Is timing of haemorrhage by spectrophotometry similar for haemorrhages in the subdural and subarachnoid space?

The haemoglobin (Hb) and bilirubin (Bil) spectral amplitudes were converted to micromoles per litre using a nomogram 3 and the Haemoglobin Index [HBI=Hb ([mu]mol/l)/Bil ([mu]mol/l)] and Haemoglobin Coefficient (HC=arc sine[radical] {[Hb]/[Hb + Bil + 1]} + arc sine [radical] {[Hb + 1]/[Hb + Bil + 1]}) calculated on the 30 spectrograms. 4 Absorbance indices (HBI and HC) of oxyhaemoglobin and bilirubin in subdural specimens did not correspond with those reported for subarachnoid haemorrhage and were unrelated to the time from admission.