Advanced Airway Lavage and Suction: The Latest Evidence

When it comes to lavage and suctioning patients on a ventilator there is a debate brewing. It's not a new debate, as in my 13 years as an RT I've heard both sides, and both sides have convinced me at one point or another. So my quest by researching and writing this post is to determine which side is best to follow.

First we must define lavage and suction. To lavage and suction means to insert normal saline into the endotracheal tube (ETT) and then to suck it up with the suction catheter. The theory here is that the normal saline will loosen up any thick secretions so they can be suctioned out. This is also believed to be a good method of preventing and removing mucus plugs.

So, why was lavage and suctioning started in the first place.  According to a study by Ji and company in 2002, the following is truer: (6)

• The purpose of endotracheal suctioning is to clear secretions from the airway to maintain a patent airway and to optimize ventilation and oxygenation. 
• Instillation of normal saline prior to suction in patients with an artificial airway is a traditional nursing intervention (and no one knows when or why it was started)
• Lacking empirical evidence to support this practice, nurses may arbitrary decide when instillation of saline is appropriate.
• Nurses routinely instill 3-10 ml of normal saline solution into the airway prior to suction to loosen secretions, lubricate the suction catheter and increase secretion clearance due to an enhanced cough stimulation
• Normal saline was believed to mobilize (due to cough) and dilute (due to no theory whatsoever). 
• Research on the benefits of this have been inconclusive (6)

Now for the two theories.

 #1: Lavage and suction is a good thing because not only does it decrease the chance of VAP, it is a great method of preventing mucus plugs. This crowd usually thinks a patient should be lavaged and suctioned at least once a shift.

Interestingly, there truly was no evidence for this argument when it got started.  It was probably another thing we medical care practitioners started simply because it sounded like a good idea.  To spotlight the absurdity of this, consider the following conclusion by researchers to a 1973 study regarding lavage and suctioning: (1)

Demers and Saklad in 1973 reported "water in the form of a vapor or an aerosol is of proven value in thinning secretions and promoting their clearance: mucus and water in bulk form are immiscible and occupy separate phases in vitro, even after vigorous shaking.  Therefore, endotracheal instillation and rapid removal by suctioning is of dubious value.  (1)

 There was nothing in the article that suggested that water thinned secretions; this was something the author simply made up.  There is plenty of evidence that squirting saline into the airway may help clear secretions, but there is nothing to support the claim that it thins secretions.  Such claims are poppycock, and do nothing to advance science in medicine.

However, there is some evidence to support the argument of lavage and suctioning.  A 2009 article in Critical Care Medicine, "Salin instillation before tracheal suctioning decreases the incidence of ventilator-associated pneumonia," was performed "To compare the incidence of ventilator-associated pneumonia (VAP) with or without isotonic saline instillation before tracheal suctioning." (2)

The conclusion: "Instillation of isotonic saline before tracheal suctioning decreases the incidence of microbiological proven VAP."  (emphasis added) (2)

There were other studies that showed that saline instillation increased mucus clearance, although many of these revealed other side effects that were undesirable, such as a 1999 study that revealed suctioning with saline resulted in an increased duration of suctioning by nearly 4 minutes, while a similar study in 2002 showed that this resulted in an "undesirable, although not significant, alteration in oxygen saturation and arterial blood gas levels. Other studies show that it increases dyspnea, or causes a "drowning feeling." (3)

#2: Lavage and suction increases the risk of ventilator acquired pneumonia (VAP), and therefore saline bullets should never be instilled into the patient's airway.  This crowd generally thinks a patient should only be suctioned on an as needed basis. 

So it is true that mucus is bacteria all balled up. The theory here is that if you add normal saline to the mix, and break up that mucus ball with your normal saline and forceful bagging, you are basically causing that bad bacteria to spread throughout the lungs, and this can cause pneumonia. Plus this crowd is concerned that you only suction up a quarter of the fluid you put into the lungs.

Based on this theory you definitely do not want to bag with an Ambu Bag because when you do this you are basically pushing the mucus and bacteria back into the lungs and this too can cause pneumonia. So basically the only kind of suctioning that you should do is inline suctioning (like with a Ballard).

Now for the evidence.  A 2010 article in Advance for Respiratory Care and Sleep Medicine, "Saline Instillation: helpful or harmful," by C. Farnan and M. Patrick noted the following: (3)

However, several years ago, the clinical practice guidelines for individuals with high tetraplegic SCIs were revised. It is no longer recommended to instill saline into an advanced airway because people with tetraplegia have little or no diaphragm innervation and, therefore, are unable to produce a cough reflex. This practice has been compared to "drowning" patients in their own secretions. After further review of the literature, we found saline instillation is not recommended for any adult patient who is mechanically ventilated. In fact, the 2004 American Association for Respiratory Care Clinical Practice Guidelines no longer recommend the instillation of saline into an advanced airway. (3)

Other studies were also noted by Advance, such as: (3)

