Altered Level of Consciousness: Evidence-Based Management in the Emergency Department (Pharmacology CME)

Table of Contents

 

1. Abstract
2. Case Presentations
3. Introduction
4. Critical Appraisal of the Literature
5. Etiology And Pathophysiology
6. Differential Diagnosis
   1. Toxicologic Etiologies
   2. Traumatic Etiologies
   3. Neurologic Etiologies
      1. Seizures
      2. Encephalopathy
      3. Ruptured Aneurysm Or Arteriovenous Malformation
      4. Stroke
      5. Cerebrospinal Fluid Shunt Malfunction
      6. Central Nervous System Vasculitis
      7. Infectious Causes
   4. Cardiac Etiologies
      1. Syncope
      2. Posterior Reversible Encephalopathy Syndrome
      3. Pericardial Tamponade
      4. Other Cardiac Etiologies
   5. Pulmonary Etiologies
   6. Endocrinologic Etiologies
      1. Hypoglycemia
      2. Diabetic Ketoacidosis
      3. Hyperglycemic Hyperosmolar State
      4. Hashimoto Encephalopathy
   7. Gastroenterological Etiologies
   8. Renal, Genetic, And Metabolic Etiologies
   9. Hematologic/Oncologic Etiologies
   10. Infectious Etiologies
       1. Meningitis
       2. Encephalitis And Encephalopathy
       3. Intracranial Abscess
       4. Tick-Borne Diseases
       5. Sepsis
   11. Environmental, Autoimmune, And Psychiatric Etiologies
7. Prehospital Care
8. Emergency Department Evaluation
   1. Initial Management
   2. History
   3. Physical Examination
9. Diagnostic Studies
   1. Laboratory Studies
   2. Imaging Studies
10. Treatment
    1. General Treatment Strategies
    2. Condition-Specific Treatment
       1. Electrolyte Abnormalities
       2. Ingestion Or Exposure
       3. Fever
       4. Elevated Intracranial Pressure
       5. Seizure
       6. Neurologic Conditions
       7. Diabetic Ketoacidosis/Hyperglycemic Hyperosmolar State
       8. Hypertensive Encephalopathy
       9. Inborn Errors Of Metabolism
11. Special Populations
12. Controversies And Cutting Edge
13. Disposition
14. Summary
15. Risk Management Pitfalls In Patients With Altered Level Of Consciousness
16. Time- And Cost-Effective Strategies
17. Case Conclusions
18. Clinical Pathway For Managing The Patient With Altered Level Of Consciousness In The Emergency Department
19. Tables
    1. Table 1. Mnemonic For Differential Diagnosis Of Altered Level Of Consciousness
    2. Table 2. Differential Diagnosis Of Altered Level Of Consciousness
    3. Table 3. Toxidromes Resulting In Altered Levels Of Consciousness
20. References

Abstract

A child who presents to the emergency department with an altered level of consciousness can be clinically unstable and can pose a great diagnostic challenge. The emergency clinician must quickly develop a wide differential of possible etiologies in order to administer potentially life-saving medications or interventions. The history, physical examination, and appropriate diagnostic tests can aid greatly in rapidly narrowing the differential diagnosis. Once initial stabilization, workup, and first-line interventions are completed, most patients who present with unresolved or unidentified altered level of consciousness should be admitted for further evaluation and close monitoring. This issue provides a review of the etiologies of altered level of consciousness as well as guidance for the management and disposition of patients with this condition.

Case Presentations

A 7-year-old previously healthy girl presents to the ED with fever, neck pain, and increased sleepiness since the previous day. The patient’s mother reports that she has had a nonproductive cough for the past 2 days, with associated nasal congestion and runny nose. She also notes that the girl has had a decreased appetite since the previous day, a temperature of 38.5ºC, neck pain, and has been lethargic. The patient’s mother does not report a rash, and the remainder of the review of systems is negative. On examination, the patient is found to be sleepy and slowly arousable to commands. The girl's pupils are equal, 4 mm, and react briskly to light. She winces with extension of her knees and has reflex flexion of her hips and knees upon passive neck flexion. As you discuss the likely diagnosis with the girl's mother, you start to think about the management of this patient: What laboratory studies should be sent? Which medications should be administered? Are imaging studies indicated at this time?

