Hypocalcaemia predicts coronavirus disease 2019 (COVID-19) severity and mortality. We hypothesized an association between respiratory alkalosis secondary to hypoxia and low ionised calcium (iCa) concentration in patients with COVID-19. Arterial blood gas samples taken from January 2019 to March 2021 were retrospectively matched with infection status. Principal components regression was undertaken to determine the correlation between pH, partial pressure arterial oxygen (PaO), partial pressure arterial carbon dioxide (PaCO), and iCa. We included 4056 patients (300 COVID-19 detected, 19 influenza detected), corresponding to 5960 arterial blood samples. The COVID-19 detected group had a statistically significantly lower iCa, PaO and PaCO, and more alkalotic pH than infection-free groups. The influenza group had a lower iCa and PaCO, higher PaO, and a more alkalotic pH than infection-free groups, but these differences were non-significant. Principal components regression revealed that pH, PaCO, and PaO explain just 2.72 % of the variance in iCa. An increase in pH by 1 unit was associated with an iCa reduction of 0.141 ​mmol/L (p ​< ​0.0001). Reduction in iCa concentration in patients with COVID-19 is not associated with pH derangement. Influenza infection was associated with a minor reduction in iCa in our small sample, a hitherto unreported finding, although statistical significance was not demonstrated.

中文翻译：

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动脉 pH 值的变化并不能解释在 COVID-19 感染期间观察到的离子钙的减少

低钙血症可预测 2019 年冠状病毒病 (COVID-19) 的严重程度和死亡率。我们假设 COVID-19 患者继发于缺氧的呼吸性碱中毒与低离子钙 (iCa) 浓度之间存在关联。 2019年1月至2021年3月采集的动脉血气样本与感染状况进行回顾性匹配。进行主成分回归以确定 pH、动脉氧分压 (PaO)、动脉二氧化碳分压 (PaCO) 和 iCa 之间的相关性。我们纳入了 4056 名患者（检测到 300 名 COVID-19，检测到 19 名流感患者），相当于 5960 份动脉血样本。与未感染组相比，检测到 COVID-19 的组 iCa、PaO 和 PaCO 显着降低，并且碱性 pH 值更高。与无感染组相比，流感组的 iCa 和 PaCO 较低，PaO 较高，且碱性 pH 值较高，但这些差异并不显着。主成分回归显示，pH、PaCO 和 PaO 只能解释 iCa 方差的 2.72%。 pH 值增加 1 个单位与 iCa 减少 0.141 mmol/L (p < 0.0001) 相关。 COVID-19 患者 iCa 浓度的降低与 pH 值紊乱无关。在我们的小样本中，流感感染与 iCa 略有减少有关，这是迄今为止尚未报告的发现，尽管尚未证明统计显着性。