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The interface geometry of human and artificial hearts was defined. It included: 1) the approximate mitral orifice and mitral orifice planes; 2) the approximate tricuspid orifice and tricuspid orifice planes; 3) the long and short diameters of the aorta; 4) the long and short diameters of the pulmonary artery; and 5) the angles between the mitral orifice and tricuspid orifice planes, as well as the axes of the aorta and pulmonary artery. The orifice plane was defined as a plane such that the sum of the squared distances between the plane and points on the orifice contour was minimized. A standard coordinate system was also defined, whose origin was the centroid of the approximate mitral orifice. Its X-Y plane was the approximate mitral orifice plane. One set of interface parameters was determined using magnetic resonance images of a volunteer's heart. The angle between the approximate mitral orifice plane and tricuspid plane was found to be 19.9 degrees. The areas of the approximate mitral and tricuspid orifices were 1020 and 1655 mm2, respectively. The approximate mitral orifice was covered by a 44 x 40 mm rectangle and the approximate tricuspid orifice was covered by a 59 x 41 mm rectangle. This interface geometry is important, not only in the manufacture of artificial hearts of precise dimensions, but also in avoiding complications due to their long-term use.

The dextran sulfate (DS) cellulose column usually used for low-density lipoprotein (LDL) apheresis, is an activator of the contact phase of intrinsic coagulation pathway. Hageman factor (factor XII), high-molecular-weight kininogen (HMWK) and prekallikrein (PK) form a complex on the surface of this activator, and bradykinin is released from HMWK by the action of kallikrein converted from PK. Heparin, a frequently used anticoagulant, has no effect on this process, whereas a protease inhibitor, nafamostat mesilate (FUT-175) is thought to inhibit the process. Five patients with severe hypercholesterolemia were treated with LDL apheresis using heparin or FUT-175, each on a different day. During treatment with heparin, factor XII, HMWK, and PK were markedly decreased by passing through the DS column. A distinct generation of bradykinin was observed by passing through the DS column, which led to an increase of blood bradykinin levels from 12.5 +/- 5.3(Mean +/- SEM) pg/ml to 127.3 +/- 67.1 pg/ml after 1000 ml plasma treatment. FUT-175 almost completely suppressed this bradykinin generation. Because bradykinin generated during LDL apheresis seems to have some vasodilative effect, FUT-175 might be preferred in cases with unstable hemodynamics, although this presumption remains to be demonstrated.

Hypertonic solutions of dextrose (D), mannitol (M), and saline (S) are effective treatments for hemodialysis-associated muscle cramps, but have not been directly compared to one another. Concern exists that postdialysis retention of M and S may lead to increased thirst, interdialytic weight pain (IDWG), and elevated blood pressure. The authors performed a prospective, randomized, double-blind crossover study to compare the efficacy of D, M, and S in 24 chronic hemodialysis patients. Cramps were treated with 50 ml (126 mOsm) D, 100 ml (138 mOsm) M, and 16 ml (126 mOsm) S. All patients were assigned to each regimen for a 2 week period. For the entire patient group (n = 24), mean cramp duration (+/- SD) was less for M compared to D (9 +/- 5 vs 13 +/- 12 min, p less than 0.05), but not to S (10 +/- 6, p = NS) although not every patient had a cramp episode during each 2 week period of study. In a subgroup of 11 patients with a mean of 3.7 (range 1-6) cramps during each 2 week period, the efficacy of D, M, and S was similar. In both patient groups, IDWG, blood pressure control, and the frequency of adverse effects was similar with the use of all three agents. Mild postdialysis hyperglycemia and hypernatremia during D and S, respectively, were the only significant laboratory abnormalities. The authors conclude: 1) the safety and efficacy of D, M, and S are equivalent, and 2) the nonmetabolized osmotic agents M and S do not lead to increased IDWG or decreased blood pressure control.

Monitoring of the influence of cardiopulmonary bypass (CPB) on hematologic parameters is relevant to an improved understanding of the pathophysiology produced, as well as for the development of improved methods. The selection of suitable parameters is highly important. In this study, both contact phase activation and leukocyte response have been studied. Contact activation was determined by a novel assay for the measurement of Factor XII activity (FXIIA), and leukocyte response was measured by the release of granulocyte elastase. Five patients undergoing elective coronary artery surgery using a bubble oxygenator and pulsatile perfusion were studied. A notable feature of this study was the gradual increase of FXIIA during the study period, with granulocyte elastase levels following a similar pattern. Both FXIIA and granulocyte elastase are appropriate parameters for monitoring CPB, and could be useful in studying alternative bypass procedures and antithrombotic agents.

