Aspiration Pneumonia

[cfdavid]

How big of a concern is this in anesthesiology? Isn't atropine given upon intubation, to block oral parasympathetic activity? Obviously, there are more practical and immediate reasons to not have someone aspirate their saliva during ventilation.... But, are there other risk factors that you may look for (i.e. obesity etc.), that may make aspiration in general more likely?(aside from immunocompromised patients, in which case they're at risk for pretty much everything..)??

Also, after emergence, do you listen to the lungs to determine if any aspiration may have taken place? If so, do you treat for oral anaerobes prophylactically???

Thanks,

cf

p.s. cleary, we're in Micro right now....lol

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[Idiopathic]

Aspiration pneumonia is not a huge problem in terms of absolute risk, but aspiration is a potentially devastating and preventable cause of morbidity.

Obvious risk factors would seem to be obesity, recent meal/beverage, diabetes, etc. and we usually induce and intubate these people rapidly, without excessive mask ventilation so as not to introduce any air into their stomach.

The main worry is not oral secretions, but aspiration of gastric contents.

You likely wont be able to hear aspiration immediately afterwards, and pneumonia likely wont show up on CXR for 48 hours, although a massive aspiration may. In that case you should cover the patient for gut bugs.

 

[cfdavid]

Aspiration pneumonia is not a huge problem in terms of absolute risk, but aspiration is a potentially devastating and preventable cause of morbidity.

Obvious risk factors would seem to be obesity, recent meal/beverage, diabetes, etc. and we usually induce and intubate these people rapidly, without excessive mask ventilation so as not to introduce any air into their stomach.

The main worry is not oral secretions, but aspiration of gastric contents.

You likely wont be able to hear aspiration immediately afterwards, and pneumonia likely wont show up on CXR for 48 hours, although a massive aspiration may. In that case you should cover the patient for gut bugs.

Interestingly enough, I'm watching a lecture on treating hospital acquired aspiration pneumonia right now. The ID Pharm guy just stated that in hospital acquired aspiration (perhaps more common on long term ventilation in the ICU than short surgical procedures), what happens is that oral anaerobes are not a concern since there's a turn over of commensals in the mouth over time in the hospital. He said, you must consider Gram negatives such as E. coli, Klebsiella, Pseudomonas, and even Staph aureus.....
Is this what you're refering to as "gut" bugs? (i.e. E.coli and Klebsiella etc.)

However, he also made the point that GENERALLY the stomach is sterile (aside from perhaps H. pylori and patients on proton blockers). So, it still seems most logical that oral anaerobes would be the concern in low risk (hence short stay, if at all) surgical procedures.

That being said, I may be overanalyzing this........

 

[bubalus]

1: Anesthesiology. 1993 Jan;78(1):56-62.

Clinical significance of pulmonary aspiration during the perioperative period.

Warner MA, Warner ME, Weber JG.
Mayo Medical School, Department of Anesthesiology, Rochester, Minnesota 55905.

BACKGROUND: Pulmonary aspiration of gastric contents during the perioperative period may be associated with postoperative mortality or pulmonary morbidity. Recent determination of the incidence of perioperative pulmonary aspiration and evaluation of factors related to clinical outcomes is lacking. METHODS: We retrospectively reviewed the perioperative courses of 172,334 consecutive patients 18 yr of age or older who underwent 215,488 general anesthetics for procedures performed in all surgical specialties from July 1985 to June 1991. Pulmonary aspiration was defined as either the presence of bilious secretions or particulate matter in the tracheobronchial tree or, in patients who did not have their tracheobronchial airways directly examined after regurgitation, the presence of an infiltrate on postoperative chest roentgenogram that was not identified by preoperative roentgenogram or physical examination. RESULTS: Pulmonary aspiration occurred in 67 patients (1:3,216 anesthetics). Fifteen aspirations occurred in 13,427 (1:895) anesthetics of patients undergoing emergency surgery, and 52 occurred in 202,061 (1:3,886) anesthetics of patients undergoing elective surgery (P < .001). Of the 66 patients who survived their surgery, 42 (64%) did not develop a cough or wheeze, a decrease in arterial hemoglobin oxygen saturation while breathing room air > 10% less than the preoperative value, or radiographic abnormalities within 2 h of aspiration. These 42 patients had no respiratory sequelae. Of the 24 patients who had one or more of these findings, 13 required mechanical ventilatory support for more than 6 h. Three of the six patients whose lungs required mechanical ventilation for more than 24 h died from pulmonary insufficiency (overall mortality = 1:71,829 anesthetics). CONCLUSIONS: This study suggests that patients with clinically apparent aspiration who do not develop symptoms within 2 h are unlikely to have respiratory sequelae.

