Ventilators are life-saving breathing devices that are essential in some situations; but ventilator-associated pneumonia (VAP)? It's fair to say that we would all happily do without.
Ventilators are life-saving breathing devices that are essential in some situations; but ventilator-associated pneumonia (VAP)? It’s fair to say that we would all happily do without.
On the positive side, researchers have been rather busy studying ways to learn more about VAP and how to detect it as soon as possible. At the CHEST 2015 meeting in Montréal, Canada, Richard Wunderink, MD, from Northwestern University in Illinois, spoke on one of the most important aspects of the illness — prevention.
One of the key components of VAP prevention is elevating the head in the hospital bed. According to Wunderink, research has pinpointed 30 degrees as being sufficient but it may go up to 45 degrees, which is easily done with newer hospital beds. Besides this one act of prevention, there are many studies that have analyzed ways to prevent VAP with the ventilator equipment.
A report in the Annals of Internal Medicine indicated that the main thing to focus on is the tracheal tube itself. For example, putting a second port to aspirate the secretions out may decrease the occurrence of pneumonia.
Continuous aspiration of subglottic secretions (CASS) is one technique that has gotten its fair share of spotlight. Many studies that have been done have shown a fairly consistent pattern — CASS helps decrease VAP in early cases. However, Wunderink pointed out that there have been “very inconsistent” lengths of hospital stay in these studies and there is no change in mortality. Although it helps keep the infection rate down, CASS comes with its own problem. When it fails in terms of respiratory airway care, it can actually increase the risk of pneumonia – but this was only observed in patients who were are not on antibiotics. There was also a minimal effect on multidrug-resistant (MDR) pathogens, and again, it only prevented early VAP.
Cuff pressure in endotracheal tubes is another factor that can influence VAP instances. Low cuff pressure is associated with an increased risk of pneumonia, and in a high volume/low pressure cuff situation it’s important to remember that “if it’s only partially inflated, you have these areas around it that can leak,” Wunderink explained. Even when fully inflated there can be indentations, and the thought is that indentations can promote colonization, and thus, leading to infections.
Continuous control of tracheal cuff pressure could also contribute to VAP risk. The device is only made and commercially available by two or three companies, at least one in the United States and one in Europe. It monitors the tracheal tube and automatically runs when needed. Wunderink warned that some companies give off the impression that their technology does this, but really it only monitors the pressure. This strategy isn’t practiced everywhere, but a study found that it significantly reduced pneumonia occurrences which were confirmed by culture tests.
Research has looked at polyurethane cuffs versus polyvinyl cuffs. In one analysis which gather information from multiple intensive care units (ICU), there were not statistical significance from hospital to hospital. However, viewing it all together showed that polyurethane was connected with a decrease in VAP instance rates.
The size of the endotracheal tube played a role in bronchoalveolar lavage (BAL) amylase levels, which helps predict the risk of VAP. There appeared to be no difference in women, however, the BAL amylase levels were a lot higher when using a 7.5 instead of an 8 in men. Findings such as these could help physicians make more beneficial decisions regarding their patients.
While there are a lot of factors to take into consideration, effectively carrying out certain practices can result in lower VAP instances. With 27% of critically ill patients becoming infected with VAP, prevention is key.