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Biomedical subjects

M Ohi

Publications and source records attributed to M Ohi.

At least 19 recordsLinked to original sources
PubMed1992

Dynamic control of breathing during exercise and hypercapnia.

The dynamic influences of end-tidal CO2 and exercise on ventilation are compared when CO2 and exercise are imposed separately and when they are imposed simultaneously. Five human subjects are studied. The subjects performed three trials: random work rate forcing, random CO2 inhalation and their simultaneous loading. The work rate was varied between 20 and 80 W as a pseudorandom binary sequence. The concentration of inspired CO2 was varied randomly between 0 and 7 per cent, adjusted so that it produced approximately the same amount of ventilatory fluctuations as the random work load. The relative contribution of each variable was analysed using multivariate autoregressive analysis at frequencies ranging from 0.1 to 1 cycle min-1. The results show that the dynamics of the response to CO2 inhalation, exercise and their combination are nonlinear and that the combination of CO2 inhalation and exercise magnifies the nonlinear behaviour. Ventilation is largely unaffected by either work rate or end-tidal CO2 at 1 cycle min-1. During simultaneous CO2 and work rate forcing, ventilation tends to follow the change in the end-tidal CO2.

Adult↗
PubMed1992

[Hyperventilation syndrome].

Of 16 patients with hyperventilation syndrome (HVS), 11 experienced hypoxemic episodes (defined as PaO2 < or = 60 Torr or SaO2 < or = 90%). To investigate the relationship between hypoxemia in HVS patients and their hypoxic ventilatory response (HVR), we examined 9 of 11 HVS patients who experienced hypoxemic episodes after acute hyperventilation attacks. In order to investigate the genesis of hypoxemia after hyperventilation, we also examined minute ventilation and visual analog scale (VAS) scores representing the sensation of dyspnea at the start and at 70% arterial O2 saturation (SaO2) during HVR in 9 normal subjects under isocapnia and hypocapnia following voluntary hyperventilation (VHV). The HVR of 9 HVS patients who experienced hypoxemic episodes was normal. In 9 normal subjects, minute ventilation and VAS scores representing the sensation of dyspnea at 70% SaO2 during HVR were higher under isocapnia than under hypocapnia following VHV (p < 0.01). VAS scores taken during the HVR immediately following VHV and at 70% SaO2 were not significantly different. HVR and VAS scores representing the sensation of dyspnea were decreased under hypocapnia following VHV. These reductions were thought to be the main factors responsible for the genesis of hypoxemia following acute hyperventilation attacks in HVS patients. We conclude that hypoxemia is an important clinical sign in HVS patients, and it is important to investigate the breathing and chemical drive under hypocapnia, in order to understand the chemical regulation of breathing in HVS patients.

Adult↗
PubMed1992

[Therapy and clinical symptoms in patients with obstructive sleep apnea in Japan].

To investigate the long-term outcome of therapy and clinical symptoms of patients with OSAS (obstructive sleep apnea syndrome) in Japan, we studied 34 patients with OSAS who had been diagnosed by standard polysomnography more than one years (36.0 +/- 19.7 months: mean +/- SD) previously. They were 53.8 +/- 10.5 years old, body mass index was 27.8 +/- 5.2 kg/m2, and AHI (apnea & hypopnea index) was 50.0 +/- 24.2/h. The subjects had achieved weight loss (p less than 0.01), but had regained their initial weight at our follow-up. Eleven patients with OSAS were initially candidates for NCPAP (nasal continuous positive airway pressure), but only 5 patients used it for a prolonged time. The other 6 patients with OSAS could not use NCPAP because they did not wish to purchase a NCPAP instrument. One of 5 patients who used NCPAP for a long time died from lung cancer; thus, 4 patients used NCPAP continuously. Ten patients were commenced on ACZ (acetazolamide); however, only 5 patients took it continuously. ACZ resulted in some improvements in the sleep parameters (AHI index, desaturation time below SaO2 90%), but apnea & hypopnea duration and the difference in transcutaneous PCO2 between wake and sleep were not significantly improved by ACZ administration. ACZ was not as effective as NCPAP. Almost 60% of patients with OSAS had excessive daytime sleepiness. Hypertension was detected in about 60% of patients. Nine of 25 patients who had an automobile license had had more than one automobile accident. Nine patients who had had more than one automobile accident showed AHI greater than or equal to 30 in our study.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidents, Traffic↗
PubMed1992

[Application of nasal intermittent positive pressure ventilation to a case of limb-girdle muscular dystrophy].

