Juznic G, Emri I, Peterec D, Prepadnik M
Bibl Cardiol. 1979(37):180-94.
We determined the indices of local vibrations (resonance frequency, damping coefficient, stiffness constant, extinction time) and transfer function H(s) . 10(-6) for three somatotypes and three respiratory positions on 88 points of the thorax. The examinees were males (age 21 years). We found the resonance frequencies of 36.86--54.75 cps, damping coefficient (delta) 0.121--0.217. This means the damping is less than critical (delta = 1). We applied shocks (a force of 2 N) with a reflex hammer on 88 points of the thorax. The force diminished from the exciting place (say ictus) to the recording place (accelerometer on the sternum) from 2 to 0.2 N. The athletic type has the highest resonance frequency and stiffness constant; the leptosomic type has the highest damping; the longest extinction time belongs to the pyknic type. The pyknic type has also the highest value of the transfer function. The respiratory position (quiet respiration, Valsalva and Müller experiment) influences the values of the indices of local vibrations and of the transfer function. The influence is evident especially on the intercostal points: the transfer of the oscillations is alleviated at a higher stiffness of the thorax (Valsalva; the value of H(S) . 10(-6) rises from 7.00 to 9.39 sec2), it deteriorates at a small stiffness of the thorax (in Müller's experiment falls to 2.78 sec2). With the fall in the intrathoracic pressure the damping in the intercostal points decreases. On the basis of experiments the conclusion was made that a short testing of the thorax of an examinee will give the dynamic characteristics of the thorax (indices of local vibrations and transfer functions) of the individual. This procedure will alleviate the quantitative use of noninvasive mechanical methods in the assessment of the cardiovascular function.
我们测定了三种体型和三种呼吸状态下，胸部88个点的局部振动指标（共振频率、阻尼系数、刚度常数、消光时间）以及传递函数H(s)·10⁻⁶。受试者为男性（21岁）。我们发现共振频率为36.86 - 54.75 cps，阻尼系数（δ）为0.121 - 0.217。这意味着阻尼小于临界值（δ = 1）。我们用反射锤在胸部88个点施加冲击（2 N的力）。从激励点（比如敲击点）到记录点（胸骨上的加速度计），力从2 N减小到0.2 N。运动型体型的共振频率和刚度常数最高；瘦长型体型的阻尼最大；矮胖型体型的消光时间最长。矮胖型体型的传递函数值也最高。呼吸状态（安静呼吸、瓦尔萨尔瓦动作和米勒实验）会影响局部振动指标和传递函数的值。这种影响在肋间点尤其明显：在胸部刚度较高时（瓦尔萨尔瓦动作；H(S)·10⁻⁶的值从7.00升至9.39 sec²），振动传递得到缓解，在胸部刚度较小时（米勒实验中降至2.78 sec²），振动传递变差。随着胸腔内压力下降，肋间点的阻尼减小。基于实验得出结论，对受试者胸部进行简短测试就能得出个体胸部的动态特征（局部振动指标和传递函数）。该程序将有助于在评估心血管功能时更定量地使用非侵入性机械方法。
