The Effects of Different Weaning Modes on the Endocrine
Introduction: The aim of the present study was to investigate the effects of the stress response on plasma insulin, cortisol, glucose, and urinary vanilmandelic acid during weaning and after extubation, using pressure support (PS), continuous positive airway pressure (CPAP) and T-piece modes.
Methods: Sixty patients were randomly divided into three groups (n = 20). The PS group received FiO₂ ≤ 0.4, PS ≤ 10 cmH₂O, and positive end expiratory pressure ≤ 5 cmH₂O for 2 hours. The CPAP group was given FiO₂ ≤ 0.4 and CPAP 5 ≤ cmH₂O for 2 hours. The T-piece group (group T) received 4 l/min oxygen via a T-piece for 2 hours. After 1 hour and 2 hours in their respective weaning modes, blood and urine samples were taken for insulin, cortisol, glucose and vanilmandelic acid measurements. Forty-eight hours after extubation, blood and urine samples were again taken.
Results: Plasma insulin was greater in group T than in the PS and CPAP groups (P < 0.01 and P < 0.01). The plasma cortisol concentration was greater in group T than in group PS during weaning (P < 0.05) and after extubation (P < 0.05). Blood glucose concentrations were greater in group T than in the other groups (both P < 0.01) both during weaning and post extubation. Urine vanilmandelic acid was greater in group T than in the other groups during weaning and after extubation (both P < 0.001).
Conclusion: Weaning via the T-piece caused a greater stress response than the PS and CPAP modes.

Intubation and mechanical ventilation are safe and effective treatments for critically ill patients with respiratory failure. However, while unnecessary prolongation of mechanical ventilation increases the risk of complications, including bronchopulmonary infections, barotrauma, and oxygen toxicity, its premature discontinuation may also increase morbidity and mortality. Intensive care can indeed be prolonged if reintubation is needed. 'Weaning' is the withdrawal of mechanical ventilatory support, although the term 'liberation' may be more appropriate. Selection of the most appropriate mode for weaning can be difficult.

The effect of weaning on the stress response in critically ill patients is uncertain, as are the effects of different weaning modes. The aim of the present study was to compare changes in plasma concentrations of insulin, cortisol and glucose, and in urine vanilmandelic acid (VMA) during weaning and after extubation, using the three different modes of pressure support (PS) ventilation, continuous positive airway pressure (CPAP) and T-piece, in intensive care patients.