Search PubMed⌕ Search

Biomedical subjects

A Okamura

Publications and source records attributed to A Okamura.

At least 145 records · Page 8Linked to original sources
PubMed1992

Hemodynamic effects of nicardipine-induced hypotension during enflurane/nitrous oxide anesthesia in man.

Hemodynamic effects of nicardipine-induced hypotension during enflurane/nitrous oxide were evaluated in 10 surgical patients. An infusion of nicardipine was titrated to maintain mean arterial pressure at 60 to 70 mmHg under enflurane 1.5 to 2.0 vol% and nitrous oxide 60 vol%. Mean arterial pressure was well controlled with the nicardipine infusion, whereas cardiac index increased with decreased systemic vascular resistance. Heart rate increased concomitantly with decreased blood pressure, which indicated that enflurane 1.5 to 2.0 vol% did not suppress baroreceptor reflex during nicardipine administration. However, rate-pressure-product was not increased by the nicardipine. Right and left ventricular systolic work indices were not increased by the nicardipine. Right ventricular ejection fraction was not also changed by the nicardipine. Although serum norepinephrine level increased during the nicardipine infusion, the values remained within physiological ranges. Our results suggest that nicardipine-induced hypotension may be safely performed during enflurane/nitrous oxide anesthesia because neither ventricular work nor myocardial oxygen demand was increased by nicardipine.

Journal Article↗
PubMed1992

Very-low-calorie-diet therapy in severe obesity.

This study investigated the effects of very-low-calorie-diet (VLCD) therapy on body weight, plasma glucose, and lipid metabolism in severely obese patients. Ninety-one patients were subjected to VLCD therapy for 4-24 wk. Reduction of body weight was remarkable during the first 4 wk, then leveled off despite continuous treatment. Fasting plasma glucose, triglyceride, and 75-g oral glucose-tolerance test showed a significant improvement. Total cholesterol fell in the early stages but then increased more than the pretreatment level during VLCD. VLCD therapy is useful for the treatment of severe obesity.

Adult↗
PubMed1992

Papillary adenoma of the lung. Histological and ultrastructural findings in two cases.

Two cases of papillary adenoma of the lung are presented along with results of histological and ultrastructural examinations. The tumors were encountered in two asymptomatic patients in a mass-survey chest X-ray examination. The chest X-ray films showed the tumors as well demarcated small lesions. Histologically, both tumors arose in the bronchioles and consisted of cuboidal cells resembling type II pneumocytes showing papillary growth with accompanying edematous connective tissue. Several tumor cells each possessed a large eosinophilic intranuclear inclusion. In case 1, ciliated cells and Clara-like cells were also present in the tumor. Ultrastructurally, most of the tumor cells had various numbers of lamellar bodies in their cytoplasm, indicative of type II pneumocytes, and some of case 1 showed features of Clara cells and ciliated cells. The intranuclear inclusions appeared as aggregates of tubular structures or had lamellar body-like features. These findings are identical to those of papillary adenoma arising from the bronchiole.

Adult↗
PubMed1992

[Measurement of functional residual capacity by sulfur hexafluoride washout].

An open circuit tracer gas washout method for measurement of functional residual capacity (FRC) during mechanical ventilation is described and tested. The system employed a piezo-valve for dispensing sulfur hexafluoride (SF6) gas, a fast response infrared SF6 analyzer, Servo 900-C ventilator and a computer. The piezo-valve unit delivers SF6 into the airway in proportion to instantaneous inspiratory flow so that inspiratory SF6 concentration was held constant regardless of the inspiratory flow pattern. The washin concentration was approximately 0.6% which was so low that the supply of other gases was hardly influenced. The amount of SF6 at the end of a washin was calculated during washout by signals of expired SF6 concentration and expired flow. The results obtained in model lungs were accurate and reproducible; mean difference (limits of agreements) was 14 +/- 48ml (M +/- 2SD) in the range between 0.5 and 3.0 liters. Comparison with helium dilution methods in 24 healthy subjects gave a regression equation: y = 0.98x + 56, r = 0.98. The mean difference of the values between the two methods was 21 +/- 142 ml (M +/- 2SD). The authors conclude that the system is quite useful in determining FRC of the patients under mechanical ventilation.

Functional Residual Capacity↗
PubMed1991

Slope of human left ventricular end-systolic force-length relation is independent of myocardial length.

