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Aspiration

6 min read

References:

  1. Brunner & Suddarth’s Textbook of Medical-Surgical Nursing, 15th Edition, ISBN 978-197-51-6103-3, by Janice L. Hinkle, Kerry H. Cheever, and Kristen J. Overbaugh (Ch. 19, pp. [ebook] 1572–1576)

Aspiration is the inhalation of foreign material into the lungs. It is a serious complication that can cause pneumonia and result in tachycardia, dyspnea, central cyanosis, hypertension, hypotension, and potentially death. It can occur when the protective airway reflexes are decreased or absent due to a variety of factors. Esophageal conditions may also be associated with aspiration pneumonia. These include dysphagia, esophageal strictures, neoplasm or diverticula, tracheoesophageal fistula, and gastroesophageal reflux disease. Studies suggest that aspiration pneumonia accounts for 5% to 15% of CAP. Some aspirates include:

  1. A full stomach contains solid particles of food. If these are aspirated, the problem then becomes one of mechanical blockage of the airways and secondary infection.
  2. During periods of stomach, acidic gastric juice is present, which, if aspirated, can be very destructive to the alveoli and capillaries.
  3. Fecal contamination, such as in cases of intestinal obstruction, increases the likelihood of death, because endotoxins produced by intestinal organisms may be absorbed systemically, or the thick proteinaceous material found in the intestinal contents may obstruct the airway, leading to atelectasis and secondary bacterial invasion.

Risk Factors for Aspiration (AACN, 2019)

  1. Seizure Activity
  2. Brain Injury
  3. Decreased level of consciousness from trauma, drug or alcohol intoxication, excessive sedation, or general anesthesia
  4. Flat body positioning
  5. Stroke
  6. Swallowing disorders
  7. Cardiac arrest

The primary factors responsible for death and complications after aspiration are the volume and character of the aspirated contents.

  • Aspiration pneumonia develops after inhalation of colonized oral or pharyngeal material.
  • The pathologic process involves an acute inflammatory response to bacteria and bacterial products.
  • Most commonly, the causative organisms in community-acquired aspiration pneumonia may include S. aureus, S. pneumoniae, H. influenzae, and Enterobacter species.

Prevention

The risk of aspiration is indirectly related to the level of consciousness of the patient. While small amounts of material from the buccal (oral) cavity is not uncommon, particularly during sleep, disease as a result of aspiration does not occur in healthy people because the material is cleared by the mucociliary tree and the macrophages. Witnessed aspiration of large volumes occurs occasionally; however, small-volume clinically silent aspiration is more common. Prevention is the primary goal when caring for patients at risk for aspiration.

Silent Aspiration via NGT Failure

When a nonfunctioning nasogastric tube allows gastric contents to accumulate in the stomach, silent aspiration may occur. This unobserved aspiration is more common than suspected, and can lead to massive inhalation of gastric contents over a period of several hours.

Compensating for Absent Reflexes

Aspiration may occur if the patient cannot adequately coordinate protective glottic, laryngeal, and cough reflexes. This hazard is increased if the patient has a distended abdomen, is supine, has the upper extremities immobilized in any manner, receives local anesthetic agents to the oropharyngeal or laryngeal area for diagnostic procedures, has been sedated, or has had long-term intubation.

  1. Swallowing screen is done for patients with known swallowing dysfunction or who have recently been extubated following prolonged ET intubation. Those considered at risk are further assessed by a speech therapist.
  2. Positioning to a semirecumbent and upright position prior to eating. A soft diet eaten with small bites further prevent aspiration. Keeping the chin tucked and head turned with repeated swallowing to narrow the airway entrance. It may also help patients with hemiplegia direct food to the stronger side of their pharynx.
  3. Avoid straws when drinking. Drinking through straws make it harder to control liquid that enters the mouth, which may overwhelm the swallowing mechanism.

The American Association of Critical Care Nurses (AACN) published clinical practices that prevent aspiration:

  1. Maintain head-of-bed elevation at an angle of 30 to 45 degrees, unless contraindicated.
  2. Use sedatives as sparingly as possible.
  3. Before initiating enteral tube feeding, confirm the tip location.
  4. For patients receiving tube feedings, assess placement of the feeding tube at 4-hour intervals, assess for gastrointestinal residuals (<150 mL before next feeding) to the feedings at 4-hour intervals.
  5. For patients receiving tube feedings, avoid bolus feedings in those at risk for aspiration.
  6. Consult with primary provider about obtaining a swallowing evaluation before oral feedings are started for patients who were recently extubated but were previously intubated for >2 days.
  7. Maintain endotracheal cuff pressures at an appropriate level, and ensure that secretions are cleared from above the cuff before it is deflated. ET cuff pressures should be maintained at >20 cm H₂O (and <30 cm H₂O to minimize injury) to prevent leakage of secretions from around the cuff into the lower respiratory tract. In addition, hypopharyngeal suctioning is recommended before the cuff is deflated.

Vomiting and the Gag Reflex

When vomiting, people can normally protect their airway by sitting up or turning on he side and coordinating breathing, coughing, gag, and glottic reflexes. If these reflexes are active, an oral airway should not be inserted.

  1. If an airway is in place, it should be pulled out the moment the patient gags so as not to stimulate the pharyngeal gag reflex and promote vomiting and aspiration.
  2. When suctioning oral secretions, there should be minimal pharyngeal stimulation by the catheter.

Assessing Feeding Tube Placement

Tube feedings must be given only when it is certain that the feeding tube is positioned correctly in the stomach. Many patients receive enteral feeding directly into the duodenum through a small-bore flexible feeding tube or surgically implanted tube.

Identifying Delayed Stomach Emptying

Increased intragastric and extragastric pressure on a full stomach can result in aspiration. The following may delay emptying of the stomach:

  1. Intestinal obstruction
  2. Gastroesophageal reflux disease resulting in increased gastric secretions
  3. Anxiety, stress, or pain resulting in increased gastric secretions
  4. Abdominal distention due to paralytic ileus, ascites, peritonitis, the use of opioids or sedatives, severe illness, or vaginal delivery.

Managing Effects of Prolonged Intubation

Prolonged ET intubation or tracheostomy can depress the laryngeal and glottic reflexes because of disuse.

  1. Patients with prolonged tracheostomies are encouraged to phonate and exercise their laryngeal muscles.
  2. After long-term intubation or tracheostomies, it may be helpful to have a speech therapist experienced in swallowing disorders work with the patient to address swallowing problems, as noted previously.

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