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Biomedical subjects

I Yoshiya

Publications and source records attributed to I Yoshiya.

At least 145 records · Page 8Linked to original sources
PubMed1990

Measurement of functional residual capacity during high-frequency oscillatory ventilation (HFOV) by argon washout method without interruption of HFOV.

A modified indicator gas washout method was developed to measure functional residual capacity (FRC) during high-frequency oscillatory ventilation (HFOV) without interruption of HFOV. A hot-wire flowmeter and medical gas analyzer measured the flow rate and argon concentration, respectively, at the expiratory end of the respiratory circuit. Upstream of the hot-wire flowmeter, two heat-and-moisture exchangers for resistance and a rubber balloon for capacitance were placed to convert the oscillating expiratory flow to an almost continuous flow. This made it possible to measure FRC during HFOV without interrupting HFOV. To measure the volume of the entire respiratory circuit, a 10 percent argon in 90 percent oxygen gas mixture was initially used as a bias flow, and after equilibration, the test gas was switched to 100 percent oxygen. By electrical integration of the product of the expiratory flow rate and argon concentration, the total amount of argon equilibrated in the entire respiratory circuit was calculated. The volume of the circuit was calculated by dividing the total amount of argon by the initial argon concentration. Functional residual capacity plus the volume of the respiratory circuit was similarly calculated and the difference was estimated as FRC. The accuracy and reproducibility of our method were evaluated by using a one-compartment lung model. There was a high correlation between the volume setting of the model lung and the estimated FRC. This method can be used to estimate FRC in a one-compartment lung model during HFOV, and it is potentially useful in clinical situations.

Argon↗
PubMed1990

[A study on the utility of flumazenil for patients in the ICU].

Flumazenil, a specific antagonist of benzodiazepines, was administered to adult patients receiving treatment at ICU, and its utility to hasten recovery from sedation was evaluated in 40 patients and its usefulness for differential diagnosis of sedated conditions was also evaluated in 5 patients. The efficacy rate for recovery from sedation induced by benzodiazepines was 85.0%. Moreover, flumazenil was considered to be useful for differentiation of sedated conditions when causes were unknown. Depression of respiration improved in association with improvement of consciousness level. In some patients an elevation in blood pressure was also observed with improved consciousness.

Adult↗
PubMed1990

[Measurement of flow-resistive work of heat and moisture exchangers during simulated active breathing].

The performance of seven commercially available heat and moisture exchangers (HME) was evaluated in the dynamic flow state. A piston pump was used as a simulator with operative conditions with stroke volume of 500 ml and with respiratory rates of 20 and 40 cycles.min-1. A pressure-volume loop was produced for each HME and the flow-resistive work calculated. Each HME was studied under both dry and wet conditions. It was found that the flow-resistive work of the Humid-Vent 2 was the smallest and that of the Breathaid the largest under both conditions. The results suggest that application of HME causes a significant increase in resistance and demands a greater breathing effort from patients. Its use should thus be avoided in marginal patients.

Anesthesiology↗
PubMed1989

Effects of pentazocine and other opioids on the potassium-evoked release of [3H]noradrenaline from guinea pig cortical slices.

Noradrenaline release and its modulation via presynaptic opioid receptors were examined in guinea pig cortical slices. Slices preloaded with [3H]noradrenaline were superfused in the presence of desipramine (1 microM) and were stimulated by 16 mM K+. 1-Pentazocine inhibited the K+-evoked release of [3H]noradrenaline in a dose-dependent manner (3 x 10(-7)-10(-5) M), while d-pentazocine did not inhibit. This inhibitory effect of 1-pentazocine was antagonized by Mr 2266 (10(-6) M) but not by naloxone (10(-6) M). Among other opioids, dynorphin A-(1-13) and ethylketocyclazocine (kappa agonists) decreased the K+-evoked release of [3H]noradrenaline. Tyr-D-Ala-Gly-NMe-Phe-Gly-ol (DAGO, mu agonist) also inhibited [3H]noradrenaline release but was less potent than the kappa agonists. [D-Pen2,D-Pen5]enkephalin (DPDPE, delta agonist) and phencyclidine (sigma agonist) had no effects on the stimulated release of [3H]noradrenaline. Thus, it was shown that kappa receptors are the major subtype of opioid receptor involved in modulation of noradrenaline release in guinea pig cortex, and that 1-pentazocine inhibits the K+-evoked release of noradrenaline through activation of these receptors.

Animals↗
PubMed1989

Myocardial sensitization by thiopental to arrhythmogenic action of epinephrine in dogs.

