Monday, September 11, 2006

Silent Aspiration

If you ever want to induce paranoia in a speech pathologist who treats swallowing disorders, mention the term "silent aspiration." It is generally regarded as an ever-present possibility with potentially disasterous consequences if not immediately recognized and treated appropriately.

So what is it? Silent aspiration is variously defined as aspiration without any signs or symptoms whatsoever, aspiration without a cough, or aspiration without an immediate cough. I have seen some doctors use the term referring to aspiration of small amounts of refluxed gastric contents without obvious symptoms. I tend to avoid using the term because it can be so unclear. What if a patient aspirates but doesn't cough until several minutes later? Is it still silent aspiration? Even though the aspiration did eventually trigger a cough? What about a patient who only clears his or her throat in response to aspiration? Or who has a change in vocal quality, but no cough? Is that "silent"? In the interest of clarity, I tend to just describe a patient's response to aspiration -- or lack thereof.

My thoughts on silent aspiration:

The possibility of silent aspiration is often given as one reason (among many) for performing an instrumental assessment -- usually a videofluroscopic swallowing study (VFSS) -- in every patient in whom pharyngeal dysphagia is suspected, or in some cases even a remote possibility. I don't do this. In many cases I think it's overkill and a waste of resources that won't yield any additional information beyond what was already obtained during the bedside (clinical) swallowing evaluation. Now, I certainly do request videos at times, and in some cases I may even insist on them; but I do not routinely perform them on every case of pharyngeal dysphagia that comes down the pike.

And why not? Well, aside from the fact that a VFSS does NOT show what happens when a patient is eating a meal, I don't believe that silent aspiration is nearly as common as is often supposed. Although some studies have put the number as high as 60%, I have several reservations: (1) What quantity was being aspirated? Just because a patient doesn't cough with trace aspiration to just below the vocal cords doesn't mean that they won't cough if a larger amount is aspirated; (2) How long after the aspiration was the patient observed for cough or other symptoms?; and (3) What were the patients' diagnoses? Some disorders are more likely to produce impaired sensation that can lead to "silent" aspiration. Was sensation tested during the bedside eval before the video?

In addition, there is no indication that all "silent aspiration" is clinically significant, especially in smaller quantities. Patients who do not cough with aspiration are somewhat more likely to develop pneumonia, but there's still not a one to one relationship between the aspiration and the pneumonia.

And finally, even though a patient may not cough or have other obvious symptoms, this does not mean that it is impossible to determine clinically that a patient is at increased risk for aspiration. People do not just up and aspirate for no reason. Something has to go wrong with the swallow, whether it is decreased coordination, poor hyolaryngeal movement, poor airway protection, and so on -- all of which can be detected clinically. I have never had a patient in whom I had no suspicion of aspiration at bedside aspirate significantly on VFSS (now, granted, I am less likely to request videos on these patients, but I do on occasion, and sometimes a doctor will insist on one.) So, while I recognize that the absence of overt signs of aspiration is a very real possibility, by paying attention to the entire clinical picture, I can keep it from being a surprising occurence.


Blogger Jamie said...

My father was in a horrific motorcycle accident and had to be intubated, then later a trach was done. He had sputum coming out of the trach quite a bit and it was what you would expect the sputum to look like. One day before his final surgery he had dark brown sucreations (excuse my spelling)coming from the area around the trach then from his mouth. The CNL told me he had aspirated. She said they would tell the doctors and stop the PEG tube feedings, but I don't know if they ever did. Two days later he died. The chest x-ray was completly white with a few ribs on the left visible. He did cough alot, but the RNs always said it was because of the sputum coming up. I did not see him the day before he died so I don't know if there was alot of coughing for sure, but does this sound anything like what you are describing in your article?

1:56 PM  
Blogger Amanda said...

I have a one year old son who had to have the VFSS done today, and unfortunately, silent aspiration was the answer. My son has been through a lot in his short life (meningitis, hydrocephalus, strokes, seizures, and most recently he had to have a tracheostomy.) Now, I have been feeding my son by mouth for a little over a month now. Things were slow at first (and I'm ALWAYS careful!!!!) and he has even been able to take a whole ounce of formula by mouth! Can a whole ounce go into his lungs without anything happening? They only tried half an ML twice... I know when he is uncomfortable, he gets upset (which happens when they try to prop his head straight, which they did) Could that cause aspiration? idk....

12:36 PM  
Anonymous Anonymous said...

