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Evaluating the mechanisms of the innovative negative pressure therapy for obstructive sleep apnea treatment by upper airway dynamic imaging



Background: The innovated iNAP system creates a negative pressure in oral cavity by applying a suction power through the soft mouth bite. Theoretically, the tongue and soft palate are pushed forward by the pressure differences between upper airway and oral cavity and keep airway potent. Objective: This study applied dynamical magnetic resonance imaging (MRI) to explore the effect of the negative pressure on the upper airway structure and the relationship between the structural changes of the upper airway and the effectiveness of treatment for OSA patients. Materials and Methods: After consent form was signed, the subject underwent dynamical and 3 dimensional MRI scan with and without iNAP. Then, the subject was asked to sleep and the same MRI procedure repeated while the iNAP was turned off or on. The volume and area of different segments of the upper airway were calculated from the MRI images by a commercial program. The differences in the upper airway volume and area between iNAP on and off or between the subject with and without mouth bite were analyzed. In addition, the subjects were subdivided into responder and non-responder by whether the AHI can decrease 50% and lower than 20 after treatment. The characteristics of the upper airway in responder and non-responder were compared. Results: Totally 10 subjects were recruited and aged 36.9±6.04 years. There were 7 subjects respond to the treatment and the AHI was significantly decreased after treatment (14.1±10.82; P=0.0009). The volume of the upper airway was significantly increased when iNAP was turned on during both awake (P=0.005) and sleep (P=0.001). The maximal and minimal areas of upper airway were also significantly increased when iNAP was on during both awake (P=0.0002 and P=0.0042 respectively) and sleep (P=0.0068 and p=0.0161 respectively). The baseline characteristics of the upper airway during awake showed no differences between responder and non-responder. Conclusion: The severity of AHI can be significantly ameliorated in most of the patients by iNAP. The effect of the treatment can be mainly attributed to the increased the upper airway area and volume during both awake and sleep. A larger group of the non-responder warranted for further study to understand the limitation of the treatment and improve patient selection.

Parallel abstracts

背景:新型的負壓治療儀器(iNAP)使用柔軟的口部介面含在口腔內,抽吸口腔內的空氣,讓原本會造成塌陷阻塞的舌根和軟颚組織因為壓力差的關係而往前牽引,進而維持呼吸道的通暢。團隊利用磁振造影中上呼吸道阻塞位置及空間的變化,以便探討其療效與構造組織的相關性,並做為未來評估此治療方式改進的參考。方法:受試者在動態核磁共振攝影時分別在清醒及睡著時,記錄配戴負壓儀器在關閉和開啟時的上呼吸道3D立體影像與2D動態影像;之後利用軟體影像重組進行三維空間與二維面積,計算在清醒與睡著狀況下負壓儀器對於空間改變的影響。進一步利用治療前後的睡眠檢查報告評估療效差異性進行分組,探討此分組與各部位空間及面積的變化相關性。結果:受試者總共10人(成功組7人;有效治療的定義為AHI下降50%且<20/每小時),年紀36.9±6.04歲,身體質量指數27.8±4.37;治療前v.s.治療後AHI(40.72±22 v.s. 14.1±10.82, P=0.0009)。3D影像立體空間變化清醒時配帶負壓與無配帶負壓有顯著增加的差異(P=0.005);睡著時配帶負壓與無配帶負壓也有顯著增加的差異(P=0.001)。2D動態影像面積變化(依時間找出上呼吸道面積最大值影像及面積最小值的影像進行比較)清醒時配帶負壓與無配帶負壓有顯著增加的差異(面積最小值P=0.0002、面積最大值P=0.0042);睡著時配帶負壓與無配帶負壓也有顯著增加的差異(面積最小值P=0.0068、面積最大值P=0.0161)。治療成功與失敗的組別在3D影像立體空間變化、2D動態影像面積變化均無顯著相關性。結論:負壓治療儀器可顯著增加在清醒及睡眠時的上呼吸道的體積或面積,進而改善睡眠呼吸中止症,但在睡眠時並治療成功及失敗組並無差異,建議未來研究可透過擴大樣本數了解此儀器對治療病人的限制並可選擇適用的病患以增進治療功效。