Objective

To determine the specific lung elastance (SE_L) in anesthetized dogs and to evaluate the efficacy of a SE_L-based recruiting airway pressure (RP_aw) at improving global and regional lung aeration.

Study design

Retrospective and prospective clinical study.

Animals

A total of 28 adult dogs were included in the retrospective study and six adult dogs in the prospective study.

Methods

Retrospective study: SE_L and SE_L-based RP_aw were determined using previously published data. In mechanically ventilated dogs undergoing thoracic computed tomography (CT), SE_L was calculated as ΔP_L/(V_T/EELV), where ΔP_L is the driving transpulmonary pressure, V_T is the tidal volume and EELV is the end-expiratory lung volume. The ratio of lung to respiratory system elastance (E_L/E_rs) was determined. SE_L and E_L/E_rs were used to calculate the SE_L-based RP_aw. Prospective study: dogs underwent thoracic CT at end-expiration and at end-inspiration using the SE_L-based RP_aw, and global and regional aeration was determined. For analysis of regional aeration, lungs were divided into cranial, intermediate and caudal regions. Regional compliance was also calculated. A p value <0.05 was considered significant.

Results

The SE_L and E_L/E_rs were 12.7 ± 3.1 cmH₂O and 0.54 ± 0.07, respectively. The SE_L-based RP_aw was 29.1 ± 7.6 cmH₂O. In the prospective study, the RP_aw was 28.2 ± 1.3 cmH₂O. During RP_aw, hyperinflation increased (p = 0.0003) whereas poorly aerated (p < 0.0001) and nonaerated (p = 0.01) tissue decreased. Normally aerated tissue did not change (p = 0.265). Regional compliance was higher in the intermediate (p = 0.0003) and caudal (p = 0.034) regions compared with the cranial region. Aeration did not differ between regions (p > 0.05).

Conclusions and clinical relevance

An SE_L-based RP_aw reduces poorly and nonaerated lung tissue in anesthetized dogs. In nonsurgical anesthetized dogs, an RP_aw near 30 cmH₂O is effective at improving lung aeration.

中文翻译：

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基于特定肺弹性的麻醉犬呼吸气道压力的定义和临床评估

客观的

要确定具体的肺弹性（SE_大号麻醉犬），并评估SE的疗效_大号为基础的招聘气道压力（RP _AW改进全球和区域肺通气）。

学习规划

回顾性和前瞻性临床研究。

动物

回顾性研究中总共包括 28 只成年犬，前瞻性研究中包括 6 只成年犬。

方法

回顾性研究：使用先前公布的数据确定SE _L和基于SE _L的RP _aw。在机械通气的狗开胸计算机断层扫描（CT），SE_大号计算为Δ P_大号/（V _Ť / EELV），其中Δ P_大号是驱动肺压力，V _Ť是潮气量和EELV是最终呼气肺容积。确定肺与呼吸系统弹性的比率(E _L /E _rs )。SE _L和 E _L /E _rs用于计算 SE _L基于RP _aw。前瞻性研究：狗行胸部CT在呼气末和吸气末使用SE_大号基础的RP _AW，并确定全球性和区域性通气。为了分析区域通气，将肺分为颅区、中间区和尾区。还计算了区域合规性。甲p值<0.05被认为显著。

结果

SE _L和 E _L /E _rs分别为 12.7 ± 3.1 cmH ₂ O 和 0.54 ± 0.07。基于 SE _L的RP _aw为 29.1 ± 7.6 cmH ₂ O。在前瞻性研究中，RP _aw为 28.2 ± 1.3 cmH ₂ O。在RP _aw期间，过度充气增加 ( p  = 0.0003) 而通气不良 ( p < 0.0001)和非充气 ( p  = 0.01) 组织减少。通常充气组织没有变化（p  = 0.265）。区域依从性在中间 ( p = 0.0003) 和尾部 ( p  = 0.034) 区域与颅骨区域相比。曝气在区域之间没有差异（p > 0.05）。

结论和临床相关性

基于 SE _L的RP _aw减少了麻醉狗的不良和未充气肺组织。在非手术麻醉的狗中，接近 30 cmH ₂ O的RP _aw可有效改善肺通气。