Biomedical subjects

T Mizuguchi

Publications and source records attributed to T Mizuguchi.

At least 91 records · Page 5Linked to original sources

PubMed1991

Fluctuating CPAP (F-CPAP) versus conventional CPAP (C-CPAP) in dogs with blood aspiration.

Fluctuating CPAP(F-CPAP) is a combination of spontaneous ventilation and fluctuating PEEP, in which end-expiratory pressure (EEP) is periodically changed within a certain range. In a dog model with localized lung injury induced by the aspiration of non-heparinized blood (2 ml.kg(-1) body weight), we carried out a comparative study of the effects of F-CPAP in which the EEP was cyclically changed from 4 to 12 cmH(2)O with periods of 10 min and those of conventional CPAP with a fixed EEP of 8 cmH(2)O (C-CPAP), on hemodynamics and pulmonary oxygenation. The blood aspiration produced significant increases in the intrapulmonary shunt (Qsp/Qt), the alveolar-arterial difference of partial pressure of oxygen (A-aD o(2)), and the respiratory rate (RR). Although both F-CPAP and C-CPAP reduced Qsp/Qt and A-aD o(2) and RR, 7 dogs treated with F-CPAP showed a significantly greater recovery of Qsp/Qt and A-aD o(2) than 7 dogs treated with C-CPAP. There were no significant differences in hemodynamic variables between the two groups. These results suggest that F-CPAP is more useful in the treatment of some kinds of hypoxic respiratory failure due to uneven distribution of lung injury.

Journal Article↗

PubMed1991

Enflurane suppresses phrenic nerve-diaphragm transmission in vivo.

We examined the effects of enflurane on the diaphragmatic function in 15 pentobarbital-anesthetized, mechanically ventilated dogs. They were divided into three groups of five animals each, according to the administered concentration of enflurane. The diaphragmatic function was assessed from transdiaphragmatic pressure (Pdi) and integrated diaphragmatic electromyography (Edi) developed at functional residual capacity against an occluded airway during bilateral supramaximal phrenic nerve stimulation at 0.5, 10, 20, 50 and 100 Hz under quasiisometric condition. After a control measurement, enflurane was administered at a constant end-expired concentration (0, 0.5 and 1 MAC) and the measurement was repeated after 1 hour of exposure. The Pdi amplitude generated by single twitch (0.5 Hz) and during 10, 20 and 50 Hz stimulation was unchanged between the groups. No change in Pdi during 100 Hz stimulation was noted during 0 and 0.5 MAC exposure, while it was reduced by 1 MAC of enflurane. When the values of Pdi were expressed as % of maximum Pdi (%Pdi,max) that developed during control measurement and analyzed in terms of %Pdi,max-stimulus frequency relationship, a significant decrease in %Pdi,max was noted for 100 Hz stimulation in 0.5 and 1 MAC groups compared to the control. Similarly, Edi during 100 Hz stimulation obtained in 0.5 and 1 MAC groups was markedly depressed compared to the control. Edi during 50 Hz stimulation was also decreased at 1 MAC. Relative changes in Edi following enflurane administration were greater than the corresponding changes of Pdi. These results demonstrate that enflurane impairs diaphragmatic function through its inhibitory effects on neuromuscular transmission.

Journal Article↗

PubMed1991

Effects of portal vein occlusion on myocardial contractility.

We studied canine left ventricular contractile performance following 15 min of portal vein occlusion by analyzing the end-systolic pressure diameter relationship (ESPDR) which many investigators have reported as being independent of changes in preload and afterload but sensitive to changes in ventricular contractility. Portal vein occlusion for 15 min decreased the mean arterial pressure, left ventricular peak systolic pressure, and cardiac index, while the release of the occlusion gradually increased these values, although it did not restore them to the control values. The systemic vascular resistance index increased during portal vein occlusion and returned to the control values after release. Left ventricular end diastolic diameter decreased during portal clamping and returned to the control values after release. ESPDR and percent shortening were not significantly changed during or after portal clamping. These results indicate that the decrease in blood pressure during portal vein occlusion was not due to a reduction in myocardial contractility but rather was due to a reduction in preload.

Journal Article↗

PubMed1991

Evaluation of analgesic effect of low-power He:Ne laser on postherpetic neuralgia using VAS and modified McGill pain questionnaire.

