Life support systems : the journal of the European Society for Artificial Organs最新文献

The case of a 20-year-old male patient, with a history of addiction to parenteral heroin and recurrent prosthetic valve endocarditis, is presented. In this case the final procedure consisted of a complete translocation of the aortic root and coronary bypass grafting with a composite graft made from a microporous polyurethane (Mitrathane) cardiac patch, a prosthetic valve and two Mitrathane vascular grafts for the coronaries. This is a complex operation, only indicated in cases of extensive destruction of the aortic root due to recurrent endocarditis. To our knowledge, it is the first case of this type performed using Mitrathane.

We have developed and improved a method for the continuous on-line registration of cardiac output. By measuring blood velocity with a hot-film anemometer probe in the pulmonary artery, cardiac output can be estimated by gated systolic integration of the velocity signals. The integrated value for a certain period can be converted to a cardiac output proportional value. A thermistor placed next to the velocity probe enables thermodilution measurement of cardiac output, which serves as in vivo and in situ calibration. In this paper an in vitro study of the method applied to pulsatile flow is presented. A good correlation was found between real flow and both the velocity method and the thermodilution method. Fluid temperature and changing stroke volume and/or pulse frequency had minimal influence on accuracy, whereas altered probe position required recalibration for the velocity method but not for the thermodilution method. The advantages of the velocity method for the measurement of cardiac output are: The continuous on-line monitoring of cardiac output. The need for the injection of only very small volumes of cold saline, as the frequency of thermodilution measurements is reduced.

Familial hypercholesterolaemia is caused by genetic defects in the cellular metabolism of cholesterol (C) and is characterized by high levels of low-density lipoproteins (LDL) and premature atherosclerosis. The C is carried in the plasma mainly as an LDL-C complex, and removal of the latter from plasma is highly desirable. This task can be achieved by selective haemoperfusion (HP), thereby eliminating the need for plasmapheresis. Agarose beads (2 per cent agarose, 0.85 to 1.4 mm in diameter) were prepared, and crosslinked with epichlorohydrin. Heparin and/or ethanolamine were subsequently attached. The beads thus obtained were found to be suitable for the removal of LDL-C from the whole blood of hypercholesterolaemic rabbits, using a simple HP technique. A single two-hour HP treatment with a 40 ml column packed with active agarose beads resulted in a 30 per cent decrease in the C plasma level in the experimental animals. Our previous, in vitro, studies with the plasma of hypercholesterolaemic patients showed a high selectivity of the beads for LDL. Yet when used with hypercholesterolaemic rabbits, a relatively high amount of HDL was also removed from the blood. This can be attributed to a significant difference between the structure of human hypercholesterolaemic lipoproteins and that of rabbits. Upon treatment of blood using the active agarose beads, no abnormalities in plasma and blood composition were detected, except for some prolongation of PT. It is to be hoped that this new system will replace the presently used and highly expensive plasmapheresis.

From January 1984 to August 1985, 51 out of 2138 patients undergoing cardiac surgery (2.38 per cent) had an intra-aortic balloon pump (IABP) inserted or an attempted insertion. The patients ranged in age from 24 to 68 years (mean 54.2 years). An IABP was inserted preoperatively in four patients, all of whom were in cardiogenic shock; peroperatively in 27 patients who could not be weaned from cardiopulmonary bypass; and postoperatively in 16 patients who had haemodynamic deterioration. Failed insertion occurred in a further four patients. Twenty-eight patients (59.6 per cent) had percutaneous insertion of the balloon, in 17 (36.2 per cent) the common femoral artery was exposed prior to insertion and in two (4.2 per cent) the balloon was inserted into the thoracic aorta. The overall survival rate was 38.3 per cent for patients with successful insertion. Major complications that threatened life or limb occurred in 10.25 per cent of patients. These complications were confined to females and in these patients the percutaneous technique for inserting intra-aortic balloons should be used with caution.

This paper describes the performance of a microfiltration plasmapheresis unit operating with reversing oscillatory flows. The device consists of a flat channel duct between cellulose nitrate membranes and was used to extract plasma from anticoagulated fresh whole bovine blood. Measurements were made of plasma flux, haematocrit concentration, haemolysis and protein sieving coefficients. The effects on plasma flux are reported for alterations in the stroke and frequency of flow pulsations, transmembrane pressure, membrane properties and blood throughput. It was found that the imposition of oscillatory flows enhanced the plasma extraction rate by a factor of 3, producing about 0.9 litre/min/m2 membrane.

The utilization of a computer-assisted information system may be both useful and efficacious in the care and follow-up of diabetic patients. The model developed by us operates under GCOS-6 on a Microsystem 6/10 Honeywell computer (20 MB hard-disk storage, 512 kb central memory) and allows the creation of clinical data files for individual patients, statistical analysis of the data, and a print-out of clinical records. The package, which may be employed on a multi-user system, is supplied with an easy to understand user's manual. It represents an effective tool for the precise management of the care of diabetic patients and also provides several opportunities for research.