Dixon Claire E, Bedenice Daniela, Mazan Melissa R
Department of Clinical Sciences, Cummings School of Veterinary Medicine at Tufts University, North Grafton, MA, United States.
Front Vet Sci. 2021 Feb 22;7:511023. doi: 10.3389/fvets.2020.511023. eCollection 2020.
Airway hyperresponsiveness (AHR) is linked to airway inflammation and is considered a key manifestation of mild/moderate equine asthma (EA). The study purpose was to determine whether two modalities of non-invasive lung function testing (FOM-forced oscillatory mechanics vs. FP-flowmetric plethysmography) establish the same clinical diagnosis of AHR in horses, using histamine bronchoprovocation. Nineteen horses (3-25 years, 335-650 kg) with clinical signs suggestive of mild/moderate equine asthma were enrolled. FOM and FP testing was performed in each horse on two consecutive days, using a randomized cross-over design. AHR was defined by the histamine dose needed to double FOM baseline resistance, or to achieve a 35% increase in FP delta flow. Bronchoalveolar lavage fluid (BALF) was subsequently collected and stained with modified Wright's and toluidine blue stains. Binary statistical tests (related samples -test, Mann-Whitney , Chi-square analyses) were performed to compare study groups, with < 0.05 considered significant. Abnormal BALF cytology confirmed EA in 14/19 (73.7%) horses. Both FOM and FP revealed AHR in 7/14 (50%) of these EA horses. An additional 4/19 (21.1%) horses showed AHR based on FP but not FOM, including two horses with normal BALF cytology. A diagnosis of AHR was more often associated with FP than FOM ( = 0.013), although the prevalence of AHR was significantly higher in EA vs. non-EA horses, regardless of testing methodology. The phase angle between thoracic and abdominal components of breathing did not differ between test groups. In conclusion, FP diagnosed AHR more frequently than did FOM, including horses with no other diagnostic evidence of EA. Without further evaluation, these two testing modalities of AHR cannot be used interchangeably.
气道高反应性（AHR）与气道炎症相关，被认为是轻度/中度马哮喘（EA）的关键表现。本研究的目的是确定两种非侵入性肺功能测试方法（强迫振荡力学法-FOM与流量容积描记法-FP）在组胺支气管激发试验中对马的AHR是否能做出相同的临床诊断。纳入了19匹有轻度/中度马哮喘临床症状的马（3 - 25岁，335 - 650千克）。采用随机交叉设计，在每匹马连续两天进行FOM和FP测试。AHR的定义为使FOM基线阻力加倍或使FP流量变化增加35%所需的组胺剂量。随后收集支气管肺泡灌洗液（BALF），并用改良的瑞氏染色和甲苯胺蓝染色。进行二元统计检验（相关样本t检验、曼-惠特尼检验、卡方分析）以比较研究组，P<0.05被认为具有统计学意义。异常的BALF细胞学检查在14/19（73.7%）的马中确诊为EA。在这些EA马中，FOM和FP均在7/14（50%）的马中显示出AHR。另外4/19（21.1%）的马基于FP显示出AHR，但FOM未显示，其中包括两匹BALF细胞学检查正常的马。AHR的诊断与FP的相关性高于FOM（P = 0.013），尽管无论测试方法如何，EA马中AHR的患病率显著高于非EA马。测试组之间呼吸的胸腹部成分之间的相位角没有差异。总之，FP诊断AHR比FOM更频繁，包括没有其他EA诊断证据的马。未经进一步评估，这两种AHR测试方法不能互换使用。
