based on the history of presumed ethanol intoxication. The ma- jority of these patients who were not ethanol intoxicated were altered due to illicit substances as noted in previous reports of AMS in the ED.

[4] But unlike these findings, in our study of Very low risk ED patients, we identified 179 patients who required hospital admission, and 19 who required ICU services for AMS.


We note several limitations in our study, including those based on the retrospective study design. Bias was limited by using standard

methods for data abstraction. Our single site study design and findings may not generalize to other institutions, but we believe that our find- ings are germane in light of the increased number of intoxicated pa- tients presenting to the ED on an annual basis [2]. Serum ethanol concentrations were not employed in the study protocol. Breath alcohol levels are specifically used in our ED; breathalyzers are readily available and provide an immediate ethanol concentration. Lastly, there is the po- tential for selection bias, as our dedicated clinical unit cares for most, but not all low risk, presumed Intoxicated patients in our ED. Patients with significant medical or traumatic issues requiring treatment are placed in the main ED whether presumed intoxicated or not. We believe, how- ever, our study design and search criteria provided the most appropriate method to identify patients presumed to be very low risk patients with ethanol intoxication.


The presumptive diagnosis of ethanol intoxication in ED patients presenting with altered mental status was flawed in 5% of our study population. Ten percent of patients with negative ethanol levels re- quired hospitalization, and nearly 2% of these patients required ICU level of care. A high index of suspicion should be maintained in all pa- tients presumed to be intoxicated with ethanol, as serious etiologies of altered mental status were identified. Physician impression of alcohol intoxication can be inaccurate and masquerade serious illness. Rapid ethanol testing should be performed and breath over serum analysis may be preferable.



Funding sources

This research did not receive any specific grant from funding agen- cies in the public, commercial, or not-for-profit sectors.


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