Reducing the duration of mechanical ventilation
The requirement for mechanical ventilatory support is the most common indication for admission to an intensive care unit - and up to 50% of the time that a patient receives such treatment may be taken up by attempts to discontinue it: a process termed weaning.
Ensuring an optimal multidisciplinary approach to the management of the ventilated patient will minimise the duration of ventilatory support and reduce complications such as ventilator-associated pneumonia (VAP).
Conventional ventilatory support is applied through an endotracheal tube. In non-invasive ventilation (NIV) ventilatory support is applied with a facemask and avoids endotracheal intubation. In certain patient groups, such as Chronic Obstructive Airways Disease, NIV is associated with a reduction in morbidity, length of ICU stay and mortality. NIV may also facilitate weaning of patients with underlying chronic respiratory disease. However, inappropriate use of NIV may adversely affect outcome and appropriate patient selection and prompt recognition of failure is essential.
A number of non pharmacological approaches have been shown to reduce the incidence of VAP including nursing patients in the semi-recumbent position (30-45 degrees), avoiding unnecessary manipulaation or changes in the respiratory circuit and the prevention of ventilator circuit condensate, either by regular drainage or the use of heat and moisture exchangers. Meticulous hand washing and disinfection, by all healthcare workers, will reduce cross infection and readily available, alcohol-based lotions, at every bed space, improves compliance.
The optimal approach to weaning includes daily screening of all patients to assess readiness combined with a single daily short (30 minute) trial of unassisted breathing (T piece trial) and gradual withdrawal of ventilatory support with pressure support ventilation in patients who fail a T piece trial. The use of a protocol to guide non-physicians allows nurses or respiratory therapists to undertake weaning confidently and may be more effective than physician directed weaning.
Administration of excessive sedation to ventilated patients is a common factor which delays weaning from mechanical ventilation. Daily interruption of sedative infusions ensures that the continuing requirement for sedation is regularly reviewed and excessive administration avoided. This simple practice has been shown to reduce the duration of mechanical ventilatory support and length of ICU stay and should be included in all sedation protocols.
The organisation of ventilatory support within ICU will influence outcome. Protocols are required to minimise the risk of developing VAP, encourage daily interruption of sedative infusions and allow non-physician directed weaning. Appropriate use of NIV complements invasive support. Whilst a single change may have a limited effect upon outcome, combining all these changes into a respiratory care bundle is likely to have a significant effect on length of stay ensuring that ICU beds are used efficiently.
Contact: peter.macnaughton@phnt.swest.nhs.uk
01.03.2005
