Ganesh pilot study: The evolution of metabolism during different levels of NIV in healthy volunteers

Abstract BackgroundMetabolism of critically ill adult patients is variable and influenced by intrinsic and extrinsic factors. Energy expenditure and thereby metabolism can be captured with indirect calorimetry (IC). An increased respiratory muscle use due to acute hypercapnic failure during Chronic Obstructive Pulmonary Disease exacerbation or other pulmonary problems may increase energy expenditure. Therefore, noninvasive ventilation (NIV) can be used in these conditions. It decreases the work of breathing by supporting muscle activity which will in turn cause a lower muscle metabolism. When this therapy fails, a higher mortality is observed due to delayed intubation. No good single early clinical parameter for NIV failure has been identified. Metabolism seems a promising parameter that has not been researched yet. We explored if IC connected to the NIV device will capture metabolic alterations due to different levels of support with NIV in healthy subjects. Patient and methodsIn this pilot study, metabolism objectified by Resting Energy Expenditure was measured with IC in 5 healthy subjects receiving NIV with increasing levels of support. Noninvasive hemodynamic monitoring was applied. Rate of perceived exertion was also assessed. ResultsDuring increasing levels of inspiratory support, linear regression showed increasing energy expenditure with a function of Y 1 =18,42*X+743,3 and decreasing levels of dyspnea with a function of Y 5 = -0,565*X + 4,42. Friedman test was not significantly different (p=0,364) for energy expenditure but was significantly different (p= 0,014) for the rate of perceived exertion. Further analysis of the rate of perceived exertion with Wilcoxon matched-pairs rank test showed no difference for the different levels of support compared to only positive end-expiratory pressure (PEEP).ConclusionIndirect calorimetry captures metabolic alterations induced by NIV treatment. Metabolism is influenced by increasing levels of support in healthy volunteers. Rate of perceived exertion is not correlated with metabolic alterations induced by NIV.