Kiyokawa H, Yonemaru M, Horie S, Ichinose Y, Toyama K
First Department of Internal Medicine, Tokyo Medical College, Japan.
Nihon Kyobu Shikkan Gakkai Zasshi. 1995 Dec;33(12):1341-47.
Crackles were recorded with one of two systems in a total of 58 cases and compared. In one system a stethoscope was attached to a microphone; in the other system no stethoscope was used (see reference 9). Coarse crackles were recorded with the stethoscope system in 11 patients, and with the microphone-only system in 12 patients. Most patients with coarse crackles had bronchiectasis. Fine crackles were recorded with the stethoscope system in 13 patients, and with the microphone-only system in 22 patients. Most patients with fine crackles had idiopathic pulmonary fibrosis. Each record was examined visually, and all crackles recorded during one inspiration were selected. Power spectra were estimated with the maximum entropy method and peak frequencies were determined with the damped least-squares method. Type-I crackles were defined as those with all peak frequencies below 800 Hz; these low-pitched sounds may correspond to coarse crackles. Type-II crackles were defined as those with peak frequencies over 800 Hz regardless of the existence of peaks below 800 Hz; these high-pitched sound may correspond to fine crackles. The "%Type II" was defined as the percentage of the total crackles that were Type-II crackles. The %Type II value among coarse crackles was 10 +/- 16% with the stethoscope and 3 +/- 7% with the microphone. Among fine crackles, the values were 65 +/- 22% with the stethoscope and 79 +/- 23% with the microphone. For both kinds of equipment, the %Type II differed significantly between coarse and fine crackles (p < 0.01). The stethoscope-transmitted sound had components that could be used to differentiate fine crackles from coarse crackles. For clinical purposes, crackles recorded with a stethoscope are as useful as those recorded with a microphone only.
在总共58例病例中，使用两种系统之一记录了啰音并进行比较。在一种系统中，将听诊器连接到麦克风；在另一种系统中，未使用听诊器（见参考文献9）。使用听诊器系统在11例患者中记录到粗啰音，使用仅带麦克风的系统在12例患者中记录到粗啰音。大多数有粗啰音的患者患有支气管扩张。使用听诊器系统在13例患者中记录到细啰音，使用仅带麦克风的系统在22例患者中记录到细啰音。大多数有细啰音的患者患有特发性肺纤维化。对每份记录进行目视检查，并选择一次吸气过程中记录到的所有啰音。用最大熵方法估计功率谱，用阻尼最小二乘法确定峰值频率。I型啰音定义为所有峰值频率低于800Hz的啰音；这些低调声音可能对应于粗啰音。II型啰音定义为峰值频率超过800Hz的啰音，无论是否存在低于800Hz的峰值；这些高调声音可能对应于细啰音。“II型百分比”定义为II型啰音占总啰音的百分比。粗啰音中，听诊器记录的II型百分比为10±16%，麦克风记录的为3±7%。细啰音中，听诊器记录的值为65±22%，麦克风记录的为79±23%。对于两种设备，粗啰音和细啰音的II型百分比差异均有统计学意义（p<0.01）。听诊器传输的声音具有可用于区分细啰音和粗啰音的成分。对于临床目的，用听诊器记录的啰音与仅用麦克风记录的啰音一样有用。
