There are many potential causes of altered mental status. The classic mnemonic is AEIOU TIPS (see Box 36-1). This provides a concise overview of multiple entities that may lead to altered consciousness. This section will focus on specific conditions that may be identified and corrected in the field setting. This section will also discuss conditions that may require presumptive treatment based on suspicion alone in the absence of field diagnostics.
Box 36-1 Altered Mental Status (AEIOU TIPS)
|A ||Alcohol |
|E ||Endocrine, Electrolytes, Encephalopathy|
|I ||Insulin |
|O ||O2, Opiates |
|U ||Uremia |
|T ||Toxidromes, Trauma, Temperature |
|I ||Infection |
|P ||Psychiatric, Pharmacy |
|S ||Space occupying CNS lesion, Subarachnoid hemorrhage, Stroke, Sepsis, Shock |
The ABCs are as applicable in the altered mental status patient as any other patient, if not more. Airway and breathing issues may readily account for alterations in mental status. Hypoxia, hypoventilation, hypercapnia, and carbon monoxide poisoning are high on the list of initial concerns. Pulse oximetry is now ubiquitous in the prehospital setting and readily assists in diagnosing hypoxia. Less common, but gaining in popularity, are end-tidal CO2 detectors which are a tremendous asset in evaluating ventilatory status and impending respiratory failure. A more recent addition to the prehospital environment is the CO monitor. Its presence is still sporadic, but when available it is able to give a confirmation of suspected CO exposure as well as a quantifiable number by which the EMS physician can evaluate the level of poisoning and possibly affect the destination hospital if hyperbaric treatment facilities are available.
If circulation, measured as blood pressure of perfusion status, is altered, then this etiology must be addressed. These scenarios are beyond the scope of this chapter and are fully discussed in other chapters such as Chapter 35 or Chapter 39. Acute blood loss is addressed in the chapters on gastrointestinal emergencies (Chapter 41), blunt and penetrating trauma (Chapter 54), and wounds and hemorrhage (Chapter 57).
Blood glucose problems are rapidly detectable in the field and low levels are easily corrected. IV administration of D50 has long been the mainstay for correcting hypoglycemia in adults that is not amenable to more basic interventions such as oral intake of foods or liquids that are high in sugar content. Recently there has been investigation on the use of alternative IV dextrose solutions.1 D10 administration in adults showed equal time to regain consciousness without the characteristic posttreatment hyperglycemia that is present with D50 administration. Currently, D50 remains the standard of care in this country, but more dilute solutions are apparently efficacious and may be administered to adults at the discretion of the EMS physician. D10 (<1 year old) and D25 (1-12 years old) are recommended for children.2 Some EMS systems utilize D12.5 in place of D103 for ease of conversion which should hopefully increase safety. If IV access is unobtainable, IM/SQ glucagon may be administered. The dose is 1 mg IM/SQ for patients greater than 20 kg (44 lb). Patients below approximately 20 kg should receive 0.5 mg IM/SQ.
Electrolyte abnormalities are not easily identifiable in the field and usually require a significant level of presumption. Traditionally, a patient undergoing heavy exertion in a hot environment and who has been ingesting only free water would be suspected of hyponatremia, especially if a new onset seizure is observed. This should be expanded to any excessive fluid consumption during strenuous activity, regardless of fluid type.4 Psychogenic polydipsia could result in hyponatremia in the setting of a psychiatric patient who has unrestricted water consumption. Treatment for uncomplicated hyponatremia would consist of 0.9% NS IV. Three percent NS could be considered if the patient is in extremis, is experiencing repetitive or protracted seizures unresponsive to benzodiazepines, or has lapsed into a comatose state. In such situations where cerebral edema and herniation is suspected, 50 to 100 mL of 3% saline may be bolused5,6 followed by up to 200 mL over the next 4 to 6 hours. Three percent saline should be stopped once signs of cerebral edema and herniation have ceased.
Hypernatremia and severe dehydration are suspected by a history of decreased fluid intake and by clinical presentation. The treatment of both entities would be 0.9% NS IV. Dehydration to the point of mental status changes would require significant boluses of NS due to significant volume depletion. As long as the patient remains symptomatic from dehydration, there is no upper limit on NS administration, as long as pulmonary edema and other signs of fluid overload are monitored. Acute hypernatremia may also be corrected quickly. However, a slower correction should be employed, in the hospital setting, for sodium levels that are suspected to have been high for a longer time.
