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Biomedical subjects

W Hida

Publications and source records attributed to W Hida.

At least 91 records · Page 5Linked to original sources
PubMed1989

Effects of submental electrical stimulation during sleep on upper airway patency in patients with obstructive sleep apnea.

We examined the effects of percutaneous electrical stimulation of the genioglossus in six patients with obstructive sleep apnea syndrome (OSAS) during sleep and investigated the possible applicability of this procedure as a treatment of OSAS. Six patients with OSAS were polysomnographically studied in the supine position during all-night sessions with and without electrical stimulation of the genioglossus. Using an apnea demand-type stimulator that we developed, electrical pulses of 0.5 ms (repetition rate, 50 Hz) and 15 to 40 V were delivered through bipolar electrodes (10 mm in diameter) attached to the skin of the submental region when apnea lasted more than 5 s, and was stopped immediately after breathing resumed or after 10 s at the longest. With submental stimulation, the apnea index, apnea time/total sleep time, longest apnea duration, and the number of times per hour that oxygen saturation dropped below 85% decreased significantly compared with those on control nights. The lowest arterial oxygen saturation and the duration of sleep stages III and IV increased significantly. The stimulation employed did not cause arousal, and it did not affect blood pressure or heart rate significantly. These findings show that submental stimulation decreases the incidence of apnea episodes and promotes deeper sleep without accompanying serious side effects, suggesting that the apnea demand-type stimulator may be a noninvasive and effective treatment for OSAS.

Electric Stimulation↗
PubMed1989

New assessment of airway responsiveness. Effect of pretreatment with procaterol on allergen-induced bronchoconstriction.

We examined airway responsiveness to allergen inhalation using a novel technique by which dynamic compliance (Cdyn) and pulmonary resistance (Rl) are simultaneously calculated by Fourier-series analysis of flow and transpulmonary pressure during tidal breathing. C0 and C0.5 (Cdyn at the frequency of zero and 0.5 Hz, respectively) were computed using the regression line of Cdyn versus frequency measured at the fundamental and first three harmonics in each breathing cycle. First, the validity of this system was tested by comparing Rl, C0 and C0.5 during five consecutive breaths with those obtained by the conventional method. A good correlation was seen in Rl, C0 and C0.5 between the two methods. Second, we studied airway response to allergen inhalation before and after oral administration of a long-acting beta 2-stimulant (procaterol, 50 micrograms or 100 micrograms) or placebo in a double-blind crossover trial in six atopic asthmatic subjects. In control allergen inhalation tests by administration of placebo, Rl increased progressively, and C0.5, expressed as percentage of control compliance at zero frequency (C0.5/COcont), decreased progressively. After 100 micrograms procaterol, Rl response to allergen was almost completely inhibited. However, a decrease in C0.5/C0cont was still observed. These findings suggest that pretreatment of asthmatic patients with procaterol can release allergen-induced bronchoconstriction of the central airways, but cannot release that of the peripheral airways.

Adult↗
PubMed1989

Change in P wave height during progressive exercise in patients with chronic obstructive pulmonary disease.

We examined changes in P wave height in lead II of electrocardiogram during progressive exercise in patients with chronic obstructive pulmonary disease (COPD), and obtained the slope (delta P/delta VO2, %/ml/min) of the regression line calculated from the relationship between percent change of P wave height and oxygen consumption (VO2). Four COPD patients, who had a decrease over 5 mmHg in arterial oxygen tension (PaO2) at maximal exercise (group A), had significantly greater slope (0.45 +/- 0.14%/ml/min, mean +/- S.E.) than in five COPD patients (group B, 0.14 +/- 0.05), who did not have a decrease over 5 mmHg in PaO2 at maximal exercise. The increase in P wave height during exercise was inhibited by oxygen inhalation at the given VO2 in group A. These findings suggest that increase in P wave height during exercise in COPD patients may be correlated with hypoxemia during exercise.

Adult↗
PubMed1989

Respiratory muscle strength and gas exchange in neuromuscular diseases: comparison with chronic pulmonary emphysema and idiopathic pulmonary fibrosis.

To examine whether or not the respiratory muscle weakness is correlated with decrease in arterial oxygen tension (PaO2), respiratory muscle and pulmonary functions in 14 patients with neuromuscular diseases (NMD) were studied and compared with those of 12 patients with chronic pulmonary emphysema (CPE) and 15 patients with idiopathic pulmonary fibrosis (IPF). Respiratory muscle strength was assessed by maximal static inspiratory and expiratory mouth pressure at three lung volumes (RV, FRC and TLC). Although mean pulmonary functions in NMD showed virtually normal function, respiratory muscle strength was significantly less than the corresponding values in CPE and IPF. In NMD, maximal inspiratory mouth pressure at RV level (PImax) correlated positively with %TLC and %VC (r = 0.652 and r = 0.536, respectively). Moreover, PImax was significantly correlated with PaO2 (r = 0.561), but not with PaCO2. Maximal expiratory mouth pressure at TLC (PEmax) correlated positively with %TLC and %VC. In CPE and IPF, respiratory muscle strength had no correlation with PaO2 and PaCO2. These findings suggest that inspiratory muscle dysfunction in NMD may be one of the factors responsible for determination of the level of hypoxemia and lung volume.

