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K Tsuzaki

Publications and source records attributed to K Tsuzaki.

32 records · Page 2Linked to original sources
PubMed1993

Regional coupling between chest wall and lung expansion during HFV: a positron imaging study.

Apparently conflicting differences between the regional chest wall motion and gas transport have been observed during high-frequency ventilation (HFV). To elucidate the mechanism responsible for such differences, a positron imaging technique capable of assessing dynamic chest wall volumetric expansion, regional lung volume, and regional gas transport was developed. Anesthetized supine dogs were studied at ventilatory frequencies (f) ranging from 1 to 15 Hz and eucapnic tidal volumes. The regional distribution of mean lung volume was found to be independent of f, but the apex-to-base ratio of regional chest wall expansion favored the lung bases at low f and became more homogeneous at higher f. Regional gas transport per unit of lung volume, assessed from washout maneuvers, was homogeneous at 1 Hz, favored the bases progressively as f increased to 9 Hz, and returned to homogeneity at 15 Hz. Interregional asynchrony (pendelluft) and right-to-left differences were small at this large regional scale. Analysis of the data at a higher spatial resolution showed that the motion of the diaphragm relative to the excursions of the rib cage decreased as f increased. These differences from apex to base in regional chest wall expansion and gas transport were consistent with a simple model including lung, rib cage, and diaphragm regional impedances and a viscous coupling between lungs and chest wall caused by the relative sliding between pleural surfaces. To further test this model, we studied five additional animals under open chest conditions. These studies resulted in a homogeneous and f-independent regional gas transport. We conclude that the apex-to-base distribution of gas transport observed during HFV is not caused by intrinsic lung heterogeneity but rather is a result of chest wall expansion dynamics and its coupling to the lung.

Animals↗
PubMed1993

Regional lung mechanics and gas transport in lungs with inhomogeneous compliance.

The effect of respiratory frequency (f) on the distributions of ventilation, regional gas transport, lung volume, and regional impedance was assessed with positron imaging in lungs with nonuniform lung mechanics after unilateral lung lavage. Supine dogs were studied during eucapnic oscillatory ventilation at f between 1 and 15 Hz and at a constant mean airway pressure of 5 cmH2O. Substantial differences in mean lung volume and tidal volume (VT) between lavaged and control lungs were found at all f values, but pendelluft never exceeded 2% of mouth flow. For f < or = 10 Hz, VT distributed in direct proportion to lung volume, whereas gas transport per unit of lung volume, measured from washout maneuvers, was reduced by 20% in the lavaged lung. At 15 Hz, however, the distributions of VT and gas transport approached equality between both lungs. Regional impedance was analyzed with a model that included a Newtonian resistance, an inertance, and Hildebrandt's model of tissue viscoelasticity. The data obtained from this work provide useful insights with respect to the mechanisms of gas transport during high-frequency ventilation and suggest the impact of operating frequency in clinical situations where substantial interregional heterogeneity in lung compliance could be expected.

Animals↗
PubMed1992

[Direct effects of prostaglandin E1 on renal blood flow and renal function during acute reduction of cardiac output in dogs].

During low cardiac output state induced by inflating the balloons inserted into both superior and inferior caval veins, direct effects of PGE1 (10 ng.kg-1.min-1, infused into renal artery) on renal blood flow and renal function were investigated. In control group, acute reduction of cardiac output resulted in decrease of renal blood flow (RBF) and significant increase of filtration fraction (FF), suggesting tight constriction of the efferent arteriole by activation of renin-angiotensin system and sympathetic nervous system. In PGE1 group, glomerular filtration rate (GFR) and FF decreased significantly although there was no decrease in RBF. No significant change was seen in distribution of intrarenal blood flow during low cardiac output state in both groups. These results indicate that decrease in GFR by direct infusion of PGE1 into renal artery during low cardiac output state is probably due to reduction of glomerular filtration pressure produced by dominant inhibition of the efferent arteriole constriction rather than the inhibition of the afferent arteriole by PGE1.

Acute Disease↗
PubMed1991

[Differential lung ventilatory management during bronchoplasty].

We compared two methods of respiratory managements during bronchoplasty surgery. In one lung ventilation group (OLV-G), 10 patients were ventilated with Broncho-cath tube or Univent tube. On another 10 patients, ventilation was performed with Univent tube following insertion of bronchial blocker into main bronchus of dependent lung. Dependent lung was then ventilated using high frequency jet ventilation (HFJV) through bronchial blocker superimposed with low tidal volume IPPV (selective HFJV, S-HFJV-G). Oxygenation index (O.I.) of S-HFJV-G was significantly higher than that of OLV-G when bronchus was open. These phenomena might have occurred through prevention of pulmonary blood flow shift to the non-dependent lung when S-HFJV was used.

Aged↗
PubMed1990

Flow distribution in a single bifurcation during high-frequency oscillation.

The distribution of flow in a single bifurcation was studied to examine what factors played a critical role. Flow was preferentially directed down the straightest pathway when higher frequencies and/or larger tidal volumes were used, but otherwise followed the pattern dictated by the distal impedance regardless of bifurcation geometry. In a symmetrical model, the observed flow distribution was in good agreement with a mathematical prediction based on linear impedance theory, though this was not the case when tidal volumes were increased. The difference in mean pressure between the two terminal units was also a strong function of branching angle and the Reynolds number. These findings suggest that the geometrical factors and local flow conditions contribute to both the flow and mean pressure distribution in an inertia-induced nonlinear manner. Consequently, linear impedance theory can be applied only to the limited situation of low tidal volume and symmetric configuration.

