The International journal of artificial organs
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In an attempt to identify current indications and patient selection criteria for the use of mechanical circulatory support, we reviewed our experience in 83 patients who received a total artificial heart (TAH; n = 43), ventricular assist device (VAD) (n = 13), centrifugal pump (n = 17) or extracorporeal membrane oxigenation (ECMO) (n = 8) as a bridge to transplantation (Group I, n = 50) or for recovery from heart failure (Group II, n = 33). Comparing patients successfully transplanted (n = 20) or weaned (n = 9) who survived initial hospitalization, and those who died on mechanical support, there were no differences in preoperative renal, hepatic or pulmonary functions. ⋯ In postcardiotomy patients, duration of cardiopulmonary by-pass (CPB) was significantly different comparing survivors with those who died in either bridge or recovery groups and all patients who had a CPB greater than 4 hours died on MS or after transplantation or weaning. In conclusion, preoperative indices indicating reversibility of multiple organ dysfunction remain to be identified.(ABSTRACT TRUNCATED AT 250 WORDS)
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Problems associated with specific physiological properties of Hb-based blood substitutes, such as low P50, short plasma half-life and nephrotoxicity are still major issues to be addressed. Extensive investigations aimed at overcoming these problems have resulted in the preparation of pyridoxalated-hemoglobin-polyoxyethylene conjugate (PHP). PHP was developed from human hemoglobin by two major chemical modifications; pyridoxylation for the purpose of lowering the oxygen affinity (P50 of 19.5 +/- 1.2 mmHg), and coupling with polyoxyethylene (POE) to increase its molecular weight (to approximately 90 kdaltons). ⋯ Its efficacy in transporting oxygen has been shown in ET and intracoronary perfusion, and in in vitro studies with sickle cells. Studies to date suggest that PHP is a promising candidate as a physiological oxygen carrier. In this paper the properties of PHP, its safety and efficacy aspects, and its potential as a clinical oxygen carrier are reviewed based on studies conducted in the Author's laboratory.
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Ten pigs with experimental respiratory distress syndrome were treated by extracorporeal CO2 removal (ECCO2-R) combined with low frequency positive pressure ventilation (LPPV). After lung damage had been induced by repeated lung lavages a PEEP trial was conducted in order to find the appropriate PEEP for the damaged lungs. This PEEP was then applied during the ECCO2-R/LPPV period. ⋯ During controlled mechanical ventilation (CMV), comparable adequate gas exchange was only achieved at a significantly higher mean airway pressure (Paw 14.1 +/- 0.08 vs 21.2 +/- 0.47 cmH20, p less than 0.0001). Hemodynamic variables did not change significantly during bypass time. ECCO2-R/LPPV driven by a simple renal perfusion system allows adequate gas exchange in experimental respiratory failure.
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Comparative Study
Metabolic CO2 removal by dialysis: THAM vs NaOH infusion.
New methods of respiratory support are needed to reduce the high mortality rate of acute respiratory failure. To simplify the procedures of extracorporeal CO2 elimination under apneic oxygenation, one approach is to replace the membrane lung by a hemodialyzer and to administer an alkali, since hemodialysis requires a lower blood flow rate than blood-gas exchange. This study compared the effectiveness of trishydroxymethyl aminomethane (THAM) and NaOH in this procedure. ⋯ However, hemolysis was six times greater with NaOH than with THAM. Despite ultrafiltration, a similar marked weight gain was observed from the second hour of the experiment in the NaOH series, but only after 7 hours with THAM. It thus appears that hemodialysis combined with alkalinisation is still too complex a procedure to be safely applied in acute or chronic pulmonary failure.