Aim:

The aim of the current study was to evaluate the relationship of intrapulmonary shunt with FiO2 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 PaO2/FiO2, PaO2/PAO2, P(A-a)O2 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)O2, PaO2/FiO2, PaO2/PAO2 values were calculated at each FiO2 level for each patient.

Results:

The lowest median shunt value was measured at FiO2: 0.3 There was a significant correlation between shunt values at FiO2 0.5 and 0.7 (r=0.850). The highest mean value of P(A-a)O2 was measured at FiO2: 1 (382.91±106.46), and the lowest value of P(A-a)O2 was measured at FiO2: 0.21 (38.64±16.97). PaO2/FiO2 and PaO2/PAO2 ratios measured at FiO2: 0.3 and 0.5 were found to be statistically significant.

Conclusion:

In this study, we have shown increased shunt fraction at FiO2: 1 level. Different oxygenation indices and shunt measurements give us important and useful knowledge about the patients’ current condition.

Keywords: Pulmonary ventilation, respiration, ventilation-perfusion ratio