Portela Diego A, McKenzie Stuart R, Moura Raiane A, Gonzalez Margaret, Donati Pablo A, Sandez Ignacio, Araos Joaquin, Chiavaccini Ludovica, Maxwell Elizabeth A, Otero Pablo E
Department of Comparative, Diagnostic, and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
Department of Comparative, Diagnostic, and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
Vet Anaesth Analg. 2025 Aug 20. doi: 10.1016/j.vaa.2025.08.038.
To evaluate the effect of 5 cmHO positive end-expiratory pressure (PEEP) and end-inspiratory pause (EIP) on airway dead space (V) and its resultant effects on alveolar tidal volume (V) and physiological dead space-to-tidal volume ratio (V/V) in dorsally recumbent anesthetized dogs.
Prospective, controlled clinical study.
Healthy adult dogs (n = 20, > 20 kg) undergoing elective surgery.
Dogs were mechanically ventilated across three 5 minute phases: 1) without PEEP (PEEP); 2) with 5 cmHO PEEP (PEEP); and 3) with PEEP plus an EIP (30% of inspiratory time) (PEEP+EIP), allowing 15 minutes of stabilization between phases. During each phase, expired CO tension and tidal volume (V) were measured using volumetric capnography, and arterial blood gases assessed. V, V and V/V were calculated offline and compared between phases using mixed-effect linear models. Data are presented as mean ± standard deviation (95% confidence interval) and indexed to the predicted ideal body mass when appropriate.
The V was 16.8 ± 1.7 (16.3-17.19) mL kg. PEEP significantly increased V [7.9 ± 1.6 (7.1-8.6) to 8.4 ± 1.8 (7.6-9.3) mL kg; p = 0.001] and V/V [0.52 ± 0.1 (0.49-0.55)% to 0.55 ± 0.1 (0.52-0.59)%; p = 0.001]. PEEP decreased V [8.9 ± 0.8 (8.6-9.4) to 8.3 ± 0.8 (7.9-8.7) mL kg; p = 0.001]. EIP reversed these changes, decreasing V back to baseline [7.8 ± 1.6 (7.1-8.6) mL kg], resulting in V/V and V returning to baseline values. Arterial PaCO remained stable across phases.
Although PEEP increased V and decreased V, the addition of a 30% EIP mitigated these effects, suggesting that incorporating an EIP may be an effective strategy to optimize dead space and ventilation in dogs receiving mechanical ventilation with PEEP.
评估5cmH₂O呼气末正压（PEEP）和吸气末暂停（EIP）对背卧位麻醉犬气道死腔（Vd）的影响及其对肺泡潮气量（Va）和生理死腔与潮气量比值（Vd/Vt）的影响。
前瞻性对照临床研究。
接受择期手术的健康成年犬（n = 20，体重>20 kg）。
犬在三个5分钟阶段进行机械通气：1）无PEEP（PEEP⁻）；2）5cmH₂O PEEP（PEEP⁺）；3）PEEP加EIP（吸气时间的30%）（PEEP⁺ + EIP），各阶段之间有15分钟的稳定期。在每个阶段，使用容量式二氧化碳描记法测量呼出二氧化碳张力和潮气量（Vt），并评估动脉血气。离线计算Vd、Va和Vd/Vt，并使用混合效应线性模型在各阶段之间进行比较。数据以平均值±标准差（95%置信区间）表示，并在适当的时候根据预测的理想体重进行指数化。
Vd为16.8±1.7（16.3 - 17.19）mL/kg。PEEP显著增加Vd [7.9±1.6（7.1 - 8.6）至8.4±1.8（7.6 - 9.3）mL/kg；p = 0.001] 和Vd/Vt [0.52±0.1（0.49 - 0.55）%至0.55±0.1（0.52 - 0.59）%；p = 0.001]。PEEP降低Va [8.9±0.8（8.6 - 9.4）至8.3±0.8（7.9 - 8.7）mL/kg；p = 0.001]。EIP逆转了这些变化，使Vd降至基线水平[7.8±1.6（7.1 - 8.6）mL/kg]，导致Vd/Vt和Va恢复到基线值。各阶段动脉血PaCO₂保持稳定。
虽然PEEP增加了Vd并降低了Va，但增加30%的EIP可减轻这些影响，这表明在接受PEEP机械通气的犬中加入EIP可能是优化死腔和通气的有效策略。
