Heart Rate Recovery and Oxygen Kinetics After Exercise in Obstructive Sleep Apnea Syndrome

Background: Patients who suffer from obstructive steep apnea (OSA) have a decreased exercise capacity and abnormal autonomic nervous function. However, the kinetics of early oxygen (O-2) and heart rate recovery (HRR) have not been described.Materials and Methods: We evaluated 21 men with moderate to severe OSA (mean age: 48 +/- 11 yrs, mean apnea-hypopnea index [AHI]: 55 +/- 13) and without known heart disease and 10 healthy men matched for age and body mass index (BMI; controls). Men with OSA underwent overnight polysomnography, and both groups underwent symptom-limited incremental cardiopulmonary exercise testing (CPET). We recorded the CPET parameters including peak O-2 uptake (Vo(2)p), kinetics of early O-2 recovery by the first degree slope of Vo(2) during the first minute (Vo(2)/t slope), the time required for a 50% decline of Vo(2)p during recovery (T-1/2), and early heart rate recovery (HRR = HR at maximal exercise - HR at 1 min of recovery), as well as the chronotropic reserve to exercise ([CR] = [peak HR - resting HR/220 - age - resting HR] x 100). Patients with OSA had a lower Vo(2)p (28.7 +/- 4.0 vs 34.7 +/- 6.2 mL/kg/min), Vo(2)/t slope (1.04 +/- 0.3 vs 1.4 +/- 0.17 mL/kg/min(2)), and T-1/2 (74 +/- 10 vs 56 +/- 6 sec) compared to controls (all P < 0.001). In addition, both HRR and CR were lower in the OSA group(22.0 +/- 7.0 vs 31.0 +/- 6.0 bpm, P:0.003, and 79.0% +/- 15% vs 99.0% +/- 13.0%, P:0.01, respectively).Conclusions: Patients with OSA demonstrate reduced exercise capacity, delayed oxygen kinetics, and reduced HRR. These data point to abnormal oxygen delivery and/or oxidative function of the peripheral muscles and impaired autonomic nervous activity in OSA patients.

背景：患有阻塞性睡眠呼吸暂停（OSA）的患者运动能力下降，自主神经功能异常。然而，早期氧（O₂）和心率恢复（HRR）的动力学尚未被描述。 材料与方法：我们评估了21名患有中重度OSA的男性（平均年龄：48±11岁，平均呼吸暂停 - 低通气指数[AHI]：55±13），他们无已知心脏病，同时选取了10名年龄和体重指数（BMI）匹配的健康男性作为对照。患有OSA的男性接受整夜多导睡眠监测，两组均接受症状限制性递增心肺运动试验（CPET）。我们记录了CPET参数，包括峰值氧摄取量（Vo₂p）、通过第一分钟内Vo₂的一级斜率计算的早期氧恢复动力学（Vo₂/t斜率）、恢复期间Vo₂p下降50%所需的时间（T - 1/2）以及早期心率恢复（HRR = 最大运动时心率 - 恢复1分钟时心率），以及运动变时性储备（[CR] = [峰值心率 - 静息心率/220 - 年龄 - 静息心率]×100）。与对照组相比，OSA患者的Vo₂p（28.7±4.0对34.7±6.2 mL/kg/min）、Vo₂/t斜率（1.04±0.3对1.4±0.17 mL/kg/min²）和T - 1/2（74±10对56±6秒）均较低（所有P < 0.001）。此外，OSA组的HRR和CR均较低（22.0±7.0对31.0±6.0次/分钟，P = 0.003；79.0%±15%对99.0%±13.0%，P = 0.01）。 结论：OSA患者表现出运动能力降低、氧动力学延迟和HRR降低。这些数据表明OSA患者外周肌肉的氧输送和/或氧化功能异常以及自主神经活动受损。