Abstract：
OBJECTIVE: The human congenital central hypoventilation syndrome (CCHS) is caused by mutations in the PHOX2B (paired-like homeobox 2B) gene. Genetically engineered PHOX2B rodents exhibit defective development of the brainstem retrotrapezoid nucleus (RTN), a carbon dioxide sensitive structure that critically controls expiratory muscle recruitment. This has been linked to a blunted exercise ventilatory response. Whether this can be extrapolated to human CCHS is unknown and represents the objective of this study.
METHODS: Thirteen adult CCHS patients and 13 healthy participants performed an incremental symptom-limited cycle cardiopulmonary exercise test. Responses were analyzed using guideline approaches (ventilation V\'E, tidal volume VT, breathing frequency, oxygen consumption, carbon dioxide production) complemented by a breathing pattern analysis (i.e. expiratory and inspiratory reserve volume, ERV and IRV).
RESULTS: A ventilatory response occurred in both study groups, as follows: V\'E and VT increased in CCHS patients until 40 W and then decreased, which was not observed in the healthy participants (p<0.001). In the latter, exercise-related ERV and IRV decreases attested to concomitant expiratory and inspiratory recruitment. In the CCHS patients, inspiratory recruitment occurred but there was no evidence of expiratory recruitment (absence of any ERV decrease, p<0.001).
CONCLUSIONS: Assuming a similar organization of respiratory rhythmogenesis in humans and rodents, the lack of exercise-related expiratory recruitment observed in our CCHS patients is compatible with a PHOX2B-related defect of a neural structure that would be analogous to the rodents\' RTN. Provided corroboration, ERV recruitment could serve as a physiological outcome in studies aiming at correcting breathing control in CCHS.
METHODS: Thirteen adult CCHS patients and 13 healthy participants performed an incremental symptom-limited cycle cardiopulmonary exercise test. Responses were analyzed using guideline approaches (ventilation V\'E, tidal volume VT, breathing frequency, oxygen consumption, carbon dioxide production) complemented by a breathing pattern analysis (i.e. expiratory and inspiratory reserve volume, ERV and IRV).
RESULTS: A ventilatory response occurred in both study groups, as follows: V\'E and VT increased in CCHS patients until 40 W and then decreased, which was not observed in the healthy participants (p<0.001). In the latter, exercise-related ERV and IRV decreases attested to concomitant expiratory and inspiratory recruitment. In the CCHS patients, inspiratory recruitment occurred but there was no evidence of expiratory recruitment (absence of any ERV decrease, p<0.001).
CONCLUSIONS: Assuming a similar organization of respiratory rhythmogenesis in humans and rodents, the lack of exercise-related expiratory recruitment observed in our CCHS patients is compatible with a PHOX2B-related defect of a neural structure that would be analogous to the rodents\' RTN. Provided corroboration, ERV recruitment could serve as a physiological outcome in studies aiming at correcting breathing control in CCHS.
摘要：
目的：人类先天性中枢性通气不足综合征（CCHS）是由PHOX2B（配对样同源异型盒2B）基因突变引起的。基因工程PHOX2B啮齿动物表现出脑干后梯形核（RTN）的发育缺陷，一种对二氧化碳敏感的结构，可严格控制呼气肌的募集。这与运动通气反应减弱有关。这是否可以外推到人类CCHS是未知的，代表了这项研究的目的。
方法：13名成年CCHS患者和13名健康参与者进行了增量症状受限周期心肺运动试验。使用指南方法分析反应(通气V\'E，潮气量VT,呼吸频率,耗氧量,二氧化碳产生)辅以呼吸模式分析(即呼气和吸气储备体积，ERV和IRV）。
结果：两组均出现通气反应，如下：CCHS患者的V\'E和VT增加直到40W，然后下降，在健康参与者中未观察到（p<0.001）。在后者中,运动相关的ERV和IRV减少证明了伴随的呼气和吸气募集.在CCHS患者中，发生了吸气募集，但没有呼气募集的证据（没有任何ERV降低，p<0.001)。
结论：假设人类和啮齿动物的呼吸节律发生组织相似，在我们的CCHS患者中观察到缺乏与运动相关的呼气募集,这与PHOX2B相关的神经结构缺陷相似,这与啮齿动物RTN相似.提供佐证，在旨在纠正CCHS呼吸控制的研究中，ERV募集可以作为生理结果。
方法：13名成年CCHS患者和13名健康参与者进行了增量症状受限周期心肺运动试验。使用指南方法分析反应(通气V\'E，潮气量VT,呼吸频率,耗氧量,二氧化碳产生)辅以呼吸模式分析(即呼气和吸气储备体积，ERV和IRV）。
结果：两组均出现通气反应，如下：CCHS患者的V\'E和VT增加直到40W，然后下降，在健康参与者中未观察到（p<0.001）。在后者中,运动相关的ERV和IRV减少证明了伴随的呼气和吸气募集.在CCHS患者中，发生了吸气募集，但没有呼气募集的证据（没有任何ERV降低，p<0.001)。
结论：假设人类和啮齿动物的呼吸节律发生组织相似，在我们的CCHS患者中观察到缺乏与运动相关的呼气募集,这与PHOX2B相关的神经结构缺陷相似,这与啮齿动物RTN相似.提供佐证，在旨在纠正CCHS呼吸控制的研究中，ERV募集可以作为生理结果。
