Compliance and dead space fraction indicate an optimal level of positive end-expiratory pressure after recruitment in anesthetized patients
Compliance and dead space fraction indicate an optimal level of positive end-expiratory pressure after recruitment in anesthetized patients
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DOI：
10.1213/01.ane.0000287684.74505.49
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发表时间：
2008-01-01
影响因子：
5.7
通讯作者：
Bohm, Stephan H.
中科院分区：
文献类型：
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作者：
Maisch, Stefan;Reissmann, Hajo;Bohm, Stephan H.
背景：“最佳”呼气末正压 (PEEP) 可以定义为防止复张操作后复发、避免过度扩张、从而在最小死腔通气下实现最佳肺力学的 PEEP。在本研究中，我们分析了 PEEP 和复张对功能残气量 (FRC)、顺应性、动脉氧分压 (Pao(2)) 和死腔分数的影响，并确定了指示最佳 PEEP 的最合适变量。 方法：我们研究了 20 名接受面颌手术的肺部健康的麻醉患者。使用压力控制通气模式逐步增加 PEEP/吸气压力（0/10、5/15、10/20、15/25 cm H(2)O，每个水平持续 20 分钟）后，进行肺复张操作（20/45 cm H(2)O 最多 20 分钟），然后逐步降低压力（15/25、10/20、 5/15、0/10 cm H(2)O，每个水平 20 分钟）。在每个压力水平下，测量 FRC、顺应性、Pao(2) 和死腔分数。结果：在相同 PEEP 水平下比较复张前后的值时，所有变量在 10/20 cm H(2)O 下均显示出显着变化；在 10/20 cm H(2)O 下，所有变量均显示出显着变化。在压力步骤 15/25 cm H(2)O 下，顺应性也显着更高。此外，FRC 值在 5/15 cm H(2)O 和 15/25 cm H(2)O 下显示出显着差异。结论：所有变量均显示 PEEP 与肺复张操作结合的积极作用。最佳 PEEP 为 10 厘米。 H(2)O，因为在此压力水平下，最高的顺应性值与最低的死腔分数相结合表明了有效扩张的肺泡的最大量。 FRC 和 Pao(2) 对肺泡过度扩张不敏感。
BACKGROUND: "Optimal" positive end-expiratory pressure (PEEP) can be defined as the PEEP that prevents recollapse after a recruitment maneuver, avoids over-distension, and, consequently, leads to optimal lung mechanics at minimal dead space ventilation. In this study, we analyzed the effects of PEEP and recruitment on functional residual capacity (FRC), compliance, arterial oxygen partial pressure (Pao(2)) and dead space fraction, and we determined the most suitable variables indicating optimal PEEP.METHODS: We studied 20 anesthetized patients with healthy lungs undergoing faciomaxillary surgery. After a stepwise increase of PEEP/inspiratory pressures (0/10, 5/15, 10/20, 15/25 cm H(2)O, each level lasting for 20 min) using a pressure-controlled ventilation mode, a recruitment maneuver (at 20/45 cm H(2)O for a maximum of 20 min) was performed, followed by a stepwise pressure reduction (15/25, 10/20, 5/15, 0/10 cm H(2)O, with 20 min at each level). At each pressure level, FRC, compliance, Pao(2), and dead space fraction were measured.RESULTS: When comparing the values before and after recruitment at identical PEEP levels, all variables showed significant changes at 10/20 cm H(2)O; compliance was also significantly higher at the pressure step 15/25 cm H(2)O. In addition, FRC values showed significant differences at 5/15 cm H(2)O and 15/25 cm H(2)O.CONCLUSIONS: All variables showed the positive effects of PEEP in conjunction with a recruitment maneuver. Optimal PEEP was 10 cm. H(2)O because at this pressure level the highest compliance value in conjunction with the lowest dead space fraction indicated a maximum amount of effectively expanded alveoli. FRC and Pao(2) were insensitive to alveolar over-distension.