Biomedical subjects

M Sakagami

Publications and source records attributed to M Sakagami.

147 records · Page 9Linked to original sources

PubMedDate not supplied

Improvements in determination of cardiac output with a Swan-Ganz catheter.

The time constant for heat transfer may affect exact determination of cardiac output with Swan-Ganz catheters. Commercially available Swan-Ganz catheters are provided with thermistors with varying time constants. Current monitoring of cardiac output is not corrected for these time constants, so the conventional method of determining cardiac output using the equation of Stewart-Hamilton produces marked errors. The authors propose a new method of determining cardiac output with Swan-Ganz catheters with varying time constants from thermal dilution curve data based on Newton's cooling law. Values for blood flow rate determined by the new method using a completely stirred tank of original design, mimicking the natural heart and using bovine blood, are almost the same as values observed at varying saline infusion volumes, saline temperatures, and saline infusion times.

Blood Flow Velocity↗

PubMedDate not supplied

Nondestructive evaluation by x-ray computed tomography of dialysate flow patterns in capillary dialyzers.

It is hard to evaluate dialysate flow patterns inside the fiber bundle of capillary dialyzers. The current study describes a novel determination of dialysate flow by x-ray computed tomography. The authors did steady and nonsteady state tracer experiments with adipiodone to observe the dialysate flow pattern in capillary dialyzers held vertically and horizontally. The hollow fibers were filled with paraffin to avoid permeation of adipiodone from the dialysate to blood compartment. In steady state tracer experiments, adipiodone solution (50 vol%) was injected into the dialysate compartment at a flow rate of 1.5 ml/min. Horizontal sectional dialysate flow patterns were observed every 2 cm from the point of the adipiodone injection. Adipiodone solution flowed along broken and twisted fiber bundles at dialysate flow rates ranging from 200 to 600 ml/min. In nonsteady state tracer experiments, dialysate was switched from pure water to adipiodone solution by solenoid-controlled valves after a steady state was reached, and adipiodone solution (2.4 vol%) was infused into the dialysate compartment for 30 sec at a flow rate of 500 ml/min. Vertical sectional dialysate flow patterns were observed every 2 sec after the start of adipiodone infusion. Values for dialysate flow velocity at the outer and inner regions of the fiber bundle were 3.5 and 0.6 cm/sec for the CA-170, and 1.4 and 0.7 cm/sec for the HF-200 capillary dialyzer, respectively. This study demonstrates the usefulness of x-ray computed tomography in visually and quantitatively determining dialysate flow patterns in capillary dialyzers.

Iodipamide↗

PubMedDate not supplied

Quantitative evaluation of pinocytosis of capillaries of the stria vascularis under normal and experimental conditions.

In order to examine evidence of high activity of pinocytosis in capillaries of the stria vascularis, quantitative morphometry of pinocytotic vesicles was carried out ultrastructurally by the horseradish peroxidase (HRP) tracer method. In guinea pigs, there was a significant difference between the stria vascularis and spiral ligament in the number of vesicles per micron 2 (p less than 0.05) and labelled vesicles per micron 2 (p less than 0.001). In normotensive control rats, the number of labelled vesicles per micron 2 in capillaries of the stria vascularis was significantly greater (p less than 0.001) than that of the spiral ligament. Results of acute hypertensive and acute hypotensive experiments both indicated that enhanced permeable capillaries of the stria vascularis showed no significant increase in the number of pinocytotic vesicles per micron 2, but that they showed a more significant increase in the number of labelled vesicles per micron 2 than non-enhanced permeable capillaries of the stria vascularis (p less than 0.01) and capillaries of the spiral ligament (p less than 0.001). These findings provide ultrastructural confirmation of our previous studies (4, 8, 9) that pinocytosis contributes to the high permeability of capillaries of the stria vascularis under normal and experimental acute hypertensive and acute hypotensive conditions.

Animals↗