PEEP 和 I:E 比对 ARDS 患者脑氧合的影响：麻醉兔的实验研究。

Effect of PEEP and I:E ratio on cerebral oxygenation in ARDS: an experimental study in anesthetized rabbit.

机构信息

Unit for Anesthesiological Investigations Department of Anesthesiology Pharmacology and Intensive Care, University of Geneva, Geneva, Switzerland.

University of Milano-Bicocca, Milan, Italy.

出版信息

BMC Anesthesiol. 2019 Jun 19;19(1):110. doi: 10.1186/s12871-019-0782-y.

DOI:10.1186/s12871-019-0782-y

PMID:31216981

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC6582519/

Abstract

BACKGROUND

Although PEEP and inversed I:E ratio have been shown to improve gas exchange in ARDS, both can adversely affect systemic hemodynamics and cerebral perfusion. The goal of this study was to assess how changes in PEEP and I:E ratio affect systemic and cerebral oxygenation and perfusion in normal and injured lung.

METHODS

Eight anesthetized Chinchilla-Bastard rabbits were ventilated at baseline with pressure-regulated volume control mode, V = 6 ml/kg, PEEP = 6 cmHO, FIO = 0.4; respiratory rate set for ETCO = 5.5%, and I:E = 1:2, 1:1 or 2:1 in random order. Ultrasonic carotid artery flow (CF), arterial (PaO), jugular venous blood gases and near infrared spectroscopic cerebral oxygenation (∆HBO) were recorded for each experimental condition. After induced lung injury, the animals were ventilated with PEEP = 9 followed by 6 cmHO.

RESULTS

At baseline, inverse-ratio ventilation (IRV) significantly reduced cerebral oxygenation (∆OHB; - 27 at 1:2; - 15 at 1:1 vs. 0.27 μmol/L at 2:1; p < 0.05), due to a significant reduction in mean arterial pressure and CF without modifying gas exchange. In injured lung, IRV improved gas exchange but decreased cerebral perfusion without affecting brain oxygenation. The higher PEEP level, however, improved PaO (67.5 ± 19.3 vs. 42.2 ± 8.4, p < 0.05), resulting in an improved ∆HBO (- 13.8 ± 14.7 vs. -43.5 ± 21.3, p < 0.05), despite a drop in CF.

CONCLUSIONS

Our data suggest that unlike moderate PEEP, IRV is not effective in improving brain oxygenation in ARDS. In normal lung, IRV had a deleterious effect on brain oxygenation, which is relevant in anesthetized patients.

摘要

背景

尽管 PEEP 和反比通气（IRV）已被证明可改善 ARDS 中的气体交换，但两者均可能对全身血液动力学和脑灌注产生不利影响。本研究的目的是评估 PEEP 和 I:E 比值的变化如何影响正常和受损肺中的全身和脑氧合和灌注。

方法

在基线时，8 只麻醉的 Chinchilla-Bastard 兔通过压力调节容量控制模式进行通气，V=6ml/kg，PEEP=6cmHO，FIO=0.4；呼吸频率设置为 ETCO=5.5%，I:E=1:2、1:1 或 2:1 随机排序。记录每一种实验条件下的颈总动脉血流（CF）、动脉（PaO）、颈内静脉血气和近红外光谱脑氧合（∆HBO）。在诱导性肺损伤后，动物以 PEEP=9 进行通气，然后以 6cmHO 进行通气。

结果

在基线时，反比通气（IRV）显著降低脑氧合（∆OHB；1:2 时为-27，1:1 时为-15，而 2:1 时为 0.27μmol/L；p<0.05），这是由于平均动脉压和 CF 的显著降低，而不改变气体交换。在受损的肺中，IRV 改善了气体交换，但降低了脑灌注而不影响脑氧合。然而，较高的 PEEP 水平改善了 PaO（67.5±19.3 vs. 42.2±8.4，p<0.05），导致 ∆HBO 改善（-13.8±14.7 vs. -43.5±21.3，p<0.05），尽管 CF 下降。