Gillespie Amanda I, Slivka William, Atwood Charles W, Verdolini Abbott Katherine
J Speech Lang Hear Res. 2015 Jun;58(3):638-52. doi: 10.1044/2015_JSLHR-S-13-0270.
The larynx has a dual role in the regulation of gas flow into and out of the lungs while also establishing resistance required for vocal fold vibration. This study assessed reciprocal relations between phonatory functions-specifically, phonatory laryngeal airway resistance (Rlaw)-and respiratory homeostasis during states of ventilatory gas perturbations.
Twenty-four healthy women performed phonatory tasks while exposed to induced hypercapnia (high CO2), hypocapnia (low CO2), and normal breathing (eupnea). Effects of gas perturbations on Rlaw were investigated as were the reciprocal effects of Rlaw modulations on respiratory homeostasis.
Rlaw remained stable despite manipulations of inspired gas concentrations. In contrast, end-tidal CO2 levels increased significantly during all phonatory tasks. Thus, for the conditions tested, Rlaw did not adjust to accommodate ventilatory needs as predicted. Rather, stable Rlaw was spontaneously accomplished at the cost of those needs.
Findings provide support for a theory of regulation wherein Rlaw may be a control parameter in phonation. Results also provide insight into the influence of phonation on respiration. The work sets the foundation for future studies on laryngeal function during phonation in individuals with lower airway disease and other patient populations.
喉部在调节进出肺部的气流方面具有双重作用，同时还建立了声带振动所需的阻力。本研究评估了发声功能（具体而言，发声时的喉部气道阻力[Rlaw]）与通气气体扰动状态下呼吸稳态之间的相互关系。
24名健康女性在暴露于诱导性高碳酸血症（高二氧化碳）、低碳酸血症（低二氧化碳）和正常呼吸（平静呼吸）的情况下执行发声任务。研究了气体扰动对Rlaw的影响以及Rlaw调节对呼吸稳态的相互影响。
尽管对吸入气体浓度进行了操作，但Rlaw仍保持稳定。相比之下，在所有发声任务期间，呼气末二氧化碳水平显著升高。因此，对于所测试的条件，Rlaw并未如预期那样进行调整以适应通气需求。相反，稳定的Rlaw是以牺牲这些需求为代价自发实现的。
研究结果为一种调节理论提供了支持，即Rlaw可能是发声中的一个控制参数。结果还提供了对发声对呼吸影响的见解。这项工作为未来研究下呼吸道疾病患者和其他患者群体发声时的喉部功能奠定了基础。