We applied nocturnal ventilation (NV) with nasal intermittent positive pressure ventilation with custom molded mask (NIPPV-C Mclermott, 1989), as well as NV with tracheostomy intermittent positive pressure ventilation (TIPPV) to a male patient with limb-girdle muscular dystrophy who had developed chronic respiratory failure at the age of 47. NV with both methods successfully corrected nocturnal hypoxemia, improved daytime arterial blood gas values, and achieved a stable clinical course without marked deterioration for four years. Daytime PaO2 higher than 60 Torr and PaCO2 lower than 70 Torr while breathing room air were maintained with both methods, whereas PaO2 was lower than 50 Torr and PaCO2 higher than 70 Torr before the implementation of NV. TIPPV was safely suspended repeatedly for as long as two weeks, maintaining daytime PaO2 higher than 50 Torr. NIPPV-C was also repeatedly suspended for two weeks. Occasionally PaO2 dropped as low as 40 Torr after periods without NV; however, it was restored to higher than 60 Torr after one or two nights' NIPPV-C. These facts suggest that NV had a restorative effect on respiratory muscle fatigue in the present case. While on NIPPV-C, nighttime SaO2 was higher than 90% for 94% of the total time, and between 80% and 90% for the remaining 6% of the time. Desaturation for short periods was thought to be due to oral air leakage, which made the method slightly less effective than TIPPV. However, the overall clinical effectiveness of NIPPV-C was comparable to that of TIPPV.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic Disease↗
PubMed1991

Diagnostic value of Lipiodol injection in focal nodular hyperplasia of the liver.

We encountered a case of small focal nodular hyperplasia (FNH) of the liver. It was difficult to distinguish FNH from hepatocellular carcinoma by means of sonography, computed tomography (CT), and angiography. After the injection of Lipiodol, it accumulated densely on FNH, but was washed away after a short time, as observed on the follow-up CT. This progress was different from that in hepatocellular carcinoma.

Adult↗
PubMed1990

[Tuberculosis sequelae: pathophysiological aspect (ventilation)].

The percentage of the patients with PaCO2 more than 60 Torr and PaO2 more than 50 Torr were 13% in the patients with tuberculosis sequela (N = 502) and 4% in the patients with chronic obstructive lung disease (COLD, N = 727), who were treated with home oxygen therapy in the western region of Japan. Patients with chronic respiratory failure caused by tuberculosis sequela have higher PaCO2 than patients with COLD. Although the prognosis of patients with hypercapnia and moderate hypoxemia is not necessarily poor, some patients may need treatment for severe hypoventilation to prevent respiratory muscle fatigue and abnormal breathing during sleep. In this study, nine patients with hypercapnic chronic respiratory failure caused by tuberculosis sequela were ventilated by Chest Negative Pressure Ventilation (CNPV). The patients were monitored as in polysomnography by transcutaneous PCO2 (PtcCO2) electrode and Respiratory Inductance Plethysmography (RIP). Tidal volume induced by CNPV was larger during mouth breathing (504 +/- 128 ml, mean +/- s.d.) than during nose breathing (438 +/- 109 ml) calculated from RIP in awake state (N = 7). Oxygen saturation measured by ear oximeter and PtcCO2 were 94.4 +/- 2.9% and 57.8 +/- 12.2 Torr in awake state. Following CNPV SaO2 and PtcCO2 were 95.7 +/- 3.0%, 42.7 +/- 12.1 Torr in awake state (N = 9) and 93.0 +/- 4.4%, 57.0 +/- 15.7 Torr in Non-REM sleep (N = 5), respectively. CNPV is effective in these patients in awake state. During Non-REM sleep, CNPV maintains the PtcCO2 level only in awake state.