In order to investigate the efficacy of low-power He:Ne laser in treatment of pain, we irradiated 18 outpatients with severe postherpetic neuralgia. The efficacy of the low-power laser treatment was evaluated using a four-grade estimation, visual analog scale (VAS), and modified McGill pain questionnaire (m-MPQ) after every 10 of as many as 50 irradiations. The efficacy rate using a four-grade estimation at the end of 50 treatments was 94.4%. VAS decreased from 6.2 before irradiation therapy to 3.6 after 50 treatments, and the degree of pain relief was reduced to 44.6% and correlated with the number of treatments. The total numbers of words and the total scores of the m-MPQ decreased as the number of treatments increased. No complications attributable to the laser therapy were observed. These results suggest that repeated irradiation with low-power He:Ne laser is an effective and safe therapy for postherpetic neuralgia.

Adult↗

PubMed1991

Red and green low-powered He-Ne lasers protect human erythrocytes from hypotonic hemolysis.

The effect of low-powered He-Ne lasers (red beam, 632.8 nm, 10.2 mW, and green beam, 543.5 nm, 0.44 mW) on hypotonic hemolysis in human red cells was investigated. Red cell solutions (0.9% NaCl, pH 7.00) were centrifuged and the sediments were irradiated with the red or the green beam for 0 (control), 1, 3, 5, 7, 10, 15 and 30 minutes. Each of the 40 irradiated samples were transferred into hypotonic solution (0.405% NaCl, pH 7.00). After leaving the samples at room temperature for 10 minutes, optical density of every suspension was measured spectrophotomechanically at a wavelength of 545 nm to determine hemoglobin content. Hemolysis percentages of the control samples in hypotonic solution were 52.2 +/- 10.7% (mean +/- SD, N = 20) in the red group and 55.0 +/- 12.0% (N = 20) in the green group. Relative values of hemolysis in the hypotonic solution after irradiation with the red or the green beam decreased significantly between the 7- and 30-minute irradiation. These results demonstrate that low-powered He-Ne lasers have a protective effect on red cell membranes from hypotonic hemolysis and stabilize the cell membranes.

Erythrocyte Membrane↗

PubMed1991

Effects of partial paralysis on the swallowing reflex in conscious humans.

The ability to swallow may be affected by administration of a small dose of muscle relaxant. To test the hypothesis that a subparalyzing dose of a muscle relaxant can impair swallowing, effects of partial paralysis produced by pancuronium on the swallowing reflex were investigated in eight conscious subjects. The swallowing reflex was induced by a bolus injection or a continuous infusion of distilled water into the mesopharynx. The swallowing function was assessed by electromyogram of suprahyoid muscles (EMGSH), mesopharyngeal pressure (Pmeso), and hypopharyngeal pressure (Phypo). Peripheral muscle activity was simultaneously determined by train of four ratio (TOFR) of hypothenar muscles to electrical stimulation of ulnar nerve and by hand grip strength (HGS). Following control measurements, measurements during partial paralysis and after recovery from partial paralysis were performed after intravenous administration of pancuronium 0.02 mg/kg. Partial paralysis significantly depressed EMGSH (bolus injection 44.1 +/- 10.0%, continuous infusion 55.9 +/- 10.2% of control value, P less than 0.01). Pmeso also significantly decreased (bolus injection 64.9 +/- 6.7 to 47.8 +/- 5.8 mmHg, P less than 0.01; continuous infusion 63.4 +/- 7.7 to 52.5 +/- 5.8 mmHg, P less than 0.05). The TOFR of peripheral muscles decreased to 81.4 +/- 6.7% of control value (P less than 0.01), and HGS was reduced from 44.6 +/- 1.9 to 39.4 +/- 2.0 kg (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Breathing pattern and occlusion pressure waveform in humans anesthetized with halothane or sevoflurane.

To examine the ventilatory effects of sevoflurane, breathing pattern, airway occlusion pressure waveform, and the mechanical variables of the respiratory system were determined in seven subjects anesthetized with sevoflurane and in an additional seven subjects anesthetized with halothane. All patients breathed 1 MAC of anesthetic using oxygen as the carrier gas, and the measurements were performed in the absence of surgical stimulation. The durations of inspiration and expiration were significantly longer during sevoflurane than during halothane administration. Tidal volumes were larger in the sevoflurane group than in the halothane group. Occlusion pressure waveforms were also markedly different between the two groups. Occlusion pressure during the initial 300-400 ms tended to be less in the sevoflurane-anesthetized than in the halothane-anesthetized subjects. There was no evidence of an active Hering-Breuer reflex with either anesthetic. Mechanical variables of the respiratory system were essentially identical between the two anesthetics. We conclude that (a) the ventilatory effects of halothane and sevoflurane are different, (b) the difference in the respiratory timing and depth of breathing originates from the action of the anesthetics on the central respiratory neural network, and (c) the different shape of the tracheal occlusion pressure may be largely due to the different effects of halothane and sevoflurane on the muscles of the rib cage.

