Background and aim

Pleural effusions (PE) are a common clinical entity resulting from pathologies that affect the pleural space such as congestive heart failure, malignancy and pneumonia. The osmolality of the pleural fluid has never been studied as well as the effects of its changes on the pleural membrane. The purpose of this study was to identify the osmolality levels of PEs of different etiologies and to assess the potential effects of osmolality imbalance on the pleural permeability.

Materials and methods

We measured the osmolality of the PEs of 64 consecutive patients (6 with transudative, 11 with parapneumonic and 47 with malignant pleural effusions) that were hospitalized in the University Hospital of Larissa. Subsequently, we selected clinically relevant hyper- and hypo- osmolality levels and performed assessment of the permeability of sheep parietal pleura by means of Ussing chamber experiments.

Results

The mean pleural fluid osmolality was 291.7 ± 24.89 mOms/Kg (95 % CI: 285.4–297.9), and it varied among the three groups of PEs (p = 0.05). Transformed osmolality values were associated with pH and glucose levels in the PEs. After exposure of the sheep parietal pleura to 240 mOsm/kg (hyposmolar) the transmesothelial resistance (R_TM) significantly increased (p < 0.05) while at 340 mOsm/kg (hyperosmolar) the R_TM was not significantly altered.

Conclusions

PEs osmolality differs depending on the underlying pathology and is linked to PE pH and glucose. Hypo-osmotic PEs can lead to decreased pleural permeability. These results warrant further study of the PEs osmolality levels on the function of the pleural mesothelial cells.

中文翻译：

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胸腔积液渗透压与胸水pH和葡萄糖水平的相关性及其对胸膜通透性的影响

背景与目标

胸腔积液 (PE) 是一种常见的临床实体，由影响胸膜腔的病理学引起，例如充血性心力衰竭、恶性肿瘤和肺炎。从未研究过胸水的渗透压及其变化对胸膜的影响。本研究的目的是确定不同病因的 PEs 的渗透压水平，并评估渗透压失衡对胸膜通透性的潜在影响。

材料和方法

我们测量了在拉里萨大学医院住院的 64 名连续患者（6 名有漏出液，11 名有肺炎旁和 47 名有恶性胸腔积液）的 PE 的渗透压。随后，我们选择了临床相关的高渗透压和低渗透压水平，并通过 Ussing 室实验对羊壁层胸膜的渗透性进行了评估。

结果

平均胸水渗透压为 291.7 ± 24.89 mOms/Kg（95 % CI：285.4–297.9），并且在三组 PE 之间有所不同（p = 0.05）。转化的渗透压值与 PE 中的 pH 值和葡萄糖水平相关。绵羊壁层胸膜暴露于 240 mOsm/kg（低摩尔）后，跨间皮电阻（R _TM）显着增加（p < 0.05），而在 340 mOsm/kg（高渗）时，R _TM没有显着改变。

结论

PEs 渗透压因潜在病理而异，并与 PE pH 值和葡萄糖有关。低渗 PE 可导致胸膜通透性降低。这些结果值得进一步研究 PE 渗透压水平对胸膜间皮细胞功能的影响。