Department of Anaesthesia, Auckland City Hospital, Auckland, New Zealand.
Department of Anaesthesiology, University of Auckland, Auckland, New Zealand.
J Appl Physiol (1985). 2021 May 1;130(5):1490-1495. doi: 10.1152/japplphysiol.00111.2021. Epub 2021 Apr 8.
Arterial blood gas (ABG) measurements at both maximum depth and at resurfacing prior to breathing have not previously been measured during free dives conducted to extreme depth in cold open-water conditions. An elite free diver was instrumented with a left radial arterial cannula connected to two sampling syringes through a low-volume splitting device. He performed two open-water dives to a depth of 60 m (197', 7 atmospheres absolute pressure) in the constant weight with fins competition format. ABG samples were drawn at 60 m (by a mixed-gas scuba diver) and again on resurfacing before breathing. An immersed surface static apnea, of identical length to the dives and with ABG sampling at identical times, was also performed. Both dives lasted approximately 2 min. Arterial partial pressure of oxygen ([Formula: see text]) increased during descent from an indicative baseline of 15.8 kPa (after hyperventilation and glossopharyngeal insufflation) to 42.8 and 33.3 kPa ( and ) and decreased precipitously (to 8.2 and 8.6 kPa) during ascent. Arterial partial pressure of carbon dioxide ([Formula: see text]) also increased from a low indicative baseline of 2.8 kPa to 6.3 and 5.1 kPa on and ; an increase not explained by metabolic production of CO alone since [Formula: see text] actually decreased during ascent (to 5.2 and 4.5 kPa). Surface static apnea caused a steady decrease in [Formula: see text] and increase in [Formula: see text] without the inflections provoked by depth changes. Lung compression and expansion provoke significant changes in both [Formula: see text] and [Formula: see text] during rapid descent and ascent on a deep free dive. These changes generally support predictive hypotheses and previous findings in less extreme settings. Arterial blood gas measurements at both maximum depth and the surface before breathing on the same dive have not previously been obtained during deep breath-hold dives in cold open-water conditions and competition dive format. Such measurements were obtained in two dives to 60 m (197') of 2 min duration. Changes in arterial oxygen and carbon dioxide (an increase during descent, and a decrease during ascent) support previous observations in less extreme dives and environments.
动脉血气（ABG）测量值在最大深度和呼吸前重新浮出水面，以前在寒冷的开放水域中进行的极端深度自由潜水期间没有进行过测量。一位精英自由潜水员配备了一根左侧桡动脉导管，通过一个小容量分流装置连接到两个采样注射器。他以恒定重量带脚蹼的形式进行了两次深度为 60 米（197'，7 个绝对大气压）的开放水域潜水。在 60 米处（由混合气体水肺潜水员）抽取 ABG 样本，并在呼吸前再次在浮出水面时抽取。还进行了一次浸入式表面静态暂停，其长度与潜水相同，并且在相同时间进行 ABG 采样。两次潜水都持续了大约 2 分钟。动脉血氧分压（[Formula: see text]）在下降过程中从指示性基线 15.8kPa（在过度通气和舌咽鼓管充气后）增加到 42.8 和 33.3kPa（和），并在上升过程中急剧下降（至 8.2 和 8.6kPa）。动脉血二氧化碳分压（[Formula: see text]）也从低指示性基线 2.8kPa 增加到 6.3 和 5.1kPa 上；这一增加不能仅用 CO 的代谢产生来解释，因为[Formula: see text]实际上在上升过程中下降（至 5.2 和 4.5kPa）。表面静态暂停导致[Formula: see text]稳定下降和[Formula: see text]增加，而没有深度变化引起的波动。在深自由潜水的快速下降和上升过程中，肺部压缩和扩张会引起[Formula: see text]和[Formula: see text]的显著变化。这些变化通常支持在不太极端的环境中进行的预测假设和先前的发现。在寒冷的开放水域条件和竞赛潜水形式下，以前在深度呼吸暂停潜水期间没有在最大深度和同一潜水的呼吸前在表面获得动脉血气测量值。在两次持续 2 分钟的 60 米（197'）潜水期间获得了这些测量值。动脉氧和二氧化碳的变化（下降时增加，上升时减少）支持在不太极端的潜水和环境中的先前观察结果。
