Time course of air hunger mirrors the biphasic ventilatory response to hypoxia
Time course of air hunger mirrors the biphasic ventilatory response to hypoxia
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DOI：
10.1152/japplphysiol.00056.2004
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发表时间：
2004-12-01
影响因子：
3.3
通讯作者：
Butler, JP
中科院分区：
文献类型：
--
作者：
Moosavi, SH;Banzett, RB;Butler, JP
确定低氧空气饥饿的反应动力学可以提供临床实践中使用的信息，并将提高对基本呼吸困难机制的理解。据推测，空气饥饿是由反射性脑干反射驱动（“必然放电”）投射到前脑中枢引起的。如果感知反应动力学不受脑干和皮层意识之间的事件的影响，这一假设预测，空气饥饿将准确地跟踪解释性反应。因此，在持续缺氧期间，空气饥饿的初始增加之后将是反映双相反射性驱力的进行性下降。为了验证这一预测，我们应用了一个急性发作20分钟的步骤，正常碳酸性缺氧和比较动态响应特性的空气饥饿与通气在10名健康受试者。在机械通气期间测量空气饥饿（每分钟通气量= 9 +/- 1.4 l/min;潮气末PCO 2 = 37 +/- 2 Torr;潮气末PO 2 = 45 +/- 7 Torr）;在相同受试者的单独自由呼吸试验期间测量呼吸反应。由“呼吸冲动”引起的不适在视觉模拟量表上每30秒评定一次。两个解释和空气饥饿响应建模为延迟双指数对应于一个简单的线性一阶响应，但与一个单独的一阶适应。这些模型提供了足够的拟合，以澄清和空气饥饿数据（r（2）= 0.88和0.66）。平均感知反应的平均时间常数和达峰时间（分别为0.36 min（-1）和3.3 min）与平均解释反应的相应值（0.39 min（-1）和3.1 min）非常接近。持续低氧引起的空气饥饿反应追踪到延迟约30 s的兴奋性冲动。我们的数据提供了进一步的支持的必然放电假说的空气饥饿。
Determining response dynamics of hypoxic air hunger may provide information of use in clinical practice and will improve understanding of basic dyspnea mechanisms. It is hypothesized that air hunger arises from projection of reflex brain stem ventilatory drive ("corollary discharge") to forebrain centers. If perceptual response dynamics are unmodified by events between brain stem and cortical awareness, this hypothesis predicts that air hunger will exactly track ventilatory response. Thus, during sustained hypoxia, initial increase in air hunger would be followed by a progressive decline reflecting biphasic reflex ventilatory drive. To test this prediction, we applied a sharp-onset 20-min step of normocapnic hypoxia and compared dynamic response characteristics of air hunger with that of ventilation in 10 healthy subjects. Air hunger was measured during mechanical ventilation ( minute ventilation = 9 +/- 1.4 l/min; end-tidal PCO2 = 37 +/- 2 Torr; end-tidal PO2 = 45 +/- 7 Torr); ventilatory response was measured during separate free-breathing trials in the same subjects. Discomfort caused by "urge to breathe" was rated every 30 s on a visual analog scale. Both ventilatory and air hunger responses were modeled as delayed double exponentials corresponding to a simple linear first-order response but with a separate first-order adaptation. These models provided adequate fits to both ventilatory and air hunger data (r(2) = 0.88 and 0.66). Mean time constant and time-to-peak response for the average perceptual response (0.36 min(-1) and 3.3 min, respectively) closely matched corresponding values for the average ventilatory response (0.39 min(-1) and 3.1 min). Air hunger response to sustained hypoxia tracked ventilatory drive with a delay of similar to30 s. Our data provide further support for the corollary discharge hypothesis for air hunger.