Paralysis in the head and neck can affect any motor or mixed cranial nerves and the cervical roots. Most conspicuous deficits, however, involve the larynx and the face. The capacity for denervated striated muscle to undergo reinnervation, and the presence of remaining sources of information, have allowed coordinated rehabilitation of incapacitated cervical neuromuscular systems. The object of further related research should focus on the long-term efficacy of the reinnervated muscle machinery and the potential complexities of electronic integration.

Bleeding due to systemic heparinization represents the major side effect of extracorporeal respiratory support. In the present animal study, a surface heparinized system (Carmeda Biological Active Surface) was applied to assess the feasibility of prolonged perfusion at low circulating heparin levels. Eight sheep divided into two groups: group A (5 animals) and group B (3 animals) underwent venovenous bypass using a heparin coated surface circuit. The following protocol was used: a) 24 hours at high heparin dose (30 to 100 U/kg/hr with an ACT [activated coagulation time] three to four times normal); b) 24 hours at low heparin dose (3 to 8 U/kg/hr with an ACT within the normal range); c) 24 hours at high heparin dose. Group B animals also received fresh frozen sheep plasma (14 ml/kg/day). During Period b, the clotting times were within baseline range. The bleeding time showed a dramatic decrease after change from a to b (27.9 +/- 3 minutes vs. 10.2 +/- 5.6 minutes). There was a negative relationship between antithrombin III (AT III) and thrombin coagulase time (TC); the latter is considered to be an aspecific indicator of circulating fibrin(ogen) degradation products. Maintaining AT III over 70%, TC changes were only minor. The use of the bioactive heparin surface allowed the performance of a 24 hour bypass, with normal coagulation times, at low circulating heparin levels.

To determine whether any potentially reversible variables are related to the development of hand gangrene in diabetic patients on dialysis, the authors compared 15 patients with hand gangrene (group A) to three control groups of diabetics on dialysis: 20 patients with foot gangrene (group B); 31 patients without gangrene of the extremities (group C); and 20 patients without hand arterial calcifications (group D). All patients in groups A-C had medial arterial calcifications of the hands. Group A patients started dialysis at an earlier age (p less than 0.05), were treated for end-stage renal disease (ESRD) for a longer time period (p less than 0.05), and had a lower mean serum albumin concentration during the dialysis period (p less than 0.05) than the patients in the control groups. Hand gangrene also appeared to be associated with the presence of a functioning arterio-venous fistula in the extremity with the gangrene, with loss of function of renal transplant, and with hyperaluminemia. Other variables, including serum parathormone, were not different for the four groups. Logistic regression showed that the following were risk factors for hand gangrene: hypoalbuminemia, long duration of ESRD treatment, hyperphosphatemia, high insulin dose, hypercholesterolemia, and hypoglycemia. In diabetics on dialysis, gangrene develops in hands with medial arterial calcifications, but does not correlate with measures of calcium or phosphorous metabolism. Predictors of hand gangrene include certain potentially reversible clinical and biochemical variables.

Term or near term newborns whose severity of cardiac or respiratory failure makes them candidates for extracorporeal membrane oxygenation (ECMO) are often too unstable to be safely transported to an ECMO-competent center. Faced with a large military and civilian referral population that is distributed across the entire continental United States, the authors have addressed this dilemma by developing a transportable ECMO system that can be taken to the referring hospital in a small transport aircraft. This system was on hand, but was not required, to stabilize and transport the infant in question in four cases. All had uneventful transports. Thirteen infants were placed on ECMO at their referring hospitals, one of whom died shortly after the institution of bypass. The remaining 12 infants were stabilized and transported successfully on ECMO over distances ranging from 17 to 1,437 miles, with 11 of these being long distance air transports. Four patients are long-term survivors. The authors conclude that a properly configured and managed ECMO system can effectively stabilize and transport even extremely ill neonates if the pertinent physiologic and aeromedical considerations are addressed.