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Biomedical subjects

H Yamabayashi

Publications and source records attributed to H Yamabayashi.

At least 55 records · Page 3Linked to original sources
PubMed1988

An EMG analysis on regulation of the diaphragm and abdominal muscles.

Neural mechanisms regulating activities of diaphragm and abdominal muscles were investigated on anesthetized, tracheostomized and spontaneously breathing dogs. EMGs of costal diaphragm and external oblique (EO)abdominal muscle were recorded by fine-wire electrodes. The electrodes for diaphragm-EMG were implanted without opening abdominal cavity using laparoscopy. During quiet breathing the mean firing frequency of diaphragm-EMG was 7.6 +/- 0.7 (S.D.) Hz. The discharge spikes of diaphragm-EMG observed in early-inspiration or in post-inspiratory phase, were low in amplitudes, consistent with previous reports that phrenic motoneurons were comprised of two populations. During quiet breathing spikes were not observed in EO-EMG in a half of the animals, and were tonically-firing in the remaining dogs. Hypercapnia increased firing frequency of diaphragm-EMG, but did not recruit spikes of high amplitude. On the other hand, hypercapnia recruited EO-spikes of higher amplitude, and increased firing frequency. When spikes fired tonically in EO-EMG, hypercapnia suppressed these spikes during inspiration. Airway occlusion gradually recruited EO units of higher amplitude. Mechanical stimulation of upper airway suppressed tonic-EO activity during inspiration. In conclusion, we demonstrated that 1) abdominal wall is not related with control mechanism of diaphragm; 2) the control mechanism of dog's EO differs from cat's internal intercostal muscles; and 3) the tonic component of EO is affected by respiratory commands from higher neuronal architecture.

Abdominal Muscles↗
PubMed1985

[Blood volume measurement of newborn using stable isotope 50Cr].

A technique for the blood volume measurement of newborns was established in which nonradioactive 50Cr was used in patients for whom radioactive labels were not advisable. The red blood cells (RBC) in the newborn's blood withdrawn from umbilical cord after birth were tagged with enriched stable isotope 50Cr (96%, normal abundance 4.3%) and reinjected into the newborn. Blood samples (0.5 ml) were withdrawn at 30 min and thereafter at 6, 12, 24, 48, 72 and 120 hours old. Samples were centrifugalized and portion of RBC was then freeze-dried, weighed and sealed into polyethylene sheet bag together with 50Cr standard. Neutron irradiation was performed in the reactors of the JAERI with thermal neutron flux 5 X 10(13), 2 X 10(13), 8 X 10(13) cm-2s-1 at JRR-2, -3 and -4 respectively for 20 min and samples were left for about two weeks after irradiation. Induced radioactivity (51Cr, 59Fe) of the sample was measured with a Ge(Li) gamma-ray detector system and 4096 channels pulse height analyzer. Analysis of activity data was carried out by BOB-76 code. The RBC and total blood volume of the newborn was calculated using an isotopic dilution technique. We have investigated on tagging efficiency of 50Cr to RBC, washing effect and dilution rate by 50Cr content or 51Cr/59Fe ratio. Significant difference was observed in the total blood volume of newborns depending on the delivery style and in addition, it changed dynamically along the time elapsed after birth.

Blood Volume Determination↗
PubMed1983

Diaphragmatic flutter with a manifestation of high frequency ventilation.

A case of diaphragmatic flutter following status asthmaticus is presented. The initial symptom was tachypnea resembling hyperventilation syndrome. When spontaneous ventilation was completely suppressed for 15 minutes with intravenous administration of pethidine, levels of arterial blood gases were not much deviated from normal limits, because of possible high frequency ventilation. Although the medical therapeutics previously reported in literatures, including diphenylhydantoin, were ineffective in this case, butylophenones provided favourable results despite of some complications. The etiology and management of diaphragmatic flutter are discussed.

Adolescent↗
PubMed1983

Multiplicity of functional behavior of human intercostal muscles.

