Critical Care Medicine

Acute altered mental status, Mental status changes, depressed mental status, lethargic, obtunded, altered level of consciousness

Acute Altered Mental Status

Synonyms: Mental status changes, depressed mental status, lethargic, obtunded, altered level of consciousness

Related Topics: Hypoxia, hypercarbia, arrhythmia, delirium, depression, toxic ingestion, hypoglycemia, uremia, encephalopathy, stroke, intracranial hemorrhage, sepsis, dementia, sleep deprivation, drug withdrawal

Description of the Problem

Acute altered mental status is a very broad topic, and can encompass any number of states, from mild agitation to delirium, or from sleepy to coma. In many patients, particularly the elderly, there may exist some degree of chronic, ongoing, cognitive impairment, psychiatric illness, or dementia. However, a decreased level of alertness is not typical, even in patients with primary psychiatric illnesses, and this usually points to a medical cause. Approximately 85% of patients who present to an emergency room with acute altered mental status have either a metabolic or systemic cause.

A patient's mental status can be affected by virtually any organ system: cardiac, circulatory, pulmonary, metabolic, endocrine, immunologic, allergic, and neurologic or psychiatric. Therefore, in working up the patient with acute mental status changes, one should have a broad differential, but initially focus on problems that are easily correctible, or most life-threatening.

Because the degree of altered mental status can be so varied, there may be a wide range of clinical features. Patients may present as hyper-vigilent and confused, or they may simply be forgetful, or obtunded and completely unresponsive. Any evaluation of mental status should consider the patient's cognition, behavior, and alertness. Cognition refers to one's ability to understand his or her environment, being able to integrate and process information. Behavior refers to one's reactions to one's environment. Both cognition and behavior will be affected greatly by one's level of alertness. In a patient presenting with altered mental status and decreased alertness, one should rule out medical causes such as systemic illness, infection, intoxication, acute drug reactions, or trauma. The Glasgow Coma Scale can be an easy assessment tool initially to gauge a patient's alertness.

The initial approach to patient with acute alteration in mental status should be systematic and focus on stabilizing the patient. The most important part of the work-up will be the history and physical (of which the vital signs are of critical importance). If the patient is alert and cooperative, or there are family members available, important information can be quickly obtained regarding the patient's current medical illnesses, medications taken or started, or possible toxic ingestions. While attempting to get a history, a focused physical exam should be obtained and vital signs checked, most important of which are pulse oximetry, heart rate and rhythm, blood pressure, and respiratory rate. The goal is to quickly rule out causes that have the potential to harm patients quickly, and those that are more readily correctable.

Emergency Management

  1. Obtain vital signs and perform a focused physical exam. It is important to start with the ABC's. This will guide the next steps in stabilizing and resuscitating the patient. It will determine if a patient needs an immediate intervention, or if there is time, and a need, to gather more information to guide therapy.

    • - HR, BP, pulse oximetry, and respiratory rate. These will quickly help rule out systemic, life-threatening physiologic states.

    • - Physical Exam: should focus on cardiopulmonary processes that are most likely to become quickly lethal, i.e. arrhythmias, shock states, cardiac tamponade, acute respiratory failure, stridor, tension pneumothorax.

    • - Cardiopulmonary processes may require immediate intervention in order to stabilize the patient; for example, defibrillation/cardioversion, pericardiocentesis, volume resuscitation, vasopressors, intubation, chest tube, or bronchodilators.

  2. Laboratory studies

    • - An arterial blood gas and blood glucose level can quickly rule in or out many life-threatening and/or correctable causes of an altered mental status, such as hypoglycemia, hypoxia, hypercarbia, and respiratory acidosis. Electrolytes can also be obtained quickly from an ABG. Abnormal electrolytes can contribute to acute mental status changes either indirectly, by affecting the cardiac conduction system, or directly, as is the case with hypercalcemia, hyponatremia, hypermagnesemia.

Acute alteration in a patient's mental status is merely a symptom, much like tachycardia. In working towards the cause of this symptom, it helps to know the circumstances and setting in which the patient presents. Again, this is where a focused history and physical will be most important. Patients presenting from in the community, depending on their age, are more likely to be experiencing conditions like stroke, or adverse response to medications, infections, or drug intoxication. Patients already in the hospital, particularly peri-operative patients, are more likely to display mental status changes related to possibly myocardial infarction, dysrhythmias, opioid overdose, respiratory failure, or wound infection. The key to finding the cause of a patient's acute change in mental status is heavily reliant on getting a good history of the events leading up to the patient's presentation.

In the meantime, while trying to find the cause, initial efforts must be made to stabilize the patient, and resolve the more lethal causes quickly.

Diagnosis & Treatment

One can come to a specific diagnosis after working through a focused history and physical, in addition to ordering laboratory data and radiographic imaging pertinent to the patient's history and exam findings. It is best to start with the ABC's and work toward stabilizing the patient initially. Once the patient is stabilized, work through the patient's organ systems as they may pertain to the patient's history. The following is a systems-based approach to more common causes of acute mental status changes. However, systems should be considered based on previously gained information from the patient's history.

