醫學筆記匯整 ED Notes

Syncope or fainting  
Brief loss of consciousness + Inability to maintain postural tone
+ Spontaneously resolves without medical intervention

 

 Patho 
10 seconds of complete disruption of blood flow
or nutrient delivery to both cerebral cortices or to the brainstem RAS,
or reduction of cerebral perfusion by 35 -50%
 

較常見是 Drop in cardiac output
較少見是 Vasospasm reduces CNS blood flow
之後 Cerebral perfusion and consciousness are restored by the supine position

Vasovagal (Reflex mediated, 21%)
Cardiac (10%), Orthostatic (9%)
Medication related (7%)
Neurologic (4%), unknown (37%)
 

 Cardiac syncope 最重要的 ! 
Structural disease and Dysrhythmias

- Consider AS as a structural cardiac cause of syncope in the elderly.
- Hypertrophic cardiomyopathy cause sudden death in young adults
- Massive acute pulmonary embolism
- AMI

 Vasovagal 
Prodrome of lightheadedness, nausea, pallor, sweating, feeling of warmth
may accompany vasovagal syncope.
A slow, progressive onset with associated prodrome suggests vasovagal syncope.

Situational syncope occurs during or immediately after coughing, micturition,
defecation, swallowing.

Carotid sinus hypersensitivity, characterized by bradycardia or hypotension
Most commonly, there is an abnormal vagal response, leading to bradycardia and asystole of >3s.
Less commonly, there is a vasodepressor response, leading to a decrease in BP of >50 mm Hg
without a significant change in HR.
shaving or turning of the head, 

Consider carotid sinus hypersensitivity in older
patients with recurrent syncope and negative cardiac evaluations. 

 Orthostatic 
Postural hypotension + Syncope
Orthostasis does not always result in syncope.
Causes of orthostatic syncope include intravascular volume loss and
poor vascular tone caused by α-receptor disorders or medications.

Many serious causes of syncope may be associated with orthostatic changes,
so consider other life-threatening causes before attributing syncope
to orthostasis, especially in the elderly. 

 Psychiatric
Generalized anxiety disorder and MDD, Hyperventilation
In general, a patient with syncope and a psychiatric disorder
is likely to be young, with repeated episodes of syncope and multiple prodromal symptoms

 Neurologic  rare
Patients with loss of consciousness with persistent neurologic
deficits or AMS do not have true syncope. 其實不在定義裡

Brainstem ischemia, vertebrobasilar atherosclerotic disease, basilar artery migraine
may result in a decrease in blood flow to the RAS 
typically preceded by other signs or symptoms,
such as diplopia, vertigo, focal neurologic deficits, or nausea

Subclavian steal is a rare cause of brainstem ischemia
when exercise of the ipsilateral arm
PE : decreased pulse volume and diminished BP in the affected arm
 

SAH may present as syncope 
and accompanied with focal neurologic deficits, headache, or persistent AMS.

Seizure confusion (postictal state) lasting several minutes,
tongue biting, incontinence, or an epileptic aura suggests a seizure.
Seizure is the most common event mistaken as syncope.

 Medication 
The most common mechanism is orthostasis : CCB, beta Blocker
Diuretics may produce volume depletion.
Some medications have proarrhythmic properties.

 History 
 - Witnesses
 - Events preceding the loss of consciousness, 
    premonitory symptoms
    Duration of loss of consciousness

 - Symptoms occurring after regaining consciousness : 
    Headache, diplopia, vertigo, or focal weakness : SAH
    Chest pain : AMI, dissection, PE, AS
    Palpitations : Arrythmias 
    Shortness of breath : PE, CHF 
    Abdominal or back pain : AAA, ruptured ectopic pregnancy

Sudden event without warning and events associated with exertion
​​​​​​​raise suspicion for a cardiac dysrhythmia or structural cardiopulmonary lesion

 - Alcohol ingestion or substance abuse
 - Family history is important in regard to history of prolonged QT syndrome,
    dysrhythmias, sudden cardiac death, or other cardiac risks

 San Francisco Syncope Rule 

原因不明的 Syncope 主要評估 Risk 

除了 San Francisco Syncope Rule 外
Guideline 也有提到 : 
  - Syncope while supine, syncope during exercise,
  - Syncope without prodromal symptoms,
  - Palpations preceding syncope
  - Specific age cut points of >60 or > 65  y/o 

 

Elderly syncope 危險很多Aortic stenosis is the most
更要考量 AS, DM ANS dysfunction, Medication, volume depletion ... 

Pregnancy 可能是子宮壓迫 IVC 減少回心血流
要小心 Ruptured ectopic pregnancy and Pulmonary embolism