Kinetics of oxygen uptake during unassisted breathing trials in prolonged mechanical ventilation: a prospective pilot study

Abstract

psychological, metabolic, anemia, and nutritional problems 7. This condition may be associated with insufficient strength and endurance of respiratory muscles due to the increased respiratory mechanical load 8. In addition, the change from MV support to unassisted breathing can increase the work of breathing (WOB) 9. However, measuring WOB may not be practical in a post-acute setting due to the need for invasive placement of pressure sensors. Oxygen uptake (V O 2) assesses the global ability of oxygen intake by the respiratory system, delivery by the cardiovascular system, and use by working tissues. In physiologic studies, maximum V O 2 is traditionally used to evaluate cardiorespiratory capacity 10. For example, in cardiopulmonary exercise tests it is used to differentiate the cause of dyspnea 11 , in which an incremental external work rate is usually applied to determine whether the V O 2 is above the anaerobic threshold 12-15. The kinetics of V O 2 during exercise have also been correlated with the prognosis in patients with chronic heart failure 13,16-20. Previous studies have shown that the change in V O 2 when reducing ventilator support can be used as an alternative measurement to represent the change in WOB in patients receiving ventilator support 21. Although previous studies have evaluated associations between changes in V O 2 at different levels of ventilator support and the ability to spontaneously breathe and the outcomes of weaning 19,22,23 , few studies have investigated measurements of the kinetics of V O 2 in tracheostomized patients undergoing UBTs. Understanding the kinetics of V O 2 and associated metabolic and spirometry parameters may help clinicians to differentiate the cause of weaning failure in this last stage. Therefore, the aim of this pilot study was to investigate the kinetics of V O 2 during UBTs in patients with prolonged MV. Methods Design and setting. This prospective study was conducted from January to December 2018 at the Respira

Mechanical power density, spontaneous breathing indexes, and prolonged weaning failure: a prospective cohort study

“…Another limitation is that no information is available regarding patients’ respiratory drive and inspiratory effort before and during SBT. Finally, we did not compare MP density with other measures of spontaneous work of breathing, such as esophageal manometry-derived tidal changes in esophageal pressure 25 , spontaneous mechanical power ratio and pressure-rate index (4DPRR) 35 , or changes in oxygen consumption during SBT 36 , which should be explored in future research.…”