Study of Periodic Breathing in Healthy Humans
试验速览
- 阶段
- 不适用
- 发起方
- 入组人数
- 120
- 试验地点
- 1
- 主要终点
- Periodic pattern of ventilation
研究概览
简要总结
We made a fortuitous observation of periodic breathing in a healthy subject coming to our outpatient mountain medicine consultation at Avicenne hospital in Bobigny (France). During this consultation, subjects perform a hypoxia exercise test, which allows a good prediction of their risk factors for severe high altitude illnesses. Surprisingly, breath-by-breath recording of the ventilation signal showed a periodic breathing pattern, which increased when the subject started to exercise in hypoxic conditions and was maintained during normoxic exercise.
Therefore, our objective was to confirm this observation in a retrospective study led in 82 subjects who passed this test. We tested the hypothesis that subjects with a brisk ventilatory response to hypoxia might show a more pronounced periodic pattern of ventilation, due to a higher gain of the chemoreceptor feedback loop. Then, our objective is to investigate the mechanisms involved in the periodic pattern in healthy subjects, as a function of exercise intensity, altitude intensity, role of peripheral and central chemoreceptors to O2 and CO2. Finally, we want to investigate the possible role of this ventilatory instability in patients with obstructive or central apneas.
详细描述
In a preliminary study, among the population coming to the outpatient consultation of mountain medicine at Avicenne hospital in 2012, 82 subjects (38 females and 44 males) were randomly selected and separated in two groups of 41 high and 41 low responders to hypoxia according to the median value of the hypoxic ventilatory response to hypoxia at exercise (HVRe > or < 0.84 L/min/kg) derived from the hypoxic exercise test (inspired fraction of O2: 0.115, exercise intensity of 30% of maximal aerobic power), as previously described.
The hypoxic exercise test consists in 4 successive phases of 3 to 4 minutes each with the following sequence: rest in normoxia (RN), rest in hypoxia (RH), exercise in hypoxia (EH) and exercise in normoxia (EN). Minute ventilation ( E, L.min-1) is measured through a metabograph (Vmax Encore, SensorMedics, Yorba Linda, CA). Pulse O2 saturation (SpO2, %) is measured by transcutaneous oximetry (Nellcor N-595, Nellcor, Pleasanton, CA) on a pre-warmed ear lobe. End tidal PCO2 (PETCO2) is measured by infrared thermopile (Vmax Encore, SensorMedics, Yorba Linda, CA). During the whole test, VE, SpO2 and PETCO2 were recorded breath-by-breath. Continuous blood pressure is measured by a Finapres system. Data are transferred to a computer for further spectrum analysis. A Fast Fourier Transform (FFT) is then applied to the ventilation signal in sequences of 128 points in each phase of the test. This method will allow us to detect the presence of peaks in the frequency domain of the ventilation signal. Two main parameters are derived from the FFT: the frequency in hertz (or period in seconds) of the larger peak and its power estimated as the area under the peak at ± 0.02 Hz around the peak (in L2.s-2).
The main study will be designed in order to unravel the mechanisms and role of these oscillations in ventilation. An overall population of 90 healthy subjects and 30 patients will be included in the study.
Step 1. Effect of exercise intensity.
Step 2. Effect of altitude level.
研究设计
- 研究类型
- Observational
- 观察模型
- Cohort
入排标准
- 年龄范围
- 18 Years 至 65 Years（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •depending on the group: see definition of groups
排除标准
- •BMI > 30
- •history of severe cardiac arrhythmia
- •pulmonary hypertension
- •history of coronary disease
结局指标
主要结局
Periodic pattern of ventilation
时间窗: The measure is made at the end of the 6-min exercise period, only once in each condition (normoxia, hypoxia, hyperoxia, hypercapnia),
Presence of oscillation in the ventilation signal
次要结局
- Oscillations in arterial blood pressure(The measure is made at the end of the 6-min exercise period, only once in each condition (normoxia, hypoxia, hyperoxia, hypercapnia))
- Oscillations in heart rate(The measure is made at the end of the 6-min exercise period, only once in each condition (normoxia, hypoxia, hyperoxia, hypercapnia))
研究者
Pr. Jean Paul RICHALET
Director of Department
Association pour la Recherche en Physiologie de l'Environnement