Airway Resistance↗

PubMed1991

[Effects of erythroid differentiation factor on inhibition of erythroid colony-formation (CFU-E and BFU-E) by the sera and on BPA secretion by peripheral mononuclear cells in patients with chronic renal failure].

The effect of erythroid differentiation factor (EDF) on the colony formation of erythroid cells (CFU-E and BFU-E) inhibited by the sera from the patients with chronic renal failure (CRF) was evaluated by methylcellulose assay. EDF restored the inhibited formation of CFU-E colony irrespective of the absence or presence of the accessory cells. In addition, EDF was considered to recover BFU-E colony formation through the burst promoting activity (BPA) secreted by the adherent cells. A suicide experiment using 3H-thymidine revealed that EDF acted to induce BFU-E from resting phase to S phase of the cell cycle. Moreover, the number of circulating BFU-E and the secretion of BPA by the mononuclear cells, both of which were significantly low in CRF patients, were also moderately increased by the addition of EDF. These data suggest that EDF could be utilized as a therapeutic agent for pathogenetic factors except hypoproduction of erythropoietin on the anemia of the patients with CRF.

Activins↗

PubMed1991

The incidence of cancer pain and improvement of pain management in Japan.

A nation-wide survey (1987) of cancer pain and analgesic methods showed that the incidence of pain in the terminal stage was in the range of 68 to 72% without any significant difference between hospital groups. Irrespective of the stage of illness, a certain analgesic effect was obtainable with oral/parenteral use of opioids. As a result of a year-to-year comparison of pain in cancer clinics, it was found that the rate of complete pain relief has increased for all stages of illness, especially in the terminal stage. Here the rate of complete pain relief steadily increased from 37.8% in 1986 to 42.7% in 1987 and 48.6% in 1988. Propagation of WHO-advocated cancer pain therapeutics has led to an improvement of the rate of pain relief in the terminal stage. Marketing of MS Contin tablets resulted in a dramatic increase in the consumption of morphine, but there was no increase in the rate of pain relief due to poor measures to counter adverse reactions, and to administration of morphine in insufficient doses. The consumption of morphine for medical use increased year by year, but a greater number of doctors experienced in the use of opioids would further improve the management of pain. To realize that, it would be necessary to incorporate terminal care into medical education programmes as soon as possible. Further efforts will be required for extensive research and propagation of analgesic methods in various fields including education in medicine, science of nursing and postgraduate education.

Adult↗

PubMed1991

[An analysis of the ventilatory response to carbon dioxide during halothane, isoflurane, or enflurane anesthesia in humans].

To analyze the effects of halothane, isoflurane, or enflurane on the ventilatory response to CO2, minute volume (VE), respiratory rate (f), occlusion pressure, mean inspiratory flow rate (VT/TI), and effective elastance (Pmax/VT) were measured in 26 patients during quiet breathing and when the respiratory system was stressed by CO2. Comparison was made at equipotent anesthetic concentration (1 MAC) and all measurements were made in the absence of surgical stimulation. Respiratory rate and Pmax/VT were unchanged in all groups after end-tidal CO2 was elevated. By contrast, VE, VT/TI, and occlusion pressure increased in all the groups when the respiratory system was stressed by CO2. Among the parameters tested delta VE/delta PaCO2 and delta VT/TI/delta PaCO2 were significantly (P less than 0.05) greater during halothane anesthesia than during isoflurane or enflurane anesthesia. We conclude that, at equipotent anesthetic concentrations, isoflurane and enflurane depress CO2 chemosensitivity more than halothane does, and that such effect is primarily related to the greater depressant effects of isoflurane and enflurane on the respiratory driving mechanisms.

Adult↗

PubMed1991

Suppression of hematopoiesis by activated T-cells in infectious mononucleosis associated with pancytopenia.