Hyperkalemia is most often suspected in a dialysis patient. Altered mental status is not the hallmark of hyperkalemia, but its presence could lead to arrhythmias which could induce an altered mental status prior to progression into cardiac arrest. The ECG may be beneficial in diagnosing peaked T waves or a sine wave, but it may be nondiagnostic if the patient has a sinus tachycardia or PSVT that precludes thorough examination of the morphology. Suspicion of hyperkalemia is enough to warrant treatment with IV calcium chloride with or without sodium bicarbonate.
Alcohol consumption is a common practice in this country and ethanol intoxication is always a high concern in a patient with an altered mental status. No specific antidote exists and support of the airway and respiratory status is warranted. This is the ideal patient to employ not only pulse oximetry, but end-tidal CO2 monitoring as well to monitor for changes in the respiratory status that may not be appreciated by physical examination alone. This approach would also apply to other sedative medications. Blood glucose abnormalities should not be overlooked in someone who is intoxicated, or just appears intoxicated.
Opiates are a classic cause for altered mental status.7,8 Pinpoint pupils and decreased consciousness are the hallmarks, although a person occasionally may present in an agitated state. The treatment is naloxone (Narcan) IV, IM, or IN. The usual starting dose is between 0.4 and 2 mg, but there is no upper limit on the amount of naloxone that may be administered and large doses may be required in large overdoses and in certain opiates.9 Since narcotic overdose does not have a test in either the field or hospital, the EMS physician must have an index of suspicion, or a blanket treatment plan, to utilize Narcan (naloxone). Usage in patient with compromised respiratory status is unquestionable. Usage in patient with a lesser degree of alteration is less clear. The EMS physician must remain cognizant about the potential for mixed drug overdoses. Removal of the opiate effect and its sedative properties may result in unopposed effects of cocaine, methamphetamine, PCP, or something similar. It may also precipitate acute narcotic withdrawal which may create a combative and uncooperative patient. In these situations, the EMS physician is usually best served by weighing the patient's airway and ventilatory status along with the perceived safety of the patient and providers. If any of these are compromised, administration is warranted. If none are compromised, diagnostic trials of naloxone in the field are unwarranted and supportive care is recommended until this patient arrives at the hospital. However, it is important to consider that there is a growing availability of public access naloxone programs, and that the patient may have already received 2 mg of naloxone prior to arrival of EMS providers.10–13
On a related note, flumazenil (Romazicon) should not be utilized in the prehospital setting for suspected benzodiazepine overdoses or overdoses of unknown etiology. The safety of its usage in such situations is questionable14–16 and should be avoided. Fatal, intractable seizures are possible and are a significant concern. Supportive airway and breathing management are safer options.
Other substances such as cocaine, methamphetamines, or PCP may also be encountered and usually present with agitation but may also include hallucinations, aggression, and violence. No specific antidote exists, but benzodiazepines are appropriate and large amounts may be necessary for effect in such patients. If the patient progresses into excited delirium, then more aggressive measures may be indicated and will be discussed later in this chapter.
CNS injury is often suggested by history provided by the patient or bystanders. Sometimes, the mechanism is less clear and requires a high index of suspicion. Stroke, both hemorrhagic and ischemic, may mimic CNS injury. No specific prehospital intervention is available to the EMS physician and supportive care and transport to the most appropriate facility is warranted.
Psychiatric conditions are widespread and more commonly lead to agitation rather than a depressed level of consciousness. An acute psychotic episode is characterized by abrupt disturbance of thought, behavior, and mood.17 Anxiolysis and mild sedation may be required to provide comfort to the patient, provide safety, and prevent deterioration. When the acute psychotic episode includes agitation and violence, the patient has crossed into excited delirium, which will be discussed in more detail later in this chapter. Other specific psychiatric conditions are discussed in Chapter 51.
Temperature regulation issues and environmental exposure can lead to alterations in consciousness and can be addressed in the field. Thermometers may or may not be available so presumptive treatment may be required. Patient and environmental clues can be used to develop a suspicion of hyper- or hypothermia. Warming or cooling as needed is appropriate and can be accomplished in the prehospital environment and is discussed in Chapter 37.
While temperature abnormalities undeniably need treatment, acidosis treatment is less clear. An acidotic state is not reliably identified in the field setting so the EMS physician must be presumptive to suspect this state. Patients exhibiting hyperventilation may be showing a clinical sign of respiratory compensation, or the increased respiratory rate may be attributed to something entirely unrelated. Behavior such as vigorous fighting and physical exertion or history obtained from bystanders may lead the EMS physician to suspect an acidotic state. Some acidotic conditions such as DKA are usually best treated with ventilatory support, fluids, ensuring adequate volume status and transport. Infection and sepsis also benefit from similar care.