[Clinical effects of four weeks of respiratory muscle stretch gymnastics in patients with chronic obstructive pulmonary disease].

We developed a program of respiratory muscle stretch gymnastic (RMSG), and measured lung function, exercise capacity, dyspnea, and quality of life before and after 4 weeks of training with this program. Thirteen patients with chronic obstructive pulmonary disease (mean FEVi, 1.24 liters) began the program. They participated in three sessions of RMSG each day. Twelve patients completed all 4 weeks. RMSG significantly (p < 0.01) decreased functional residual capacity (from 4.19 +/- 1.27 to 3.88 +/- 1.03 liters), total lung capacity (from 5.98 +/- 1.35 to 5.66 +/- 1.20 liters), residual volume (from 3.29 +/- 1.16 to 2.89 +/- 0.89 liters), and residual volume as a percent of total lung capacity (from 53.9 +/- 11.2% to 50.6 +/- 9.74%). The distance walked in 6 min increased by an average of 43 +/- 30 meters (+ 15%, p < 0.01). Dyspnea after a 6-minute walk (measured with a 150-mm visual analog scale) decreased significantly (from 65.1 +/- 40.8 to 36.1 +/- 36.8, p < 0.05). Quality of life was measured with the Chronic Respiratory Disease Questionnaire of Guyatt, et al., and was found to have improved significantly. Respiratory muscle stretch gymnastics may be useful in pulmonary rehabilitation.

Reconstruction of tonic vibration reflex in the biceps brachii reinnervated by transferred intercostal nerves in patients with brachial plexus injury.

The transfer of intercostal nerves to musculocutaneous nerves has been performed to reconstruct elbow flexion in patients with brachial plexus injury. In nine of 15 such patients, 2-3 Hz tapping of the distal tendon of the biceps muscle reinnervated by the transferred intercostal nerves (IC-biceps) induced a mode in the correlogram between tap and EMG pulse of IC-biceps. In five of the mode-positive patients, tapping of various frequencies induced gradual augmentation of integrated EMG of IC-biceps. This reflex was consistent with the tonic vibration reflex (TVR) in normal controls. Conduction velocity and frequency property of the reflex were compatible with the speculation that rapid-conducting muscle afferents (group Ia or II or both) reinnervate mechanoreceptors, such as muscle spindles. The clinical significance of muscle sensory reinnervation is not clear; however, the reconstruction of TVR following this operation is worthy in that it confirms the specific sensory reinnervation of denervated muscle in humans.

Effect of acupuncture at the Hoku point on vibration-induced finger flexion reflex in man: comparison between press needle technique, electroacupuncture, and in-situ technique.

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.

Effect of chest wall vibration on dyspnea in patients with chronic respiratory disease.

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.

[Clinical usefulness of visual analog scale for assessment of dyspnea at rest in patients with chronic respiratory diseases].

To evaluate the validity and clinical usefulness of the visual analog scale (VAS) for the measurement of dyspnea at rest, we employed the 150 mm VAS in 29 chronic respiratory disease patients who were clinically stable, and repeated the measurement 4 weeks and 8 weeks later for the evaluation of reproducibility. For the 8-week period, the individual medical treatments remained generally unchanged in all patients. Two patients were excluded from the study due to infection and pneumothorax. Dyspnea at rest was detected on VAS in 23 patients at the first measurement. The VAS measurement was 23.9 +/- 28.4 (mean +/- SD) mm at the first time, 22.0 +/- 23.1 mm at the 4th week, and 22.4 +/- 26.0 mm at the 8th week. There was no significant change among the three measurements. Twenty among the 23 patients with VAS indicative of dyspnea at rest were categorized into grades 4 and 5 of the Fletcher dyspnea category. However, the intensity of dyspnea was distributed widely within each Fletcher category. These results lead to the conclusion that VAS shows good reproducibility over a period of as long as 8 weeks and that VAS measurements can reveal patient-to-patient individual differences in dyspnea intensity which cannot be detected by the Fletcher dyspnea category. We propose that measuring dyspnea at rest using VAS is a useful method to obtain a valid clinical parameter.

Sensory reinnervation of muscle receptor in human.

This report describes sensory reinnervation of muscle receptors in humans. In this study, sensory function was investigated in fourteen patients with brachial plexus injury, whose musculocutaneous nerve was surgically sutured with intercostal nerves for reconstruction of elbow flexion. Tapping the intercostal nerve-reinnervated brachial biceps muscle (IC-biceps) induced somatosensory evoked potentials (IC-biceps SEP) in four patients. Tapping also induced reflex IC-biceps activity in all IC-biceps SEP (+) patients, but not in eight out of nine IC-biceps SEP (-) patients. Results show that muscle afferent fibers in the intercostal nerves reinnervated mechanoreceptors in IC-biceps, and induced both cortical sensory activity and muscle activity that indicated the classical stretch reflex.