Cardiac: MI, cardiogenic shock, dysrhythmias (Vtach, Vfib, Afib, complete heart block, symptomatic bradycardia)

  1. Check the patient's pulse and blood pressure. It may be necessary to obtain an EKG. Check the patient's electrolytes (Potassium, Calcium, Magnesium, Sodium).

  2. In the case of acute dysrhythmias, it may be necessary to leave the patient on continuous monitoring, activate the ACLS protocols, and initiate CPR.

  3. Patients with bradycardia or cardiogenic shock may need to have continuous chronotropic and inotropic medications started, in addition to having more invasive forms of monitoring initiated.

  4. If the patient is stable, it would be reasonable to obtain a transthoracic echocardiograph in addition to consultation with a cardiologist for further management.

  5. Correct electrolytes as needed.

Pulmonary: Acute respiratory failure, hypercapnea, hypoxia, COPD exacerbation, asthma, pulmonary embolus, pulmonary edema (related to CHF, or volume overload)

  1. Listen to breath sounds, obtain pulse oximetry, send an arterial blood gas to determine sufficiency of oxygenation and ventilation.

  2. Chest x-ray may help confirm in circumstances when physical exam is difficult to discern.

  3. Patient may need emergent intubation prior to chest x-ray.

  4. Patient may respond to nasal cannula oxygen, or may require non-invasive positive pressure ventilation.

- In the case of hypercapnea, it is important to know the patient's circumstances. Is the hypercapnea related to narcotic overdose in a patient during the perioperative period, who may benefit from receiving naloxone? Or is this patient an asthmatic, or COPD patient, who is having an exacerbation, poorly ventilating, who may benefit from bronchodilators?

- If patient is hypoxic, in respiratory distress, has crackles on exam and pulmonary edema on chest x-ray, the patient may benefit from diuretic therapy.

- Patients with a history of malignancy, or immobility, post-surgical, or other hypercoaguable state or risk factors, now with anxiety and tachypnea should have suspicion for pulmonary embolus. If no contraindication, consider starting anticoagulation. Consider obtaining spiral CT of the chest, or V/Q scan and duplex of lower and upper extremity deep veins for thrombus, while supporting patient's oxygenation.

Circulatory: Hypotension/shock states, hypertensive encephalopathy

  1. Check patient's blood pressure. Initially, try to gauge patient's volume status based on history and physical (check mucous membranes, skin turgor, waveform variation on pulse oximetry).

  2. Give intravenous fluid boluses, and gauge responsiveness.

- History and physical will determine which shock states are most suspected: hypovolemic, distributive, cardiogenic, obstructive.

- Wheezing, angioedema, in addition to either environmental or medication exposure elicited from history would indicate anaphylaxis, in which case patient will be more responsive to IVF's, epinephrine, histamine blockers, and steroids.

- Febrile, tachycardia, along with history or signs of concomitant infection would indicate septic shock. This will require aggressive volume resuscitation, early source control, possibly vasopressors (as indicated in Surviving Sepsis guidelines).

- History of trauma involving head and neck, cervical spine fracture. Likely neurogenic shock, after ruling out other potential injuries and sources of bleeding. Bradycardia and hypotension are found on physical exam, in addition to physical exam consistent with a high cervical spine fracture. Can start with volume resuscitation, but may need vasopressors and/or chronotropic medication.

- History of chronic steroid use, now post-operative, or post-trauma, and hypotensive and tachycardic. May potentially be exhibiting signs of Addisonian crisis, in which case the patient may need initiation of stress-dose steroid therapy.

- History of hypothyroidism, patient possibly not taking medication, or now with additional illness. Elevated TSH, low T4. May be indicative of hypothyroidism. Recommend starting patient on thyroid replacement therapy.

- Listen for breath sounds and look at tracheal position to rule out pneumothorax. If pneumothorax is suspected, or confirmed radiographically, proceed with needle or tube thoracostomy for decompression.

- Conversely, if muffled heart sounds are noted, and patient has jugular venous distention, bedside echocardiography may be warranted to rule in or out cardiac tamponade.

- History of coronary heart disease, CHF, new-onset chest pain. Based on echocardiographic findings, or other invasive monitoring, patient may be in cardiogenic shock state, in which case, after revascularization (if needed), patient may benefit from combination of inotropes, chronotropes, afterload-reducing agents, and potentially intra-aortic balloon pump counter-pulsation.

- In addition, patients with chronic hypertension will have a shift in their cerebral autoregulatory curve, in which case they may require higher-than-normal blood pressure in order to maintain cerebral perfusion.

- Conversely, patients with extreme hypertension may develop disruption of the blood-brain barrier and experience overflow of plasma and plasma proteins contributing to cerebral edema. In these cases, patients will need acute lowering of their blood pressure with continuously titrated vasodilators.

