not have a syncopal event. It is debatable whether these situations should be treated as syncope or not. Some authors have suggested that patient outcomes are the same, and therefore both presyncopal and syncopal patients should receive the same treatment [8]. For the purposes of this discussion, both patient populations will be considered to be the same.
As with all medical problems, proper assessment and evaluation begin with an appropriate but focused history and physical examination. Although 85% to 90% of all patient pathology can be determined by history and a physical, these are even more important in the case of syncope. Very few diagnostic tests will aid in determining the cause of a syncopal episode or in ascertaining syncope as the problem versus another malady. If one takes a diagnosis such as appendicitis, we know that it can be determined clinically almost 90% of the time, but it also can be “confirmed” by computed tomography scanning, by surgical findings, or by the pathology results. However, in the case of a syncopal episode, few laboratory or other diagnostic studies aid significantly in the diagnosis.
History is the most important aspect of evaluation. For patients in the prehospital setting, the history obtained by EMS clinicians is vital. Because true syncope involves a loss of consciousness, there will be details of the event that patients will not be able to convey. Frequently, these patients arrive alone to the ED, and the emergency physician has no opportunity to interview others who may have witnessed the episode. Therefore, maximizing history obtained at the scene through witness interviews and relaying this information to the ED staff is pivotal to accurate diagnosis and treatment.
It is important to ask the patient what he or she can remember before the event. No recollection at all is of particular importance. If the patient felt no prodromal symptoms, and then had a period of unconsciousness, this is particularly concerning for cardiac causes of syncope. Chest pain, palpitations, and shortness of breath are other symptoms that can be associated with dysrhythmia or other cardiac pathology. Abdominal pain, nausea, or lightheadedness frequently precede reflex‐mediated syncope. The EMS clinician should always attempt to ascertain the last thing the patient remembered before the event, as well as the first thing he or she remembered after regaining consciousness. In the case of a true syncopal event, the patient will not be able to recall information during his or her period of unconsciousness. Bystander interviews are important, and as mentioned previously, EMS personnel may be the only clinicians able to obtain this relevant information. Did the bystanders notice anything before the patient lost consciousness? Was there any seizure activity noted (tonic/clonic, focal, etc.)? Where there any periods of apnea noted?
Bystander‐provided history is also imperative for determining the length of the unresponsive period. Unfortunately, this time interval will frequently be overestimated due to the anxiety provoked in seeing someone unresponsive. Still, thoughtful and compassionate interviews by EMS personnel can frequently elucidate valuable references to attempt to establish a time course. Was the patient unconscious for the entire 9‐1‐1 phone call? How long before EMS arrival did the patient regain consciousness?
Finally, EMS clinicians must obtain the bystanders’ history of events as the patient regained consciousness. Did the patient’s mental status improve rapidly or was there a period of confusion? Did the patient have any complaints on awakening that he or she cannot recall now? Did the patient appear hot or cold, sweaty, or pale? If the bystanders took the patient’s pulse, what was the rate and quality?
Beyond the history of present illness, EMS clinicians should obtain other pertinent medical history. Chronic health problems such as cardiac, vascular, or neurologic issues need to be documented because they are important risk factors in syncope. A complete medication list is important because many medications can predispose a patient to syncope. Additionally, medications can frequently point to other causes of loss of consciousness that are not syncopal episodes, such as seizures or hypoglycemia. Last oral intake should be ascertained to determine if the patient is at risk for hypoglycemia and to identify potential confounders to the mental status examination, such as drugs or alcohol.
A focused physical examination is always important for any complete patient assessment. Vital signs; skin condition; heart, lung, and abdominal examination; and thorough neurologic examination are essential. Many recommend checking orthostatic vital signs, at least lying and sitting. However, there are many confounders to positive or negative orthostatic vital signs and even much debate as what are the appropriate and inappropriate changes, though there are consensus guidelines on the blood pressure parameters [9]. Moreover, if the patient becomes symptomatic with changes in position, this is important to note.
Remember that, at the time of EMS assessment, the physical examination may be completely normal. Vital signs may be within normal limits, and the remainder of the examination may be unremarkable. Unfortunately, this does not preclude the presence of serious pathology. Cardiac syncope in particular is likely to present with a normal physical examination, despite being potentially lethal.
Consistent with most prehospital encounters, diagnostic testing is of limited value. A glucometer reading should be obtained, although glucose derangement rarely causes transient loss of consciousness.
A prehospital 12‐lead ECG is indicated because this may help risk‐stratify the patient’s potential syncopal etiology. Even in the hospital setting, the 12‐lead ECG is the only Class 1 recommendation for diagnostic studies for a syncope evaluation [10]. The following ECG findings are considered diagnostic for syncope due to a dysrhythmia [11]:
Persistent sinus bradycardia <40 bpm
Repetitive sinoatrial blocks or sinus pauses >3 seconds
Mobitz II–second‐degree heart block
Third‐degree heart block
Alternating left bundle branch block and right bundle branch block
VT
Rapid paroxysmal supraventricular tachycardia
AICD or pacemaker dysfunction
However, a normal 12‐lead ECG does not preclude life‐threatening causes of syncope, as the event has usually passed by the time of EMS assessment.
Differential diagnosis
One of the most important steps in evaluating syncope is to ensure the event was truly a syncopal episode and not a loss or alteration of consciousness attributable to some other pathology. The most common pathology confused for syncope is seizures. Both clearly involve loss of consciousness, and other findings classically associated with seizures can occur with true syncopal episodes. Incontinence is rare in syncope but does occur. Also, shortly following a syncopal episode, a patient may experience myoclonic jerks that can be confused with a seizure. The most important distinguishing feature is the postictal period. Generalized seizure patients typically have postictal phases lasting minutes, whereas the return to normal mentation after a syncopal episode rarely exceeds 30 seconds.
Pseudosyncope is a psychiatric condition in which there is no actual loss of consciousness, and a syncopal episode is fabricated for whatever psychiatric reason exists. This condition is separate from psychogenic syncope, which involves a true syncopal episode (with an actual loss of consciousness) that is caused by a psychiatric stimulus (e.g., severe emotional distress, pain, other psychiatric condition). Frequently, it will be difficult to separate these in the prehospital environment (or in the ED). Confronting the patient regarding presumed pseudosyncope will frequently disrupt the therapeutic relationship in an uncontrolled environment and therefore should be discouraged.
Two other rare conditions that may be confused with syncope are narcolepsy and cataplexy. Narcolepsy is a condition in which patients have profound daytime
