The effect of chest wall vibration on dyspnea at rest was investigated in 15 patients with severe chronic respiratory diseases. The magnitude of their baseline dyspnea was 17.9 +/- SE 3.3 mm on a 150-mm visual analog scale. One hundred hertz out-of-phase vibration (OPV; inspiratory intercostal muscles vibrated during expiration and expiratory intercostal muscles vibrated during inspiration) increased dyspnea an average of 21.9 +/- SE 7.8 mm (p < 0.05). One hundred hertz in-phase vibration (IPV; inspiratory intercostal muscles vibrated during inspiration and expiratory intercostal muscles vibrated during expiration) decreased dyspnea an average of 6.9 +/- SE 2.8 mm (p < 0.05). Changes in the respiratory pattern and arterial blood gas determinations elicited by 5-min IPV were investigated in eight of the 15 patients. Tidal volume was significantly increased in all eight of these patients. Respiratory frequency was decreased in seven patients and increased in one. Functional residual capacity, measured before and during the application of IPV for a period of about 10 breaths, was increased in one patient and decreased in the remaining seven. PaCO2 decreased by 1.3 +/- 1.0 mm Hg (p < 0.05), from 49.6 +/- 8.4 mm Hg; PaO2 increased by 3.4 +/- 2.3 mm Hg (p < 0.05), from 67.7 +/- 12.7 mm Hg. The results indicate that in-phase chest wall vibration decreased pathologic dyspnea in patients with chronic respiratory disease and suggest that the effects on respiratory sensation are mediated by afferent information from chest wall respiratory muscles to supraspinal centers.

The effects of bilateral alternating out-of-phase vibrations were studied in 10 normal healthy subjects and five asthmatic patients. The second or third intercostal spaces were vibrated during expiration, and the seventh to ninth intercostal spaces were vibrated during inspiration. Most subjects sensed breathlessness during such vibrations, and 100 Hz was most effective. The degree of breathlessness correlated positively with increased respiratory rate. Respiratory rate increased from 14.1 +/- 3.78 (mean +/- SD) to 22.3 +/- 7.14 breaths/min (P less than 0.05) during relatively severe breathlessness and to 20.39 +/- 5.66 breaths/min (P less than 0.05) during less uncomfortable sensation. Slight or negligible breathlessness induced no significant increase in rate (15.33 +/- 4.19 breaths/min). All asthma patients described the sensations during vibration as similar to those during asthma attacks, and their respiratory rates increased 20.7 +/- 11.03% during 100 Hz vibration (P less than 0.01). It is suggested that the uncomfortable sensation of breathlessness may be induced by muscle spindles in the intercostal muscles being activated out of phase with the respiratory cycle. The central mechanism that receives the intercostal afferents may have a certain gate that operates in relation to the sensation of breathlessness.

No abstract

Vibration applied to the volar side of the finger tip has been reported to induce finger flexion reflex. Acupuncture is reported to inhibit this vibration-induced finger flexion reflex (VFR) in the ipsilateral hand. The purpose of this study was to investigate the effect of unilateral acupuncture in the hand on VFR in both hands. As no systematic study on the relationship between VFR and the force of voluntary contraction with no vibration (Initial Force: IF) has been reported, this relationship was studied prior to the present study on acupuncture. VFR was induced by mechanical vibration on the volar side of the middle finger tip with 10 g to 500 g IF. With approximately 300 g IF, VFR was consistent. Therefore, approximately 300 g IF was applied for VFR induction to study the effect of acupuncture on VFR. A stainless steel needle was inserted into the right Hoku point and remained inserted (in-situ technique) for 10 minutes. VFR in both hands was significantly decreased by acupuncture at the right Hoku point (% control force of VFR: right, 67.8%; left, 74.6%). The present results suggest that acupuncture in the unilateral hand influences the bilateral reflex arc of VFR.

Effects of press needle technique (PN), electroacupuncture (EA), or in-situ technique (IS) on vibration-induced finger flexion reflex (VFR) were examined in 31 healthy adults. VFR, which is tonic finger flexion evoked by vibration applied to the finger tip, was induced by vibrating the volar side of the middle finger tip before and after acupuncture. Acupuncture was applied to the Hoku point on both sides. The three techniques, each studied on separate days, inhibited VFR and there was no significant difference in VFR inhibition among the three techniques (percentage of pre-acupuncture VFR was 71.5 +/- SE 2.2% after PN, 72.6 +/- SE 2.4% after EA, and 75.6 +/- SE 2.8% after IS). The results suggest that afferent signals from muscles contracting due to electrical stimulation had no significant effect on the reflex arcs of VFR; and that the intradermal stimulation by acupuncture played a significant role in VFR inhibition.