Physio-Metabolic Monitoring via Breath Employing Real-Time Mass Spectrometry: Importance, Challenges, Potentials, and Pitfalls

Abstract

AbstractA tiny fraction of our breath contains trace volatile organics of various chemical classes. Due to their endogenous and/or exogenous origins, these volatiles can denominate many intrinsic and extrinsic effects. Exhaled volatile profiles are super dynamic in nature and their expressions may change from seconds to years. Exhaled volatile concentrations largely depend on normal or abnormal fluctuations in physiological and metabolic attributes. Minute or pronounced alterations in cardiorespiratory and other bronchopulmonary gas-exchange parameters due to simple changes in respiratory patterns, routes, and rhythms, posture, expiratory/inspiratory flow, and upper-airway resistance can immediately affect volatile profiles. Similarly, the subject’s age, gender, sexual orientation, metabolic state or status, diet, nutrition, therapy, lifestyle habits and habitats, menstrual phases, contraception, pregnancy, menopause, as well as any acute or chronic condition and comorbidities may cause transient or long-lasting differences in breath compositions. Applications of real-time mass spectrometric techniques along with alveolar sampling enabled us to frame fast occurring and continuous changes under diverse physio-metabolic conditions. Physio-metabolic conditions affected breath components more pronouncedly than the differential expression proposed as disease biomarkers in the literature. Investigations of such regulating factors helped us to develop the present state of the art for clinical breath sampling and analysis. Besides, assessments of ventilation and hemodynamics driven changes in exhaled volatiles have depicted potential for physio-metabolic monitoring. Longitudinal personalized analysis of breath profiles may offer unconventional path toward pathophysiological and therapeutic monitoring.KeywordsPathophysiologyBiomarkersBreath analysisMetabolismMonitoringOmicsPhysiologySamplingStandardizationVolatile organic compounds (VOCs)