用于测定肺弥散能力的屏气对心血管系统的影响。

Gotshall R W, Davrath L R

Department of Exercise and Sport Science, Colorado State University, Fort Collins 80523-1582, USA.

Aviat Space Environ Med. 1999 May;70(5):471-4.

BACKGROUND

The single-breath technique for determination of the diffusion capacity of the lung for CO (DlCO) requires a 10-s breathhold at total lung capacity. The assumption has been that this breathhold does not alter the components of DlCO, i.e., the diffusion capacity of the membrane (Dm) and the pulmonary capillary blood volume (Qc), and therefore measurement of these variables during breathhold represents these variables as they exist during normal breathing. The purpose of this study was to determine the effect of the 10-s breathhold on cardiac output (Q) and Qc while supine and standing. The hypothesis was that the standing posture would have a greater influence on Q and Qc during the breathhold than would the supine posture.

METHODS

Twelve male subjects participated. Q, stroke volume (SV), heart rate (HR), BP (MAP), and total peripheral resistance (TPR) were determined before and during the 10-s breathhold determination of DlCO, Qc, and Dm.

RESULTS

Results while supine were compared with those while standing. DlCO was reduced on standing, due mainly to a reduction in Qc. SV and Q decreased significantly during the 10-s breathhold in both postures. Both SV and Q decreased more when standing (-53% and -49.5%, respectively) than when supine (-40.5% and -36.5%, respectively). Thus, the 10-s breathhold caused significant reductions in Q and therefore may alter the measurement of DlCO and Qc.

CONCLUSIONS

The greater decline in Q during the measurement of DlCO when standing would suggest that the DlCO and Qc values while breathing might be underestimated in the upright posture.

背景

用于测定肺一氧化碳弥散量（DlCO）的单次呼吸技术要求在肺总量时屏气10秒。一直以来的假设是，这种屏气不会改变DlCO的组成部分，即膜弥散量（Dm）和肺毛细血管血容量（Qc），因此在屏气期间对这些变量的测量代表了它们在正常呼吸时的状态。本研究的目的是确定仰卧位和站立位时10秒屏气对心输出量（Q）和Qc的影响。假设是站立姿势在屏气期间对Q和Qc的影响比仰卧姿势更大。

方法

12名男性受试者参与研究。在测定DlCO、Qc和Dm的10秒屏气之前和期间，测定Q、每搏输出量（SV）、心率（HR）、血压（MAP）和总外周阻力（TPR）。

结果

将仰卧位时的结果与站立位时的结果进行比较。站立时DlCO降低，主要是由于Qc降低。在两种姿势下，10秒屏气期间SV和Q均显著降低。站立时SV和Q的降低幅度（分别为-53%和-49.5%）大于仰卧时（分别为-40.5%和-36.5%）。因此，10秒屏气导致Q显著降低，因此可能会改变DlCO和Qc的测量值。