 

[proman]

I think you have to separate the 2 populations (and I've never heard of "hospital acquired aspiration pneumonia"). There is community acquired pneumonia, hospital acquired pneumonia, healthcare-associated pneumonia, and ventilator acquired pneumonia.

Patients aspirate oral secretions when they have inadequate airway reflexes. The mouth anaerobes are definitely included. That's why clindamycin is the first line drug for suspected aspiration pneumonia (the demented stroke patient or the drunk).

Aspiration of gastric contents related to anesthesia is how Idiopathic described. It's more of a chemical pneumonitis than a true pneumonia, and I think that the pH of the gastric contents is more important than lack of sterility.

This PharmD guy you've quoted says some suspect things.

 

[W222]

This PharmD guy you've quoted says some suspect things.

Agreed. Pseudomonas pneumonia is typically ventilator associated and Staph pneumo is hospital acquired. Klebsiella comes up as that classic board question: "A 50yo alcoholic comes into the emergency room in respiratory distress, with a high fever, and is coughing up 'currant jelly' sputum; what is the causative organism?"

Also, a major issue with anyone who has been on a ventilator for any period of time is that this is such a profound change in the normal physiology. You have changes in the amount/viscosity of secretions, changes in normal clearance mechanisms, and atelectasis; all of which, alone or in combination, predisoposes someone to infection without even throwing aspiration into the mix.

 

[jetproppilot]

1: Anesthesiology. 1993 Jan;78(1):56-62.

Clinical significance of pulmonary aspiration during the perioperative period.

Warner MA, Warner ME, Weber JG.
Mayo Medical School, Department of Anesthesiology, Rochester, Minnesota 55905.

BACKGROUND: Pulmonary aspiration of gastric contents during the perioperative period may be associated with postoperative mortality or pulmonary morbidity. Recent determination of the incidence of perioperative pulmonary aspiration and evaluation of factors related to clinical outcomes is lacking. METHODS: We retrospectively reviewed the perioperative courses of 172,334 consecutive patients 18 yr of age or older who underwent 215,488 general anesthetics for procedures performed in all surgical specialties from July 1985 to June 1991. Pulmonary aspiration was defined as either the presence of bilious secretions or particulate matter in the tracheobronchial tree or, in patients who did not have their tracheobronchial airways directly examined after regurgitation, the presence of an infiltrate on postoperative chest roentgenogram that was not identified by preoperative roentgenogram or physical examination. RESULTS: Pulmonary aspiration occurred in 67 patients (1:3,216 anesthetics). Fifteen aspirations occurred in 13,427 (1:895) anesthetics of patients undergoing emergency surgery, and 52 occurred in 202,061 (1:3,886) anesthetics of patients undergoing elective surgery (P < .001). Of the 66 patients who survived their surgery, 42 (64%) did not develop a cough or wheeze, a decrease in arterial hemoglobin oxygen saturation while breathing room air > 10% less than the preoperative value, or radiographic abnormalities within 2 h of aspiration. These 42 patients had no respiratory sequelae. Of the 24 patients who had one or more of these findings, 13 required mechanical ventilatory support for more than 6 h. Three of the six patients whose lungs required mechanical ventilation for more than 24 h died from pulmonary insufficiency (overall mortality = 1:71,829 anesthetics). CONCLUSIONS: This study suggests that patients with clinically apparent aspiration who do not develop symptoms within 2 h are unlikely to have respiratory sequelae.

This has been my experience as well.

If you arent having seeing something in the immediate post operative period in the PACU it is unlikely aspiration has occurred, or if it occurred it is clinically insignificant

I cant remember the last true aspiration I've seen. It is rare.

When it happens, though, you will know it. Usually the sat will be lower than expected, i.e. patient looks pretty good but Sp02 is in the 80s despite FiO2 .40-1.0 via facemask or nonrebreather, tachypnea, SOB. Pt may have all 3 of these manifestations, or maybe just an unexpected low sat.

If mild, the pt may feel fine, deny SOB or mild SOB, but sats in 80s. I'd say this is the most common presentation of aspiration postoperatively.

If severe you'll see the full gammet....tachypnea, retractions, low sat. But if it is severe you will know it occurred before you get to the PACU.

 

[jetproppilot]

How big of a concern is this in anesthesiology? Isn't atropine given upon intubation, to block oral parasympathetic activity? Obviously, there are more practical and immediate reasons to not have someone aspirate their saliva during ventilation.... But, are there other risk factors that you may look for (i.e. obesity etc.), that may make aspiration in general more likely?(aside from immunocompromised patients, in which case they're at risk for pretty much everything..)??