Adult↗
PubMed1989

[New methods for measurement of peripheral airway resistance].

We have developed two new methods to evaluate the peripheral resistance of the lung. The first is a method for continuous measurement of the frequency dependence of dynamic compliance (Cdyn, f.d.) and pulmonary resistance (RL) from a single-breath cycle by Fourier-series analysis. In this method, we have found that procaterol my first dilate the central airway and then gradually dilate the peripheral airway in bronchial asthma. The second is a method for the direct measurement of peripheral resistance by the anterograde catheter system using a catheter tip micromanometer. The catheter tip was inserted into the 3 mm diameter small airway anterogradely and intrabronchial pressure was measured simultaneously with transpulmonary pressure and mouth flow. We have found that the values of peripheral resistance in patients with COPD are four to seven times higher than that of normal subjects. These results suggest that the behavior of the peripheral and central airway may differ between patients and that the peripheral airway may be important to examine the pathogenesis of COPD.

Adult↗
PubMed1989

Comparison of intermittent and continuous inhalation provocation tests.

To improve standardization of inhalation provocation tests, two tests utilizing intermittent and continuous inhalation of methacholine aerosol were compared in five normal and ten asthmatic patients. During the intermittent inhalation test, methacholine aerosols with stepwise incremental concentrations were inhaled during tidal breathing for two minutes with a following 5-minute pause interval. Specific airway conductance (SGaw) and respiratory resistance (Rrs) were measured one-half, one and one-half, and five minutes after the end of each inhalation period. Specific airway conductance and Rrs were measured with the panting and forced oscillation methods, respectively. During the continuous inhalation test, the same stepwise incremental concentrations of methacholine aerosol were inhaled during tidal breathing for two minutes without a pause while Rrs was continuously measured. The cumulative dose of methacholine required to reduce SGaw by 35% of the baseline value (PD35 SGaw) during the intermittent inhalation test was significantly correlated with the cumulative methacholine dose required to reduce Grs (= 1/Rrs) by 35% of the baseline value during the continuous inhalation test (PD35 Grs) (r = .98). There was also a significant correlation between the slopes of the intermittent inhalation test and continuous inhalation test curves (r = .80). The results indicate that methacholine provocation can be measured as reliably using a simple continuous inhalation method as by a more complex intermittent one.

Adult↗
PubMed1989

Breathing 30 per cent oxygen attenuates bronchial responsiveness to methacholine in asthmatic patients.

The effect of breathing 30% oxygen on bronchial responsiveness to inhaled methacholine was studied in 30 asthmatic patients using a direct graphical recording method. An aerosol of methacholine solution was inhaled during tidal breathing by measuring respiratory resistance (Rrs) continuously, and dose-response curves were obtained on two separate days during air and 30% oxygen inhalation. Oxygen inhalations for 20 min caused no change in baseline Rrs. The threshold dose of methacholine, the dose which increased Rrs from the baseline value while breathing 30% oxygen, increased significantly compared with that while breathing air (p less than 0.01). No significant difference was found between the mean values of the slopes of the dose-response curves of the two groups. End-expiratory oxygen concentration (FETO2) during air breathing decreased significantly from 13.7% to 12.0% at the point where methacholine dosage reached threshold. This study suggests that hyperoxia attenuates the bronchial responsiveness to methacholine in asthmatic patients.

Adolescent↗
PubMed1989

[Pulmonary hemodynamics during exercise in anesthetized dogs with inspiratory loading and in patients with chronic obstructive pulmonary disease].

We studied 1) the effects of inspiratory elastic loading on pulmonary hemodynamics and pulmonary gas exchange with and without electrically induced hindlimb exercise in 8 anesthetized dogs, 2) pulmonary hemodynamics at rest and during single stage exercise on a supine cycle ergometer in 6 patients with chronic obstructive pulmonary disease (COPD) and 3) changes in P wave height in lead II of electrocardiogram during progressive exercise on a treadmill in 9 COPD patients. The pulmonary arterial pressure-flow relationship from resting to exercise was not affected by inspiratory elastic loading, but elastic loading accompanied by exercise increased alveolar-arterial O2 tension difference (AaDO2). The pulmonary arterial pressure-flow relationship in COPD from rest to exercise showed higher pulmonary vascular resistance than that in control group. Moreover, we found a greater increase in P wave height during exercise in COPD with decrease in PaO2 during exercise than in COPD without decrease in PaO2 during exercise. This increase in P wave height during exercise was inhibited by oxygen inhalation. We speculated that 1) increased AaDO2 during exercise with elastic loading may be due to increased shunt effects with low ventilation-perfusion ratio and 2) increased P wave height during exercise in COPD may be correlated with hypoxia during exercise and may be useful to detect latent cor pulmonale in COPD.

