Centro de Estudo, Diagnóstico e Investigação de Hipertermia Maligna (CEDHIMA), Disciplina de Anestesiologia, Dor e Terapia Intensiva, Universidade Federal de São Paulo, Rua Napoleão de Barros, 715, 5 andar, CEP 04024-002, São Paulo, SP, Brazil.
Inflammation. 2014 Apr;37(2):486-94. doi: 10.1007/s10753-013-9762-4.
Although assist ventilation with FIO2 0.21 is the preferable mode of ventilation in the intensive care unit, sometimes controlled ventilation with hyperoxia is needed. But the impact of this setting has not been extensively studied in elderly subjects. We hypothesized that a high fraction of inspired oxygen (FiO(2)) and controlled mechanical ventilation (CMV) is associated with greater deleterious effects in old compared to adult subjects. Adult and old rats were submitted to CMV with low tidal volume (6 ml/kg) and FiO(2) 1 during 3 or 6 h. Arterial blood gas samples were measured at 0, 60 and 180 min (four groups: old and adult rats, 3 or 6 h of CMV), and additionally at 360 min (two groups: old and adult rats, 6 h of CMV). Furthermore, total protein content (TPC) and tumor necrosis factor-alpha (TNF-α) in bronchoalveolar lavage were assessed; lung tissue was used for malondialdehyde and histological analyses, and the diaphragm for measurement of contractile function. Arterial blood gas analysis showed an initial (60 min) greater PaO(2) in elderly versus adult animals; after that time, elderly animals had lowers pH and PaO(2), and greater PaCO(2). After 3 h of CMV, TPC and TNF-α levels were higher in the old compared with the adult group (P < 0.05). After 6 h of MV, malondialdehyde was significantly higher in elderly compared with the adult animals (P < 0.05). Histological analysis showed leukocyte infiltration and edema, greater in old animals. In diaphragm, twitch contraction with caffeine significantly declined after 6 h of CMV only for the elderly group. These data support the hypothesis that relatively short-term CMV with low tidal volume and hyperoxia has greatest impact in elderly rats, decreasing diaphragmatic contractile function and increasing lung inflammation.
虽然在重症监护病房中，使用吸入氧浓度（FIO2）为 0.21 的辅助通气是首选通气模式，但有时需要进行高浓度氧的控制通气。然而，这种设置对老年人的影响尚未得到广泛研究。我们假设与成人相比，高吸入氧分数（FiO2）和控制机械通气（CMV）在老年患者中会产生更大的有害影响。成年和老年大鼠分别接受低潮气量（6ml/kg）和 FiO2 为 1 的 CMV 通气 3 或 6 小时。在 0、60 和 180 分钟（四组：老年和成年大鼠，CMV 通气 3 或 6 小时）时测量动脉血气样本，并在 360 分钟（两组：老年和成年大鼠，CMV 通气 6 小时）时额外测量。此外，还评估了支气管肺泡灌洗液中的总蛋白含量（TPC）和肿瘤坏死因子-α（TNF-α）；肺组织用于丙二醛和组织学分析，膈肌用于测量收缩功能。动脉血气分析显示，与成年动物相比，老年动物在初始（60 分钟）时具有更高的 PaO2；此后，老年动物的 pH 和 PaO2 较低，而 PaCO2 较高。CMV 3 小时后，老年组的 TPC 和 TNF-α水平高于成年组（P<0.05）。MV 6 小时后，老年组的丙二醛明显高于成年组（P<0.05）。组织学分析显示，老年动物的白细胞浸润和水肿更严重。在膈肌中，只有老年组在接受 CMV 6 小时后，对咖啡因的抽搐收缩显著下降。这些数据支持以下假设：在老年大鼠中，低潮气量和高浓度氧的相对短期 CMV 具有最大的影响，降低了膈肌的收缩功能并增加了肺部炎症。
