Artificial organs
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For many years it has been assumed that patients undergoing cardiac surgery utilizing cardiopulmonary bypass accumulate an "oxygen debt" that requires a higher postoperative hemoglobin concentration for its reversal. Much of this evidence has now been discredited due to mathematical error with recent research suggesting critical levels of oxygen delivery are lower than previously thought. This article aims to explore the relationship between observed and critical oxygen delivery with an estimation of the minimal hemoglobin required. ⋯ Observed measurements of oxygen delivery were recorded and compared with calculated "critical" values adjusted for temperature. The hemoglobin value that represented critical oxygen delivery was compared with the observed value to identify any "hemoglobin reserve." At no perioperative time point did observed oxygen delivery or critical hemoglobin concentration significantly approach its corresponding critical value. Current transfusion practice in noncritically ill cardiac surgery patients may be considered excessive if systemic oxygen requirement is the sole parameter considered.
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There is increasing evidence showing that adult stem cells are useful for tissue regeneration. Bone marrow mesenchymal stem cells (MSCs) are self-renewing and are potent in differentiating into multiple cells and tissues. To investigate the practicability of repairing burn wounds with tissue-engineered (TE) skin combined with bone MSCs, we established a burn wound model in the porcine skin. ⋯ When grafted to the burn wounds, the TE skin containing MSCs showed better healing and keratinization, less wound contraction, and more vascularization. Grafts proliferated well and contributed to the neo-tissues. These data suggest that TE skin containing MSCs in a burn defect can accelerate wound healing and receive satisfactory effects.
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Small animal cardiopulmonary bypass (CPB) model would be a valuable tool for investigating pathophysiological and therapeutic strategies on bypass. However, the rat CPB models have a number of technical limitations. Effective maintenance and control of core temperature by heat exchanger (HE) is among them. ⋯ Arterial blood gases and hematocrits showed no further significant findings. We confirmed the effect of rectal temperature maintenance and hypothermic control using an HE of cardioplegia system in CPB model for rats. This model would be a valuable tool for further use in hypothermic CPB experiments in rats.
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Ultrasound image and augmented reality guidance for off-pump, closed, beating, intracardiac surgery.
Our project is the reintroduction of off-pump intracardiac surgery using the Universal Cardiac Introducer (UCI) for safe intracardiac access. The purpose of this study was to evaluate multimodality visualization using three ultrasound modalities and ultrasound augmented with virtual reality. Image guidance was tested on implanting a mitral valve prosthesis via the UCI in 12 pigs. ⋯ Positioning of the clip was difficult because of artifacts with multiple reflections and shadowing. Augmented reality displayed the entire prosthesis and the tools without artifacts; provided intuitive information on navigation, positioning, and orientation of tools; and improved significantly image guidance and surgical skill. Augmented virtual reality, with tracked 2-D or 3-D ultrasound imaging, provides guidance that can effectively substitute for direct vision during beating heart intracardiac surgery.
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The aim of this study was to determine the optimal positive end-expiratory pressure (PEEP) required during extracorporeal lung membrane support (interventional lung assist [iLA]; Novalung GmbH, Hechingen, Germany). Twenty healthy pigs were initially (4 h) mechanically ventilated with a tidal volume (V(T)) of 10 mL/Kg, respiratory rate (RR) of 20 breaths/min, PEEP of 5 cm H(2)O, and fraction of inspired O(2) (FiO(2)) of 1.0. ⋯ Gas exchanges with PEEP < or = 10 cm H(2)O were significantly worse than those with PEEP > 12 cm H(2)O, and this without hemodynamical imbalance. This study suggests that the iLA may provide adequate gas exchange during static ventilation only with PEEP levels > 10 cm H(2)O, and this without pulmonary or systemic hemodynamic imbalance.