I have an 18-month old daughter with "silent aspiration". We have done about 5 swallow studies which slways show aspirating of a trace of thin liquids. Solids and nectar consistencies are safe for her. Thickening her liquids is a pain, especially since the Simply Thick scare. What are the risks of long term trace silent aspiration? Her diapers seem to be wetter when I'm diligent about nectar consistencies. Could the aspiration cause dehydration? Any insight you have would be great!

11:24 PM  
Anonymous Anonymous said...

My father is very weak right now, in the hospital with a horrible kidney infection, and they won't let him have water. He is chewing out all the nurses and calling them names, he wants water! The said that a speech therapist tested him, he can not talk, and can aspirate. Well he sure call the nurses names and yell for water. But the therapists caught his as he was half asleep, and had horrible dry mouth. My dad wants water but can't have it, don't know what to do.

2:08 PM  
Anonymous Anonymous said...

Ice chips! Insist on them even if AMA. Your Dad should live as if he is alive- not live afraid of dying.

10:42 AM  
Anonymous Anonymous said...

Jamie: Silent aspiration is very common (over half) with people who have been intubated over 2 weeks. Most of the time after the tube has been removed the vocal cords are very swollen which makes it hard for them to close and protect the airway. He more than likely did have aspiration pneumonia.
Amanda: Yes, a whole oz. could go into his lungs and could cause aspiration pneumonia.
To the mother/father of the 18-month old: Aspiration does not cause dehydration nor do thickened liquids. As long as you give her enough fluids ( thickened or thin) she will not dehydrate . As long as she has wet diapers and her skin rebounds she is not dehydrated. Aspiration pneumonia occurs with 35-45% of individuals with aspiration.
To the individual with the father in the hospital, I hope all is well now. Ice chips are fine to give him AS LONG AS EXCELLENT ORAL CARE HAS BEEN PROVIDED IMMEDIATELY PRIOR. The though behind this is that if your father gets some water into his lungs with a clean mouth, his body will absorb it and no pneumonia will occur.

Hope this helps all!

7:16 PM  
Anonymous Anonymous said...

i have a client whpo had a stroke 3 years ago he is bed bound now for 8 months he eats baby food well with a little baby cereal included in it and his juice has thick it in it but he does have a lot of secreations in his throat I suction it when possible and he has a strong cough.he has some coughing in the day time about an hour after eating and his wife states he has a lot of coughing at night hardly anything comes out at suction do you think this is silent aspiration please tell me what I can do to help this

9:00 AM  
Blogger MichelleB. said...

my name is michelle b. I have a husband that had a stroke in 2009. I am his sole caregiver and I am 20 years his junior. silent aspiration sends the speech therapist into a tailspin. like with all of you, he was denied water and he cried. I gave him ice chips. that want everything to have a pudding like thickness. he has lost so much weight because he can't eat pureed or mechanical chopped. there is always the possibility that we can aspirate, but what is the quality of life going to be. they even wanted to put a peg in, I think not. we all love our loved ones and we don't want to see thing suffer, but we cannot live on what ifs.

12:01 PM  
Blogger MichelleB. said...


12:04 PM  
Blogger lori hibberd said...

My dad is in a similar situation and has a right to choose. I would not see him suffer like that. they tell me my dad can have water and not get pneumonia if his mouth is very clean. His lungs with absorb it.

5:21 AM  
Blogger crack'n fresh eggs said...

my husband has a peg and I am giving him canned nutrition.He is not to have food by mouth because he is a slient aspirater. It has only been since he had a stroke April 15th 2015. with speech therapy and different doc., maybe he will be able to eat again or not. Is there anything I can do to help him. He is strong healthy except for this and I am sad for him not to be able to eat, he is doing all his excercies.

3:30 PM  
Anonymous Anonymous said...

Hello, I'm 17 years of age. I have a son which is 5 weeks old and was in hospital for his whole life. We only came out today finally! My son has to be tube fed. He has had a bad chest infection ( most probbaly) 3 days after he was born however the doctors didn't know his got silent aspiration. The think his also has a autonomic disfunction (sorry for the spelling) I just want to ask 1)if his got autonomic disfunction does that mean he will never recover? 2) how often do people recover from silent aspiration? 3)how can we help him or support him?

12:23 PM  
Blogger hcgdietmarket said...

I was diagnosed with silent aspiration, and the speech pathologist told me to research what has caused this, along with swallow therapy. The therapist and my primary care physician don't think it is important to research what caused it. I'm at a loss on who to listen too.

4:39 PM  

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