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After tracheal extubation, upper and total airway resistances may frequently be increased resulting in an increase in inspiratory effort to breathe. We tested whether breathing a helium-oxygen mixture (HeO(2)) would reduce inspiratory effort in the period after extubation. Eighteen consecutive patients with no chronic obstructive pulmonary disease who had received mechanical ventilation (> 48 h) were successively studied immediately after extubation (N(2)O(2)), 15 min after breathing HeO(2), and after return to N(2)O(2). Effort to breathe, assessed by the transdiaphragmatic pressure swings (DeltaPdi) and the pressure-time index of the diaphragm (PTI), comfort, and gas exchange, were the main end points. The mean reduction of the transdiaphragmatic pressure under HeO(2) was 19 +/- 5%. All but three patients presented a decrease in transdiaphragmatic pressure under HeO(2), ranging from - 4 to - 55%, and a significant reduction in DeltaPdi was observed between HeO(2) and N(2)O(2) (10.2 +/- 0.7 versus 8.6 +/- 1.1 versus 10.0 +/- 0.8 cm H(2)O for the three consecutive periods; p < 0.05). PTI also differed significantly between HeO(2) and N(2)O(2) (197 +/- 19 versus 166 +/- 22 versus 201 +/- 23 cm H(2)O/s/min for the three periods; p < 0.05). Breathing HeO(2) significantly improved comfort, whereas gas exchange was not modified. We conclude that the use of HeO(2) in the immediate postextubation period decreases inspiratory effort and improves comfort.

The use of helium-oxygen (HeO(2)) was tested in combination with noninvasive ventilation (NIV) in 10 patients with acute exacerbation of chronic obstructive pulmonary disease (COPD). Effort to breathe as assessed by the respiratory muscle pressure-time index (PTI), work of breathing (WOB), and gas exchange were the main endpoints. Results of NIV-HeO(2) were compared with those obtained with standard NIV (AirO(2)), at two levels of pressure-support ventilation (PSV), 9 +/- 2 cm H(2)O and 18 +/- 3 cm H(2)O. Significant reductions in PTI were observed between HeO(2) and AirO(2) at both the low PSV level (n = 9; 160 +/- 58 versus 198 +/- 78 cm H(2)O/s/ min; p0.05) and the high PSV level (n = 10; 100 +/- 45 versus 150 +/- 82 cm H(2)O/s/min; p0.01). WOB also differed significantly between HeO(2) and AirO(2) (7.8 +/- 4.1 versus 10.9 +/- 6.1 J/min at the low PSV level, p0.05; and 5.7 +/- 3.3 versus 9.2 +/- 5. J/min, p0.01 at the high PSV level). HeO(2) reduced Pa(CO(2)) at both the low PSV level (61 +/- 13 versus 64 +/- 15 mm Hg; p0.05) and the high PSV level (56 +/- 13 versus 58 +/- 14 mm Hg; p0.05), without significantly changing breathing pattern or oxygenation. We conclude that use of HeO(2) during NIV markedly enhances the ability of NIV to reduce patient effort and to improve gas exchange.

To assess the feasibility of following a decisional flowchart to decide whether to remove tracheotomy in long-term mechanically ventilated patients. Prospective study in a respiratory intensive care unit, with beds dedicated to weaning from prolonged mechanical ventilation 108 tracheotomized patients with respiratory failure of different causes (chronic obstructive pulmonary disease, postsurgical complications, recovery from hypoxemic respiratory failure, neuromuscular disorders), 36 of whom died or could not be weaned from mechanical ventilation. We applied a decisional flowchart based on some simple clinical and physiological parameters aimed at assessing the patient's ability to remove secretions, swallowing function, absence of psychiatric diseases, possibility of reaching spontaneous breathing, and amount of respiratory space. Following our flowchart 56 of the remaining patients were successfully weaned from the tracheotomy cannula, with a reintubation rate at 3 months of 3%. The main reasons for not proceeding to decannulation were inability to remove secretions and severe glottic stenosis. No statistical differences were found between patients who received a surgical or percutaneous tracheotomy. Using a simple decisional flowchart we were able to remove tracheotomy cannula in almost 80% of the patients with spontaneous breathing autonomy without major clinical complications. Further larger prospective studies are needed to confirm this clinical approach in larger and different populations.

Introduction Physiological determinants of weaning success and failure are usually studied in ventilator-supported patients, comparing those who failed a trial of spontaneous breathing with those who tolerated such a trial and were successfully extubated. A major limitation of these studies was that the two groups may be not comparable concerning the severity of the underlying disease and the presence of comorbidities. In this physiological study, we assessed the determinants of weaning success in patients acting as their own control, once they are eventually liberated from the ventilator. Methods In 30 stable tracheotomised ventilator-dependent patients admitted to a weaning center inside a respiratory intensive care unit, we recorded the breathing pattern, respiratory mechanics, inspiratory muscle function, and tension-time index of diaphragm (TTdi = Pdisw/Pdimax [that is, tidal transdiaphragmatic pressure over maximum transdiaphragmatic pressure] × Ti/Ttot [that is, the inspiratory time over the total breath duration]) at the time of weaning failure (T0). The measurements were repeated in all the patients (T1) either during a successful weaning trial (successful weaning [SW] group, n = 16) or 5 weeks later, in the case of repeated weaning failure (failed weaning [FW] group, n = 14). Results Compared to T0, in the FW group at T1, significant differences were observed only for a reduction in spontaneous breathing frequency and in TTdi (0.21 ± 0.122 versus 0.14 ± 0.054, P = 0.008). SW patients showed a significant increase in Pdimax (34.9 ± 18.9 cm H2O versus 43.0 ± 20.0, P = 0.02) and decrease in Pdisw/Pdimax (36.0% ± 15.8% versus 23.1% ± 7.9%, P = 0.004). Conclusions The recovery of an inadequate inspiratory muscle force could be the major determinant of 'late' weaning success, since this allows the patients to breathe far below the diaphragm fatigue threshold.