Artificial organs
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Adequate venous access is an essential component of therapeutic plasma exchange (TPEX). The simplest kind of venous access is venipuncture of antecubital veins, but this technique may be limited by venous size or scarring following the procedure, requiring the placement of a specialized vascular access device (VAD). ⋯ Their use, however, is potentially limited by the risk of complications. We discuss indications for insertion, choice of catheter and access site, and complications of VAD placement for TPEX.
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Central vascular catheters are used to access the central vascular system in both acute and chronic uremic patients undergoing hemodialysis. Among different approaches, the internal jugular vein seems to have less adverse effects. We describe our long-term experience with a two-catheter system. ⋯ Blood flow rate was 284 mL/min; venous pressure at 1 year was 90 mm Hg. Complications included accidental withdrawal (6), dysfunction (4), catheter clotting (11), mediastinal hematoma (2), pneumothorax (1), and sepsis (7). Good long-term survival and a low complication rate make this system a safe and reliable method of access for long-term hemodialysis.
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Cardiopulmonary bypass (CPB) is known to induce several pathogenic responses in cardiovascular surgery. To explore leukocyte activation during PCB, we investigated superoxide anion (O2-) production by granulocytes in 6 patients undergoing aortocoronary bypass surgery. O2- production was determined with chemiluminescence amplified by a cypridina luciferin analogue. ⋯ However, significant complement activation was detected, and the plasma level of granulocyte elastase increased gradually during and after CPB. This discrepancy between the unchanged O2- production by stimulated granulocytes and the increase in inflammatory mediators including granulocyte elastase may be due to sequestration of activated granulocytes in extravascular tissues. Namely, it was highly likely that activated granulocytes responsible for the increased plasma elastase level were sequestered and remained outside the blood circulation.
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Comparative Study
The renin-angiotensin-aldosterone system and hematologic changes during pulsatile and nonpulsatile cardiopulmonary bypass.
The effects of pulsatile and nonpulsatile cardiopulmonary bypass using a roller pump on levels of vasoactive hormones and hematologic changes were studied in 32 patients subjected to elective primary coronary artery bypass graft surgery. Seventeen patients had nonpulsatile perfusion (nonpulsatile group) and 15 patients had pulsatile perfusion (pulsatile group) during the period of cardiac arrest. Vasoactive hormones (plasma renin, angiotensin II, aldosterone, epinephrine, and norepinephrine) were measured in these patients. ⋯ In the pulsatile group, however, the rise of plasma free hemoglobin levels was significantly higher than that in the nonpulsatile group during and after cardiopulmonary bypass. We did not see the benefit of pulsatile perfusion using a roller pump on vasoactive hormones. Evidence of increased hemolysis with pulsatile flow was demonstrated in our cases.