Loss of Consciousness
In an unconscious patient, assess ABC’s and resuscitate as needed.
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.
Examine unconscious patients for localizing and diagnostic signs (e.g., ketone smell, liver flap, focal neurologic signs).
In patients with a loss of consciousness and a history of head trauma, rule out intracranial bleeding.
In patients with a loss of consciousness who are anticoagulated, rule out intracranial bleeding.
Assess and treat unconscious patients urgently for reversible conditions (e.g., shock, hypoxia, hypoglycemia, hyperglycemia, and narcotic overdose).
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.
In patients who have had a loss of consciousness without a clear diagnosis, pursue investigations (e.g., rule out transient arythmia, seizure).
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).
In patients with loss of consciousness following head trauma, treat and follow up according to current concussion guidelines.
Advise authorities about appropriate patients with loss of consciousness (e.g., regarding driving status).
Syncope is a transient loss of consciousness (T-LOC)
Spontaneous complete recovery
Reflex (neurally-mediated) syncope
Structural cardiopulmonary disease
History (from witnesses)
PMH and Fam Hx (sudden death, cardiac)
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
Consider DRE for GI bleed
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)
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
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
CCS 2020. https://www.onlinecjc.ca/article/S0828-282X(19)31549-1/fulltext
ACC/AHA/HRS 2017. http://circ.ahajournals.org/content/136/5/e60
AAFP 2017. http://www.aafp.org/afp/2017/0301/p303.html
CJC 2011. http://www.onlinecjc.ca/article/S0828-282X(10)00003-6/fulltext
AAFP 2011. http://www.aafp.org/afp/2011/0915/p640.html
Fitness to Drive