Aged↗
PubMed1990

[Upper airway function and non-intubated, assisted ventilation].

The influence of upper airway patency on ventilation assisted by chest negative pressure ventilation (CNPV) or nasal intermittent positive pressure ventilation (nIPPV) was studied as follows. 1) In seven patients with chronic respiratory failure (PaCO2 more than 50 Torr), the increase in tidal volume (VT) induced by CNPV was larger during mouth breathing than during nose breathing in the awake state. On CNPV transcutaneous PCO2 (PtcCO2) decreased during awake state, but increased during NREM sleep. 2) In four patients with chronic respiratory failure (PaCO2 more than 60 Torr), nIPPV induced the leakage of air from mouth in more than 20 cmH2O of nasal mask pressure during sleep. PtcCO2 increased during sleep, especially during REM sleep in spite of nIPPV. The change in PtcCO2 during REM sleep on nIPPV comparing awake state was 16.1 +/- 1.4 torr and comparing REM sleep in usual sleep was -6.0 +/- 1.4 Torr. 3) Upper airway resistance (UAR) was measured in two patients with tracheostomy. An increase in UAR was associated with a linear decrease in VT during nIPPV, although associated with a curvilinear decrease in VT during CNPV. These results indicate that the efficiency of CNPV and nIPPV depends on the patency of upper airway.

Adult↗
PubMed1989

Breathing during sleep with mild hypoxia.

To investigate ventilatory response to mild hypoxia during non-rapid-eye-movement sleep, we administered approximately 16% O2 (which corresponds to concentrations found in commercial high altitude air craft) to 12 normal subjects by using a Venturi mask, which did not alter the breathing pattern during this study. Under mild hypoxia, inspiratory minute ventilation during sleep showed an initial rapid increase (P less than 0.001) but then declined significantly (P less than 0.001) and stabilized. Stable levels differed among individuals and, compared with those measured before hypoxia, were significantly lower in some subjects, higher in one, and essentially unchanged in the others. The initial rapid increase in minute ventilation after mild hypoxia during sleep correlated with the respective values of hypoxic ventilatory response during the awake state (P less than 0.01), but the final lowered levels did not. We conclude that the ventilatory response after mild hypoxia during sleep is biphasic and hypoxic depression exerts considerable influence on ventilation under mild hypoxia during sleep. So we should take hypoxic depression into consideration to evaluate the response to hypoxia during sleep.

Adult↗
PubMed1979

Topical heat therapy for cutaneous chromomycosis.

An aged man with a large scaly plaque over the left buttock was successfully treated by local heat therapy using an electric bed-warmer with a surface temperature of 46 degrees C. Clinically, the lesion involuted completely after two months of treatment. This was concomitantly confirmed by histopathological and mycological studies of biopsy specimens obtained from the lesion at an interval of several weeks. The isolated fungus strain of Fonsecaea pedrosol could grow at 37 degrees C on Sabouraud's dextrose agar, but was totally eradicated 24 hours after the culture was incubated at 46 degrees C. We consider that local heat therapy carried out under strict supervision is a quite effective treatment for chromomycosis. Moreover, it can be performed safely and without much discomfort to patients, and can yield satisfactory results in a relatively short time.

Aged↗
PubMed1978

Doxapram hydrochloride in the treatment of acute exacerbation of chronic respiratory failure. A patient with four episodes treated without use of a respirator.

A 51-year-old woman with chronic respiratory failure (status after tuberculosis) was given an infusion of doxapram hydrochloride (1 to 2 mg/kg of body weight per hour) for four episodes of acute exacerbation of her condition. Treatment with the drug prevented worsening of hypercapnia in the four episodes, when administration of 24 percent oxygen had occasioned rises in the arterial carbon dioxide tension of 23, 10, 9, and 7 mm Hg.

Carbon Dioxide↗