Safety of the Methacholine Challenge Test in Patients with Severe Airway Obstruction

氣道的過度敏感為氣喘的特徵之一，可能會因時間的不同、氣喘發作與否，或是規則性抗發炎藥物的使用而呈現不同的敏感程度。使用methacholine來操作激發測試已被證明於診斷上的可靠性。然而，在先前的文獻中，在第一秒吐氣量較低的病人在進行激發試驗時，有可能因methacholine惡化氣道阻塞而造成不適，並增加操作時的風險，故這類病患被列為執行此項檢查的禁忌。在我們的研究中，有241個氣喘病人其第一秒吐氣量低於1公升者進入分析（開始之第一秒吐氣量0.77±0.15L，為預估值的38.8±11.6%；PC20:3.1±4.6 mg/ml）。經過methacholineru激發試驗者，其第一秒吐氣量均會降低，但經乙型支氣管擴張劑治療後，有45%病患其第一秒吐氣量相等或大於基礎值。至於氣喘患者其第一秒吐氣量大於一公升者，只有22%患者其第一秒吐氣量相等或大於基礎值。在操作激發試驗的過程及追蹤期中並沒有產生併發症。因此，嚴重氣道阻塞的病人不宜視為操作methacholine激發試驗的絕對禁忌！但是於安排此項檢查前仍應慎選病人並評估此項檢查對治療的助益性，同時操作過程中、及操作後仍應注意病人狀況，並適度使用支氣管擴張劑以改善激發試驗所造成之氣道問題。

關鍵字

激發試驗；第一秒吐氣量；氣喘

並列摘要

Airway hyperresponsiveness (AHR) is defined as an increased sensitivity to bronchoconstrictor stimuli. It is regarded as the physiological hallmark of bronchial asthma. The methacholine challenge test has proved to be helpful in the diagnosis of asthma and the evaluation of AHR. The aim of this study was to investigate the safety of the methacholine challenge test among patients with low FEV1, who posed a substantial risk for deterioration of airway obstruction. We retrospectively investigated 241 asthmatic patients who had an initial FEV1 less than 1L and who underwent a methacholine challenge test (initial FEV1: 0.77±0.15L, 38.8±11.6% of predicted value; PC20: 3.1±4.6 mg/ml). Among the 241 asthmatic patients with FEV1＜1L, 108 (44.8%) had full post-challenge reversibility after b2 agonist inhalation. In contrast, only 58 controls with FEV1＞1L (22%) had significant postchallenge reversibility. The degree of post-challenge reversibility in asthmatic patients with FEV1＜ 1L was significantly inversely correlated with the initial FEV1 and the end FEV1 after a methacholine challenge. There were no major respiratory complications related to the methacholine challenge test. Thus, the methacholine challenge test is relatively safe but potentially dangerous in patients with severe airway obstruction. The patient’s condition should be monitored closely during the test, and a bronchodilator should be used to reverse the airway obstruction related to the methacholine challenge.

並列關鍵字

Methacholine challenge ； FEV1 ； asthma

國際替代計量

Safety of the Methacholine Challenge Test in Patients with Severe Airway Obstruction

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