Evaluation of Intrapulmonary Shunt Alterations at Different Oxygen Concentrations and Oxygenation Parameters

Abstract

The aim of the current study was to evaluate the relationship of intrapulmonary shunt with FiO 2 alterations in patients treated with mechanical ventilation in intensive care unit for extrapulmonary disorders. Also, we aimed to assess the role of correlation between shunt ratio and PaO 2 /FiO 2 , PaO 2 /PAO 2 , P(A-a) O 2 values in determining the treatment strategies. Methods: Twenty patients between ages of 19 and 75 years, requiring mechanical ventilation were enrolled into the study. We excluded two patients due to congestive heart failure and two patients due to acute respiratory distress syndrome (ARDS). Shunt fraction, P(A-a)O 2 , PaO 2 /FiO 2 , PaO 2 /PAO 2 values were calculated at each FiO 2 level for each patient. Results: The lowest median shunt value was measured at FiO 2 : 0.3 There was a significant correlation between shunt values at FiO 2 0.5 and 0.7 (r=0.850). The highest mean value of P(A-a)O 2 was measured at FiO 2 : 1 (382.91±106.46), and the lowest value of P(A-a)O 2 was measured at FiO 2 : 0.21 (38.64±16.97). PaO 2 /FiO 2 and PaO 2 /PAO 2 ratios measured at FiO 2 : 0.3 and 0.5 were found to be statistically significant. Conclusion: In this study, we have shown increased shunt fraction at FiO 2 : 1 level. Different oxygenation indices and shunt measurements give us important and useful knowledge about the patients' current condition.