A 14-year-old previously healthy adolescent boy presents to the ED after being found by his parents in his room, unconscious. Hours prior to being found, the patient was reportedly with his friends at the movies and was in his usual state of health. His parents deny any fever, nausea, vomiting, or known trauma. The physical examination is notable for a well-developed male who is lethargic and makes only incomprehensible sounds. His physical examination is otherwise normal. What are the likely etiologies for this patient’s altered mental status? What are some interventions that can be initiated to prevent morbidity?

A 9-year-old girl with propionic acidemia presents to the ED with 3 days of nonbloody, nonbilious emesis, and 1 day of lethargy and increased work of breathing. She has not been able to eat anything as a result of the vomiting. Her parents report that she woke up this morning looking very tired and sleepy, which prompted them to bring her to the hospital. The parents deny any fever, diarrhea, or preceding upper respiratory symptoms. The physical examination is notable for disorientation to person, place, and date. She has dry mucous membranes and a capillary refill time of 2 seconds. Her vital signs are as follows: temperature, 37ºC; heart rate, 150 beats/min; respiratory rate, 28 breaths/min; and blood pressure, 80/40 mm Hg. You know that you’ll need to hydrate this patient, but which intravenous fluids should you use? At what rate should the intravenous fluids run? What other interventions will be needed?

Introduction

The term altered level of consciousness (ALOC) can be used to describe a spectrum of disorders that includes clouding of consciousness, confusion, lethargy, obtundation, stupor, or coma.^1,2 In young children, ALOC may manifest as fussiness or irritability. Due to the varying degrees of altered consciousness, it is important for the emergency clinician to be familiar with the various terms that can be used to describe a patient’s clinical status, and to recognize that there is much similarity among them.

• Clouding of consciousness can include a very mild form of ALOC in which there is inattention, decreased alertness, and reduced wakefulness.
• Confusion involves a state of disorientation, along with bewilderment and difficulty following commands.
• Lethargy describes severe drowsiness, though the patient can still be aroused with moderate stimuli.
• Obtundation is similar to lethargy but with slowed responses to stimulation and decreased periods of time spent in wakefulness.
• Stupor refers to a mental state when the patient can only be aroused by repeated and vigorous stimuli (such as pain).
• Coma is a persistent state of unresponsiveness despite attempts of arousal.^1,2

ALOC can be induced by traumatic or nontraumatic mechanisms. In a British epidemiological study completed in 2001, the incidence of nontraumatic coma in children aged < 16 years was reported to be 30.8 per 100,000 per year, with a noted increased incidence in children aged < 1 year (160 per 100,000 per year).³ In other hospital-based studies, nontraumatic coma was noted to be more common in children aged < 6 years than in older children.⁴

Etiologies for ALOC can be numerous, but a broad differential can be reviewed quickly with the aid of mnemonics such as MOVESTUPID, which is adapted from adult emergency medicine practice. (See Table 1.) Other commonly used mnemonics include AEIOU TIPS (alcohol/acidosis, epilepsy, insulin, overdose, uremia, trauma, infection, psychosis, stroke) or DPT OPV HIB MMR (dehydration, poisoning, trauma; occult trauma, postictal/ postanoxia, ventriculoperitoneal shunt; hypoxia/ hyperthermia, intussusception, brain masses; meningitis/encephalitis, metabolic, Reye syndrome/rare causes).⁵ Of these etiologies, the most common cause of nontraumatic coma is an infectious etiology.^3,6

This month’s issue of Pediatric Emergency Medicine Practice will review a broad differential diagnosis for pediatric patients who present to the emergency department (ED) with ALOC, as well as present the initial workup and interventions to stabilize such patients.

Critical Appraisal Of The Literature

An online literature search was performed using the PubMed and Ovid MEDLINE^® databases with the search terms altered level of consciousness, acute loss of consciousness, altered mental status, and coma. For literature searches using the search terms altered mental status and coma, fields were limited to the age group between 0 and 18 years of age and articles written in the English language. A total of 381 articles were reviewed. In addition, individual literature searches were performed for each of the differential diagnoses listed in Table 2 and reviewed for relevance to ALOC or altered mental status. The Cochrane Database of Systematic Reviews was searched using the key terms altered level of consciousness, acute loss of consciousness, and altered mental status, but no reviews were found; using the key term coma, 31 reviews were identified.

