Department of Biomedical Sciences, University of Padova, Padova, Italy.
Department of Anesthesiology, Center for Hyperbaric Medicine and Environmental Physiology, Duke University Medical Center, Durham, North Carolina, United States.
J Appl Physiol (1985). 2023 Oct 1;135(4):863-871. doi: 10.1152/japplphysiol.00777.2022. Epub 2023 Aug 31.
Pulmonary gas exchange in breath-hold diving (BHD) consists of a progressive increase in arterial partial pressures of oxygen ([Formula: see text]) and carbon dioxide ([Formula: see text]) during descent. However, recent findings have demonstrated that [Formula: see text] does not consistently rise in all subjects. This study aimed at verifying and explaining [Formula: see text] derangements during BHD analyzing arterial blood gases and searching for pulmonary alterations with lung ultrasound. After ethical approval, 14 fit breath-hold divers were included. Experiments were performed in warm water (temperature: 31°C). We analyzed arterial blood gases immediately before, at depth, and immediately after a breath-hold dive to 15 m of fresh water (mfw) and 42 mfw. Signs of lung interstitial edema and atelectasis were searched simultaneously with a marinized lung ultrasound. In five subjects (15 mfw) and four subjects (42 mfw), the [Formula: see text] at depth seems to decrease instead of increasing. [Formula: see text] and lactate showed slight variations. At depth, no lung ultrasound alterations were seen except in one subject (hypoxemia and B-lines at 15 mfw; B-lines at the surface). Lung interstitial edema was detected in 3 and 12 subjects after resurfacing from 15 to 42 mfw, respectively. Two subjects developed hypoxemia at depth and a small lung atelectasis (a focal pleural irregularity of triangular shape, surrounded by thickened B-lines) after resurfacing from 42 mfw. Current experiments confirmed that some BH divers can experience hypoxemia at depth. The hypothesized explanation for such a discrepancy is lung atelectasis, which could not be detected in all subjects probably due to limited time available at depth. During breath-hold diving, arterial partial pressure of oxygen ([Formula: see text]) and arterial partial pressure of carbon dioxide ([Formula: see text]) are believed to increase progressively during descent, as explained by theory, previous end-tidal alveolar gas measurements, and arterial blood gas analysis in hyperbaric chambers. Recent experiments in real underwater environment found a paradoxical [Formula: see text] drop at depth in some divers. This work confirms that some breath-hold divers can experience hypoxemia at depth. The hypothesized explanation for such a discrepancy is lung atelectasis, as suggested by lung ultrasound findings.
屏气潜水（BHD）中的肺气体交换包括在下降过程中动脉血氧分压 ([Formula: see text]) 和二氧化碳分压 ([Formula: see text]) 的逐渐升高。然而，最近的研究结果表明，并非所有受试者的 [Formula: see text] 都一致升高。本研究旨在通过分析动脉血气并通过肺超声寻找肺部改变来验证和解释 BHD 期间的 [Formula: see text] 紊乱。经过伦理批准，纳入了 14 名健康的屏气潜水员。实验在温水（温度：31°C）中进行。我们在潜水员潜水至 15 米淡水（mfw）和 42 米淡水之前、深度和之后立即分析动脉血气。同时用 marinized 肺超声检查肺间质水肿和肺不张的迹象。在五名受试者（15 mfw）和四名受试者（42 mfw）中，[Formula: see text] 在深度似乎下降而不是升高。[Formula: see text] 和乳酸略有变化。在深度，除了一名受试者（15 mfw 时缺氧和 B 线；表面时 B 线）外，没有发现肺超声改变。从 15 米到 42 米浮出水面后，分别在 3 名和 12 名受试者中检测到肺间质水肿。两名受试者在深度出现缺氧，42 米浮出水面后出现小面积肺不张（三角形局灶性胸膜不规则，周围有增厚的 B 线）。目前的实验证实，一些 BHD 潜水员在深度可能会出现缺氧。对于这种差异的假设解释是肺不张，这可能由于在深度上可用的时间有限而不能在所有受试者中检测到。在屏气潜水期间，正如理论、先前的终末肺泡气体测量和高压舱中的动脉血气分析所解释的那样，人们认为在下降过程中动脉血氧分压 ([Formula: see text]) 和动脉二氧化碳分压 ([Formula: see text]) 会逐渐升高。在真实水下环境中的最近实验发现，一些潜水员在深度出现了矛盾的 [Formula: see text] 下降。这项工作证实，一些屏气潜水员在深度可能会出现缺氧。对于这种差异的假设解释是肺不张，这是由肺超声检查结果提示的。
