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OC-072 Identification of psychophysiological biomarkers of nausea using a novel visual induction method

Introduction Nausea is a common and complex multisystem subjective symptom with considerable inter-individual variation in nausea susceptibility which makes it difficult to recruit homogenous subgroups of patients and controls for clinical studies. Preliminary studies have demonstrated that the autonomic nervous system (ANS)1 plays an important role in modulating nausea perception. However it is not known if ANS parameters can be used as biomarkers of nausea perception and susceptibility. Aim The aim of our study was to study the autonomic response to a novel method of nausea induction. Methods A 10-minute video that induced motion sickness and another that did not (neutral video) were presented to 20 healthy volunteers (aged 20 to 49 years, 10 male). All subjects filled out a motion sickness assessment questionnaire MSAQ; Autonomic nervous system was continuously monitored for sympathetic (cardiac sympathetic index CSI, heart rate HR, mean blood pressure MBP) and parasympathetic (cardiac vagal tone CVT, cardiac sensitivity to baroreceptor reflex CSB) measures. Results All 20 subjects completed the study. The nausea scores were higher during the nausea video compared to the neutral video (nausea scores MSAQ, +196%±55, p<0.01). Furthermore, during nausea video compared to neutral video, there was increased cardiac sympathetic activity (HR +6%±2, p<0.01; MBP +7%±2, p<0.01; CSI +18%±8, p<0.01) and decreased parasympathetic activity (CSB −11%±6, p<0.01; with significantly lower CVT in subjects with more nausea (nausea scores MSAQ >+100%) compared with those without nausea (no nausea on MSAQ): (percentage change −0.29±0.01 vs −0.01±0.05, p<0.01, respectively). Conclusion This visual nausea induction method is safe and effective. We also demonstrate that nausea induction is associated with increased sympathetic activity and parasympathetic withdrawal. Furthermore, there is more marked CVT withdrawal to nauseogenic stimuli for nausea susceptible subjects suggesting that this parameter may have validity as a biomarker of nausea susceptibility. As motion sickness is known to induce gastrointestinal (GI) physiological changes, this model can be used to study the effects of nausea on GI function in health and disease together with the option of correlating these changes to objective autonomic physiological biomarkers.