Article Text

Download PDFPDF

Is timing of haemorrhage by spectrophotometry similar for haemorrhages in the subdural and subarachnoid space?
  1. K Kamath Tallur,
  2. N R Belton,
  3. R Stephen,
  4. R A Minns
  1. University of Edinburgh, UK
  1. Correspondence to:
    Dr R A Minns
    Child Life and Health, University of Edinburgh, 20 Sylvan Place, Edinburgh EH9 1UW, UK;

Statistics from

We investigated whether quantifying the spectral peaks for oxyhaemoglobin, methaemoglobin, and bilirubin (and their ratios) and comparing them to established standards for timing subarachnoid haemorrhage, might permit timing of the subdural haemorrhage.

When red cells enter the subarachnoid space, they are visible for a few days to several weeks.1 Lysis of red cells results in oxyhaemoglobin release predominantly between 2 and 12 hours but continues up to 48 hours. A microsomal enzyme haeme oxygenase, released from macrophages (and the arachnoid membrane) converts oxyhaemoglobin to bilirubin. Bilirubin usually appears after 3–4 days but may exceptionally occur as early as 9–10 hours. The “bilirubin transforming capacity” is a rate limiting reaction, and when the concentration of oxyhaemoglobin rises rapidly, additional amounts are oxidised non-enzymatically to methaemoglobin.2

Thirty spectrograms performed on centrifuged, undiluted samples of subdural aspirates from 14 infants (mean age 4.6 months) admitted with subdural haematoma/effusion of suspected non-accidental origin, were reviewed retrospectively and peaks of oxyhaemoglobin (absorption peak at 413–415 nm), bilirubin (peak at 450–460 nm), and methaemoglobin (absorption peak at 405 nm) identified.

The haemoglobin (Hb) and bilirubin (Bil) spectral amplitudes were converted to micromoles per litre using a nomogram3 and the Haemoglobin Index [HBI = Hb (μmol/l)/Bil (μmol/l)] and Haemoglobin Coefficient (HC = arc sine√ {[Hb]/[Hb + Bil + 1]} + arc sine √ {[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. Pigment concentrations were higher than those reported from patients with subarachnoid haemorrhage, confirming similar observations of Wahlgren and Lindquist who suggested that this was due to “packing” of the erythrocytes and their subsequent lysis.5 Unlike a subarachnoid haemorrhage which disperses within the cerebrospinal fluid spaces and will dilute and disappear fast, the subdural haemorrhage is in a more encapsulated space without a natural circulation.

We concluded that while spectrophotometry of the subdural fluid can identify fresh blood, oxyhaemoglobin, bilirubin, or methaemoglobin in the aspirate, and the presence of bilirubin indicates that bleeding has occurred between 24 hours and 3 days prior to admission, it is not possible to time the original haemorrhage by using spectral peak data from existing models of subarachnoid haemorrhage.



  • Competing interests: none declared

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.