The International journal of artificial organs
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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.