Weaning from mechanical ventilation
In the majority of cases, mechanical ventilation can be withdrawn after resolution or significant improvement of the underlying indication for mechanical ventilation. However, it is estimated that ≈20-30% of patients require gradual withdrawal of ventilatory support, namely weaning.
This process of discontinuing mechanical ventilation may be a major challenge, especially in patients with chronic respiratory disorders, where weaning is particularly difficult. In addition, it is estimated that the proportion of intubated and ventilated COPD patients needing a weaning procedure ranges between 35-67%.
Weaning is a complex clinical intervention that usually entails different components such as: 1) the organisation of the unit, 2) the characteristics of the staff and 3) the protocols. Improving the process of ventilator weaning to reduce the duration of mechanical ventilation has been the subject of research in recent years.
Weaning from mechanical ventilation was categorised as simple, difficult or prolonged by an international task force of the American Thoracic Society/European Respiratory Society/European Society of Intensive Care Medicine/Society of Critical Care Medicine/Sociétée de Réanimation de Langue Française in 2007.
Patients receiving prolonged mechanical ventilation (PMV) consume 2/3 of hospital resources allocated to the mechanical ventilation population and are nearly twice as likely to be discharged to a skilled nursing facility. Recent estimates indicate that in the US the number of PMV patients is expected to double by year 2020, reaching more than 600,000 patients. Moreover, one-year follow-ups of these patients show that 29% are discharged to a Long-Term Acute Care Facility (LTAC), 67% are readmitted to hospital at least once, and one-year mortality was 44%.
There have been several recent key developments in the field of weaning - the use of weaning protocols, ventilatory strategies to reduce the need for invasive ventilation and facilitate successful extubation, and also the creation of regional long-term ventilation units.
Early physiotherapy and weaning
Prolonged immobilisation is common in the ICU and plays an important role in the development of neuromuscular weakness, which may complicate the clinical outcome of a disease. Recent research suggests that early physical therapy reduces the duration of mechanical ventilation and provides a more rapid return to ambulation.
Non-invasive ventilation as a weaning method
Non-Invasive Ventilation (NIV) should be considered early in the process of weaning, before a tracheostomy is performed, unless there are specific contraindications for this such as upper airway obstruction or severe bulbar weakness.
The use of standardised weaning protocols has been traditionally associated with better ICU outcomes.
New extubation strategies
Spontaneous breathing trials (SBT) provide an overall guide to ventilatory capacity, but signify little regarding cough efficacy and the ability to clear bronchial secretions if an endotracheal tube or tracheostomy is in situ. A new management paradigm (including the use of continuous NIV via oral interfaces and masks together with Mechanical Assisted Coughing-MAC) reported a 95% success rate in extubating patients with neuromuscular weakness who systematically failed SBT. So in these patients with ineffective cough and ventilatory dependence a new protocol including aggressive MAC to expel secretions and full-time NIV was very successful in assisting their extubation.
The decision to perform a tracheostomy is more of an experience than an evidence-based decision and should be made with caution. Moreover, decannulation should be an important goal since several studies show that lack of decannulation before ICU discharge to the general ward is associated with higher mortality. Although there is a general belief that tracheostomy speeds ICU discharge and thus increases ICU survival, more of these patients die on the ward, resulting in a null effect on overall hospital mortality.