反射性昏厥及姿勢性昏厥的診斷與治療

Diagnosis and Treatment of Reflex Syncope and Orthostatic Syncope

反射性暈厥，是暈厥最常見的原因，佔暈厥原因的五成到七成。反射性暈厥又可分四種型態。血管迷走性暈厥是最常見的型態，其觸發因子可以是疼痛、醫療器械、情緒或是站立。情境性暈厥是指由特定情境觸發的暈厥，如排尿、排便、吞嚥、咳嗽。第三型為頸動脈竇暈厥，因頸動脈竇被壓迫而觸發。第四型為非典型反射性暈厥，指在沒有明顯觸發因子的情況下發生的反射性暈厥。反射性暈厥的診斷主要靠詢問病史，包括病人及目擊者，並排除其他暈厥的原因，以及陽性的直立傾斜試驗。檢查尚需包括心電圖監測，以了解暈厥與心律相關性。有數種藥物可用於反射性暈厥的治療，但長期前瞻性安慰劑對照臨床試驗顯示效果有限。少數特定高齡患者可考慮永久性心臟節律器。直立姿勢耐受不良是因身體直立時所需要的適應機制受損所引起，站立狀態引起血壓下降或合併過度的心跳速率增加，產生頭暈、噁心和心悸。除了慢性衰弱的症狀外，直立姿勢耐受不良也可能會導致暈厥。直立姿勢耐受不良可分兩種型態：直立姿勢性低血壓和直立姿勢性心動過速症候群。直立姿勢性低血壓又可分三型：初始型姿勢性低血壓、經典型姿勢性低血壓和延遲型姿勢性低血壓。直立姿勢性低血壓的盛行率隨著年齡的增長而增加，在高血壓和糖尿病等慢性疾病患者中教高，帕金森氏症和晚期腎臟衰竭病人可達到百分之三十五以上。直立姿勢性低血壓病人的死亡率較高，而心血管疾病的發生率也較高，但大多數患者在正常情況下無明顯症狀。直立姿勢性心動過速症候群主要影響年齡在十五至四十歲之間的年輕女性，並且通常伴有非特異性症狀，如無力、頭暈、視力模糊、胃腸功能障礙甚至嚴重會產生昏厥的情況。直立姿勢耐受不良的治療包括生活型態改變、攝取足夠的水與鹽分和藥物治療，但在嚴重病例中效果有限。

Reflex syncope is the most common (50-70%) cause of syncope. Reflex syncope can be classified into four types. Vasovagal syncope is the most common type, and the triggering factor can be pain, medical equipment, mood, or standing. Situational syncope refers to syncope triggered by a specific situation, such as urination, defecation, swallowing, and coughing. The third type is carotid sinus syncope, triggered by compression of the carotid sinus. The fourth type is atypical reflex syncope, which refers to reflex syncope that occurs without a significant triggering factor. The diagnosis of reflex syncope is mainly based on a medical history from patients and witnesses and an investigation to exclude other causes of syncope, as well as a positive upright tilt test. ECG monitoring during an episode of syncope is essential. Several drugs can be used for the treatment of reflex syncope. However, their effectiveness is limited in long-term placebo-controlled prospective trials. Permanent pacemaker should only be considered in specific elderly patients. Orthostatic intolerance is caused by impairment of the compensatory response to orthostasis. The standing state leads to a drop in blood pressure or an excessively increased heart rate. Susceptible individuals may experience dizziness, nausea and palpitations. In addition to chronic debilitating symptoms, orthostatic intolerance can also cause syncope. Orthostatic intolerance syndromes include orthostatic hypotension and postural orthostatic tachycardia syndrome. There are three types of orthostatic hypotension, initial orthostatic hypotension, classical orthostatic hypotension and delayed orthostatic hypotension. The prevalence of orthostatic hypotension increases with age. It is higher in patients with chronic diseases such as hypertension, diabetes and the prevalence in Parkinson's disease and advanced kidney failure can be more than 35%. Patients with orthostatic hypotension have a higher mortality rate and a higher incidence of cardiovascular diseases. However, most patients have no obvious symptoms under normal conditions. Postural orthostatic tachycardia syndrome affects primarily young women between 15 and 40 years and is often associated with non-specific symptoms such as weakness, dizziness, blurred vision, gastrointestinal dysfunction or fainting. Treatments of orthostatic intolerance syndromes include appropriate lifestyle measures, adequate intake of salt and fluid and pharmacological therapy.