Application of near infrared spectroscopy in the ICU for follow-up of patients with subdural haematomas

Background

Secondary haemorrhage is an important cause of brain injury following initial therapy of subdural haematoma (SDH). Early identification and treatment of secondary haemorrhage improve neurologic outcome. Nearinfrared light at a wavelength of 760 nm shows a high absorption for haemoglobin. In a previous study we were able to show the potential of Near Infrared Spectroscopy (NIRS) as a noninvasive tool to detect intracranial haemorrhage. Aim of our study was to analyse the capabilities of NIRS for follow-up of SDH patients.

Methods

We prospectively studied 21 patients with the CT diagnosis of SDH using MRS (RunMan^™, NIM Inc.). The difference in absorbance of light (ΔOD) at a wavelength of 760 nm between both hemispheres was measured at three different measuring points. The first measurement was performed upon hospital admission. Measurements were repeated on day 1, 2, 3 and at discharge. Additional measurements were performed in case the patients' neurological conditions had changed.

Results

17 patients showed unilateral SDH at admission, 16 of these were correctly identified by NIRS; four patients showed bilateral SDH at admission. All patients received neurosurgical treatment. At day 1 after surgery NIRS measurements identified 3 patients with complete drainage of the haematoma, 4 patients were identified at day 2 and 5 patients were identified at day three. At discharge there were no pathologic NIRS findings in 13 patients, indicating the complete resorption of the haematoma. CT scans at discharge proved these findings. In 8 patients we found pathologic NIRS values at discharge, indicating an incomplete resorption of the haematomas. CT scans prior to discharge demonstrated residual SDH in all of these 8 patients.

Conclusion

Our results showed that repeated NIRS measurements in patients with SDH help to document the clinical course after surgical treatment. As a non-invasive, easily transportable diagnostic device, the RunMan^™ helps to avoid time delay in diagnosis of secondary haemorrhage and facilitate early treatment, thus possibly saving time and reducing secondary injury as well as treatment costs.