Biomedical Engineering and Physics, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands.
Foundation for Dive Research (SDR), Aerdenhout, The Netherlands.
Undersea Hyperb Med. 2021 First Quarter;48(1):81-88. doi: 10.22462/01.03.2021.10.
The snorkel allows a surface swimmer to observe the underwater world through the face mask without being disturbed by inhaling. The effect of a snorkel on breathing resistance and cost is widely held to be substantial. This study aims to model these parameters and to measure indirectly the actual increases. Further, resistances of differing designs and dimensions were assessed and recommendations were made concerning use and choice. Maximal voluntary ventilation in 12 seconds (MVV12) was measured in 19 volunteers seated on dry land with and without a classic J-type snorkel (inner diameter 20.5 mm). The extra and total resistances and costs were calculated using the MVV12 data and using estimated airways resistance extrapolated from subject's demography and spirometric literature data. MVV12 measurements with snorkel showed a minute volume of 152 ±38 L∙min-1, 6.0 ±3.7% lower than without snorkel (p = 7.0x10-6). The theoretical MVV12, calculated from snorkel and airways resistances, decreased by 3.2%. Experimental total breathing resistance (457±83 Pa∙s∙L-1) was 6.5 ± 3.2% higher than without snorkel (p = 2.6x10-7), but the total mechanical breathing cost was unaffected by the snorkel (13.58 Watts with; 13.64 Watts without). Divers' estimations of resistance increase were exaggerated (8.8% at rest, 23% swimming). Classical J-type snorkels with an inner diameter ≥19.5 mm add 3-16% resistance . There is no risk of hypercapnia. Scuba divers are recommended to use their snorkel to breathe more comfortably on the surface. It is recommended the snorkel be made a mandatory safety accessory. The best multipurpose snorkel (19-21 mm) has no top appendages and no water release valve.
通气管允许水面游泳者通过面罩观察水下世界，而不会因吸气而受到干扰。通气管对呼吸阻力和成本的影响被广泛认为是巨大的。本研究旨在对这些参数进行建模，并间接测量实际增加的阻力。此外，还评估了不同设计和尺寸的通气管的阻力，并就其使用和选择提出了建议。19 名志愿者在干燥的陆地上坐着，分别测量了他们在使用和不使用经典 J 型通气管（内径 20.5 毫米）的情况下，12 秒内的最大自主通气量（MVV12）。使用 MVV12 数据以及从受试者的人口统计学和肺功能文献数据中推断出的气道阻力来计算额外阻力和总阻力及成本。使用通气管时的 MVV12 测量值为 152±38 L∙min-1，比不使用通气管时低 6.0±3.7%（p=7.0x10-6）。从通气管和气道阻力计算得出的理论 MVV12 下降了 3.2%。实验总呼吸阻力（457±83 Pa∙s∙L-1）比不使用通气管时高 6.5±3.2%（p=2.6x10-7），但通气管对总机械呼吸成本没有影响（使用时为 13.58 瓦特；不使用时为 13.64 瓦特）。潜水员对阻力增加的估计过高（休息时为 8.8%，游泳时为 23%）。内径≥19.5 毫米的经典 J 型通气管会增加 3-16%的阻力。不存在发生高碳酸血症的风险。建议水肺潜水员使用通气管在水面上更舒适地呼吸。建议将通气管作为强制性安全配件。最好的多用通气管（19-21 毫米）没有顶部附件，也没有水释放阀。
