Exhalation of volatile organic compounds during hemorrhagic shock and reperfusion in rats: an exploratory trial.

Ischemia and reperfusion alter metabolism. Multi-capillary column ion-mobility spectrometry (MCC-IMS) can identify volatile organic compounds (VOCs) in exhaled gas. We therefore used MCC-IMS to evaluate exhaled gas in a rat model of hemorrhagic shock with reperfusion. Adult male Sprague-Dawley rats (n = 10 in control group, n = 15 in intervention group) were anaesthetized and ventilated via tracheostomy for 14 h or until death. Hemorrhagic shock was maintained for 90 min by removing blood from the femoral artery to a target of MAP 35 ± 5 mmHg, and then retransfusing the blood over 60 min in 15 rats; 10 control rats were evaluated without shock and reperfusion. Exhaled gas was analyzed with MCC-IMS, VOCs were identified using the BS-MCC/IMS analytes database (Version 1209). VOC intensities were analyzed at the end of shock, end of reperfusion, and after 9 h. All normotensive animals survived the observation period, whereas mean survival time was 11.2 h in shock and reperfusion animals. 16 VOCs differed significantly for at least one of the three analysis periods. Peak intensities of butanone, 2-ethyl-1-hexanol, nonanal, and an unknown compound were higher in shocked than normotensive rats, and another unknown compound increased over the time. 1-butanol increased only during reperfusion. Acetone, butanal, 1.2-butandiol, isoprene, 3-methylbutanal, 3-pentanone, 2-propanol, and two unknown compounds were lower and decreased during shock and reperfusion. 1-pentanol and 1-propanol were significant greater in the hypotensive animals during shock, were comparable during reperfusion, and then decreased after resuscitation. VOCs differ during hemorrhagic shock, reperfusion, and after reperfusion. MCC-IMS of exhaled breath deserves additional study as a non-invasive approach for monitoring changes in metabolism during ischemia and reperfusion.

Exhalation pattern changes during fasting and low dose glucose treatment in rats.

The analysis of exhaled metabolites has become a promising field of research in recent decades. Several volatile organic compounds reflecting metabolic disturbance and nutrition status have even been reported. These are particularly important for long-term measurements, as needed in medical research for detection of disease progression and therapeutic efficacy. In this context, it has become urgent to investigate the effect of fasting and glucose treatment for breath analysis. In the present study, we used a model of ventilated rats that fasted for 12 h prior to the experiment. Ten rats per group were randomly assigned for continuous intravenous infusion without glucose or an infusion including 25 mg glucose per 100 g per hour during an observation period of 12 h. Exhaled gas was analysed using multicapillary column ion-mobility spectrometry. Analytes were identified by the BS-MCC/IMS database (version 1209; B & S Analytik, Dortmund, Germany). Glucose infusion led to a significant increase in blood glucose levels (p < 0.05 at 4 h and thereafter) and cardiac output (p < 0.05 at 4 h and thereafter). During the observation period, 39 peaks were found collectively. There were significant differences between groups in the concentration of ten volatile organic compounds: p < 0.001 at 4 h and thereafter for isoprene, cyclohexanone, acetone, p-cymol, 2-hexanone, phenylacetylene, and one unknown compound, and p < 0.001 at 8 h and thereafter for 1-pentanol, 1-propanol, and 2-heptanol. Our results indicate that for long-term measurement, fasting and the withholding of glucose could contribute to changes of volatile metabolites in exhaled air.