Wong Adrian M, Lum Hei Y, Musk Gabrielle C, Hyndman Timothy H, Waldmann Andreas D, Monks Deborah J, Bowden Ross S, Mosing Martina
School of Veterinary Medicine, Murdoch University, Perth, WA, Australia.
Animal Care Services, University of Western Australia, Perth, WA, Australia.
Front Vet Sci. 2024 Mar 13;11:1202931. doi: 10.3389/fvets.2024.1202931. eCollection 2024.
The applicability of electrical impedance tomography (EIT) in birds is unknown. This study aimed to evaluate the use of EIT in anaesthetised chickens in four recumbency positions. Four adult Hyline chickens were anaesthetised with isoflurane in oxygen, and intubated endotracheally for computed tomography (CT). A rubber belt was placed around the coelom caudal to the shoulder joint. A chicken-specific finite element (FE) model, which is essential to generate anatomically accurate functional EIT images for analysis, was constructed based on the CT images obtained at the belt level. Ten additional chickens were anaesthetised with the same protocol. An EIT electrode belt was placed at the same location. The chickens were breathing spontaneously and positioned in dorsal, ventral, right and left lateral recumbency in a randomised order. For each recumbency, raw EIT data were collected over 2 min after 13 min of stabilisation. The data were reconstructed into functional EIT images. EIT variables including tidal impedance variation (TIV), centre of ventilation right to left (CoV) and ventral to dorsal (CoV), right to left (RL) ratio, impedance change (ΔZ) and eight regional impedance changes including the dorsal, central-dorsal, central-ventral and ventral regions of the right and left regions were analysed. Four breathing patterns (BrP) were observed and categorised based on the expiratory curve. A linear mixed model was used to compare EIT variables between recumbencies. Fisher's exact test was used to compare the frequencies of breathing patterns for each recumbency. The ΔZ observed was synchronous to ventilation, and represented tidal volume of the cranial air sacs as confirmed by CT. Significant differences were found in CoV and regional impedance changes between dorsal and ventral recumbencies ( < 0.05), and in CoV, RL ratio and regional impedance changes between right and left recumbencies ( < 0.05), which suggested a tendency for the distribution of ventilation to shift towards non-dependent air sacs. No differences were found for TIV and respiratory rate between recumbencies. Recumbency had a significant effect on the frequencies of each of the four BrPs ( = 0.001). EIT can monitor the magnitude and distribution of ventilation of the cranial air sacs in different recumbencies in anaesthetised chickens.
电阻抗断层成像（EIT）在禽类中的适用性尚不清楚。本研究旨在评估EIT在处于四种卧位的麻醉鸡中的应用。选用四只成年海兰鸡，用异氟烷和氧气进行麻醉，并经气管插管用于计算机断层扫描（CT）。在肩关节尾侧的体腔周围放置一条橡胶带。基于在橡胶带水平获得的CT图像，构建了一个特定于鸡的有限元（FE）模型，该模型对于生成解剖学上准确的功能性EIT图像以进行分析至关重要。另外十只鸡按照相同方案进行麻醉。将EIT电极带放置在相同位置。鸡自主呼吸，并以随机顺序置于背卧位、腹卧位、右侧卧位和左侧卧位。对于每种卧位，在稳定13分钟后，在2分钟内收集原始EIT数据。将数据重建为功能性EIT图像。分析了EIT变量，包括潮气量阻抗变化（TIV）、左右通气中心（CoV）和腹背通气中心（CoV）、左右（RL）比值、阻抗变化（ΔZ）以及包括左右区域的背侧、中央背侧、中央腹侧和腹侧区域在内的八个区域阻抗变化。观察到四种呼吸模式（BrP），并根据呼气曲线进行分类。使用线性混合模型比较不同卧位之间的EIT变量。使用Fisher精确检验比较每种卧位的呼吸模式频率。观察到的ΔZ与通气同步，并且经CT证实代表颅气囊的潮气量。在背卧位和腹卧位之间的CoV和区域阻抗变化中发现显著差异（<0.05），在右侧卧位和左侧卧位之间的CoV、RL比值和区域阻抗变化中也发现显著差异（<0.05），这表明通气分布有向非依赖气囊转移的趋势。不同卧位之间的TIV和呼吸频率未发现差异。卧位对四种BrP中的每一种频率都有显著影响（=0.001）。EIT可以监测麻醉鸡在不同卧位时颅气囊通气的大小和分布。