This study examined the interaction between thiopental and epinephrine in inducing ventricular arrhythmias in dogs. The arrhythmogenic threshold of epinephrine was determined during anesthesia with either halothane alone, thiopental alone, etomidate plus different doses of thiopental, or halothane plus different doses of thiopental. The arrhythmogenic dose and the corresponding plasma concentration of epinephrine during thiopental anesthesia (plasma thiopental concentration: 46-57 micrograms/ml) were 0.77 +/- 0.04 micrograms.kg-1.min-1 and 10.7 +/- 1.5 ng/ml, respectively. During halothane anesthesia (end-tidal: 1.3 MAC) they were 2.59 +/- 0.49 micrograms.kg-1.min-1 and 45.3 +/- 9.2 ng/ml, respectively. The dose-effect relationship for the thiopental action was examined during etomidate plus thiopental and halothane plus thiopental anesthesia. The arrhythmogenic plasma concentration of epinephrine was inversely proportional to the plasma thiopental concentration during both anesthetics. During etomidate plus thiopental anesthesia, at plasma thiopental concentrations of 0, 11.2 +/- 0.83, 20.1 +/- 1.34, and 33.2 +/- 1.95 micrograms/ml, the corresponding epinephrine concentrations were 201.3 +/- 34.3, 142 +/- 19.5, 69.1 +/- 21.2, and 22.7 +/- 4.5 ng/ml. During halothane plus thiopental anesthesia, at plasma thiopental concentrations of 0, 10 +/- 0.86, 18.3 +/- 0.87, and 31.8 +/- 1.05 micrograms/ml, the corresponding epinephrine concentrations were 45.3 +/- 9.2, 34.6 +/- 8.9, 16.2 +/- 1.74, and 15.1 +/- 1.32 micrograms/ml, respectively. These results suggest that thiopental sensitizes the heart to epinephrine in a dose-dependent manner. This sensitizing action of thiopental would in part explain the thiopental potentiation of hydrocarbon anesthetic-epinephrine arrhythmias.

Anesthetics↗
PubMed1989

High-frequency oscillation for persistent fetal circulation after repair of congenital diaphragmatic hernia.

A female neonate who had been diagnosed as having congenital diaphragmatic hernia by ultrasonography was delivered by cesarean section. After the hernia was repaired, she developed hypoxemia and hypercapnia, probably due to persistent fetal circulation (PFC). Neither conventional mechanical ventilation (CMV) nor manual ventilation improved the respiratory status. High-frequency oscillation (HFO) successfully improved pulmonary gas exchange, but we failed to wean the patient from HFO by using intermittent HFO. The patient was again placed on CMV for weaning and was extubated on the 12th ICU day. We conclude that HFO can be an alternative respiratory modality in patients with respiratory failure due to PFC after the repair of congenital diaphragmatic hernia.

Female↗
PubMed1989

Comparison of recorded values from six pulse oximeters.

Recorded values (SpO2) of oxygen saturation from six noninvasive pulse oximeters were compared to each other and to the value from a cooximeter. Simultaneous measurements were obtained from each instrument in eight healthy nonsmoking volunteers rendered hypoxic greater than 70% SpO2. Functional arterial oxygen saturation (SaO2), fractional SaO2 (%HbO2), and percent fraction of carboxyhemoglobin (HbCO) and methemoglobin (MetHb) were determined by a cooximeter. The difference between SaO2 and %HbO2 was 2.3 +/- 0.3 (SD) % (p less than .001) with 1.4 +/- 0.1% HbCO and 0.9 +/- 0.1% MetHb. The SpO2 values in two instruments were close to %HbO2, while the other instruments correlated approximately with SaO2. The greatest SpO2 difference among the instruments was 2.7 +/- 1.9% (p less than .001). These results may indicate that, under normal dyshemoglobin levels, some pulse oximeters are calibrated to estimate SaO2 and others to estimate %HbO2. Since the pulse oximeter using two wavelengths cannot measure accurately %HbO2 or SaO2 in the presence of dyshemoglobin, SpO2 values would be independent from %HbO2 and SaO2. A standard calibration method for pulse oximeters should be established by the manufacturers.

Adult↗
PubMed1989

Effects of norepinephrine on renal function in septic patients with normal and elevated serum lactate levels.

Effects of iv norepinephrine (NE) on renal function were investigated retrospectively in 15 patients with hyperdynamic septic shock. All patients had either a low systolic BP less than 80 mm Hg, and/or oliguria less than 0.5 ml/kg-h. We examined their serum creatinine level (SCr), daily urine flow (UF), 24-h creatinine clearance (Ccr), and hemodynamic indices before and during NE infusion. Before NE administration, the patients were divided into those with with a serum lactate level (Lac) less than 20 mg/dl (group A, n = 9) and greater than 20 mg/dl (group B, n = 6). NE was infused continuously at rates between 0.05 and 0.24 microgram/kg.min which increased systolic BP by greater than or equal to 20 mm Hg. Cardiac index was not significantly changed in either group. In group A, NE increased both UF (p less than .05), and systemic vascular resistance index (SVRI) (p less than .01), but did not affect Ccr. In group B, NE did not increase UF nor SVRI, and decreased Ccr significantly (p less than .05). It is concluded that NE increased UF and SVRI only when Lac was in normal range; otherwise, NE reduced renal function. Thus, when administering NE to increase UF, both Lac and renal function should be monitored carefully.

