We show that heart rate enabled wearable devices can be used to measure respiratory rate. Respiration modulates the heart rate creating excess power in the heart rate variability at a frequency equal to the respiratory rate, a phenomenon known as respiratory sinus arrhythmia. We isolate this component from the power spectral density of the heart beat interval time series, and show that the respiratory rate thus estimated is in good agreement with a validation dataset acquired from sleep studies (root mean squared error = 0.648 min⁻¹, mean absolute error = 0.46 min⁻¹, mean absolute percentage error = 3%). We use this respiratory rate algorithm to illuminate two potential applications (a) understanding the distribution of nocturnal respiratory rate as a function of age and sex, and (b) examining changes in longitudinal nocturnal respiratory rate due to a respiratory infection such as COVID-19. 90% of respiratory rate values for healthy adults fall within the range 11.8−19.2 min⁻¹ with a mean value of 15.4 min⁻¹. Respiratory rate is shown to increase with nocturnal heart rate. It also varies with BMI, reaching a minimum at 25 kg/m², and increasing for lower and higher BMI. The respiratory rate decreases slightly with age and is higher in females compared to males for age <50 years, with no difference between females and males thereafter. The 90% range for the coefficient of variation in a 14 day period for females (males) varies from 2.3–9.2% (2.3−9.5%) for ages 20−24 yr, to 2.5−16.8% (2.7−21.7%) for ages 65−69 yr. We show that respiratory rate is often elevated in subjects diagnosed with COVID-19. In a 7 day window from D₋₁ to D₊₅ (where D₀ is the date when symptoms first present, for symptomatic individuals, and the test date for asymptomatic cases), we find that 36.4% (23.7%) of symptomatic (asymptomatic) individuals had at least one measurement of respiratory rate 3 min⁻¹ higher than the regular rate.

我们展示了支持心率的可穿戴设备可用于测量呼吸率。呼吸调节心率，以等于呼吸率的频率在心率变异性中产生过大功率，这种现象称为呼吸性窦性心律失常。我们将此分量从心跳间隔时间序列的功率谱密度中分离出来，并表明由此估计的呼吸率与从睡眠研究中获得的验证数据集非常一致（均方根误差 = 0.648 min ^-1，平均绝对值误差 = 0.46 分钟⁻¹, 平均绝对百分比误差 = 3%)。我们使用这种呼吸率算法来说明两个潜在的应用（a）了解夜间呼吸率随年龄和性别的分布，以及（b）检查由于呼吸道感染（如 COVID-19）引起的纵向夜间呼吸率的变化. ^{90% 的健康成人呼吸频率值在 11.8-19.2 min -1}范围内，平均值为 15.4 min ^-1。呼吸频率显示随着夜间心率而增加。它还随 BMI 而变化，最低达到 25 kg/m ²，并随着 BMI 的降低和升高而增加。呼吸频率随着年龄的增长而略有下降，并且在年龄 <50 岁时，女性的呼吸频率高于男性，此后男女之间没有差异。女性（男性）在 14 天内变异系数的 90% 范围从 20-24 岁的 2.3-9.2% (2.3-9.5%) 到 2.5-16.8% (2.7-21.7%) 65-69 岁 我们表明，在诊断为 COVID-19 的受试者中，呼吸频率通常会升高。在从D ₋₁到D ₊₅的 7 天窗口中（其中D ₀是症状首次出现的日期，对于有症状的个体，对于无症状的病例是测试日期），我们发现 36.4%（23.7%）的有症状（无症状）个体至少有一次呼吸频率测量值比 3 min ⁻¹高正常利率。