High-Frequency Ventilation↗
PubMed1990

[Free and conjugated catecholamines in gastric and bile juice during surgical operations].

From 40 patients under surgical operation, gastric or bile juice was obtained to determine the possible excretion of free and conjugated catecholamine (CA) into the two kinds of juice. The patients were divided into normal renal function group and chronic renal failure group and former group was further divided into the dopamine (DA)-administered group and the non-DA-administered group. In the non-DA group with normal renal function, the gastric juice contained 0.30 +/- 0.11ng.ml-1 of free and 0.12 +/- 0.06ng.ml-1 of conjugated norepinephrine (NE) and also 0.09 +/- 0.07ng.ml-1 of free and 0.40 +/- 0.10ng.ml-1 of conjugated DA. In DA group, the gastric juice contained 2.01 +/- 0.41ng.ml-1 of free and 3.66 +/- 0.84ng.ml-1 of conjugated DA respectively. Significant differences in DA were observed between two groups. In the bile juice, the conjugated NE increased significantly from 0.15 +/- 0.05 ng.ml-1 to 1.24 +/- 0.34ng.ml-1 and also the conjugated DA increased significantly from 2.17 +/- 0.77ng.ml-1 to 21.33 +/- 5.23ng.ml-1 by infusion of DA at the rate of 2 micrograms.kg-1.min-1 for 197 +/- 48min. In chronic renal failure group, the conjugated NE and DA increased significantly to 1.04 +/- 0.27ng.ml-1 and 1.64 +/- 0.61ng.ml-1 respectively compared to that of normal renal group. It was confirmed that gastric juice and bile juice contain the free and conjugated CA during surgical operation and by the infusion of DA, free and conjugated DA are excreted into gastric juice and bile juice and also conjugated CA in the gastric juice from chronic renal failure group is increased.

Adult↗
PubMed1989

[The effect of nitroglycerin ointment on cardiovascular functions in hypertensive patients during emergence from anesthesia].

The present study was designed to investigate the effect of nitroglycerin (TNG) ointment to attenuate the cardiovascular response of hypertensive patients during emergence from anesthesia compared with the effects of TNG infusion and nifedipine instillation in the nose. In addition, plasma TNG concentration was measured in the TNG ointment group and TNG infusion group. TNG 30 mg in ointment reduced the arterial pressure during extubation without producing hypotension and tachycardia. There was no significant difference in plasma TNG concentration between TNG ointment group and TNG infusion group each receiving 0.3 micrograms.kg-1.min-1. The study suggests that TNG ointment is useful for regulation of arterial pressure in hypertensive patients during emergence from anesthesia.

Administration, Intranasal↗
PubMedDate not supplied

High-frequency ventilation in neonates.

STUDY OBJECTIVE: To provide a brief review of the current status of high-frequency ventilation in neonatal respiratory care. DATA IDENTIFICATION: Publications appearing between 1980 and 1990 were identified by computer searches using the National Library of Medicine's data base, MEDLINE, and by searching bibliographies of identified articles. STUDY SELECTION: Studies related to physiologic background and clinical reports of neonatal application were selected individually. DATA EXTRACTION: Data concerning the physiologic basis, clinical effectiveness and complications, and latest results of a multicenter randomized trial were evaluated and used to develop a current concept. RESULTS OF DATA SYNTHESIS: In early clinical tests of high-frequency ventilation, it was considered beneficial that airway pressure lower than that used in conventional mechanical ventilation might reduce the frequency of pulmonary barotrauma. When high-frequency ventilation was applied to infants with respiratory distress syndrome, the development of chronic pulmonary complications also was expected to decrease. Although several reports supported this hypothesis, a recent controlled trial involving multiple clinical centers did not find significant improvement in the group treated with high-frequency ventilation. Rather, they recognized the frequent occurrence of complications associated with high-frequency ventilation and suggested the prior use of conventional ventilation. However, a possible defect of this study design requires further studies to elucidate the source of these conflicting results. CONCLUSIONS: As a mode of mechanical ventilation, high-frequency ventilation is useful for maintaining ventilation in patients with air leak syndrome or bronchopulmonary fistula or during bronchoscopic examination. But in general, its role as an alternative to conventional ventilation still remains controversial.

High-Frequency Ventilation↗
PubMedDate not supplied

Cytologic appearances of pheochromocytoma and medullary thyroid carcinoma occurring within a family.

The cytologic and histochemical characteristics of the tumor cells from medullary thyroid carcinoma and pheochromocytoma are described. In cell samples obtained from medullary thyroid carcinomas, amyloid deposits were detected both intracellularly and extracellularly. Medullary thyroid carcinoma cells, as well as pheochromocytoma cells, showed positive for both argentaffin and argyrophil reactions. The diagnostic significance of intracellular amyloid deposits and of positive silver and chromaffin reactions of the intracytoplasmic granules may be stressed in establishing the cytologic diagnosis of medullary thyroid carcinoma and/or pheochromocytoma.

Adrenal Gland Neoplasms↗