踝肱指數

ㄍㄨㄥ指數,又稱為踝肱血壓指數(Ankle Brachial Pressure Index,ABPI或ABI),是小腿相對於上臂的血壓比值。如果小腿血壓比上臂低,提示可能有動脈阻塞(周圍血管疾病)。ABI是由用腳踝動脈的收縮壓除以上臂收縮壓計算出來的[1]

方法

計算踝肱指數需要一個超聲都卜勒血流探測儀和一個血壓計(血壓袖帶型),將血壓袖帶綁在有問題的動脈近端(即靠近心臟側)的部位並充氣,用超聲都卜勒探頭測量,繼續充氣直到動脈的搏動停止。然後血壓袖帶慢慢放氣,當超聲都卜勒探頭重新檢測到動脈搏動時,這時候得到的血壓數值則是所測動脈的收縮壓。

在實際評估中,通常會測量左右上臂肱動脈英語Brachial artery的收縮壓,並選擇其中數值高的一側。同樣,測量ABI也會選擇左右小腿的脛後動脈英語Posterior tibial artery足背動脈英語Dorsalis pedis artery中數值較高的一側進行計算[2]

 
PLeg是指小腿脛後動脈或足背動脈的收縮壓
PArm是指上臂肱動脈的收縮壓

踝肱指數測量是一個常用的周圍血管疾病的非侵入性評估方法。研究表明利用踝肱指數檢測經血管造影確診的下肢大動脈嚴重狹窄(狹窄程度>50%)的敏感性為90%,特異性為98%[3]

然而,踝肱指數存在下列已知問題:

  • 踝肱指數對存在動脈鈣化(血管硬化)的患者的測量結果不可靠[4],動脈硬化會導致腳踝血壓測量值虛假地升高,從而導致假陰性的出現[5]。這種情況經常發生在糖尿病患者[6](大約有41% 的周圍血管疾病患者有糖尿病[7])、腎功能衰竭或重度吸菸者。
  • 測量踝肱指數非常耗時[8]
  • 靜息踝肱指數值對檢測輕度的周圍血管疾病不敏感[9],有時需要在讓患者在跑步機運動6分鐘後在進行測試,以增加測量的靈敏度[10]。但是,這種方法對肥胖或並發有主動脈瘤的患者並不適合,而且也會增加評估的時間。
  • 踝肱指數測量缺乏標準化的規程[11],這會減低研究者 本身的觀測信度[12]
  • 測量踝肱指數需要有經驗的人員,以得到一致、準確的結果[13]

這些問題使得踝肱指數測量在一般體檢中很少被使用[14]。但是,技術的革新可以生產出測量下肢和上臂血壓的專門校準示波模塊,從而對血壓值進行同步讀數, 通過示波法血壓計算踝肱指數成為可能。目前已經有幾個廠家將類似的產品投放市場中。利用示波系統來測量踝肱指數的主要優勢在於,它規範了踝肱指數的方法並使得所有醫生都可以對患者的踝肱指數進行測量。

結果的解讀

正常人腳踝處的血壓值應該會比肘部的血壓值稍高。如果踝肱指數的數值大於0.9則認為是正常的(即沒有患周圍動脈阻塞性疾病)。

然而,如果踝肱指數大於1.3也被認為是不正常的,這種情況提示可能有動脈壁鈣化和血管硬化,可能是嚴重的周圍血管疾病的表現。

在沒有其他可以顯著影響下肢動脈的條件下,下列的踝肱指數值可以用於預測周圍動脈阻塞性疾病的嚴重程度,並對腿部潰瘍的病程和處理進行評估[2]

踝肱指數 釋義 需要採取的行動
1.0 - 1.40 正常範圍 無需
0.91 - 0.99 界限值 尋找並改變(導致周圍動脈阻塞性疾病的)危險因素
≤ 0.90 動脈疾病 戒菸、抗血小板和抗血栓治療(如阿斯匹靈每日75-325毫克氯吡格雷每日75毫克)

預測動脈粥樣硬化的病死率

在2006年的研究表明,不正常的踝肱指數可能是動脈粥樣硬化病死率的獨立預測指標,因為它反映了患者動脈粥樣硬化的負擔情況[15][16]