Adult↗
PubMed1989

Rapid screening for Staphylococcus aureus infection by measuring enterotoxin B.

We developed a simple, sensitive laser nephelometric assay (LNA) to detect circulating staphylococcal enterotoxin B (SEB). This assay yields the result within 2 h and needs no special treatment. Influence of protein A, a product generated by Staphylococcus aureus, was negligible in this assay. The levels of SEB in plasma were measured in 28 patients with and without S. aureus infection with the LNA. The levels of SEB in plasma increased significantly in patients with S. aureus infection. We also demonstrated that the levels of SEB in plasma were higher in patients with methicillin-resistant S. aureus infection than in patients with nonresistant staphylococcal infection. Our data indicate that LNA is a useful assay in the early diagnosis of methicillin-resistant S. aureus infection.

Cross Reactions↗
PubMed1989

Jet flow-regulated expiratory resistance to maintain constant CPAP during the entire respiratory phase.

We have developed a new continuous positive airway pressure (CPAP) device that consists of a microcomputer, a pressure transducer, and a pair of electronic interface valves. One of these valves creates the inspiratory demand flow, and the other creates the opposing jet flow by acting as an expiratory valve to maintain a constant CPAP. By controlling the two electronic interface valves, the airway pressure can be kept constant during the entire respiratory cycle. We compared our device with CPAP systems supplied with commercially available ventilators: the Puritan-Bennett 7200a, the Bear 5, the Servo 900C, and the CV 2000. A two-chambered spring loaded model lung was used to simulate inspiration and a piston pump model lung to simulate active exhalation. We compared both the inspiratory triggering work (WWIt) and expiratory flow-resistive work (WE) of each ventilator while in CPAP mode by calculating the corresponding areas of the pressure-volume loops using electrical integration. The WWIt of our apparatus and demand-flow ventilators was much smaller than that of the CV 2000. In our device, WE was also much smaller than those of the others. These results indicate that our device can be used for CPAP without causing airway pressure fluctuation, and therefore, without imposing an extra workload on the patient.

Humans↗
PubMed1989

[Assessment of bleomycin-induced pulmonary fibrosis by bronchoalveolar lavage].

To elucidate the pathogenesis of adult respiratory distress syndrome (ARDS), bleomycin is often used to induce lung injury because of is acute inflammatory and late fibrogenic effects on the lung. This study was undertaken to determine if fibroblast growth factors or suppressive factors might exist in bronchoalveolar lavage fluid (BALF) when acute lung injury is induced by bleomycin in rats. In the experimental group, 1.5 U of bleomycin was administered intratracheally, whereas in the control group, saline solution was given. In both groups, rats were sacrificed serially up to 4 wks. In each rat, bronchoalveolar lavage was done three times using an aliquot of 5 ml saline solution. BALF was centrifuged to obtain cells and supernatants which were further fractionated by gel-filtration. Fibroblast stimulatory and inhibitory activities were evaluated by [3H]-thymidine incorporation by fibroblasts. In the experimental group, the recovered cell count increased threefold compared with the control group and most of the increase was attributed to the increase of neutrophil. The fraction whose molecular weight is about 20,000 potentiated the [3H]-thymidine incorporation by fibroblast and its peak activity was found on the 5th day after BLM administration. On the other hand, the fraction of small molecular weight (less than 1,000) showed inhibitory activity which did not change throughout the study period. These results suggest that the imbalance between the fibroblast stimulatory and inhibitory activities after the acute lung injury may have a key role to develop pulmonary fibrosis.

Animals↗
PubMed1989

Effects of d- and l-pentazocine on the release and uptake of norepinephrine in rat brain cortex.

Effects of d- and l-pentazocine on the release and uptake of norepinephrine and other neurotransmitters were examined in rat cerebral cortex. D- and l-pentazocine (10(-6)-10(-4) M) evoked the release of tritium from rat cortex slices preloaded with [3H]norepinephrine. Both isomers of pentazocine (3 x 10(-5) M) also evoked the release of tritium from slices preloaded with [3H]dopamine and [3H]5-hydroxytryptamine ([3H]5-HT) but did not from those preloaded with [3H] gamma-aminobutyric acid ([3H]GABA) and [3H]choline. The releasing effect of pentazocine was neither dependent on the extracellular calcium nor antagonized by naloxone. Both isomers inhibited the uptake of [3H]norepinephrine, [3H]dopamine and [3H]5-HT but not that of [3H]GABA and [3H]choline into synaptosomes prepared from the cortex. These results suggest that the effects of d- and l-pentazocine on release and uptake are relatively specific to monoamines and might explain some aspects of pharmacological actions of pentazocine.

