Jan 192015

Subglottic suctioning can prevent ventilator-associated pneumonia (VAP), but much of the research showing its benefits was performed prior to wide adoption of the so-called "VAP bundle," widely believed to reduce VAP incidence. This led some to question any additive benefits of subglottic suctioning. Authors of a new randomized trial found that subglottic suctioning also reduced ventilator-associated pneumonia incidence in a hospital in which VAP bundles had been used on all patients.

Endotracheal tubes are available with integrated suction lines running along their edges, with fenestrations below the level of the vocal cords, and just above the endotracheal tube cuff. Attaching the line to wall suction or a syringe can remove contaminated oral secretions pooling above the tube cuff, before they are aspirated by the patient.


Endotracheal tube with subglottic suctioning catheter (Armstrong Medical)


The use of subglottic suctioning has risen with the demonstration in several randomized trials that subglottic suctioning reduces the incidence of ventilator associated pneumonia, and may also reduce ventilator days and length of stay.

However, much of the research supporting subglottic suctioning predates the wide implementation and acceptance of the VAP bundle. Also, subglottic suctioning systems are significantly more expensive than ordinary endotracheal tubes. These factors, combined with the supposedly negligible number of VAP cases in the U.S., have limited adoption of subglottic suctioning, which is not a part of the standard “VAP bundle” used for prevention of ventilator associated pneumonia in virtually all modern ICUs.

An aside: Ever since the U.S. Centers for Medicare and Medicaid (CMS) signaled Medicare would eventually stop paying for the medical care costs from ventilator associated pneumonia (a theoretically preventable condition), it’s been harder and harder to find anyone in the U.S. with VAP. Reported VAP rates have fallen to 1-3 / 1,000 ventilator-days in the U.S., but some believe diagnoses of nonspecific infections or "ventilator-associated tracheobronchitis" have taken their place.

It’s hard to do research on ventilator-associated pneumonia when health systems have a financial stake in pretending it doesn’t exist. If rates are near zero, any new intervention is virtually guaranteed not to seem beneficial. Partly in response to this trend, the U.S. Centers for Disease Control and Prevention (CDC) have stopped surveilling for ventilator-associated pneumonia, in favor of the more inclusive "ventilator-associated events".

In Europe, where financial penalties are not attached to the VAP diagnosis (and where the same VAP bundles are used for prevention as in the U.S.), VAP rates are a more realistic ~15 per 1,000 ventilator-days — still room for improvement, and still room to demonstrate benefits of interventions to reduce VAP in clinical trials.

In 5 ICUs at one hospital in Belgium, 352 intubated patients with sublglottic suctioning catheters were randomized to receive regular suctioning, or no suctioning. Subglottic suctioning significantly reduced the incidence of microbiologically confirmed VAP (9% vs. 18%), ventilator days (10 vs. 20), and antibiotic use (a 7% absolute reduction in antibiotic-days, from 69% to 62%). The study was unblinded (subglottic suctioning makes an audible noise).

Endotracheal tubes equipped with ordinary subglottic suctioning lines cost about $18, while more advanced systems that continuously lavage the suction line cost $200 each. This is compared to about $1 for an ordinary endotracheal tube. Cost effectiveness analyses have come out strongly in favor of subglottic suctioning, with about 11 patients needed to treat to prevent one ventilator-associated pneumonia.

One suggested way to intelligently reduce the cost bite while gaining the benefits of subglottic suctioning has been to use endotracheal tubes equipped with subglottic suctioning only for those patients likely to require intubation >48-72 hours (i.e., not using them in most surgery patients).

In the new era of "eradication" of VAP in the U.S. (as reported to payers and quality organizations, at least), adding subglottic suctioning or other preventive measures are unlikely to show a significant reduction in VAPs. But that doesn't mean they're not helping.

Read more:

Damas P et al. Prevention of Ventilator-Associated Pneumonia and Ventilator-Associated Conditions: A Randomized Controlled Trial With Subglottic Secretion Suctioning. Crit Care Med. 2015 Jan;43(1):22-30.

Winters BD, Berenholtz SM. Making Health Care Safer II: An Updated Critical Analysis of the Evidence for Patient Safety Practices. Chapter 11: Ventilator-Associated Pneumonia: Brief Update Review.

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Subglottic suctioning prevents ventilator-associated pneumonia