Qualitative Determination of Hemoglobin in Rats with Septic Shock by Photoacoustic Spectroscopy

Septic shock is the main cause of death in patients in the intensive care unit. Nowadays, few methods exist in the clinical area that provide an early diagnosis of this condition, and these methods even deliver imprecise values on the concentration of hemoglobin. Photoacoustic spectroscopy (PAS) has been previously used to determine the concentration of hemoglobin in blood, based on the identification of the γ, β, and α peaks in the optical absorption spectrum, located at approximately 412 nm, 550 nm, and 580 nm, respectively. The absorption peak γ/β and γ/α ratios have been reported to be inversely proportional to the concentration of hemoglobin, which could be related to the severity of septic shock. The main goal of this work was to analyze the evolution of the γ/β and γ/α ratios, obtained by PAS, in blood samples of rats with septic shock induced through the intravenous administration of lipopolysaccharide (LPS, 6 mg·Kg⁻¹). Ratios of γ/β and γ/α increased as a function of time, implying a decrease in the hemoglobin concentration. Hemoglobin identified by PAS seems to be a prognostic biomarker in shock.