Aged↗
PubMed1988

Possible site of bronchodilation due to inhaled procaterol aerosol in asthmatic patients.

We studied the effective site of an inhaled aerosol of procaterol, a beta 2-selective adrenergic bronchodilator, in 8 asthmatic patients whose basal lung functions are almost within the normal range in both slow vital capacity (VC) and forced expiratory volume in one second (FEV1.0), and are free from asthmatic attack. In patients who had received procaterol 30 min after inhalation of aerosol, there was no significant change in VC, although FEV1.0, maximal expiratory flow at 50% VC (V50), maximal expiratory flow at 25% VC (V25) and maximal expiratory flow at 30% VC of partial maximal expiratory flow volume curve (V30p) improved significantly. On the other hand, in those who had received placebo, none of the parameters changed. Furthermore, R1 decreased and C0.5 increased significantly during the first 5 min after inhalation of procaterol aerosol. After an interval of 5 min, R1 did not change any further, while C0.5 continued to improve until 30 min after inhalation of procaterol. These results suggest that procaterol may first dilate the large airway and then may gradually dilate the small airway in bronchial asthma.

Adult↗
PubMed1988

Effects of airway anesthesia on ventilatory responses to graded dead spaces and CO2.

Ventilatory response to graded external dead space (0.5, 1.0, 2.0, and 2.5 liters) with hyperoxia and CO2 steady-state inhalation (3, 5, 7, and 8% CO2 in O2) was studied before and after 4% lidocaine aerosol inhalation in nine healthy males. The mean ventilatory response (delta VE/delta PETCO2, where VE is minute ventilation and PETCO2 is end-tidal PCO2) to graded dead space before airway anesthesia was 10.2 +/- 4.6 (SD) l.min-1.Torr-1, which was significantly greater than the steady-state CO2 response (1.4 +/- 0.6 l.min-1.Torr-1, P less than 0.001). Dead-space loading produced greater oscillation in airway PCO2 than did CO2 gas loading. After airway anesthesia, ventilatory response to graded dead space decreased significantly, to 2.1 +/- 0.6 l.min-1.Torr-1 (P less than 0.01) but was still greater than that to CO2. The response to CO2 did not significantly differ (1.3 +/- 0.5 l.min-1.Torr-1). Tidal volume, mean inspiratory flow, respiratory frequency, inspiratory time, and expiratory time during dead-space breathing were also depressed after airway anesthesia, particularly during large dead-space loading. On the other hand, during CO2 inhalation, these respiratory variables did not significantly differ before and after airway anesthesia. These results suggest that in conscious humans vagal airway receptors play a role in the ventilatory response to graded dead space and control of the breathing pattern during dead-space loading by detecting the oscillation in airway PCO2. These receptors do not appear to contribute to the ventilatory response to inhaled CO2.

Administration, Inhalation↗
PubMed1988

Role of CO2 responsiveness and breathing efficiency in determining exercise capacity of patients with chronic airway obstruction.

We examined the role of CO2 responsiveness and breathing efficiency in limiting exercise capacity in 15 patients with chronic airway obstruction (FEV1 = 0.88 +/- 0.25 L, mean +/- SD). Responses of minute ventilation and P0.1 (mouth pressure 0.1 s after the onset of occluded inspiration) to hypercapnia (delta VE/delta PCO2, delta P0.1/delta PCO2) were measured by rebreathing, and the ratio of the two (delta VE/delta P0.1) was defined as an index of breathing efficiency during hyperventilation. Exercise capacity was measured as symptom-limited, maximal oxygen consumption (VO2max/BW) in an incremental treadmill test and also as the 12-min walking distance (TMD). All patients discontinued the treadmill test because of dyspnea, and the exercise capacity correlated with the degree of airway obstruction, although there was a wide variability among patients with comparable FEV1. There were no significant correlations between the responses to CO2 and exercise capacity. However, there was a significant correlation between delta VE/delta P0.1 and VO2max/BW (r = 0.87, p less than 0.001) or TMD (r = 0.78, p less than 0.001), and these correlations remained significant even when the relational effects of FEV1 were taken out. These results support the hypothesis that airway obstruction and breathing efficiency are important, but that CO2 responsiveness is not a major factor in determining the exercise capacity of patients with chronic airway obstruction.