Effect of acupuncture at the right Hoku point on bilateral vibration-induced finger flexion reflex in man: comparison between in-situ and Sparrow Pecking technique.

The purpose of this study was to compare the effect of the Sparrow Pecking (SP) technique with that of the In-Situ (IS) technique of acupuncture on vibration-induced finger flexion reflex (VFR). Subjects were 30 healthy adults. VFR, flexion movement of the vibrated finger, was induced by vibrating the volar side of the middle finger tip. The acupuncture point was the right Hoku point. Both techniques of acupuncture inhibited VFR in the ipsilateral and contralateral sides, but inhibition with SP was significantly greater than that with IS (percentage control force of VFR, mean +/- SD: with SP right, 62.1 +/- 24.6%, left, 60.6 +/- 27.9%, with IS right, 74.9 +/- 26.6%, left, 78.1 +/- 29.5%, P < 0.0005). The results suggest that SP suppresses facilitation of VFR in the reflex arcs more than IS does.

Inspiratory prolongation by vagal afferents from pulmonary mechanoreceptors in rabbits.

Graded inflation and deflation pressures were transiently applied to the airway, and the effects on the inspiratory (TI) and expiratory (TE) durations were studied in twelve Japanese white rabbits tracheotomized and anesthetized with urethane and chloralose. Without vagal cooling, lung inflation prolonged TE, whereas changes in TI were small and inconsistent. The bilateral vagus nerves were cooled to 7 degrees C to block myelinated fibers, and to study the effects of C-fiber afferents. During vagal cooling to 7 degrees C, inflation dose dependently prolonged the first TI with no consistent change in TE. Without vagal cooling, lung deflation shortened TE of the first and succeeding breaths, and prolonged TI of the first breath to manifest apneusis. Deflation applied at the vagal temperature of 7 degrees C induced slight shortening of TI and TE in 6 of the 12 rabbits. All these changes were blocked when the vagus nerves were cooled to 1 degree C. The results may indicate that vagal afferents from irritant receptors shorten TE, and C-fiber afferents prolong TI. High irritant afferent activity may markedly shorten TE, causing tidal inspiratory activities to merge and manifest apneusis. Capsaicin, which is suggested to be a "selective" stimulant of C-fiber receptors was injected into the right atrium in 4 of the 12 rabbits. The chief changes were TE shortening without vagal cooling, and TI prolongation during cooling to 7 degrees C. This suggests that capsaicin injected into the pulmonary circulation stimulates both the irritant and C-fiber receptors and the C-fiber afferents may prolong TI even when stimulated chemically.

[Dyspnea and respiratory reflexes].

It has been suggested that afferents from intercostal muscles may play a role in the genesis of dyspnea. In this study, lower intercostal muscles were tapped or vibrated to induce a reflex, evoked potentials, and sensation. The tapping stimulus induced H reflex in the same muscle with a latency of 12 msec. Also the same stimulus induced evoked potentials in the cerebral cortex (N1: 19.8 +/- 1.2 msec). This suggests projection of the intercostal muscle spindle afferents to the cerebral cortex. 100 Hz vibration induced a later component, presumably an event-related potential, at 250 msec after the onset of both the inspiratory and expiratory phase. Thus, it may be possible that intercostal muscle spindle afferents project to the cerebral cortex and play a role in respiratory sensation. It has been suggested that dyspnea is reduced by increasing inspiratory and expiratory intercostal muscle spindle afferents during the inspiratory and expiratory phases, respectively. Thus, stretching the inspiratory and expiratory intercostal muscles during the respective muscular contraction phase may be effective in reducing dyspnea.

Effect of acupuncture at right Hoku point on the bilateral vibration-induced finger flexion reflex in man.

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.

Pre-inspiratory burst in the caudal medulla of rabbits.

The activity of 48 respiratory units in the paraolivary region from the middle to the rostral end of the hypoglossal cranial nerve root, and the effect of electrical stimulation and L-glutamate applied to the region on phrenic nerve activity was investigated in 14 rabbits. Electrical stimulation (50 Hz, 0.2 ms current pulses at intensities 5-20 microA) and L-glutamate (30-100 ng) shortened the expiratory time and increased the respiratory rhythm with no change in tidal phrenic nerve activity. Rhythmic activity preceding the phrenic nerve activity (pre-inspiratory burst) was recorded in the paraolivary region. The temporal relationship between the pre-inspiratory (pre-I) burst and the phrenic activity remained constant even when the respiratory frequency was altered by passive lung inflation. These results suggest that structures in the paraolivary region may influence the respiratory rhythm in rabbits and that pre-I burst neurons may play a role in triggering periodic phrenic activity.

Functional mechanism of expiratory pattern generator.