Risk Management Pitfalls In Patients With Altered Level Of Consciousness

1. “The patient was drinking alcohol while driving and got into a car accident. His altered mental status must be from his intoxication.”
   Although alcohol intoxication may contribute to the patient’s ALOC, it is important to rule out any other concomitant etiologies for the patient’s ALOC, including, but not limited to, intracranial injury due to the motor vehicle crash.
    
2. “I thought that this was her neurological baseline.”
   In special populations that include developmentally delayed patients, it is imperative to ask the caretaker(s) what the patient’s neurological baseline is in order to correctly assess and evaluate any changes in levels of consciousness.
    
3. “The patient was still seizing after the first 4 doses of lorazepam and 2 doses of fosphenytoin, so we proceeded to place the patient in a phenobarbital coma without further investigation.”
   The differential for a patient presenting with seizures includes electrolyte derangements—including hyponatremia and hypoglycemia—as potential etiologies. The emergency clinician should not only prepare to administer benzodiazepines and other antiepileptic agents, but also to correct any potential electrolyte derangements that may be the cause of seizure. Other causes for seizures can include toxic exposures or ingestions that may need to be considered as well.
    
4. “Even though her GCS score was 7, I needed a CT scan emergently, so I sent her for the scan without further stabilizing her.” Unless the patient’s mental status is quickly improving and returning to neurological baseline, patients with a persistent GCS score of ≤ 8 should be intubated in order to protect their airway, given their unstable neurological status.
    
5. “I could not obtain cerebrospinal fluid from the lumbar puncture, so I held off on antibiotics.”
   If infectious causes are highly suspected in a patient with ALOC, the inability to obtain CSF should not cause unnecessary delay to administration of antibiotic therapy.
    
6. “I knew the diagnosis, so I did not do a complete neurological examination.”
   Once the ABCs of a patient with ALOC are stabilized, details of the neurological examination can provide critical information. For example, anisocoria can reflect signs of impending brain herniation and papilledema can serve as a sign indicating increased intracranial pressure secondary to mass effect on the brain.
    
7. “I thought the patient’s irregular breathing was due to his mental status.”
   Emergency clinicians should not focus solely on the patient’s neurological presentation, as this could result in failure to piece together other presenting signs and symptoms to ascertain the correct diagnosis. For example, respiratory changes can be important clinical findings to indicate Kussmaul breathing, as seen in DKA, or erratic or irregular breathing, as seen in Cushing triad.
    
8. “The patient initially presented with hypoglycemia, and a dextrose bolus was given. Once the hypoglycemia was addressed, I did not think to start dextrose-containing intravenous fluids.”
   Patients who present with hypoglycemia should not only be given a dextrose bolus, but should also have their glucose level rechecked and monitored closely. In addition, if hypoglycemia persists, dextrose-containing fluids should be started at 1.5 times maintenance rate to ensure a steady glucose infusion rate until the etiology for hypoglycemia can be ascertained. Plasma glucose checks should be completed frequently until a stable level > 70 mg/dL is attained more than once.³²
    
9. “The patient was hyponatremic and altered. I subsequently gave a 20 mL/kg normal saline bolus and started the patient on normal saline intravenous fluids at 1.5 times maintenance rate.”
   Correcting hyponatremia should be done slowly, due to the risk of central pontine myelinolysis. The recommended rate of correction is such that the patient’s serum sodium levels should not rise more than 12 to 15 mEq/L (12-15 mmol/L) over a 24-hour period.
    
10. “He initially came into the ED looking intoxicated. I did not think that there would have been any issues with cervical spine instability.”
    In all patients presenting with ALOC, trauma must be considered in the differential. If trauma is highly suspected as the etiology for the patient’s ALOC, care must be taken to ensure proper cervical spine precautions. Similarly, it is important to fully undress the patient with ALOC to avoid missing skin findings, signs of trauma, or other cutaneous clues that may otherwise be hidden underneath clothing.

Tables

References

Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report.

To help the reader judge the strength of each reference, pertinent information about the study, such as the type of study and the number of patients in the study is included in bold type following the references, where available. The most informative references cited in this paper, as determined by the authors, are noted by an asterisk (*) next to the number of the reference.

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