3 research outputs found
The relationships between air exposure, negative pressure, and hemolysis.
The purpose of this study was to describe the hemolytic effects of both negative pressure and an air-blood interface independently and in combination in an in vitro static blood model. Samples of fresh ovine or human blood (5 ml) were subjected to a bubbling air interface (0-100 ml/min) or negative pressure (0-600 mm Hg) separately, or in combination, for controlled periods of time and analyzed for hemolysis. Neither negative pressure nor an air interface alone increased hemolysis. However, when air and negative pressure were combined, hemolysis increased as a function of negative pressure, the air interface, and time. Moreover, when blood samples were exposed to air before initiating the test, hemolysis was four to five times greater than samples not preexposed to air. When these experiments were repeated using freshly drawn human blood, the same phenomena were observed, but the hemolysis was significantly higher than that observed in sheep blood. In this model, hemolysis is caused by combined air and negative pressure and is unrelated to either factor alone.</p
Use of venovenous extracorporeal membrane oxygenation and an atrial septostomy for pulmonary and right ventricular failure.
BACKGROUND: Right ventricular failure is a major contributor to morbidity and mortality on the lung transplant waiting list. This study was designed to evaluate the effectiveness of an atrial septostomy with venovenous extracorporeal membrane oxygenation (VV-ECMO) as a novel potential bridge to transplantation.
METHODS: Adult sheep (58±3 kg; n=12) underwent a clamshell thoracotomy and instrumentation to measure all relevant pressures and cardiac output (CO). Sheep with tricuspid insufficiency (TI [n=5]) and without tricuspid insufficiency (ØTI [n=7]) were examined. After creation of a 1-cm atrial septal defect and initiating VV-ECMO, the pulmonary artery (PA) was banded to allow progressive reduction of pulmonary blood flow, and data were collected.
RESULTS: The CO in both groups remained unchanged from baseline at all pulmonary blood flow conditions. With TI, the CO was 5.1±1.2 L/min at baseline versus 5.1±1.2 L/min with a fully occluded PA (p=0.99). For ØTI, the CO was 4.5±1.4 L/min at baseline versus 4.5±1.2 L/min with no pulmonary blood flow (p=0.99). Furthermore, CO was not affected by the presence of TI (p=0.76). Mean right ventricular pressures were significantly lower in the TI group (TI=20.2±11 mm Hg versus ØTI=29.9±8.9 mm Hg; p0.5). Lastly, VV-ECMO maintained normal blood gases, with mean O2 saturations of 99% ± 4.1% in both groups.
CONCLUSIONS: Right to left atrial shunting of oxygenated blood with VV-ECMO is capable of maintaining normal systemic hemodynamics and normal arterial blood gases during high right ventricular afterload dysfunction.</p
Portable Nitric Oxide (NO) Generator Based on Electrochemical Reduction of Nitrite for Potential Applications in Inhaled NO Therapy and Cardiopulmonary Bypass Surgery
A new
portable gas phase nitric oxide (NO) generator is described
for potential applications in inhaled NO (INO) therapy and during
cardiopulmonary bypass (CPB) surgery. In this system, NO is produced
at the surface of a large-area mesh working electrode by electrochemical
reduction of nitrite ions in the presence of a soluble copperÂ(II)-ligand
electron transfer mediator complex. The NO generated is then transported
into gas phase by either direct purging with nitrogen/air or via circulating
the electrolyte/nitrite solution through a gas extraction silicone
fiber-based membrane-dialyzer assembly. Gas phase NO concentrations
can be tuned in the range of 5–1000 ppm (parts per million
by volume for gaseous species), in proportion to a constant cathodic
current applied between the working and counter electrodes. This new
NO generation process has the advantages of rapid production times
(5 min to steady-state), high Faraday NO production efficiency (ca.
93%), excellent stability, and very low cost when using air as the
carrier gas for NO (in the membrane dialyzer configuration), enabling
the development of potentially portable INO devices. In this initial
work, the new system is examined for the effectiveness of gaseous
NO to reduce the systemic inflammatory response (SIR) during CPB,
where 500 ppm of NO added to the sweep gas of the oxygenator or to
the cardiotomy suction air in a CPB system is shown to prevent activation
of white blood cells (granulocytes and monocytes) during extracorporeal
circulation with cardiotomy suction conducted with five pigs