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Biomedical subjects

K Nakane

Publications and source records attributed to K Nakane.

60 records · Page 4Linked to original sources
PubMedDate not supplied

Relationship between dialysis induced hypotension and adenosine released by ischemic tissue.

Two types of dialysis induced hypotension apparently exist. One type presents as gradually decreasing blood pressure with eventual symptoms (gradual hypotension), whereas the other presents as abruptly and sharply decreasing blood pressure, along with symptoms (abrupt hypotension). In the current study, the authors found that the plasma hypoxanthine concentration during abrupt hypotension was significantly higher than before the hypotension occurred (20 min after saline was administered or at the beginning of dialysis), whereas comparison of the plasma hypoxanthine concentration during gradual hypotension and that before the hypotension occurred (20 min after saline was administered or at the beginning of dialysis) revealed no significant difference. The current results indicate that abnormally increased adenosine triphosphate (ATP) degradation associated with tissue ischemia occurred during abrupt hypotension but not during gradual hypotension. It can be speculated that the increased release of adenosine due to abnormally increased ATP degradation caused the abrupt hypotension. This conclusion seems reasonable given that adenosine directly decreases small vessel tone and inhibits prejunctional release of norepinephrine.

Adenosine↗
PubMedDate not supplied

Continuous measurement of pressure in internal arteriovenous fistulae and prevention of symptomatic hypotension during hemodialysis.

To continuously monitor the blood pressure (BP) in an internal arteriovenous fistula, the blood tubing wall was punctured with a long, fine needle (25 gauge), and the needle tip was advanced into the fistula vein through the lumen of the outflow blood access puncture needle. It was found that the intrafistula BP thus measured varied in parallel with the systemic arterial BP during hemodialysis (HD). When the intrafistula BP fell to 60% of the level at the start of HD, 50 ml of saline was administered. As a result, hypotension was prevented completely in 60 HD in five patients who often showed symptomatic hypotension during HD.

Adult↗
PubMedDate not supplied

Minor changes in regional cerebral blood flow revealed by the early distribution of I-123 IMP in brain.

To evaluate the early distribution of I-123 IMP in the brain, 10 dynamic images were obtained in the first 10 minutes after injection using a ring-type SPECT system with a high-sensitivity collimator. In cases of chronic carotid occlusion without brain CT abnormalities, areas of low perfusion were more clearly demonstrated in dynamic images than in static images obtained beginning 20 minutes after injection and continuing for 15 minutes using a high-resolution collimator. In cases of hyperperfusion following infarct or surgery, there was a difference between dynamic and static images in the visualization of hyperemic lesions. The distribution of I-123 IMP in the brain changes gradually, even in the early period after injection, and evaluation of early accumulation is useful for the detection of minor changes in regional cerebral blood flow.

Aged↗
PubMedDate not supplied

Change in sympathetic activity before, during, and after dialysis-induced hypotension.

During the hemodialyses of eight patients with end-stage renal failure, who often had sudden-onset dialysis-induced hypotension, catecholamine (CA) levels were measured in the ultrafiltrate obtained by a mini-filter placed in series upstream of the dialyzer. The water evaporation rate from the skin (reflecting the perspiration rate) was also monitored. Results showed a temporary elevation in CA levels in the ultrafiltrate before hypotension occurred. This rise did not continue for long, returning to baseline when hypotension actually occurred. The temporary elevation may reflect transient compensation by the sympathetic nervous system for the decrease in vascular wall tension. It was also found that there was considerable water evaporation from the skin during hypotension. Because sweat gland activity is reflexively modulated by the baroreceptor, perspiration after a drop in blood pressure may reflect the normal diminiution in baroreceptor activity.

Adult↗