First Department of Critical Care, Medical School, University of Athens, Evangelismos Hospital, 45-47 Ipsilantou Street, Athens 106 76, Greece
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Weaning from mechanical ventilation is usually accomplished with spontaneous breathing trials. The discontinuation of mechanical ventilation and the resumption of spontaneous breathing may increase oxygen demands, and patients, mainly those with limited cardiorespiratory reserve, are subjected to pulmonary and cardiovascular stress. In addition, emotional distress due to agitation after interruption of sedative drugs, anxiety and other sources of discomfort potentially contributes to pulmonary and cardiovascular stress. There is evidence of metabolic and endocrine stress response expressed as an increase in oxygen consumption and plasma concentration of catecholamines and other hormones involved in the stress system activation, in patients during the weaning process from mechanical ventilation, especially during failing weaning attempts. Furthermore, extrapolating from both physical exercise and inspiratory resistive breathing data, there is evidence of immune response expressed as an increase of proinflammatory cytokine blood levels. The purpose of this review is to summarise the published information about neurormonal and inflammatory stress response during weaning from mechanical ventilation.
The stress response during weaning trials from mechanical ventilation has not been studied enough. Nevertheless, there is evidence that the process of weaning from mechanical ventilation incorporates hormonal, inflammatory and neuroendocrine responses, indicating that weaning might prove physically and psychologically stressful. Further studies should evaluate this stress response more thoroughly for better management of these patients.