EMS clinicians should use the exam, history, and environmental clues to attempt to identify a specific cause or causes of AMS that could benefit from early treatment in the field with a specific remedy or antidote.
Presentations, etiologies, and treatments
The potential presentations and causes of AMS are extensive and complex. Although the definitive treatment for many of these problems may fall outside the scope of practice of EMS clinicians or the duration of the prehospital contact, the focus should be on identifying the primary cause or causes of AMS and beginning specific treatment in the field. As causes of AMS are identified in the individual patient, it is also necessary to determine whether a brief on‐scene interval and expeditious transport are required for time‐critical causes (e.g., STEMI, stroke, trauma), or whether the patient would benefit from further extended on‐scene management. A simple and frequently used mnemonic for the potential causes of AMS is AEIOU TIPPS (Box 15.1)
A major challenge with AMS patients is that they can be easily triaged into the AMS “not otherwise specified” protocol, while instead having a definable process. Dysrhythmia or hypotension associated with inferior MI may present with AMS as the predominant sign, and stroke patients with aphasia may be classified first as AMS. Indeed, all the various classes of shock may present with AMS yet may require different treatments.
Furthermore, patients with AMS may have multiple comorbidities that could be identified in the prehospital environment. For example, it is tempting to assume that a patient with seizures, who may be actively seizing or postictal, has an underlying seizure disorder. However, seizures may be caused by cardiac arrest (ventricular fibrillation), hypoxia, hypoglycemia, trauma, intracranial hemorrhage, stroke, infection, or drug overdose or withdrawal, all etiologies that can separately contribute to the patient’s AMS.
AMS patients with any of multiple etiologies may also be physically aggressive or combative, presenting a challenge as well as a risk to EMS clinicians. Patients with traumatic head injuries, those under the influence of either prescription or illicit drugs or alcohol, and those with medical emergencies such as hypoglycemia, postictal state, decompensated psychiatric disorders, and many others may be violent. The experienced EMS clinician will recognize that such a patient may have combative AMS due to an underlying medical condition, but that does not lessen the risks of physical harm to the patient or the clinician. Care should be taken to ensure both crew and patient safety. For additional information on managing the combative patient, refer to Chapter 58.
Box 15.1 Mnemonic for causes of altered mental status
A – Alcohol
E – Epilepsy, Electrolytes, Encephalopathy
I – Insulin (hypoglycemia)
O – Oxygen (hypoxia), Overdose
U – Uremia
T – Trauma, Temperature
I – Infection
P – Poisons
P – Psychiatric
S – Shock, Sepsis, Stroke, Space‐occupying lesion
Pediatric altered mental status
AMS in children can be subtle. Look for age‐specific behaviors that range from irritability to anger to sleepiness to decreased interaction. As with adults, caregivers may use the mnemonic AEIOU TIPPS (Box 15.1) to assist in developing the differential diagnosis. The pediatric assessment triangle (PAT) is defined as appearance, work of breathing, and circulation and is a rapid method of determining abnormality in pediatric patients. To use the PAT effectively, EMS personnel must have a solid understanding of age‐appropriate vital signs [9].
Alcohol
One group that deserves special mention comprises those AMS patients who are diagnosed as being “just drunk.” EMS personnel, including field physicians, often focus on the presumption of alcohol intoxication without considering other potential conditions causing AMS in the patient who abuses alcohol. The alcoholic is also prone to myriad medical and traumatic problems, including liver disease, diabetes, hypoglycemia, electrolyte imbalances, and an increased propensity for intracranial hemorrhage (Box 15.2). The intoxicated patient should always have a rapid, but thorough, evaluation for trauma and other acute conditions.
Time‐critical causes
EMS clinicians should be sure to consider early the potential for causes of AMS that require time‐sensitive evaluation treatment at the hospital or a specialty center. For example, a patient who meets trauma criteria should have a short scene time and rapid transport to a trauma specialty center. Trauma, particularly of the head and neck, is always a possibility for patients with AMS. Although AMS (decreased GCS) is a criterion for specialty transport to a trauma center, a patient with AMS and otherwise minimal signs of trauma may have another competing or underlying etiology for his or her AMS [10]. In addition to trauma patients, those with ST‐segment elevated myocardial infarction (STEMI) and those who have positive stroke screens require rapid recognition and expeditious transport.
On‐scene treatments and dispositions
Some patients with specific, reversible causes of AMS may be definitively treated on‐scene and do not necessarily warrant rapid advanced life support transport to the emergency department. EMS clinicians should be cautious when attributing AMS to a single, “fixable” cause. Nonetheless, protocols may provide guidance for when patients with resolved AMS and no other acute problems may have an appropriate disposition other than a trip to the emergency department.
Box 15.2 Causes of altered mental status in alcoholics
Intoxication
Electrolyte abnormalities
Hypothermia
Hypoxia
Infection/sepsis
Liver diseaseHepatic encephalopathyCoagulation disordersHypoglycemia
Overdose/intoxication
Seizures
Trauma
Withdrawal
Glucose evaluation and administration
The measurement of serum glucose should be a universal step in the evaluation of an AMS patient. Hypoglycemia may be the sole and reversible cause of AMS in some EMS encounters. Although the defined level for hypoglycemia varies from system to system, many use a level of less than or equal to 70 mg/dL when accompanied by appropriate signs and symptoms of hypoglycemia. A method of testing then treating is generally preferable to the empiric administration of exogenous glucose to all patients with AMS. Only 25% of patients with AMS are hypoglycemic. The common assumption that an ampule of dextrose 50% in water “won’t hurt anyone” has been refuted [11], and it is well established that the blind administration of exogenous glucose may be harmful [12, 13]. After administration of dextrose to the known hypoglycemic patient, an improvement in mental status is usually seen within 5 minutes (see