Animals↗
PubMed1989

[Changes in the electroretinogram during enflurane anesthesia].

We have investigated a method of intraoperative monitoring of anesthetic depth using the electroretinogram (ERG). The effects of enflurane on ERG were studied in 12 patients undergoing surgical procedures. Recordings were made at 0%, 0.8%, 1.7% end-tidal enflurane concentrations. There were statistically significant increases in the latencies of the a-waves, b-waves and oscillatory potentials (OP) with increasing concentrations of enflurane. The amplitudes of the a-waves were reduced with increasing concentrations of enflurane, but the amplitudes of the b-waves did not change. The latencies of OP were thought to be the most sensitive indicator of the anesthetic depth among these parameters. To apply this technique to clinical practice, there were many problems to be solved. However, this may be one of useful monitors of anesthetic depth in future.

Adult↗
PubMed1989

[Quantitative comparison of ventilator-induced work during simulated CPAP in eight demand-flow valve ventilators].

The ventilator-induced work during continuous positive airway pressure (CPAP) mode in demand-valve ventilators was evaluated by using a piston pump as a simulator for active breathing. A piston pump delivered and withdrew a stroke volume of 500 ml at rates of 10, 20 and 40 cycle.min-1 with a sinusoidal waveform. A hot-wire flowmeter and a differential pressure transducer were interposed between the pump and ventilators and their signals were fed to a microcomputer to display a pressure-volume loop. The area of the loop was divided into the four parts. Inspiratory work associated with the opening of the demand valve was represented by the area of baseline airway pressure (BPa) during inspiration. The remaining area during inspiration reflected the work done by the ventilators. Expiratory work for overcoming the flow resistance of the expiratory apparatus was represented by the area above BPa during exhalation. The fourth was the area below the baseline during exhalation. The Puritan-Bennett 7200a, the Bear 5, the Siemens Servo 900C, the Hamilton Veolar, the Bird 6400ST, the Engström Erica, the Dräger EV-A, and the CPU-1 were examined at varying CPAP and pressure support levels. Because of demand valve oscillation throughout inspiration, the inspiratory workload of the Bear 5, the Siemens Servo 900C, the Hamilton Veolar, the Bird 6400ST, and the Dräger EV-A could not be calculated. Expiratory flow-resistive work was higher in the Siemens Servo 900C and the Bird 6400ST than the others. The present system can assess the entire performance of ventilators, and may serve to compare ventilators' performance.

Evaluation Studies as Topic↗
PubMed1989

[Clinical evaluation of buprenorphine suppositories in postoperative patients--plasma concentrations and effects on the respiratory and circulatory system].

The plasma concentrations of buprenorphine were measured and blood gas analysis was done after administration of buprenorphine suppositories (0.2 and 0.4 mg) or its intramuscular injection (0.2mg) in postoperative patients. The C max for 0.4mg suppositories was comparable to that for 0.2mg injection, whereas the T max for suppositories was as large as about 2 hrs in contrast to 1.5 hrs for 0.2mg injection. The size of AUC was in the following order: 0.4mg suppositories greater than 0.2mg injection greater than 0.2mg suppositories. Neither notable increase in PaCO2 nor decrease in respiration rate was observed after administration of the suppositories, indicating that the formulation will not cause clinically significant respiratory depression. No significant changes were observed in blood pressure or pulse rate. Buprenorphine suppositories are considered to be safe for use in postoperative patients. Percent pain relief in the suppository group was smaller than that in the injection group. This appears to be due to a slower rate of increase in the plasma levels of buprenorphine after administration of suppositories than that after intramuscular injection. Therefore, it seems practical to give this drug to postoperative patients before the start of pain.

Administration, Rectal↗
PubMed1989

[Analgesia and anesthesia induced by subanesthetic concentrations of nitrous oxide].

This study was aimed to determine 1) the changes of the anesthetic and analgesic actions of inhalation of subanesthetic concentration of nitrous oxide, and 2) the possible antagonism by naloxone of these actions. Auditory response time (anesthetic action) and pain threshold (analgesic action) were examined before, during and after inhalation of subanesthetic concentration of nitrous oxide in six normal volunteers who were treated with or without intravenous administration of naloxone 1.4 mg. Analgesic action remained at 30 min after nitrous oxide inhalation, while auditory response time returned to control values. Both anesthetic and analgesic effects were unchanged during 100 min inhalation or administration of naloxone. These results indicate that the acute tolerance to these actions of nitrous oxide will not occur, and that naloxone will not show a significant antagonistic action as is observed with morphine.

Administration, Inhalation↗