Two patients with primary Epstein-Barr virus (EBV) infection followed by pancytopenia were studied. They showed increased numbers of DR-positive, activated T-cells and serological evidence of persistent EBV infection over a 12 and 18 week period. Bone marrow granulocyte-macrophage colony formation (CFU-GM) was investigated by limiting dilution assay (LDA) and methylcellulose assay. CFU-GM of bone marrow mononuclear cells (BMMNC) was markedly suppressed in both patients during the pancytopenic phase. Removal of bone marrow T-cells by E-rosetting resulted in a significant increase of CFU-GM to normal levels in BMMNC of both patients, while no significant increase was observed in the BMMNC of normal subjects. CFU-GM in BMMNC from Patient 1 in the recovery phase was normal when DR-positive T-cells were within normal levels, irrespective of the presence or absence of T-cells. These results suggest that pancytopenia due to infectious mononucleosis in these patients was due to bone marrow suppression by activated T-cells. In vitro studies with Con A activated T-cells and their culture medium showed that suppression of CFU-GM by T-cells was mediated by a lymphokine.

Adult↗

PubMed1991

[The perimedullary vascular channel does not play a particularly important role in causing respiratory depression after epidural fentanyl].

The authors studied the role of the perimedullary vascular channel on long-lasting respiratory depression after the epidural administration of fentanyl 0.2 mg. At the first step, we compared the blood concentration of fentanyl in the azygos vein after thoracic epidural and that after caudal administration. After thoracic epidural administration, the peak concentration usually occurred at 3 min post-injection and averaged 7.6 +/- 1.6 ng.ml-1. After caudal administration, fentanyl concentrations were always below the limit of detection (1 ng.ml-1) in all patients throughout the course. At the second step, based on the results of the first step, we compared the respiratory effects of thoracic epidural fentanyl with those of caudal fentanyl. Th11-12 epidural fentanyl depressed ventilatory response to CO2 in the same fashion and to the same degree as caudal fentanyl. All these results suggest that the perimedullary vascular channel does not play a particularly important role in causing respiratory depression after epidural fentanyl.

Adult↗

PubMed1990

Respiratory inductance plethysmography and pulse oximetry in the assessment of upper airway patency in a child with Goldenhar's syndrome.

The anaesthetic management of a child with Goldenhar's syndrome and upper airway dysmorphology is presented. She had a history of severe dyspnoea due to deterioration of cor pulmonale caused by upper airway obstruction. The patency of the upper airway and oxygenation were evaluated during the perioperative period with respiratory inductive plethysmography (RIP) and pulse oximetry, which did not show severe upper airway obstruction or oxygen saturation below 80 per cent. Tracheal intubation was performed under inhalational anaesthesia with spontaneous breathing. This case suggests that RIP and pulse oximetry may be useful monitoring devices in the anaesthetic management of patients with upper airway problems as in Goldenhar's syndrome.

Anesthesia, Inhalation↗

PubMed1990

Enflurane impairs canine diaphragmatic contractility in vivo.

We examined the effect of enflurane on diaphragmatic contractility in six 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. Pdi-stimulus frequency relationship was compared at three levels of anesthesia, namely 1, 1.5, and 2 MAC (minimum alveolar concentration) of enflurane. The sequence of changing anesthetic concentration was randomized between animals. Pdi at 50 and 100 Hz stimulation was significantly decreased with increasing MAC while Pdi at 10 Hz stimulation was not affected by the depth of anesthesia. Pdi of 20 Hz stimulation was significantly decreased at 2 MAC as compared to those at 1 and 1.5 MAC. We conclude that enflurane decreases contractility of the diaphragm mainly through impairment of the neuromuscular transmission and/or membrane excitability. Part of its effects is, however, probably related to the impairment of excitation-contraction coupling, as suggested by the depression of Pdi at 2 MAC in response to 20 Hz stimulation.

Journal Article↗

PubMed1990

Breathing pattern and respiratory mechanics in sevoflurane-anesthetized humans.

In order to determine the respiratory effects of sevoflurane in humans, breathing pattern and mechanical behavior of respiratory system were investigated in ten subjects at anesthetic depth of 1 MAC (minimum alveolar concentration). Average tidal volume and breathing frequency amounted to 275 ml and 20.9 breaths per minute. Arterial carbon dioxide tension amounted to 45.6 mmHg. Duration of inspiration was 1.06s and that of expiration was 1.92s. Mean inspiratory flow rate amounted to 259 ml.s(-1). Average value of passive respiratory elastance determined by the method of Zin et al. amounted to 21.8 cmH(2)O. l(-1), while those of active respiratory elastance and resistance obtained by the method of Behrakis et al. were 28.0 cmH(2)O. l(-1) and 3.15 cmH(2)O. l(-1).s(-1), respectively. Values of these variables were compared to those reported in halothane and enflurane anesthesia and possible explanations of the differences between the anesthetics are discussed.

Journal Article↗

PubMed1990

Different effects of halothane and enflurane on diaphragmatic contractility in vivo.