After ensuring that the patient is stabilized, and that the cause of the patient's acute change in mental status is not cardiopulmonary or circulatory in nature, the following systems should be considered based on the patient's past medical history:

Metabolic: Electrolyte disorders (sodium, calcium, phosphate, magnesium)

  1. During initial stabilization, send basic electrolytes so that correction can begin quickly.

  2. Care must be taken during correction of electrolytes; rapidly correcting electrolytes (particularly sodium) may also lead to mental status changes.

  3. Some vitamin deficiencies may also lead to encephalopathy, particularly in alcoholic patients. In such cases it is necessary to correct thiamine deficiency.

Endocrine: Thyroid storm, myxedema coma, pheochromocytoma, hypo- or hyperglycemia, diabetic ketoacidosis

  1. Check blood glucose.

    • - Hypoglycemia is readily correctable. Hyperglycemia is frequently severe enough to lead to acidosis and other electrolyte abnormalities. And in some circumstances may it be associated with underlying infection.

  2. Review patient's history, current medications.

  3. Check TSH, free T4, urine catecholamines and metabolites depending on history and symptoms.

GI/Hepatic: Liver failure, hepatic encephalopathy, kernicterus

1. Check hepatic enzymes, bilirubin levels, ammonia level.

- Patients may require acute treatment with lactulose for correction of ammonia level.

- Patients may also be easily overdosed with sedating medications that require hepatic clearance.

Renal: Uremic encephalopathy

1. Check BUN with basic metabolic panel.

- Patients with renal failure and uremia may require emergent hemodialysis.

Immunologic: Meningitis, severe sepsis or septic shock, SIRS, or associated severe hyperthermia

1. Check cultures (blood, sputum, urine), obtain urinalysis, and start empiric broad-spectrum antibiotics.

Drug-related: Alcohol intoxication, alcohol withdrawal, sedative effect or withdrawal, opioids, anticholinergic agents, illicit drugs, corticosteroids, local anesthetic toxicity (lidocaine, bupivacaine, etc), digitalis, anti-arrhythmic agents (procainamide, quinidine), serotonin syndrome, neuroleptic malignant syndrome, residual anesthesia

1. Review history of drug ingestion/intoxication, new medications started or dosages increased.

Neurologic: Seizure-related (Ictal, post-ictal, status epilepticus, non-convulsive status epilepticus), stroke, hypertensive encephalopathy, subarachnoid hemorrhage, intracranial hemorrhage, hydrocephalus, demyelinating disease, cerebral edema (may be related to intracranial mass), meningitis

  1. After complete neurologic examination, either CT or MRI of the brain with contrast

  2. Electroencephalogram

  3. Lumbar puncture and cerebrospinal fluid evaluation

Psychiatric: Depression, mania, schizophrenia, psychosis, catatonia, and psychiatric medication related (serotonin syndrome, neuroleptic malignant syndrome), delirium, dementia, sleep deprivation

1. In the ICU population, delirium can be very prevalent. Risk factors for developing delirium include advanced age, underlying dementia, severe illness, electrolyte disturbances, malnutrition, trauma, drug effects, infection, sleep deprivation/fragmentation, pain.

- Not only is delirium a symptom but it has also been shown to be a predictor for increased mortality in the ICU population.

The diagnostic approach to an ICU patient with acute mental status changes is the same as for any patient.

  1. Focused history, including recently given drugs, and other risk factors

  2. Focused physical exam, and complete neurologic exam

  3. Lab tests: ABG, electrolytes (Na, K, Cl, Ca, Mg), glucose, cultures, LFT's (including ammonia), CBC

  4. Drug screen: Urine toxicity screen

  5. CT or MRI of the brain with contrast

  6. If no cause yet found, EEG, LP and CSF studies/cultures


See Table I. Signs and Symptoms Related to Etiology of Mental Status Change

Table I.

Special considerations for nursing and allied health professionals.


What's the Evidence?

Casaletto, J. "Is salt, vitamin, or endocrinopathy causing this encephalopathy? A review of endocrine and metabolic causes of altered level of consciousness". Emerg Med Clin North Am. vol. 28. 2010. pp. 633-62.

Cooke, JL, Barsan, WG, Adams, JG. "Altered mental status and coma". Emergency Medicine. Saunders Elsevier. 2008. pp. 985-92.

Ely, W. "Delirium as a predictor of mortality in mechanically ventilated patient in the intensive care unit". JAMA. vol. 291. 2004. pp. 1753-62.

Kakuma, R. "Delirium in older emergency department patient's discharge home: effects on survival". J An Geriatr Soc. vol. 51. 2003. pp. 443-50.

Koita, J, Riggio, S. "The mental status examination in emergency practice". Emerg Med Clin North Am. vol. 28. 2010. pp. 439-51.

Lanken, P. The Intensive Care Unit Manual. Saunders, Elsevier. 2001. pp. 390-4.

Young, J. "Psychiatric considerations in patients with decreased levels of consciousness". Emerg Med Clin North Am. vol. 28. 2010. pp. 595-609.

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