Tidal expiratory activity and the time to its peak (TEa, i.e., time of active expiration) were measured from the integration curve of external oblique muscle activity in rabbits. The rabbits were spontaneously breathing under urethan-chloralose anesthesia in the prone position. CO2 rebreathing was performed, and the changes in the temporal profile of the integrated expiratory activity were studied. Hypercapnia increased the tidal expiratory activity before and after bilateral vagotomy. Before vagotomy, the rate of rise (tidal expiratory activity/TEa) increased significantly and TEa was shortened. On the other hand, after vagotomy, the rate of rise remained unchanged and TEa was prolonged. An expiratory off-switch model is postulated according to the quantitative relationship between the time and amplitude of the tidal expiratory activity. The expiratory activity pattern in vagotomized rabbits was similar to that in humans.

Effects of high-frequency inflation (HFI) on expiratory activity.

It has been reported that triangular-shaped positive pressure pulses applied to the airway (high-frequency inflation, HFI) stimulates pulmonary stretch receptors and prolongs expiratory duration. In the present experiment, changes in the integrated curve of expiratory activity induced by HFI were investigated. Duration until the onset of the expiratory activity (E1 stage) was unchanged. In the E2 stage, the initial ascending slope became steeper and higher peaks were reached during HFI stimulation. The period from the onset of the slope to the peak, previously designated the stage of active expiration (Ea stage), showed no consistent change in duration and remained unchanged on average. The period after the peak until the onset of the following inspiratory activity was consistently prolonged. This period was designated the declining stage of expiration (Ed stage).

Two different types of apnea induced by focal cold block of ventral medulla in rabbits.

The respiratory effects of unilateral focal cold block of ventral medulla were examined in rabbits. Focal cooling of the paraolivar region in the caudal area of ventral medulla induced prolongation of the expiratory time, with little change in the tidal inspiratory activity amplitude, leading to 'temporal apnea'. Whereas focal cooling of the region ventral to the retrofacial nucleus in the rostral part of the ventral medulla induced depression of tidal phrenic nerve activity amplitude, leading to 'suppression apnea'. Thus, two different types and regions of apnea were demonstrated in rabbits.

Inhibitory effect of acupuncture on the finger flexion reflex induced by finger tip vibration.

The effect of acupuncture on finger flexion reflex, caused by mechanical vibration applied to the finger tip, was studied by using the cross-correlation function. A stainless steel acupuncture needle was inserted into the acupuncture point called "Wai-Kuan" for 10 min. Acupuncture inhibited the reflex and suppressed the two modes seen in the cross-correlogram between unitary EMG activity of the muscle flexor digitorum superficialis and finger tip vibration with random frequency. The recovery of the primary mode, which may be via the spinal monosynaptic reflex loop, was significantly earlier than the recovery of the secondary mode, which may be via the supraspinal reflex long loop. This suggests that the distinct inhibitory effect of acupuncture takes place on the reflex at spinal and supraspinal levels.

Expiratory activity in transferred intercostal nerves in brachial plexus injury patients.

Involuntary activity of transferred intercostal motor units was examined in patients with brachial plexus injury. Since the internal intercostal nerves were detached from the thorax to reinnervate the musculus biceps brachii, it was possible to record pure intercostal motor activity in humans. Respiratory activity was seen in the latter part of the expiratory phase, thus dividing the phase into two substages (E1 and E2) by the onset of the activity. CO2 rebreathing prolonged the duration of the intercostal motor activity and increased the tidal activity as determined from the integration curve. There was a close linear correlation between these two variables. These observations indicate that expiratory activity and its duration are actively controlled in humans.

Difference in electromyographic response of finger flexion muscles between tonic vibration reflex and finger flexion reflex induced by finger tip vibration.

Vibratory stimulus applied to the skin of the finger tip induced flexion reflex in that finger. By using the cross-correlation function, characteristics of this reflex were compared to those of tonic vibration reflex (TVR). In the cross-correlogram between unitary electromyogram (EMG) activity in the muscle flexor digitorum superficialis and vibratory stimulus with random frequency, one mode was seen in TVR, and two modes in finger flexion reflex. The secondary mode was significantly wider than the primary mode. Thus it may originate from skin mechanoreceptors and manifest via a reflex center involving a long loop.

Cross-correlation between vagal afferent impulses from pulmonary mechanoreceptors and high-frequency inflation (HFI) and deflation (HFD) in rabbits.

The effects of high-frequency airway inflation (HFI) and high-frequency airway deflation (HFD) generated by a triangular pressure pulse generator on pulmonary mechanoreceptors were examined. The cross-correlograms between vagal afferent impulses from the slowly adapting (SAR) and the rapidly adapting receptors (RAR) and the HFI or the HFD pulses were analysed. HFI stimulated SAR and RAR and HFD stimulated RAR, but inhibited SAR. The time lag of the mode in the correlogram between SAR and HFI was shorter than that of the mode in the correlogram between RAR and HFI. The span of the mode and the trough of SAR was shorter than the span of the mode of RAR. This may indicate that the time to peak of the generator potential of RAR is longer than that of SAR.

Gate mechanism in breathlessness caused by chest wall vibration in humans.

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.