Hagler and Travers in 1994 examined the colonization of bacteria on 10 endotracheal tubes removed from patients after 48 hours of intubation. They found "the number of bacteria dislodged into the lower airway as a result of inserting a suction catheter increased fivefold with saline instillation compared to that without saline instillation."In 2003, Freytag, et al., also determined instillation of saline disperses bacteria to the lower respiratory tract.More research is needed in this area to determine whether suctioning increases pneumonia rates or ventilator-associated pneumonias. (3)

But, wait!  There is more.  Studies by E. Zhahran in 2011 (4) and M. Halm in 2008 (5) and Yi in 2002 (6), concluded the following:

• Elevation of PaCO2% immediately after suctioning
• SaO2% decreases, and this desaturation worsens over time after suctioning in following 5 minutes
• Increased stimulation of cough reflex was associated with increased MAP, ICP
• Dislodge bacterial colonies in tube, contaminating lower airway  (4)(5)(6)
• Lavage and suctioning results in increased anxiety, dread, pain (5)
• Increased perceived dyspnea in patients greater than 60 that persisted up to 10 minutes after suctioning, related to decrease in pulmonary compliance with aging (5)
• Normal saline and mucous do not mix, even when shaken vigorously together.Therefore, normal saline does not thin or mobilize secretions (5)  (Emphasis added my me)

Okay, now which theory is best?

In a previous version of this post, I gave the old-time respiratory therapists the benefit of the doubt, and recommended the following:

 Personally, without doing any research, I believe that whichever theory you believe in, you should do a good lavage and suction at least once a shift, and if you have a patient in respiratory distress and you suspect thick secretions to be the culprit. It's invasive, so it should only be done on an as needed basis. Some say this is the common sense approach to suctioning.

Today, in view of the latest evidence, I would like to go one step further, and eliminate the recommendation to lavage and suction once per shift.  Or, as noted by Advance:

The majority of evidence in the literature supports a change in practice. Eliminating saline instillation prior to and during suctioning of a patient with mechanical ventilation or a population without diaphragm innervation has the potential for improved outcomes by decreasing risks associated with this practice such as decreased infection. It may also improve patient comfort and satisfaction by eliminating that "drowning" sensation. 

Many studies have shown instillation of saline has negative effects on oxygenation, level of dyspnea, heart rate and blood pressure. Some studies, however, report no significant differences between the two methods (suctioning with or without saline). If the theory that normal saline instillation is beneficial in removing secretion is to be supported, one would expect to see consistent, research-based evidence indicating secretion removal is greater and oxygenation is improved. This is not the case.

It is time to abandon this non-research based practice. Respiratory therapists should focus on alternative measures of preventing dried and tenacious secretions in the patient who is mechanically ventilated. Respiratory therapists may want to recommend mycolytics and improved hydration to assist in secretion management.

Where I work "to lavage and suction or not to lavage and suction" is generally left to the discretion of the on duty respiratory therapist.  Most suctioning is performed by the nurse or respiratory therapist via an inline suction catheter (notably a Ballard).

Generally speaking, if humidification is adequate, there should be no need for ever performing lavage and suctioning.  However, should the endotracheal tube become occluded, then, and only then, should lavage and suctioning be attempted, and this should only be performed by a trained respiratory therapist.  In other words, routine use of lavage and suctioning is not a good idea.

This is my opinion based on the evidence.  What do you think?

Note:  This post was originally published on Respiratory Therapy Cave on 1/13/2010.  This is the edited and updated version with the latest evidence.  If you have any further evidence to add to the discussion, please note so in the comments below, or email me by clicking on the "contact me" icon in the right hand column of this page.  

Related posts:

• Suctioning: How deep do you go
• How to suction a patient with thinning blood

References: 

1. Demers, R.R., & Saklad, M. (1973). Minimizing the harmful effects of mechanical aspiration. Heart & Lung, 2(4), 542-545; 
2. Pedro, Caruso, et al., "Saline instillation before tracheal suctioning decreases the incidence of ventilator-associated pneumonia," Critical Care Medicine, January, 2009, 37 (1) pages 32-38; The article was also referenced to in a Ventworld.com discussion. 
3. Farnan, C., M. Patrick, "Saline Instillation: Helpful or Harmful," Advance for Respiratory Care and Sleep Medicine, (posted 8/9/2010), 
4. Zahran, E.M. and A.A. El-Razik, "Tracheal suctioning with verses without saline instillation," Journal of American Science, 2011, 7 (8), pages 23-32
5. Halm, M.A., K. Krisko-Hagal, "Instilling normal saline with suctioning: beneficial technique or potentially harmful sacred cow," American Journal of Critical Care, 2008, 17, pages 469-472
6. Ji, Y., H. Kim, J. Park, "Instillation of normal saline before suctioning in patients with pneumonia," Yonsei Medical Journal, 2002, 43 (5), pages 607-612