This research was designed to establish the validity and reliability of the Abbot Point of Care i-STAT®1 handheld device for the analysis of glucose and electrolytes in postmortem vitreous humor. As a result, the i-STAT®1 can decrease systematic errors due to pre-analytical treatment. The i-STAT®1 not only uses a smaller amount of sample, but also has a shorter analysis time, as pre-analytical treatment is not required. Single-use disposable cartridges introduce 100 μL of sample to the i-STAT®1 handheld analyzer without the need for pre-analytical treatment. The i-STAT®1 is a handheld point-of-care device created in 1983 by Abbott Laboratories for the analysis of whole blood at a patient’s bedside ( 13). Nonetheless, pre-analytical treatments require time and can increase inaccuracy and imprecision ( 7, 12). Different pre-analytical treatments including heating, centrifugation and liquefying agents had been examined to determine the most effective technique. Furthermore, these instrumental techniques are infrequently available to forensic laboratories. Although flame photometry and ISE techniques are fast and reliable, pre-analytical treatment was still needed for improved accuracy and precision, causing an increase in analysis time. In a study by Blana et al., sodium, potassium and chloride were quantitated by flame photometry while calcium, glucose, lactate, urea and creatinine were quantitated by the Ion-Selective Electrode (ISE) method ( 7). However, due to the high viscosity of vitreous humor, each technique requires pre-analytical treatment to enhance accuracy and precision of measured analytes. The thickness of this fluid is due to type II collagen fibers, as well as electrolytes, glucose and proteins ( 11).įor decades, forensic science has utilized different techniques for the quantitation of electrolytes and glucose in vitreous humor.

The vitreous is made up of 99% water however the viscosity of vitreous is roughly 4.20 (mPa), more viscous than water (1.00 mPa) ( 9, 10). Vitreous humor is more protected from autolysis and putrefaction compared to other body fluids upon death ( 5, 7, 8). Vitreous humor is the semi-clear liquid-gel housed between the lens and the retina of the eye, giving the eye its shape. When no other cause can be found, vitreous humor can give examiners a clue deviations from clinical ranges for electrolytes and glucose can be indicative of significant clinical causes ( 4, 6). The chemical analysis of vitreous humor has long been utilized in conjunction with autopsies to assist the medical examiner in determining cause of death ( 1– 5). Vitreous humor, electrolytes, i-STAT ®1, postmortem, chemical analyzer Introduction As vitreous humor continues to be used in forensic medicine to aid in diagnostic interpretation, the i-STAT®1 has the potential to give accurate results in a timely and cost-effective manner. Volume additions to ethanol spiked samples caused significant interference for all analytes and is considered a limitation for this method of analysis that requires additional studies. Significant interference with commonly found drugs were shown for creatinine and chloride but must be evaluated carefully. Throughout drug interference and stability studies, all analytes of interest were detectable except for potassium, which gave inconclusive results. Drug interference and stability studies were performed with many of the analytes demonstrating a percent error < ☒0%. All analytes of interest, except creatinine, demonstrated a percent error < ☑0% for both accuracy and precision studies. Acceptable criterion was used for each test as suggested by the Scientific Working Group for Forensic Toxicology. In this study, we utilized the i-STAT®1 using an alternative specimen matrix, postmortem vitreous humor and quantitatively determined the validity and reliability of the instrument for this purpose. With only 100 μL of sample, results are obtained in under 4 min. Different cartridge types allow for the analysis of various analytes including sodium, potassium, chloride, creatinine, urea nitrogen and glucose. The utility of the i-STAT®1 medical device to measure electrolytes and glucose in whole blood samples has been demonstrated for over two decades in a clinical setting through single-use disposable cartridges that introduce samples to the i-STAT®1. This can be both time-consuming and costly. Numerous medical examiner laboratories outsource the analysis of this important specimen for electrolyte and glucose measurements. The analytical value of vitreous humor as a specimen in postmortem forensic toxicology has been known for some time.

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