Aged↗
PubMed1988

Home sleep monitor for detecting apnea episodes by nasal flow and tracheal sound recordings.

We have developed a portable home sleep monitoring system using nasal airflow (NA), tracheal sound recordings (TSR), and electrocardiogram (ECG). NA was recorded by two thermisters. TSR was recorded by a microphone attached to the skin overlying the cervical trachea. Three kinds of signals were recorded with a cassette recorder. Thirty-seven outpatients who had sleep complaints were monitored during sleep at home using this recorder. Attachment of the pickups was performed by the patients themselves. Recordings were played back and analyzed by a personal computer to evaluate apnea episodes from TSR and R-R intervals beat by beat. This home monitoring system had labor-saving and cost-saving benefits and seemed to be a satisfactory technique for screening.

Ambulatory Care↗
PubMed1988

Effect of sleep position on obstructive sleep apnea.

In order to examine the effect of sleep position on sleep apnea episodes, seven male patients diagnosed as having obstructive sleep apnea syndrome without any organic complication of the upper airway were studied while lying in a supine or lateral position during an all-night polysomnographic study. Apnea index, apnea time/total sleep time (%) and the number of episodes per hour in which oxyhemoglobin saturation dropped below 85% decreased significantly from 51.0 +/- 8.6 (mean +/- S.D.) events/hr, 40.4 +/- 5.8% and 36.2 +/- 9.8 episodes/hr during sleep in supine position to 27.6 +/- 9.1 events/hr, 19.4 +/- 6.0% and 12.9 +/- 5.3 episodes/hr during sleep in lateral position, respectively. Lowest oxyhemoglobin saturation increased significantly from 70.7 +/- 2.6% to 78.0 +/- 2.4%. Thus, sleep in the lateral position may be a simple treatment before essential treatment for patients with obstructive sleep apnea syndrome.

Adult↗
PubMed1987

A new method of inhalation challenge with propranolol: comparison with methacholine-induced bronchoconstriction and role of vagal nerve activity.

To establish a safe procedure for examining propranolol-induced bronchoconstriction, we have developed a new method for performing inhalation challenge with propranolol. Monitoring respiratory resistance during tidal breathing with continuous inhalation of propranolol in 1.5-fold increasing concentrations from 0.78 to 30 mg/ml for 1 minute at each concentration, we tested 43 subjects with stable asthma and 10 normal subjects. We also compared bronchial responsiveness with responsiveness to inhaled methacholine on separate days. In addition, to determine the role of vagal nerve activity in propranolol-induced bronchoconstriction, we studied the effect of atropine. Inhaled propranolol caused dose-related bronchoconstriction in all subjects with asthma but not in normal subjects. None of the subjects suffered severe asthmatic attack during the test, which was performed in 15 minutes or less. The minimum cumulative dose of methacholine and of propranolol, at the point where respiratory conductance began to decrease, was not significantly correlated. Increased respiratory resistance was reversed by atropine in 70% of the subjects with asthma with marked individual differences. These data suggest that, although in most subjects with asthma, vagal nerve activity contributes in varying degree to bronchoconstriction, other constricting factors may contribute in the remaining subjects. It is also suggested that the mechanism of bronchial response to propranolol differs from that of the nonspecific airway reactivity estimated by methacholine challenge.

Adolescent↗
PubMed1987

Effect of digitalis on the diaphragm in anesthetized dogs.

We examined the effect of digitalis on diaphragmatic contractility and fatigability in 19 anesthetized mechanically ventilated dogs. The diaphragmatic force was assessed from transdiaphragmatic pressure (Pdi) developed at functional residual capacity against an occluded airway during cervical phrenic nerve stimulation. In a first group of five dogs, Pdi-stimulus frequency relationships were compared before and after administration of ouabain in doses of 0.01, 0.02, and 0.04 mg/kg. In a second group, diaphragmatic fatigue was produced by bilateral phrenic nerve stimulation at 30 Hz. Ten seconds of stimulation and 15 s of mechanical ventilation were repeated for 30 min. The rates of decrease in Pdi were compared between two groups, one of 0.05 mg/kg deslanoside-treated dogs (n = 7) and one of nontreated dogs (n = 7). After ouabain administration Pdi was significantly greater at each frequency in a dose-dependent manner. On the other hand, the rate of decrease in Pdi in the deslanoside group was significantly smaller than that in the nontreated group, whereas deslanoside did not greatly change the Pdi-frequency curves in fresh diaphragm. We conclude that ouabain improves contractility of the fresh diaphragm and that deslanoside has a protective effect against fatigability.

Animals↗