Measurement of plasma glucose under hyperbaric oxygen conditions

This study was designed to evaluate the accuracy of the bedside glucometer SureStepPro (SSP, LifeScan Inc; Milpitas, California) against a standard laboratory instrument (Yellow Springs Instruments [YSI] 2300 STAT PLUS; Yellow Springs, Ohio) during hyperbaric oxygen therapy. Human blood samples were used to prepare plasma glucose (PG) concentrations over a range 25-300 mg/dl ( 1.4-16.6 mmol/l). Samples were sequentially tonometered (Instruments Lexington [IL] 237 Lexington, Maryland) with two separate gas mixes at 203 kPa (2 bar) to PO2 values of 159 kPa (1,200 mmHg, 1.6 bar) and then 8.1 kPa (60mmHg, 0.08 bar), allowing measurement of each blood sample at both PO2 values. PG concentrations were immediately measured by a SSP at 203 kPa (2 bar) then analysed outside the chamber by both instruments. The YSI PG measurements were unaffected by high PO2. Compared with PG concentrations measured at PO2 of 8.1 kPa (60 mmHg, 0.08 bar), the YSI readings at PO2 of 159 kPa (1,200 mmHg, 1.6 bar) were higher by only 1.8 ±1.6 mg/dl (0.1 ± 0.09 mmol/l). At PO2 8.1 kPa (60 mmHg, 0.08 bar), compared with the YSI, the mean bias and imprecision (SD of bias) of the SSP were 6.8 and 5.7 mg/dl (0.38 and 0.32 mmol/l). At PO2 159 kPa (1,200 mmHg, 1.6 bar), the bias and imprecision of the SSP were 4.6 and 4.8 mg/dl (0.26 and 0.27 mmol/l). The PG concentrations at PO2 159 kPa (1,200 mmHg, 1.6 bar) measured by the SSP, when used inside the hyperbaric chamber at 203 kPa (2 bar) were lower by only 3.5 ± 4.5 mg/dl (0.19 ± 0.25 mmol/l) compared with SSP values at 101 kPa (1 bar). Therefore, the SSP provides accurate measurement of PG in blood when used either at 101 kPa(1 bar) or inside the hyperbaric chamber at 203 kPa (2 bar).

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