Development of a point-of-care device for the quantification of bilirubin in cerebral spinal fluid

In North America, an estimated 30,000 patients annually experience an aneurysmal subarachnoid hemorrhage (SAH). In approximately five percent of these patients, the hemorrhage is not visible on computerized tomography scans due to the inability to image blood at time intervals greater than 12 hours post symptom onset. For these patients (many of which have experience a sentinel hemorrhage that is a precursor to a more significant rupture) a method is needed for accurately analyzing cerebral spinal fluid (CSF) for evidence of SAH. Further, it is necessary to differentiate blood associated with the SAH from blood associated with the spinal tap procedure. This paper presents the development of a point-of-care device that is capable of performing such an analysis. The stand alone prototype device uses commercially available embedded system components to implement a hardware platform that is capable of collecting and analyzing optical absorbance spectra. A mathematical model for the hemorrhagic CSF sample is then developed using a PLSR based regression methodology that is able to differentiate between SAH and blood associated with the spinal tap. This differentiations in achieved by quantifying bilirubin (associated with the breakdown of old blood) in the CSF. Initial testing on the prototype device suggests that the device is able to quantify bilirubin in the presence of hemoglobin over concentrations ranges that are clinically relevant to the patient population of interest.