We have introduced a new contractility index (Ec), i.e., the slope of the left ventricular (LV) end-systolic force-length (Fes-Les) relation. To examine whether Ec was dependent on the LV wall myocardial length, 16 normal hearts of human subjects were evaluated to determine the LV end-systolic force-dimension (Fes-Des) and pressure-dimension (Pes-Des) relations (dimension denotes the distance between the LV septum and posterior wall). LV end-systolic pressures and dimensions were estimated simultaneously by intra-arterial cannulation and LV echocardiography. In seven subjects, the effect of a dobutamine infusion was also assessed. The Fes-Des relation was found to be nearly linear. Slopes and extrapolated dimension intercepts were obtained for the LV Fes-Des and Pes-Des relations [Ec, slope of LV Pes-Des relation (Es), and extrapolated dimension intercept of LV Fes-Des (Do), and of Pes-Des relation (D'o), respectively]. Es showed a hyperbolic relation to the baseline LV Des, whereas Ec was unrelated to it. The average variation for Ec (9.5%) was smaller than that for Es (22.5%). Dobutamine infusion increased Ec, Es, and D'o, whereas Do was not changed. Thus the assumption of linearity of the LV Fes-Les relation was found to be reasonable in normal human hearts. Do appears to provide a more accurate parameter than D'o for estimating the actual unstressed myocardial length, whereas Ec could possibly serve as an index of LV wall performance in the normal human heart that is independent of myocardial length and nearly constant between individuals.

Adult↗
PubMed1991

Blood pressure measurement by arterial tonometry in controlled hypotension.

A newly developed arterial tonometer enabled us to measure the blood pressure waveforms in addition to determining systolic and diastolic pressures noninvasively and continuously. Twenty-eight adult patients undergoing orthopedic surgery under controlled hypotension were studied. Systolic blood pressure was reduced to two-thirds of baseline values with an infusion of nitroglycerin during nitrous oxide/enflurane anesthesia. Intraarterial blood pressures were simultaneously measured in either the right or the left radial artery with a cannula and a Gould P23XL calibrated transducer; tonometric monitoring was performed on the contralateral radial artery using a Colin CBM-3000 instrument. The outputs of the two blood pressure measurement instruments were recorded for later data analysis. The shape of the tonometric pressure waveform was nearly identical to the waveform recorded intraarterially even during controlled hypotension. Regression analyses of 2039 paired tonometric and intraarterial blood pressure values during the hypotensive period showed good correlations (r = 0.78 for systolic, r = 0.81 for mean, and r = 0.70 for diastolic pressures). The accuracy of systolic, mean, and diastolic readings was from 4 to 7 mm Hg with negligible bias and did not differ significantly among six systolic, four mean, and four diastolic pressure groups. Our results indicate that arterial tonometry can provide accurate, reliable, and real-time monitoring of blood pressure even during controlled hypotension.

Adult↗
PubMed1991

[Analysis of the clinical effect of Adelavin infusion during enflurane anesthesia on post-operative hepatic function].

The protective effect of Adelavin, which is made of liver essence, for maintaining postoperative hepatic function was analysed in 85 patients who had enflurane anesthesia. The patients who showed hepatic dysfunction preoperatively were excluded from this trial. Adelavin was infused at a speed of 0.1 mg.kg-1.hr-1 during anesthesia. The group who had upper abdominal surgery in the Adelavin group showed significantly lower incidence of postoperative hepatic dysfunction. The group who had only enflurane anesthesia in the Adelavin group showed significantly lower incidence of postoperative hepatic dysfunction. These results suggest that the Adelavin infusion has a significant protective effect on hepatic function after enflurane anesthesia.

Anesthesia, Inhalation↗
PubMed1990

Is the site of action of ketamine anesthesia the N-methyl-D-aspartate receptor?

Synaptic mechanisms underlying ketamine anesthesia were studied using in vitro preparations of the lamprey CNS. Although lampreys are one of the most primitive vertebrates, the synaptic physiology and pharmacology are similar to those in the higher vertebrates. Axonal conduction, transmitter release from the presynaptic terminal, postsynaptic response to the putative neurotransmitters, and resting and activated membrane properties were studied in the absence and the presence of various concentrations of ketamine. Ketamine markedly reduced N-methyl-D-aspartate (NMDA)-activated responses, such as depolarizations to bath-applied NMDA and bursting rhythm during "fictive locomotion." The 50% block of the responses took place in the presence of 10-20 microM ketamine, whereas those induced by kainate and quisqualate (the other two subclasses of L-glutamate/L-aspartate agonists) were spared at concentrations higher than 600-800 microM. None of the other neuronal events tested were suppressed in the presence of still higher concentrations of ketamine. The results support the hypothesis that ketamine might exert its anesthetic effect by a pharmacologically specific interaction with the NMDA receptor.

