Artificial organs
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Effects of a newly introduced modified hemoglobin, pyridoxalated hemoglobin polyoxyethylene conjugate (PHP), and stroma-free hemoglobin (SFH) on cardiac rhythm and contractility were examined in isolated rat hearts. Hearts were perfused with HEPES-buffered Krebs solution containing 6% PHP, 6% SFH, or 6% hydroxyethylstarch (HES). Arrhythmia was not observed in PHP-perfused hearts, but marked sinus bradycardia occurred in SFH-perfused hearts. ⋯ There was no significant difference to the coronary flow resistance between hearts perfused with PHP and HES solutions, indicating that PHP has little vasoactive effect. The flow resistance in SFH-perfused hearts decreased significantly when compared with other groups. Results demonstrate that PHP solution can preserve cardiac function and have no toxic effects in isolated rat hearts.
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Extracorporeal membrane oxygenation (ECMO) can support neonates with severe respiratory failure. Currently, the most common application of ECMO requires venoarterial access. Venovenous (VV) ECMO is desirable to avoid common carotid artery ligation. ⋯ Higher mean bypass flow was required on DLC VV (124 ml/kg/min) compared to VA flow (101 ml/kg/min) because of recirculation of oxygenated blood. The position of the DLC in the right atrium needed to be closely monitored. Hemorrhage was noted in the myocardium after use of DLC VV ECMO.
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Ethylene oxide (ETO), an alkylating compound of high chemical reactivity, is widely used for gas sterilization, but recently serious ETO side reactions have been recognized. With chronic ETO exposure, increased spontaneous abortion, sister chromatid exchange, and leukemia are observed. After medical use of ETO outside nephrology, contact dermatitis, cardiopulmonary shock (during cardiopulmonary surgery), allergic local reactions to ETO sterilized lenses, and anaphylactoid reactions to ETO sterilized catheters have been described. ⋯ Furthermore an anaphylactoid "first-use reaction" was described in dialyzed patients, most of whom were using hollow-fiber dialyzers. After long discussions whether complement activation versus hypersensitivity is the cause of such acute anaphylactoid reactions, more recent studies using either ETO RAST or basophil degranulation tests implicate ETO hypersensitivity as their major cause. The high prevalence of sensitization to ETO and the frequency, unpredictability, and potential danger of anaphylactoid reactions to ETO lead to the conclusion that ETO sterilization of dialyzers should be discontinued, since alternative modalities of sterilization are currently available.
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The safety and efficacy of a conjugate of pyridoxalated hemoglobin and polyethylene glycol (pyridoxalated PEG hemoglobin) were evaluated after administration to rats. The LD50 (lethal dose for 50% survival of group) of pyridoxalated polyethylene glycol (PEG) hemoglobin was greater than 200 ml/kg. ⋯ However, these values were in the normal range after 3 days. With greater than 90% exchange-transfusion, all rats exchange-transfused with pyridoxalated PEG hemoglobin survived for greater than 2 weeks in contrast to the death of all the rats exchange-transfused with stroma-free hemoglobin or albumin.
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Human hemoglobin was pyridoxalated and subsequently coupled with the activated ester of polyethylene glycol (PEG) to provide an oxygen-carrying resuscitation fluid. The PEG conjugate of pyridoxalated hemoglobin (pyridoxalated PEG hemoglobin) has a longer half-life in the circulation (12.8 h) than does hemoglobin (2.2 h) when the solutions are exchange-transfused by approximately 60%. ⋯ The colloidal osmotic pressure and the viscosity were 36.5 +/- 2.4 mm Hg (n = 5) and 2.6 +/- 0.4 cp (n = 5), respectively. The results indicate that the pyridoxalated PEG hemoglobin solution has favorable properties for use as an oxygen-carrying resuscitation fluid.