Single motor unit activity from the 6th intercostal space in five healthy adults was analyzed during rebreathing, voluntary deep inspiration, Valsalve maneuver and phonation. Action potentials and pneumotach flow were stored on tape and fed to the computer for subsequent analysis. Spike-by-spike analyses revealed three functional types of intercostal motor units. One unit fired almost exclusively during inspiration and its firing was augmented by rebreathing and voluntary deep inspiration (phasic I unit). The second type fired continuously throughout the respiratory cycle with an increase in firing during expiration (tonic E unit); its activity was disrupted during phonation but not during rebreathing, suggesting a postural rather than respiratory function. The third type, silent during quiet breathing, was recruited during rebreathing, voluntary deep inspiration or Valsalve maneuver; its firing started in late inspiration and ceased in early expiration (phase-spanning I-E unit). The relationships between tidal volume and inspiratory time during rebreathing showed that the third type was recruited when tidal volume reached a critical 'volume threshold', suggesting that vagal volume feedback is essential for its activation.

Adult↗
PubMed1982

Breath-by-breath VCO2 and VO2 required compensation for transport delay and dynamic response.

Both transport delay (DELAY) and dynamic response (RESPONSE) of a mass spectrometer would theoretically result in considerable errors in the breath-by-breath calculation of VCO2 and VO2. However, curiously, the contribution of RESPONSE has been ignored. The purpose of this study is to quantify the error caused by RESPONSE. We found that RESPONSE of a mass spectrometer was regarded as a first-order response. We determined DELAY and time constant (T) of RESPONSE and compensated the on-line calculation for both DELAY and RESPONSE and for DELAY only. With T of 150 and 100 ms, deviations of VCO2 from the gas-collection method were 8 +/- 6 and 8 +/- 6 ml/min with compensation for both DELAY and RESPONSE, and 69 +/- 10 and 50 +/- 5 ml/min with compensation for DELAY only, respectively (mean +/- SD). Similar results were obtained with VO2. A computer simulation of error caused by RESPONSE disclosed that the error linearly increased with increasing T. We conclude that to be accurate within +/- 5% of the exact value, compensation should be made when T exceeds 25 ms.

Biological Transport↗
PubMed1982

Measurement of functional residual capacity and pulmonary carbon monoxide diffusing capacity during mechanical ventilation with PEEP.

First, our new simplified method to measure FRC and DLCO simultaneously during mechanical ventilation was described in detail. Secondly, we applied the method to ARDS patients and observed the effects of PEEP on arterial blood gases (ABGs), FRC and DLCO of these patients. As reported hitherto, FRC was consistently increased by PEEP, whereas ABGs in some cases were not necessarily improved with increase in FRC. DLCO/FRC remained unchanged, although DLCO increased with PEEP. We concluded that the dissociation of FRC and ABG data in a group of patients could be caused by wasted ventilation which might be attributed to VA/Q unevenness.

Adult↗
PubMed1982

Paraquat poisoning--a review of four cases.

Paraquat poisoning has been associated with very high mortality. The toxic mechanism is considered to be related to the production of superoxide ions. Review of the literatures reveals that with vigorous treatment recovery from poisoning is not impossible. Clinical experience in four cases of paraquat poisoning and the principles of management of this intoxication are presented.

Adult↗
PubMed1980

Computer simulation of exercise hyperpnea.

An analog model which describes the behavior of gas exchange in the lung and of the respiratory control system has been developed to study the physiological mechanisms of exercise hyperpnea. The model consists of three major compartments (lung, brain and tissue) which are connected by circulation. The time delay to reach to the chemoreceptor site and the time constant of the chemoreceptor in response to changes in blood gases are included. Respiration is assumed to be controlled by both neurogenic and humoral factors which act independently and additively. The results showed that the model behavior in terms of steady-state and transient response to exercise and recovery from it was consistent with the experimental observations and suggested that the combination of humoral and neurogenic theory may explain the physiological mechanism of exercise hyperpnea.

Computers, Analog↗