Also, after emergence, do you listen to the lungs to determine if any aspiration may have taken place? If so, do you treat for oral anaerobes prophylactically???

Thanks,

cf

p.s. cleary, we're in Micro right now....lol

Good questions, CF.

Atropine is not given on intubation routinely. Actually its never given. If an antisialagogue is desired, glycopyrrolate .2 mg IV is what is typically given. And again, it is not routine unless a fiberoptic is anticipated.

Lung sounds are not routinely auscultated after emergence and extubation unless something looks weird after the tube is out. Low sats despite high Fi02 and tachypnea/dyspnea would be better indicators that something is awry pulmonary-wise.

 

[cfdavid]

I think you have to separate the 2 populations (and I've never heard of "hospital acquired aspiration pneumonia"). There is community acquired pneumonia, hospital acquired pneumonia, healthcare-associated pneumonia, and ventilator acquired pneumonia.

Patients aspirate oral secretions when they have inadequate airway reflexes. The mouth anaerobes are definitely included. That's why clindamycin is the first line drug for suspected aspiration pneumonia (the demented stroke patient or the drunk).

Aspiration of gastric contents related to anesthesia is how Idiopathic described. It's more of a chemical pneumonitis than a true pneumonia, and I think that the pH of the gastric contents is more important than lack of sterility.

This PharmD guy you've quoted says some suspect things.

The bold was not disputed by the PharmD, and was presented as such. However, they lumped in anesthesia into a risk factor for aspiration pneumonia (I know this is "textbook" and not real world) in previous lectures, pehaps to make the point that "any" loss of consciousness could cause a person to aspirate oral anaerobes. Gastric contents were not really mentioned. Also, he did differentiate b/t community acquired pneumonia and hospital community acquired pneumonia (pseudomonas and MRSA primarily).

THEN, he went on to describe how hospital stays (presumably prolonged) can cause a change in the normal mouth flora, and away from anaerobes, into aerobes or facultative aerobes (listed in my previous post).

HOWEVER, he did not say what "cause" of loss of consciousness was involved in this type of "hospital acquired (perhaps associated would have been a better word) aspiration pneumonia". (i.e. perhaps someone in a coma or mechanical ventilation would have been a better example)

Regardless, thanks to all that have responded. I now understand that during anesthesia, it's more of a concern of aspirating gastric contents, and not saliva.

 

[Idiopathic]

So one confounding factor is that prolonged intubation is definitely a risk factor for pneumonia, partly due to oropharyngeal secretions draining into the trachea, around the ETT cuff. That is why we try to elevate the head of the bed to 30 degrees in ICU patients, so those secretions drain into the pharynx, rather than pool in the back of the throat, which can lead to the aspiration.

 

[bostonblaz]

we happen do do a lot of ct guided ablation of kindney/lung/liver here and the ir guys have brough it to our attention that over 75% of all pts. induced and intubated have radiographic evidence of aspiration when they are passed through the ct scanner. all of these people have a pre procedure ct from a few days before and then we bring them to the scanner and induce and intubate( all most all of them are rsi with cricoid) and then they pass through the scanner. the rads guys here are collecting data and are going to try to publish the data. also we never have had a problem with any of these pts so my guess that aspiration happens almost everytime a pt is intubed, henece we should only really talk about clinically relevent aspiration. blaz

 

[Idiopathic]

its kind of ridiculous to think that they could tell 'early aspiration' (i.e. one hour?) on CT scan

 

[InductionAgent]

However, he also made the point that GENERALLY the stomach is sterile (aside from perhaps H. pylori and patients on proton blockers). So, it still seems most logical that oral anaerobes would be the concern in low risk (hence short stay, if at all) surgical procedures.

That being said, I may be overanalyzing this........

You can have significant morbidity from the aspiration of sterile acidic gastric contents that still leads to aspiration pneumonitis (inflammation) in the absence of pneumonia (infection). Also, the salivary secretions do contain lysozymes that reduce bacterial load. Some of the worst growth of oral flora occurs in sick, dehydrated, old patients with dry mouths.

That said, it is optimal to reduce the entrance of any bodily secretions into the lungs, which is one of the reasons we use suction prior to intubation and extubation.

 

[urgewrx]

also we never have had a problem with any of these pts so my guess that aspiration happens almost everytime a pt is intubed, henece we should only really talk about clinically relevent aspiration. blaz

Aspiration happens everytime a pt goes to sleep at night. At least that is what I was taught in med school.