Action Potentials↗
PubMed1990

[Deterioration of myocardial contractility induced by nitroglycerin infusion in a case of ischemic cardiomyopathy].

To evaluate left ventricular (LV) contractility in a 42-year-old woman with ischemic cardiomyopathy, the brachial arterial pressure and LV end-systolic dimension were simultaneously measured using arterial cannulation and LV echocardiography. Blood pressure progressively decreased with the intravenous infusion of nitroglycerin. When the infusion rate reached 4 micrograms/kg/min, the LV end-systolic dimension increased from 63 mm (control) to 66 mm in association with a decrease in blood pressure (from 137 to 120 mmHg) and heart rate (from 103 to 100 bpm). With the infusion of dobutamine (1.5 micrograms/kg/min), the blood pressure increased to 126 mmHg and the LV end-systolic dimension decreased to 57 mm. These findings suggest that nitroglycerin reduced LV myocardial contractility in this patient. Thus, during the intravenous administration of nitroglycerin (especially in patients with ischemic heart disease), the infusion rate should be carefully determined.

Adult↗
PubMed1989

[Successful treatment by a drainage of subdural hematoma in a case of intracranial hemorrhage due to DIC complicated with acute promyelocytic leukemia].

A 24 year-old female was admitted because of hypermenorrhea and petechiae. The peripheral blood tests on admission were consistent with acute promyelocytic leukemia complicated with DIC. BHAC-DMP therapy was started along with platelet transfusions and heparin administration. On the day 9 of admission, on the contrary to the improvement of hematological data, the patient suffered from severe headache and nausea. The neurological examination revealed anisocoria. Right side chronic subdural hematoma was a diagnosis made by emergency CT scan and was treated with drainage of the hematoma. Post-operatively, the patient did well, and achieved complete remission on the day 43 of admission. Since intracranial hemorrhages due to DIC complicated with leukemia are often fatal, those patients are usually treated conservatively. However, as shown in this case report, some cases might have an indication for the neurosurgical operation. It is important to check conditions carefully whether the patient has an indication for the operation.

Adult↗
PubMed1988

[Left ventricular diastolic properties in dogs evaluated by stress pulsed Doppler echocardiography].

We examined diastolic properties of the left ventricle (LV) of 12 anesthetized open-chest dogs. The heart was paced at a fixed rate of 100 beats/min. The time constant (T) was calculated from the LV pressure curve, and the A/R was measured from LV diastolic velocity curves using pulsed Doppler echocardiography (PDE). Both were used as indexes of the LV diastolic properties. The afterload increased by occluding the descending aorta; the preload decreased by occluding the inferior vena cava. Both T and the A/R increased significantly (p less than 0.01) when the afterload was increased. However, when the preload was decreased, T was not significantly changed. The A/R increased significantly due to a smaller decrement of A than that of R, when the preload was decreased. The percent change of T correlated significantly with that of the A/R, when the afterload was increased (r = 0.687, p less than 0.05). However, there was no correlation between them, when the preload was decreased. We conclude that LV diastolic properties are affected by afterload and preload, and that percent changes of T do not always correlate well with percent changes in the A/R. Thus, it is important to evaluate the preload and afterload states when ever LV diastolic properties are measured clinically.

Animals↗
PubMed1988

[Left and right ventricular diastolic properties in essential hypertension during cold pressor test: noninvasive assessment by pulsed Doppler echocardiography].

The diastolic properties of the left and right ventricles of 17 essential hypertensive patients (HT) without left ventricular hypertrophy and of 12 normotensive subjects were assessed by pulsed Doppler echocardiography during the cold pressor test (CPT) and after administration of nifedipine (10 mg). The results were as follows: 1. The peak blood flow velocities due to the left and right atrial contractions (ALV, ARV) at rest in the HT group were significantly greater (p less than 0.001) than those in the control group. The ratios of peak velocities due to atrial contraction and rapid filling of each ventricle (A/R) in the HT group were significantly increased (p less than 0.001) compared with those of the controls. 2. The peak rapid filling flow velocity of each ventricle during cold pressor test in the HT group was significantly less and the A/R of each ventricle was significantly (p less than 0.001) greater compared to those at rest. 3. Diastolic indices and systolic blood pressure did not change significantly after administration of nifedipine at rest or during cold pressor test. These results indicate that abnormal diastolic properties of the left and right ventricles are further deteriorated by increasing afterload.

Adult↗