Quantitative assessment of pulmonary shunt and ventilation-perfusion mismatch without a blood sample

The automated lung parameter estimator (ALPE) system for quantitatively assessing pulmonary gas exchange in clinical practice has been shown to be useful for diagnosing lung dysfunction and monitoring treatment. However, the method requires at least one blood sample, which is routine in intensive care, but not readily available in many other hospital departments. This study investigates the feasibility of using default blood gas data and pulse oximetry to determine gas exchange parameters non-invasively. It was found that values of shunt and V/Q mismatch estimated using only non-invasively measured data, correlated well with the same values found using more accurate, multiple invasive, methods. This method greatly improves the feasibility of using the ALPE method for diagnosing and monitoring patients outside the intensive care department.