tailieunhanh - Báo cáo y học: "Assessment of gas exchange in lung disease: balancing accuracy against feasibility"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Critical Care giúp cho các bạn có thêm kiến thức về ngành y học đề tài: Assessment of gas exchange in lung disease: balancing accuracy against feasibility. | Available online http content 11 6 182 Commentary Assessment of gas exchange in lung disease balancing accuracy against feasibility Peter D Wagner Division of Physiology University of California San Diego California USA Corresponding author Peter D Wagner pdwagner@ Published 21 December 2007 This article is online at http content 11 6 182 2007 BioMed Central Ltd Critical Care 2007 11 182 doi cc6198 See related research by Karbing et al. http content 11 6 R118 Abstract While the principles underlying alveolar gas exchange have been well-known for over 50 years we still struggle to assess gas exchange in hypoxemic patients. Unfortunately simple measurements lack discrimination while complex measurements are infeasible in clinical care. The paper by Karbing et al. in this issue seeks a middle ground based on the arterial Po2 PaO2 inspired O2 fraction Fio2 ratio measured at different Fio2s with the outcomes fed into proprietary software to account for both shunting and ventilation perfusion inequality. Whether this is the optimal compromise between measurement difficulty and information available will have to be answered by those willing to test the approach in their own patients. It never ceases to amaze me that the primary function of the lungs - gas exchange - can be accurately described by one simple mass conservation equation. Such cannot be said for any other organ. However while this was well established over 50 years ago 1 2 we continue to struggle for ways to quantify abnormal gas exchange in patients with hypoxemia. The problem boils down to the complexity of gas exchange in diseased lungs where hypoxemia can stem from firstly insufficient overall ventilation secondly shunting of blood through unventilated vascular channels thirdly non-uniform distribution of ventilation perfusion or both throughout the 300 million or so alveoli and fourthly diffusion limitation of O2 exchange across the alveolar wall 3 . .