Rationale:
The ketogenic diet (KD) is a highly effective treatment for refractory epilepsies. Maintenance of ketosis is crucial for seizure control, but the most reliable ketone measurement method, serum beta-hydroxybutyrate (BHB), requires blood sampling. A non-invasive monitoring device which measures acetone concentrations in exhaled breath would improve the ease of KD maintenance. Laser absorption spectroscopy (LAS) provides highly-sensitive, species-specific concentration measurements by quantifying molecular absorption of laser light. LAS can be performed directly on breath samples with no sample pre-treatment through a compact, fast-response optical sensor. We present pilot data correlating breath acetone levels measured by laser spectroscopy with serum BHB.
Method:
Exhaled breath samples were obtained from 6 participants (4 female), 25.17 ± 18.76 (mean ± SD) (range 3-57) on ketogenic diet for refractory epilepsy in the outpatient setting. Breath samples are introduced into an optical gas cell to measure molecular absorption due to acetone and infer breath acetone concentration. Breath CO₂ concentration is similarly measured with a Fourier-transform infrared spectrometer (FTIR) and used to normalize the measured acetone concentration for consistent comparison.
Results:
Linear regression analysis indicates plasma BHB levels 1.84 ± 1.60 mmol/l (Range 0.16 to 4.50) has close correlation (r = 0.891, p = 0.017) with breath acetone levels 19.62 ± 26.77 ppm / 5% CO₂ (Range 0.42 to 72.57).
Conclusion:
Laser-based spectroscopy of exhaled breath provides a fast, noninvasive and quantifiable means to determining acetone in the breath. Breath acetone levels correlates closely with serum BHB.
Funding:
:None
FIGURES
Figure 1