Calculate the Alveolar Arterial Oxygen Difference

CalcAaDO2.vb

Sub Main
	Console.WriteLine(CalcAaDO2(50, 60, 80))
End Sub

' Calculate the Alveolar Arterial Oxygen Difference. Returns -1 if calculation not possible
' AaDO2 = (713 * FiO2) - (PaCO2 / 0.8) - PaO2
Function CalcAaDO2(dblPaCO2 As Double, dblPaO2 As Double, dblFiO2 As Double) As Double
	Dim dblRatio As Double = -1
	
	If dblFiO2 > 1 Then dblFiO2 = dblFiO2 / 100
	If dblPaCO2 > 0 And dblPaO2 > 0 And dblFiO2 > 0 Then
		dblRatio = (713 * dblFiO2) - (dblPaCO2 / 0.8) - dblPaO2
	End If
	
	Return dblRatio
End Function