Loss of Consciousness

  1. In an unconscious patient, assess ABC’s and resuscitate as needed.

  2. As part of the assessment of a patient who has lost consciousness, obtain focused history from the patient or witnesses that would include duration, trauma, preexisting conditions, drugs, toxins, medications and seizure activity.

  3. Examine unconscious patients for localizing and diagnostic signs (e.g., ketone smell, liver flap, focal neurologic signs).

  4. In patients with a loss of consciousness and a history of head trauma, rule out intracranial bleeding.

  5. In patients with a loss of consciousness who are anticoagulated, rule out intracranial bleeding.

  6. Assess and treat unconscious patients urgently for reversible conditions (e.g., shock, hypoxia, hypoglycemia, hyperglycemia, and narcotic overdose).

  7. When following up patients who have lost consciousness, assess and advise regarding return to work, sporting, driving and recreational activities to minimize the possibility of injury to self or others in the event of a recurrence.

  8. In patients who have had a loss of consciousness without a clear diagnosis, pursue investigations (e.g., rule out transient arythmia, seizure).

  9. When following up patients who have lost consciousness and where there is potential for recurrent episodes, discuss specific preventive and protective measures (e.g., position changes with orthostatic pressure changes).

  10. In patients with loss of consciousness following head trauma, treat and follow up according to current concussion guidelines.

  11. Advise authorities about appropriate patients with loss of consciousness (e.g., regarding driving status).

General overview

    • Syncope is a transient loss of consciousness (T-LOC)

      • Rapid onset

      • Short duration

      • Spontaneous complete recovery


    • Reflex (neurally-mediated) syncope

    • Orthostatic syncope

    • Cardiac arrhythmias

    • Structural cardiopulmonary disease

    • Pseudosyncope

      • Seizure

      • Sleep disturbances

      • Accidental falls

      • Psychiatric

History (from witnesses)

    • AMPLE

      • Allergy

      • Medication

      • PMH and Fam Hx (sudden death, cardiac)

      • Last meal

      • Event

        • Number, frequency, and duration of episodes

        • Onset, position, provocative factors (triggers)

        • Associated symptoms before and after the event

          • Low-risk: Prodrome, trigger, positional

          • High-risk, r/o cardiac: during exertion or supine, sudden onset palpitation, without prodrome

        • Witnessed signs by observers

          • Trauma

          • Seizure activiity

        • Drugs/toxins/medications

Physical Exam

    • Vitals (Temperature)

    • ABCDE

      • GCS

        • E4,V5,M6

        • GCS<8, intubate!

    • Cardiac

    • Neuro

    • Consider DRE for GI bleed


    • EKG

    • Orthostatic BP

      • Sustained decrease in sBP ≥20 mmHg or dBP ≥10 mmHg within 3 min of assuming upright posture

    • Labs (only if indicated)

      • Consider CBC, BhCG, troponin

    • Cardiac (if abnormal EKG or suspect cardiac)

      • Consider echocardiogram if abnormal EKG or suspect structural abnormality

      • Consider Holter 24-48h only if symptoms reoccur daily

      • Consider carotid sinus massage if >40yo and no contraindications

        • Patient supine 5-10 seconds of massage to each carotid sinus (start with right)

          • Positive if asystolic or ventricular pause > 3s or decrease in sBP of 50 mm Hg

            • If negative, repeat with patient upright at approximately 60 to 70 degrees

        • Avoid in recent stroke/TIA <3mo or if carotid bruits

    • Neurologic (only if suspect epilepsy, focal neuro deficit)

      • Consider EEG, CT head

    • Risk Stratification (can use San Francisco Syncope Rule or OESIL Score)

      • High risk (hospital admission recommended)

        • Clinical history suggestive of arrhythmic syncope (e.g., syncope during exercise, palpitations, or without warning or prodrome)

        • Comorbidities (e.g., severe anemia, electrolyte abnormalities)

        • ECG suggestive of arrhythmic syncope (e.g., bifascicular block, sinus bradycardia < 40 beats per minute in absence of sinoatrial block or medication use, QRS preexcitation, abnormal QT interval, ST segment elevation leads V1- V3 [Brugada pattern], negative T wave in right precordial leads and epsilon wave [arrhythmogenic right ventricular dysplasia/cardiomyopathy])

        • Family history of sudden death

        • Hypotension (sBP < 90 mm Hg)

        • Older age

        • Severe structural heart disease, congestive heart failure, or coronary artery disease

      • Low risk (outpatient evaluation recommended)

        • Age less than 50 years

        • No history of cardiovascular disease

        • Normal electrocardiographic findings

        • Symptoms consistent with neurally mediated or orthostatic hypotension syncope

        • Unremarkable cardiovascular findings


  • Nonpharmacological management of vasovagal syncope and orthostatic hypotension

    • Education and reassurance

    • Avoid triggers

    • Lying down quickly with onset of presyncope

    • Salt and water intake

    • Removal of offending medications

    • Counter-pressure manoeuvers (leg-crossing, limb/abdominal contractions, squatting), compression garments, and head-up tilt sleeping

  • Consider pharmacotherapy in recurrent refractory vasovagal syncope and orthostatic hypotension

    • Fludrocortisone 0.2mg PO daily or Midodrine 5-15mg PO TID (eg. q4h)

Fitness to Drive