Vanderbilt University School of Medicine
VC3 – Vanderbilt Core Clinical Curriculum

Loss of Consciousness: Coma and Syncope

 

Loss of consciousness is a common presentation of severe illness. Coma is a state of unconsciousness from which the patient cannot be aroused, even by powerful stimulation. Loss of consciousness has many etiologies, many of which can be life threatening. 

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Prerequisites

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Describe and discuss: 

  • anatomy of the brain, brain stem and nervous system, particularly the elements that relate to consciousness such as the Reticular Activating System (RAS)
  • basic physiology
  • basic pharmacology
  • varying types of AV block, bradycardias, tachycardias, and arrhythmias as they apply to syncope

Demonstrate:

  • ability to take a medical history
  • ability to conduct a basic physical examination
  • basic communication skills

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Apply Medical Knowledge in the Clinical Encounter

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1.     Describe and discuss initial assessment and strategies for stabilizing the patient.

2.     Describe and discuss principal causes of coma:

  • widespread damage in both hemispheres from ischemia, trauma, or other less common brain diseases
  • suppression of cerebral function by extrinsic drugs, toxins, or hypoxia, or by internal metabolic derangements such as hypoglycemia, azotemia, hepatic failure, or hypocalcemia
  • brainstem lesions that cause proximate damage to the RAS

3.     Describe and discuss symptoms and signs indicative of coma.

4.     Describe and discuss the key diagnostic criteria for common cases of coma, based on a history, physical exam and laboratory testing.

5.     Describe and discuss the indications and the limitations of the following clinical examinations necessary to determine existence of coma and differentiate among common causes of coma, including:

  • appearance of patient
  • interrogation
  • history from third parties (family, friends, or care givers)
  • physical examination, including vital signs
  • brief neurological exam
  • central nervous system exam

6.     Identify indications for drug therapy and therapeutic procedures in patients with common causes of coma, and describe the physiological basis and/or scientific evidence supporting each type of intervention.

7.     Identify indications for empiric therapy in patients who are comatose.

8.     Describe steps in a critical pathway for patients who are comatose.

9.     Discuss the principal causes of syncope.

10.  Differentiate syncope from seizure.

11.  Define orthostatic BP and discuss the significance of pulse changes.

12.  Describe the heart sounds of aortic stenosis and hypertrophic obstructive cardiomyopathy.

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Diagnose

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Coma

1.     Perform an initial assessment and make recommendations for stabilizing the patient who appears to be comatose: 

  • airway maintenance with cervical spine control
  • breathing and ventilation
  • circulation with hemorrhage control
  • neurological status, disability
  • environmental control 

2.     Obtain, document, and present an age-appropriate medical history, that differentiates among etiologies of disease.

3.     Perform a physical exam and CNS assessment to establish the diagnosis and severity of disease using the Glascow scale.

Syncope

4.     Perform a physical exam that focuses on determining the causes of syncope to include carotid sinus hypersensitivity, volume depletion, abnormal heart tones or heart tone changes with position, and autonomic dysfunction.

5.     Generate a differential diagnosis that differentiates between neurally mediated syncope, orthostatic hypotension, cardiovascular causes of syncope, neurological causes of syncope, and other causes.

For Coma and Syncope

6.     Generate a differential diagnosis, recognizing specific history and physical exam findings.

7.     Recommend when to order diagnostic and laboratory tests necessary to determine the cause of a patient’s coma or syncopal episode and be able to interpret them (with consultation), both prior to and after initiating treatment based on the differential diagnosis. Consider test cost and performance characteristics as well as patient preferences.

8.     Explain the results of the evaluation to the patient, taking into consideration the patient’s condition and knowledge about his/her condition.

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Develop a Management Plan

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1.     Recommend an approach to stabilize the comatose patient based on initial assessment and revise based on subsequent findings:

  • airway maintenance with cervical spine control
  • breathing and ventilation
  • circulation with hemorrhage control
  • empiric treatment of reversible causes
  • thiamine 100mg (adults)
  • dextrose 50 mls 50% (adults)
  • naloxone 0.4 mg (adults)
  • stop seizures
  • treat metabolic disturbances
  • lower intra-cranial pressure
  • treat infection

2.     Recommend elements from general management of coma as appropriate:

  • ABCDE
  • take blood test while putting in lines
  • nursing attention to pressure areas and eyes
  • bronchial toilet
  • nutrition needs - NG tube
  • bladder care - catheter
  • monitoring - vital signs and neurology

3.     Manage the cause of the patient’s syncope.

4.     Access and use appropriate information systems and resources to help delineate issues related to coma and syncope.

5.     Communicate the diagnosis, treatment plan, and prognosis of the disease to patients and their families in a caring and compassionate manner, reflecting an understanding of the emotional impact of the diagnosis and its potential effect on lifestyle (work performance, sexual functioning, etc.).

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Differential Diagnosis

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Coma

Intracranial

  • vascular
  • infection
  • tumor
  • post epileptic
  • head injury
  • psychiatric 

Extracranial

  • cardiovascular
  • infection
  • metabolic
  • drugs

Syncope

 

Neurally mediated syncope

  • vasovagal
  • carotid sinus hypersensitivity
  • situational

Orthostatic hypotension

  • volume depletion
  • drug induced
  • autonomic instability

Cardiovascular causes of syncope

  • arrhythmia,
  • obstructive shock (PE, Pulm HT,RV AMI, Pericardial Tamponade, AS, IHSS)

Neurological causes of syncope

  • subarachnoid hemorrhage
  • intracranial hemorrhage
  • intracranial mass

Other causes

  • hypoglycemia