Objective

To assess and compare the effect of intraoperative stepwise alveolar recruitment manoeuvres (ARMs), followed by individualized positive end-expiratory pressure (PEEP), defined as PEEP at maximal respiratory system compliance + 2 cmH₂O (PEEP_maxCrs+2), with that of spontaneous ventilation (SV) and controlled mechanical ventilation (CMV) without ARM or PEEP on early postoperative arterial oxygenation in anaesthetized healthy dogs.

Study design

Prospective, randomized, nonblinded clinical study.

Animals

A total of 32 healthy client-owned dogs undergoing surgery in dorsal recumbency.

Methods

Dogs were ventilated intraoperatively (inspired oxygen fraction: 0.5) with one of the following strategies: SV, CMV alone, and CMV with PEEP_maxCrs+2 following a single ARM (ARM1) or two ARMs (ARM2, the second ARM at the end of surgery). Arterial blood gas analyses were performed before starting the ventilatory strategy, at the end of surgery, and at 5, 10, 15, 30 and 60 minutes after extubation while breathing room air. Data were analysed using Kruskal-Wallis and Friedman tests (p < 0.050).

Results

At any time point after extubation, PaO₂ was not significantly different between groups. At 5 minutes after extubation, PaO₂ was 95.1 (78.1–104.0), 93.8 (88.3–104.0), 96.9 (86.6–115.0) and 89.1 (87.6–102.0) mmHg in the SV, CMV, ARM1 and ARM2 groups, respectively. PaO₂ decreased at 30 minutes after extubation in the CMV, ARM1 and ARM2 groups (p < 0.050), but it did not decrease after 30 minutes in the SV group. Moderate hypoxaemia (PaO₂, 60–80 mmHg) was observed in one dog in the ARM1 group and two dogs each in the SV and ARM2 groups.

Conclusions and clinical relevance

Intraoperative ARMs, followed by PEEP_maxCrs+2, did not improve early postoperative arterial oxygenation compared with SV or CMV alone in healthy anaesthetized dogs. Therefore, this ventilatory strategy might not be clinically advantageous for improving postoperative arterial oxygenation in healthy dogs undergoing surgery when positioned in dorsal recumbency.

中文翻译：

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肺健康麻醉犬肺泡复张操作后个体化呼气末正压：一项关于术后早期动脉氧合的随机临床试验

客观的

为了评估和比较术中逐步肺泡复张操作 (ARMs) 的效果，然后是个体化呼气末正压 (PEEP)，定义为最大呼吸系统顺应性 + 2 cmH ₂ O (PEEP _{max C rs+2} ) 时的PEEP ，与无 ARM 或 PEEP 的自主通气 (SV) 和受控机械通气 (CMV) 对麻醉健康犬术后早期动脉氧合的影响。

学习规划

前瞻性、随机、非盲临床研究。

动物

共有 32 只健康的客户拥有的狗在背卧位接受手术。

方法

犬在术中通气（吸入氧分数：0.5），采用以下策略之一：SV、单独 CMV 和 CMV 与 PEEP _{max C rs+2}跟随单个 ARM (ARM1) 或两个 ARM（ARM2，第二个 ARM）手术结束）。在开始通气策略之前、手术结束时以及拔管后 5、10、15、30 和 60 分钟，同时呼吸室内空气时进行动脉血气分析。使用 Kruskal-Wallis 和 Friedman 检验分析数据 ( p < 0.050)。

结果

在拔管后的任何时间点，各组之间的PaO ₂均无显着差异。拔管后5分钟，SV、CMV和.ARM1组的PaO _{2 分别}为95.1（78.1-104.0）、93.8（88.3-104.0）、96.9（86.6-115.0）和89.1（87.6-102.0）mmHg CMV、ARM1 和 ARM2 组拔管后 30 分钟PaO ₂下降（p < 0.050），但 SV 组在 30 分钟后没有下降。在 ARM1 组的一只狗和 SV 和 ARM2 组的每只狗中观察到中度低氧血症（PaO ₂，60-80 mmHg）。

结论和临床相关性

在健康麻醉犬中，与单独使用 SV 或 CMV 相比，术中 ARM 和 PEEP _{max C rs+2}并没有改善术后早期动脉氧合。因此，当处于背卧位时，这种通气策略在临床上可能不利于改善接受手术的健康犬的术后动脉氧合。