Calculate the oxygenation index

CalcOI.vb

Sub Main
	Console.WriteLine(CalcOI(12, 80, 60))
	Console.WriteLine(CalcOI(12, 0.8, 60))
End Sub

' Calculate the oxygenation index. Returns -1 if calculation not possible
' OI = (MAP * FiO2 * 100) / PaO2
Function CalcOI(dblMAP As Double, dblFiO2 As Double, dblPaO2 As Double) As Double
	Dim dblOI As Double = -1
	
	If dblFiO2 >= 0.21 And dblFiO2 <= 1 Then dblFiO2 = dblFiO2 * 100
	If dblPaO2 > 0 And dblMAP > 0 And dblFiO2 >= 21 Then
		dblOI = (dblMAP * dblFiO2) / dblPaO2
	End If
	
	Return dblOI
End Function