• Oral fluid
• Needle trap micro-extraction
• Heart failure
• Breath sampling
• Breath
• Analytical chemistry
• Oral fluid sampling
• Warfarin

Early detection plays a crucial role for treatment planning and prognosis of diseases. The ability to evaluate physiological conditions, trace disease progression and monitor post-treatment therapeutics, is one of the primary objectives in the field of healthcare research. The analysis of blood, tissue and urine, is the common approach used in this field, although the collection of these specimens is invasive and requires trained personnel. The possibility to obtain complementary clinical information as from traditional fluids, in a non-invasive way and without risk for the patients, represents one of the most important goal of health monitoring. The analysis of alternative matrices, such as breath and oral fluid, may meet these requirements and therefore represents an interesting approach, especially for the screening of large population.
The aim of this work is to evaluate alternative strategies for monitoring and detection of diseases. For this purpose, two research projects are presented: 1) monitoring of the concentration of warfarin and its metabolite in oral fluid and plasma samples collected from patients undergoing anticoagulant therapy and 2) monitoring of the chemical composition of breath and oral fluid samples collected from patients with heart failure symptoms during an exercise stress test.
Although such fluids are easy to collect, careful attention must be paid to the effect of possible variables (e.g. time and mode of collection) that may interfere with the quantitative or qualitative analysis. For the oral fluid samples, we preliminarily evaluated the influence of collection protocols on the measured concentration of target analytes.
The data presented here confirm the key-role of both oral fluid pH and flow rate on the transfer mechanisms of warfarin and its metabolites as well as uric acid. In particular, we found that a six-minute stimulation with a chewing gum increases the oral fluid pH to values close to 7.4 (physiological pH of blood) and creates the optimum conditions for the diffusion of hydrophobic and acidic compounds (e.g. warfarin and its metabolites) from plasma to oral fluid. On the contrary, stimulation decreases of the oral fluid concentration of uric acid. Since this compound does not diffuse through the salivary membrane due to its low hydrophobicity, we hypothesized a different transfer process, probably mediated from a particular membrane carrier namely URAT1.
Using the optimized collection protocol, we evaluated the possibility of a non-invasive approach for the monitoring of patients undergoing anticoagulant therapy. The results confirmed the advantages of a longitudinal study over a cross sectional approach in this field of research, since the pharmacological effect of warfarin is prone to several variables whose effect is more easily unravelled if more observations are available for a single patient. We observed a clear relationship within individuals between the concentration of warfarin and its anticoagulant effect. We speculated that these individual concentration-effect curves might provide useful information to improve the personalization of warfarin therapy.
In the second study, the experimental results from breath analysis confirm that variations of particular compounds (e.g. pentane and acetone) related to altered metabolic pathways (e.g. oxidative stress and ketone body metabolism) might provide useful and complementary information to the classical diagnosis, and might help to monitor patients suffering from heart disease in a non-invasive way.
Moreover, we also tested a new approach to pre-concentrate breath samples by means of needle trap devices. This new technique is combining the advantages of solid phase micro-extraction and solid phase extraction.