Journal of applied physiology
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Ischemia-reperfusion lung injury limits lung transplantation. Neutrophil activation and/or xanthine oxidase-mediated purine degradation may cause toxic oxygen metabolite production and lung injury. We investigated whether circulating blood elements are involved in the pathogenesis of ischemia-reperfusion lung injury. ⋯ Microvascular pressures were not different and could not account for the results. Toxic O2 metabolites were involved in the injury because addition of erythrocytes or catalase to the perfusate attenuated the injury. Thus reperfusion after lung ischemia causes injury that is dependent on a nonneutrophil source of toxic O2 metabolites.
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The effects of continuous positive airway pressure (CPAP) on supraglottic and total pulmonary resistance were determined in 10 healthy premature infants (postconceptional age 34 +/- 2 wk, weight at study 1,628 +/- 250 g). Nasal airflow was measured with a mask pneumotachograph, and pressures in the esophagus and oropharynx were measured with a 5-Fr Millar or fluid-filled catheter. Nasal CPAP between 0 and 5 cmH2O correlated well with oropharyngeal pressure (r = 0.94). ⋯ The decrease in total supraglottic resistance in these infants accounted for 60% of the change in total pulmonary resistance, which occurred on CPAP of 5 cmH2O. We speculate that CPAP may decrease supraglottic resistance directly through mechanical splinting of the airway. This effect of CPAP may be the primary mechanism by which this form of therapy reduces apnea with an obstructive component in premature infants.