Pulmonary aspiration

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Pulmonary aspiration
Upper gastrointestinal series at the level of the esophagus, showing pulmonary aspiration of the radiocontrast agent
SpecialtyPulmonology
CausesForeign body aspiration

Pulmonary aspiration is the entry of material such as

positive pressure ventilation
. When pulmonary aspiration occurs during eating and drinking, the aspirated material is often colloquially referred to as "going down the wrong pipe".

Consequences of pulmonary aspiration range from no injury at all, to chemical pneumonitis or pneumonia, to death within minutes from asphyxiation. These consequences depend on the volume, chemical composition, particle size, and presence of infectious agents in the aspirated material, and on the underlying health status of the person.

In healthy people, aspiration of small quantities of material is common and rarely results in disease or injury. People with significant underlying disease or injury are at greater risk for developing respiratory complications following pulmonary aspiration, especially hospitalized patients, because of certain factors such as depressed level of consciousness and impaired airway defenses (

left
, so aspirated material is more likely to end up in this bronchus or one of its subsequent bifurcations.

About 3.6 million cases of pulmonary aspiration or foreign body in the airway occurred in 2013.[1]

Presentation

Consequences

Aspiration pneumonia

Particle-related

Pulmonary aspiration of particulate matter may result in acute airway obstruction which may rapidly lead to death from arterial hypoxemia.[2]

Acid-related

Pulmonary aspiration of acidic material (such as stomach acid) may produce an immediate primary injury caused by the chemical reaction of acid with lung parenchyma, and a later secondary injury as a result of the subsequent inflammatory response.[2]

Bacterial

Pulmonary aspiration may be followed by bacterial pneumonia. Community-acquired aspiration pneumonia is usually caused by anaerobic bacteria, whereas hospital-acquired aspiration pneumonia is more often caused by mixed flora, including both aerobic and anaerobic bacteria.[2]

Death

Histopathology of aspiration, taken from an autopsy, showing plant-like cells in a bronchiole. However, alveoli were clear, indicating a finding secondary to cardiopulmonary resuscitation rather than a primary cause of death.

Pulmonary aspiration resulting in pneumonia, in some patients, particularly those with physical limitations, can be fatal.

Risk factors

trachea, bronchi, and lung
)

Risk factors for pulmonary aspiration include conditions which depress the level of consciousness (such as

lower esophageal sphincter tone, gastroesophageal reflux, full stomach, as well as obesity, stroke, and pregnancy can all increase the risk of aspiration in the semiconscious.[4] Tracheal intubation or presence of a gastric tube (for example, a feeding tube) may also increase the risk.[5]

Prevention

The lungs are normally protected against aspiration by a series of protective reflexes such as

intensive care, sitting patients up reduces the risk of pulmonary aspiration and ventilator-associated pneumonia
.

Measures to prevent aspiration depend on the situation and the patient. In patients at imminent risk of aspiration,

vomitus produced by the patient will drain out their mouth instead of back down their pharynx. Some anesthetists will use sodium citrate to neutralize the stomach's low pH and metoclopramide or domperidone
(pro-kinetic agents) to empty the stomach. In veterinary settings, emetics may be used to empty the stomach prior to sedation. Due to growing issues with patients not complying with fasting recommendations before surgery, some hospitals will now also routinely administer emetics prior to anesthesia. Newer operating rooms are often equipped with dedicated vomitoria for this purpose.

People with chronic neurological disorders, for example, after a stroke, are less likely to aspirate thickened fluids on an instrumental swallowing assessment. However, this does not necessarily translate into reduced risk of pneumonia in real life eating and drinking.[6] Also, pharyngeal residue is more common with very thickened fluids: this may subsequently be aspirated and lead to a more severe pneumonia.[7]

The location of

lingula
.

Management

See also:

Advanced Cardiovascular Life Support

Treatment of foreign body aspiration is determined by the age of the patient and the severity of obstruction of the airway involved.[8]

Basic management

An airway obstruction can be partial or complete. In partial obstruction, the patient can usually clear the foreign body with coughing.[8] In complete obstruction, acute intervention is required to remove the foreign body.[8]

If foreign body aspiration is suspected, finger sweeping in the mouth is not recommended due to the increased risk of displacing the foreign object further into the airway.[8]

For choking children less than 1 year of age, the child should be placed face down over the rescuer's arm.

Heimlich maneuver should be used in choking patients older than 1 year of age to dislodge a foreign body.[8] If the patient becomes unresponsive during physical intervention, cardiopulmonary resuscitation (CPR) should be started.[8]

Advanced management

In the event that the basic measures do not remove the foreign body, and adequate ventilation cannot be restored, need for treatment by trained personnel becomes necessary.[8] Laryngoscopy should be performed in unresponsive patients if non-invasive airway clearance techniques are unsuccessful.[9] Laryngoscopy involves placing a device in the mouth to visualize the back of the airway.[9] If the foreign body can be seen, it can be removed with forceps.[9] An endotracheal tube should then be placed in order to prevent airway compromise from resulting inflammation after the procedure.[9] If the foreign body cannot be visualized, intubation, tracheotomy, or needle cricothyrotomy can be done to restore an airway for patients who have become unresponsive due to airway compromise.[8]

If non-invasive measures do not dislodge the foreign body, and the patient can maintain adequate ventilation,

flexible bronchoscope is used, rigid bronchoscope is typically on standby and readily available as this is the preferred approach for removal.[10] Rigid bronchoscopy allows good airway control, ready bleeding management, better visualization, and ability to manipulate the aspirated object with a variety of forceps.[10] Flexible bronchoscopy may be used for extraction when distal access is needed and the operator is experienced in this technique.[10] Potential advantages include avoidance of general anesthesia as well as the ability to reach subsegmental bronchi which are smaller in diameter and further down the respiratory tract than the main bronchi.[10] The main disadvantage of using a flexible scope is the risk of further dislodging the object and causing airway compromise.[10] Bronchoscopy is successful in removing the foreign body in approximately 95% of cases with a complication rate of only 1%.[10]

After the foreign body is removed, patients should receive nebulized beta-adrenergic medication and

epinephrine, or helium oxygen therapy may be considered as part of the management plan.[10]

Patients who are clinically stable with no need for supplemental oxygen after extraction may be discharged from the hospital the same day as the procedure.[11] Routine imaging such as a follow-up chest x-ray are not needed unless symptoms persist or worsen, or if the patient had imaging abnormalities previously to verify return to normal.[11] Most children are discharged within 24 hours of the procedure.[12]


See also

References

  1. PMID 26063472
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  6. ^ O'Keeffe ST. (July 2018). Use of modified diets to prevent aspiration in oropharyngeal dysphagia: is current practice justified? BMC Geriatrics. 2018;18:167 https://doi.org/10.1186/s12877-018-0839-7
  7. ^ Robbins J, Gensler G, Hind J, Logemann JA, Lindblad AS, Brandt D, et al. Comparison of 2 interventions for fluid aspiration on pneumonia incidence: a randomised trial. Ann Intern Med. 2008;148:509–18.
  8. ^ a b c d e f g h i j k l m n Cite error: The named reference :0 was invoked but never defined (see the help page).
  9. ^ a b c d e f Cite error: The named reference :1 was invoked but never defined (see the help page).
  10. ^ a b c d e f g h i j k l m Sheperd, Wes (2019). Airway foreign bodies in adults. In: UpToDate, Post, TW (Ed), UpToDate, Waltham, MA.
  11. ^ a b Cite error: The named reference :8 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference :6 was invoked but never defined (see the help page).

Further reading

External links