Ventilator Associated Pneumonia (VAP) puts a drain on the medical community as discussed in my post earlier, “RT’s Zap Vap.” Endotracheal intubation is the primary cause for VAP. But to understand how to combat it, we first must look at the process.
As the endotracheal tube breaches airway defenses, it creates a direct path between the oral cavity and the lungs while also providing a surface for biofilm to form. The endotracheal tube impairs the cough reflex and compromises mucociliary clearance. It also facilitates the micro-aspiration of bacteria-laden secretions pooling above the inflated endotracheal tube cuff. Prolonged exposure to the hospital environment usually changes a patient’s normal respiratory flora, allowing new bacteria to cohabitate with the normal flora which is aspirated from the oral cavity to the cuffed balloon of the endotracheal tube ultimately leading to tracheobronchial colonization and VAP.
Early endotracheal and tracheostomy tubes used high-pressure cuffs, in which the design of these tubes unfortunately allowed secretions to pool below the vocal cords and above the cuff. High-volume low-pressure endotracheal tubes were then introduced with a cuff that was 2 times the diameter of the average trachea when fully inflated. This caused the cuff to fold over in places causing a channel that would accumulate secretions. Both tubes ultimately led to the secretions leaking into the lungs, thus increasing the risk of VAP.
The Subglottic Suction Endotracheal tube
In order to decrease this, a new endotracheal tube, the subglottic suction tube, was introduced. These tubes have a small hole at the rear of the tube and above the cuff. A channel runs through the endotracheal tube and is connected to a suction port, allowing easy removal of pooled secretions above the cuff. It can be attached to an intermittent suction canister or removed manually with a syringe. This in turn decreases bacteria accumulation which can lead to VAP. Over the years, the use of the subglottic tube has increased as evidence has shown effectiveness in preventing VAP.
Benefits of Subglottic Secretion Drainage
- Suctioning pooled secretions above the cuff prior to entering the lungs
- Preventing infectious material from entering the lungs
- Decreasing the need for more invasive procedures to remove fluid in the lungs
- Reduces days on antibiotics
- Reduces costs by reducing complications from VAP
- Subglottic tubes are effective in reducing VAP by allowing easy secretion management despite not reducing mechanical ventilation days and ICU length of stay.
- These endotracheal tubes are not widely implemented in the ICU due to cost, controversy of tracheal mucosal injury, the variability of subglottic secretions, and limited studies.
- Review RT’s Zap VAP for more tips in reducing VAP.
Gentile, J., & Fendler, H. (2016). Advances in Subglottic Secretion Drainage. Academia.edu. Respiratory Therapy – The Journal of Pulmonary Technique. https://www.academia.edu/34948333/Advances_in_Subglottic_Secetion_Drainage.
Lacherade, J.-C., Azais, M.-A., Pouplet, C., & Colin, G. (2018, November 2). Subglottic Secretions Drainage for Ventilator-Associated Pneumonia prevention: am Underused Efficient Measure. Annals of Translation Medicine. https://atm.amegroups.com/article/view/22181/html.