We examined the effects of halothane and enflurane on diaphragmatic contractility in 12 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. Animals were randomly assigned to two groups, a halothane group (n = 6) and an enflurane group (n = 6). The Pdi stimulus-frequency relationship was compared at anesthetic levels of 1, 1.5, and 2 MAC (minimum alveolar concentration) in each group. The sequence of changing anesthetic concentration was randomized. In addition, the Pdi-frequency relationship was also compared between 1 MAC of halothane and enflurane in 8 of 12 dogs. In animals anesthetized with enflurane, Pdi significantly decreased with 50- and 100-Hz stimulation in the presence of increasing MAC values, whereas Pdi at 10-Hz stimulation was not affected by the depth of anesthesia. Pdi with 20-Hz stimulation during 2 MAC enflurane also decreased significantly below Pdi levels seen at 1 and 1.5 MAC. By contrast, with halothane there was no difference in Pdi at any of the stimulation frequencies during any of the three levels of anesthesia. There was no statistical difference, however, between Pdi-frequency relationships during 1 MAC of halothane and enflurane in eight animals. From these results, we conclude that halothane does not impair diaphragmatic contractility any more than enflurane does, but enflurane decreases force generation of the diaphragm at high stimulation frequencies in a dose-related fashion. This depressant effect of enflurane occurs mainly through the impairment of neuromuscular transmission and/or membrane excitability.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Respiratory effects of expiratory flow-resistive loading in conscious and anesthetized humans.

The response of breathing patterns to increased expiratory resistance is not only of physiologic interest, with respect to the control of breathing, but also of clinical interest because of its clinical relevance to obstructive diseases such as asthma and emphysema. To elucidate the response of breathing patterns to increased expiratory resistance during anesthesia, the respiratory effects of expiratory flow-resistive loading on breathing patterns were studied in 15 conscious and 10 lightly anesthetized subjects. Inspiratory time, expiratory time, respiratory frequency, inspiratory duty cycle, tidal volume, minute ventilation, and mean inspiratory flow rate were determined from a respiratory inductive plethysmograph. End-tidal CO2 was continuously recorded. In awake subjects, respiratory frequency was reduced without change in tidal volume or mean inspiratory flow rate, and minute ventilation was significantly decreased; the synchrony between rib cage and abdomen wall motion was well maintained during the loads. In contrast, in anesthetized subjects, respiratory frequency was reduced with remarkable increases in tidal volume, mean inspiratory flow rate, and minute ventilation, whereas coordination between rib cage and abdomen compartments was disturbed. End-tidal CO2 did not change in conscious subjects, but it increased in anesthetized subjects during the loads. These results indicate that there are differences between conscious and anesthetized subjects in breathing patterns during expiratory loading, and suggest that the ability to coordinate rib cage-abdomen wall motion is easily disturbed during anesthesia in patients with expiratory flow limitation.

Adolescent↗

PubMed1990

[Kinetics of circulating hematopoietic stem cells following chemotherapy in patients with hematopoietic malignancies].

The number of circulating hematopoietic progenitor cells was determined during 47 courses of chemotherapy in 23 patients with hematopoietic malignancies. rhG-CSF was given subcutaneously to 14 patients to rescue chemotherapy-induced neutropenia following 22 courses of chemotherapy. The mean numbers of CFU-GM in patients with malignant lymphoma (ML), acute leukemia (AL) and myeloma (MM) were 56.0 +/- 58.8 (mean +/- SD), 46.7 +/- 66.0 and 11.0 +/- 11.1 CFU-GM/ml, respectively. The number of CFU-GM in MM was significantly less than in normal subjects (51.2 +/- 30.6 CFU-GM/ml). The number of CFU-GM in PB in all patients began to rise between 2 days before and 8 days after nadir of WBC count, and then reached the peak at the subsequent 5 days. The peak values of CFU-GM in ML, AL and MM were 711.3 +/- 974.7, 660.0 +/- 374.7 and 403.6 +/- 232.5 CFU-GM/ml, respectively, but there was no statistical difference among them. When ML patients were treated with rhG-CSF, the CFU-GM peak values increased as much as 5.5-folds compared with those following chemotherapy only. However, neither the period from nadir to start of increase in the CFU-GM count nor the time of the CFU-GM peak showed any significant change. These results indicate that the administration of rhG-CSF makes it possible to increase the number of circulating progenitor cells. It appears possible in most of the patients with hematopoietic malignancies to harvest the sufficient number of progenitor cells which are necessary for autologous blood stem cell transplantation.

Acute Disease↗