Experimental lung research
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The authors devised a novel bronchial artery catheterization technique to deliver agents directly into bronchial circulation with preserved blood flow in an awake ovine model. A polyurethane catheter was inserted into bronchial artery via an incision into the 4th intercostal space. Regional blood flow of the airway was measured by fluorescent microspheres before cannulation, after cannulation, and 7 days after the operative procedure. ⋯ The regional blood flow increased 10-fold after inhalation injury in bronchi of the sham group. Bronchial artery ligation significantly attenuated the increase of blood flow. However, cannulation preserved regional blood flow and did not prevent the blood flow increases after burn and smoke inhalation injury, thus constituting a novel bronchial artery catheterization technique.
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Inhaled nitric oxide (iNO) improves gas exchange in about 60% of patients with acute respiratory distress syndrome (ARDS). Recruitment of atelectatic lung areas may improve responsiveness and preservation of spontaneous breathing (SB) may cause recruitment. Accordingly, preservation of SB may improve effectiveness of iNO. ⋯ Significant gas exchange improvements due to iNO were only achieved during unassisted SB with BIPAP (P <.05) but not during CMV or assisted SB. The authors conclude that effectiveness of iNO may be improved by unassisted SB during BIPAP but not by assisted SB. Thus combined iNO and unassisted SB is possibly most effective to improve gas exchange in severe hypoxemic ARDS.
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Comparative Study
High-frequency oscillation combined with arteriovenous extracorporeal lung assist reduces lung injury.
In order to optimize the lung-protective potential of high-frequency oscillatory ventilation (HFOV), it is currently recommended to maximize oscillatory frequencies. However, very high frequencies may lead to insufficient CO(2) elimination with severe respiratory acidosis. Arteriovenous extracorporeal lung assist (av-ECLA) allows near total CO(2) removal, thereby allowing for maximization of the lung-protective potential of HFOV. ⋯ The authors found that the combination of HFOV and av-ECLA (1) allows significant reductions in mean and peak airway pressures; and (2) reduces histological signs of lung inflammation in the basal regions of the lung. HFOV/av-ECLA reduces histological signs of lung inflammation compared to conventional lung-protective ventilation strategies. Thus, combination of HFOV and av-ECLA might be a further lung-protective tool if conventional ventilation strategies are failing.