可攜式功率放大器應用於前庭誘發肌電位檢查

Abstract

人體平衡維持機制主要包含了前庭系統、視覺系統和本體感覺系統，而當前庭系統功能異常時，人體的平衡覺隨之出現問題，繼而肇生眩暈症。眩暈為臨床上常見的病症，全球約有兩至三成的人曾經歷眩暈症，且復發率高達四成，雖然各年齡層的人口都可能受眩暈症所苦，但其中老年患者的比例較高，且症狀隨著年紀增長而更加嚴重，而眩暈症發作時導致年長者跌倒甚至成為65歲以上人口意外事故的主要死因。 為了評估前庭功能和判斷眩暈症成因，目前臨床上普遍使用前庭誘發肌電位檢查(Vestibular Evoked Myogenic Potential, VEMP)。隨著人口高齡化的現象，眩暈症老年患者的比例上升，且由於眩暈症的高復發率，患者應定期回診檢查，避免過久的回診時間讓病程惡化。考量到以上因素，若能將VEMP檢查優化或提升便利性，甚至整合其至居家醫療，則可解決行動不便或居住地偏遠的老年患者族群就診上的困難，或是高齡患者可能因考量到感染疾病的風險而不願前往醫療院所導致延遲就醫的情況發生。 為實現將VEMP檢查整合至居家醫療的願景，在參考過去實驗室相關研究計畫成果後，本研究期望將VEMP檢查需使用到的功率放大器設計為可攜式，期在安全驅動現今VEMP檢查臨床所使用的小型振動器Type 4810 Mini-shaker之前提下，能完成VEMP檢查便利性的提升及相關流程的改善，讓病患得以在自家環境中接受VEMP檢查，減少前往醫療機構的需求。 本研究成功開發應用於VEMP檢查之可攜式功率放大器系統，不需插電使用，且裝置利用交換式電源供電，讓使用者得以僅使用單顆電池，而不需消耗兩組電池，即可提供功率放大器穩定的正負電源。本研究透過電路設計達到低功耗之目的，裝置靜態電流為1.6 mA，並具有體積小、重量輕等特點，符合可攜式之需求，解決了市售功率放大器因體積龐大受限於醫院環境且售價高的缺點，使VEMP檢查得以朝居家醫療整合、甚至社區醫療或偏鄉義診的願景邁進。

The mechanism of maintaining human body balance is mainly composed of the vestibular system, visual system and proprioception system. If there is a vestibular dysfunction, problems consequently arise in our sense of balance, resulting in vertigo afterwards. Vertigo is a common clinical disease, with twenty to thirty percent of people worldwide having been through it, and the recurrence rate is up to forty percent. Although people of all ages may suffer from vertigo, the proportion of elderly patients is higher. Moreover, the symptom gets more serious with age, and falling down due to vertigo even becomes the main cause of accidental death in people aged 65 and older. To evaluate the function of vestibular system and to determine the cause of vertigo, vestibular evoked myogenic potential(VEMP) testing is generally used in clinics. With the phenomenon of population aging, the proportion of elderly patients with vertigo has increased, and because of the high recurrence rate of vertigo, patients should have regular follow-up appointments, preventing the condition from deteriorating owing to overlong follow-up duration. In view of the above factors, if we can optimize VEMP testing, improve its convenience, or even integrate it into home medical care, we are able to resolve the difficulty of elderly patients going to the hospital on account of their disabilities or remote residences, or the delay in treatment resulting from aged patients taking the risk of infection into consideration and hence unwilling to go to the hospital. For the purpose of realizing the vision of integrating VEMP testing into home medical care, after referring to the previous laboratory research projects, this study expects to make the power amplifier in VEMP testing into a portable device, hoping to improve the convenience of VEMP testing together with relevant procedures under the premise of safely driving the Type 4810 Mini-shaker used in VEMP testing nowadays, which enables patients to take VEMP testing in their home environment and reduces the need for going to health facilities. A portable power amplifier system for VEMP testing has been successfully developed in this study, being no need for plugging in, and furthermore, the device is powered by a switching power supply, allowing users to provide stable positive and negative power for the power amplifier with only one battery instead of two. This study achieves the aim of low power through circuit design, and the quiescent current of the device is 1.6 mA, possessing features of small-sized and lightweight as well, which meets the requirement for portability and solves the drawback of power amplifier on the market being limited to hospital environment because of its large size, letting VEMP testing be able to moving toward the vision of integrating into home or community medical care, or even rural health clinics.