參考資料

  1. ^ Al-Qaisi, M; Nott, DM, King, DH, Kaddoura, S. Ankle brachial pressure index (ABPI): An update for practitioners.. Vascular health and risk management. 2009, 5: 833–41. PMC 2762432 . PMID 19851521. 
  2. ^ 2.0 2.1 Vowden P, Vowden K. Doppler assessment and ABPI: Interpretation in the management of leg ulceration. Worldwide Wounds. March 2001 [2011-11-13]. (原始內容存檔於2008-05-09).  - describes ABPI procedure, interpretation of results, and notes the somewhat arbitrary selection of "ABPI of 0.8 has become the accepted endpoint for high compression therapy, the trigger for referral for a vascular surgical opinion and the defining upper marker for an ulcer of mixed aetiology"
  3. ^ McDermott MM, Criqui MH, Liu K, Guralnik JM, Greenland P, Martin GJ, Pearce W. Lower ankle/brachial index, as calculated by averaging the dorsalis pedis and posterior tibial arterial pressures, and association with leg functioning in peripheral arterial disease. JJ Vasc Surg. December 2000, 32 (6): 1164–71. PMID 11107089. doi:10.1067/mva.2000.108640. 
  4. ^ Allison MA, Hiatt WR, Hirsch AT, Coll JR, Criqui MH. A high ankle-brachial index is associated with increased cardiovascular disease morbidity and lower quality of life. J Am Coll Cardiol. April 2008, 51 (13): 1292–8. PMID 18371562. doi:10.1016/j.jacc.2007.11.064. 
  5. ^ American Diabetes Association. Peripheral Arterial Disease in People with Diabetes. Diabetes Care. December 2003, 26 (12): 3333–3341. PMID 14633825. doi:10.2337/diacare.26.12.3333. 
  6. ^ Aboyans V, Ho E, Denenberg JO, Ho LA, Natarajan L, Criqui MH. The association between elevated ankle systolic pressures and peripheral occlusive arterial disease in diabetic and nondiabetic subjects. J Vasc Surg. November 2008, 48 (5): 1197–203. PMID 18692981. doi:10.1016/j.jvs.2008.06.005. 
  7. ^ Novo S. Classification, epidemiology, risk factors, and natural history of peripheral arterial disease. Diabetes Obes Metab. March 2002, 4 (2): S1–6. PMID 12180352. doi:10.1046/j.1463-1326.2002.0040s20s1.x. 
  8. ^ Doubeni CA, Yood RA, Emani S, Gurwitz JH. Identifying unrecognized peripheral arterial disease among asymptomatic patients in the primary care setting. Angiology. March–April 2006, 57 (2): 171–80. PMID 16518524. doi:10.1177/000331970605700206. 
  9. ^ Stein R, Hriljac I, Halperin JL, Gustavson SM, Teodorescu V, Olin JW. Limitation of the resting ankle-brachial index in symptomatic patients with peripheral arterial disease. J Vasc Med. February 2006, 11 (1): 29–33. PMID 16669410. doi:10.1191/1358863x06vm663oa. 
  10. ^ Montgomery PS, Gardner AW,. The clinical utility of a six-minute walk test in peripheral arterial occlusive disease patients. J Am Geriatr Soc. June 1998, 46 (6): 706–11. PMID 9625185. 
  11. ^ Jeelani NU, Braithwaite BD, Tomlin C, MacSweeney ST. Variation of method for measurement of brachial artery pressure significantly affects ankle-brachial pressure index values. Eur J Vasc Endovasc Surg. July 2000, 20 (1): 25–8. PMID 10906293. doi:10.1053/ejvs.2000.1141. 
  12. ^ Caruana MF, Bradbury AW, Adam DJ. The validity, reliability, reproducibility and extended utility of ankle to brachial pressure index in current vascular surgical practice. Eur J Vasc Endovasc Surg. May 2005, 29 (5): 443–51. PMID 15966081. doi:10.1016/j.ejvs.2005.01.015. 
  13. ^ Kaiser V, Kester AD, Stoffers HE, Kitslaar PJ, Knottnerus JA. The influence of experience on the reproducibility of the ankle-brachial systolic pressure ratio in peripheral arterial occlusive disease. Eur J Vasc Endovasc Surg. July 1999, 18 (1): 25–9. PMID 10388635. doi:10.1053/ejvs.1999.0843. 
  14. ^ Hirsch AT, Criqui MH, Treat-Jacobson D, Regensteiner JG, Creager MA, Olin JW, Krook SH, Hunninghake DB, Comerota AJ, Walsh ME, McDermott MM, Hiatt WR. Peripheral arterial disease detection, awareness, and treatment in primary care.. JAMA. Sep 2001, 19 (286): 1317–24. PMID 11560536. doi:10.1001/jama.286.11.1317. 
  15. ^ Feringa HH, Bax JJ, van Waning VH; et al. The long-term prognostic value of the resting and postexercise ankle-brachial index. Arch. Intern. Med. March 2006, 166 (5): 529–35. PMID 16534039. doi:10.1001/archinte.166.5.529. 
  16. ^ Wild SH, Byrne CD, Smith FB, Lee AJ, Fowkes FG. Low ankle-brachial pressure index predicts increased risk of cardiovascular disease independent of the metabolic syndrome and conventional cardiovascular risk factors in the Edinburgh Artery Study. Diabetes Care. March 2006, 29 (3): 637–42 [2011-11-13]. PMID 16505519. doi:10.2337/diacare.29.03.06.dc05-1637. (原始內容存檔於2009-02-18).